tag:theconversation.com,2011:/ca/topics/mammals-903/articlesMammals – The Conversation2024-03-14T19:25:08Ztag:theconversation.com,2011:article/2195982024-03-14T19:25:08Z2024-03-14T19:25:08ZMeet the kowari: a pint-sized predator on the fast track to extinction<figure><img src="https://images.theconversation.com/files/581179/original/file-20240312-24-tb4sa3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Ariana Ananda</span></span></figcaption></figure><p>Australia is home to <a href="https://www.publish.csiro.au/book/7010/">more than 350 species</a> of native mammals, <a href="https://www.pnas.org/doi/full/10.1073/pnas.1417301112">87% of which are found nowhere else on Earth</a>. But with 39 of these species <a href="https://www.environment.gov.au/cgi-bin/sprat/public/publicthreatenedlist.pl">already extinct</a> and a further <a href="https://www.environment.gov.au/cgi-bin/sprat/public/publicthreatenedlist.pl">110 listed as threatened</a>, there’s every chance many will vanish before you even knew they existed. So here’s one we think you simply must know (and save), before it’s too late. </p>
<p>The charismatic <a href="https://teamkowari.com.au/kowari/">kowari</a> is a small carnivorous marsupial. It was once common inland but is now found only in the remote deserts of southwest Queensland and northeastern South Australia, in less than 20% of its former range. </p>
<p>This pint-sized predator fits in the palm of your hand. Its bright eyes, bushy tail and big personality make it the perfect poster child for the Australian outback. But with just 1,200 kowari left in the wild, the federal government upgraded its conservation status in November from <a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=329">vulnerable to endangered</a>. </p>
<p>Reversing the decline of the kowari is within our grasp. But we need public support and political will to achieve this. It requires limiting grazing of cattle and sheep, while keeping feral cat numbers under control. </p>
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<figcaption><span class="caption">Introducing the kowari (Arid Recovery)</span></figcaption>
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Read more:
<a href="https://theconversation.com/threatened-species-recover-in-fenced-safe-havens-but-their-safety-is-only-temporary-200548">Threatened species recover in fenced safe havens. But their safety is only temporary</a>
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<h2>Meet the kowari</h2>
<p>The <a href="https://teamkowari.com.au/kowari/">kowari</a> (<em>Dasyuroides byrnei</em>) is a skilled hunter that stalks mice, tarantulas, moths, scorpions and even birds. Alert and efficient, they attack their prey voraciously.</p>
<p>Formerly known as the brushy-tailed marsupial rat, or Byrne’s crest-tailed marsupial rat, the kowari is more closely related to Tasmanian Devil and quolls. </p>
<p>The Wangkangurru Yarluyandi People use the name kowari, while the Dieri and Ngameni peoples use the similar-sounding name kariri.</p>
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<a href="https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Closeup of the gibber plain showing areas of flat interlocking red pebbles" src="https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581171/original/file-20240312-18-mlrrfx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The red stony gibber plains could be mistaken for the surface of Mars.</span>
<span class="attribution"><span class="source">Katherine Moseby</span></span>
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<p>Kowaris live in stony deserts. They mainly inhabit remote treeless “gibber” plains. These areas of flat, interlocking red pebbles form vast pavements that could be mistaken for the surface of Mars. </p>
<p>In the outback, where temperatures can exceed 50°C, kowaris beat the heat by sheltering in burrows dug into sand mounds. At night they emerge to race across the plains, their head and distinctive brushy tail held high, pausing regularly to scan for predators and prey. </p>
<p>During chilly winter days, kowaris slow their metabolism to conserve energy. They go into a state of <a href="https://theconversation.com/torpor-a-neat-survival-trick-once-thought-rare-in-australian-animals-is-actually-widespread-146409">torpor</a>, which is a daily version of hibernation. </p>
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Read more:
<a href="https://theconversation.com/torpor-a-neat-survival-trick-once-thought-rare-in-australian-animals-is-actually-widespread-146409">Torpor: a neat survival trick once thought rare in Australian animals is actually widespread</a>
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<p>At the two main South Australian sites, the number of animals captured in trapping surveys declined by <a href="https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/jzo.12605">85% between 2000 and 2015</a>. At this rate, the species could disappear from the area within two decades.</p>
<p>The entire population is estimated to number as few as 1,200 individuals scattered over just 350 square kilometres. That’s a combined area of less than 20km x 20km. </p>
<p>Based on this evidence, the conservation status of kowaris was upgraded from <a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=329">vulnerable to endangered</a> in November last year.</p>
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<a href="https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A kowari standing in the desert facing the camera with its long bushy tail stretched out to the right" src="https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581170/original/file-20240312-18-r54i0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Kowari are now restricted to refuge populations in northeast South Australia and southwest Queensland.</span>
<span class="attribution"><span class="source">Andrea Tschirner</span></span>
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<h2>Shrinking populations in the stony desert</h2>
<p>Kowaris have been declining for a while but are suddenly on the fast track to extinction. How can that be, when they live in one of the most vast and remote parts of Australia? </p>
<p>Threats include land degradation from pastoralism, and predation from introduced feral cats and foxes. </p>
<p>But it’s complicated. Threats can combine, having a synergistic effect (greater than the sum of their parts). And then there are climate influences. </p>
<p>Heavy rain in the desert triggers a cascade of events that culminates in an <a href="https://www.abc.net.au/news/2014-10-10/feral-cats-tear-through-last-wild-bilby-population/5803252">explosion of feral cat numbers</a>. </p>
<p>When conditions dry out again, the cats switch to eating larger or more difficult prey such as bilbies and kowaris, often causing local extinctions. In southwest Queensland, feral cats most likely wiped out one population of kowaris and decimated another. </p>
<p>Huge efforts to control cat plagues have saved the kowari and bilby populations in <a href="https://bioone.org/journals/australian-journal-of-zoology/volume-70/issue-2/ZO22027/Does-reducing-grazing-pressure-or-predation-conserve-kowaris-A-case/10.1071/ZO22027.full">Astrebla Downs National Park</a> from local extinction so far, but other areas have succumbed.</p>
<p>In SA, all the remaining kowari populations are on <a href="https://www.nespthreatenedspecies.edu.au/publications-and-tools/the-kowari-saving-a-central-australian-micro-predator">pastoral stations used for grazing cattle</a>. </p>
<p>Cattle can trample kowari burrows. They can also compact the sand mounds, making it difficult for kowaris to build burrows in the first place. And they eat the plants on the mounds, reducing the availability of both food and shelter. This makes kowaris easy prey. </p>
<p>Over the past few decades, pastoralism has intensified. <a href="https://www.pc.gov.au/research/completed/pastoral-leases#:%7E:text=Pastoral%20leases%20exist%20on%20around,to%20facilitate%20and%20support%20pastoralism.">Nearly half of Australia (44%)</a> is covered in pastoral leases where many threatened species occur. </p>
<p>Domestic stock usually graze close to watering points such as bores and troughs. More and more watering points are being established, to make more of the pastoral lease accessible to stock. So the area protected from grazing is shrinking as cattle encroach further into kowari territory. </p>
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<a href="https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sand mound surrounded by the stony desert gibber plain" src="https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=592&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=592&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581168/original/file-20240312-16-mabhg4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=592&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Kowari burrow in sand mounds that can be trampled and compacted by cattle.</span>
<span class="attribution"><span class="source">Katherine Moseby</span></span>
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<h2>How can we save the kowari?</h2>
<p>We have the knowledge and tools required to save this species from extinction. We just need decisive leadership and sufficient funding to put these plans into action. </p>
<p>State governments should provide more resources for desert parks so rangers can monitor feral cat numbers and respond rapidly to plagues. We can make use of new technology such as remote camera traps checked via satellite. These measures would also protect the last remaining stronghold of the bilby in Queensland, another nationally threatened mammal. </p>
<p>The pastoral industry and governments must work together to review watering-point placement and reduce grazing pressure in known kowari habitat. </p>
<p>By closing some pastoral watering points and ensuring a portion of each lease (possibly 20%) is away from waters, we can reduce the harm of stock and provide refuges for threatened species. Pastoral companies could show leadership and implement these actions themselves rather than waiting for governments to act.</p>
<p>In the meantime, reintroductions into safe havens is one stopgap measure helping to prevent imminent kowari extinction. In 2022, <a href="https://www.facebook.com/watch/?ref=search&v=409398861174893&external_log_id=2222a528-17bb-4f25-b0d5-d45d296c0c73&q=ecological%20horizons">12 kowaris were successfully reintroduced</a> to the 123 square km <a href="https://aridrecovery.org.au/kowari/">fenced Arid Recovery Reserve</a> in northern SA. The population has <a href="https://www.facebook.com/AridRecovery/videos/1165149370645281">expanded since release</a>. Removing cats, foxes and domestic stock from the reserve has given kowaris a chance to reclaim a small portion of their former range. </p>
<p>But safe havens are small and we need to act on a larger scale. If we don’t, the kowari may become yet another Australian species lost before you’ve even seen it.</p>
<p><em>Thanks to Genevieve Hayes, former ecologist at Arid Recovery, for coordinating the reintroduction of the kowari at Arid Recovery and commenting on the draft of this article.</em></p>
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Read more:
<a href="https://theconversation.com/so-you-want-to-cat-proof-a-bettong-how-living-with-predators-could-help-native-species-survive-170450">So you want to cat-proof a bettong: how living with predators could help native species survive</a>
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<p class="fine-print"><em><span>Katherine Moseby is co-founder and chief scientist at Arid Recovery. She receives contract work from Arid Recovery to assist with conservation and restoration works. </span></em></p><p class="fine-print"><em><span>Katherine Tuft is Chief Executive at Arid Recovery which has received grant funding from the federal government and other sources to support research and conservation for the kowari.</span></em></p>Blink and you’ll miss it. The kowari is a charismatic marsupial carnivore that needs our help.Katherine Moseby, Associate Professor, UNSW SydneyKatherine Tuft, Visiting Research Fellow, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2255962024-03-13T15:03:15Z2024-03-13T15:03:15ZIt’s a myth that male animals are usually larger than females – new study<p>Males are bigger than females, right? Generally, this is true of humans – imagine the extremes of Dwayne “The Rock” Johnson and singer Kylie Minogue. It is also true of other familiar mammals including pets, such as cats and dogs, and livestock such as sheep and cows.</p>
<p>But <a href="https://www.nature.com/articles/s41467-024-45739-5">a new study</a> by US scientist Kaia Tombak and colleagues found that, in many mammal species, males are not larger than females. In fact, in a comparison of 429 species in the wild, 50% of species including rodents and some bats – which make up <a href="https://news.mongabay.com/2022/04/of-rats-and-bats-hundreds-of-mammal-species-still-unidentified-study-says/">a large proportion</a> of all mammal species – showed no difference in body size between the sexes. Male-biased size dimorphism (where males are larger than females) was found in only 28% of mammal species.</p>
<p>So, why do a lot of people have a misconception that males are normally larger than females? </p>
<p><a href="https://www.nature.com/scitable/students-page/160/">Anisogamy</a> is the term used to describe the difference in sex cells – small, numerous, sperm, compared to relatively large eggs. Males can produce sperm throughout most of their lifespan, whereas females are born with a finite number of eggs. Therefore, females (or rather, their eggs), are a scare resource for which males compete for access. Generally, in species where females are a limited resource that males need to fight over, males are larger than females.</p>
<p>In terms of evolution, most males have been shaped to be larger, bolder, heavier, more adorned and have more weaponry than females. This is due to males fighting to acquire females – a larger stag with bigger antlers would do much better in a fight, <a href="https://www.discoverwildlife.com/animal-%20facts/mammals/understand-the-british-deer-rut">known as a rut</a>, than a small stag with tiny antlers. So, bigger usually wins.</p>
<p>This includes species such as lions and baboons, where size is an advantage when competing physically for mates. Male northern elephant seals, who fight for access to harems of females, show the largest male-biased size dimorphism, being over 3.2 times heavier than females. These are the animals that tend to attract research</p>
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<h2>The strange world of fish</h2>
<p>But, what happens in species where males don’t fight for access to females? Generally, females are larger than males. This is because larger females usually produce more offspring. Indeed, Tombak’s study noted that larger female rabbits usually have multiple litters each mating season. Being a larger female is much more advantageous in terms of reproductive success. But more so when offspring do not need extended parental care and when gestation periods are short.</p>
<p>The most extreme sexual size dimorphism is found outside of mammals. Cichlid fish (<em>Lamprologus callipterus</em>) males are up to 60 times larger than females. The males protect empty snail shells for the females to breed in. <a href="https://link.springer.com/article/10.1007/s12038-010-0030-6">Larger females</a> can produce more offspring but they need larger shells and therefore a larger male to defend those shells.</p>
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<p>In mammals, the largest female-biased size dimorphism is found in peninsular tube-nosed bats, where females are 1.4 times the size of males. However, more dimorphism in body size is seen in fish, reptiles and insects. For example, the female orb-weaving spider (<em>Nephila plumipes</em>) has a much larger body size than the male, reaching up to ten times his size. Size dimorphism also shows a correlation with cannibalism, where larger females are more likely to eat their male partner.</p>
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<a href="https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large spider and small one in a web" src="https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A female golden orb weaving spider and the smaller male.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-photograph-female-golden-orb-weaving-1692871246">Cassandra Madsen/Shutterstock</a></span>
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<p>Anglerfish that typically live at the bottom of oceans, are an example of extreme sexual dimorphism in body size. While the females look like typical fish, the males are tiny, basic organisms. In order to survive, the male needs to fuse with a female, tapping into her nutrients to produce enough sperm to fertilise her. Female deep-sea anglerfish (<em>Ceratias
holboelli</em>) are <a href="https://www.livescience.com/49330-animal-sex-anglerfish.html">60 times longer</a> and half a million times heavier than males.</p>
<p>But, the most extreme sexual size dimorphism is found in rhizocephala, types of barnacle where the male looks like a larvae. Once a male finds a mate, he <a href="https://www.wired.com/2015/07/absurd-creature-of-the-week-rhizocephalan/">inserts himself into the females</a>, transforming into nothing more than a mass of cells.</p>
<h2>What about mammals?</h2>
<p>So, why isn’t sexual size dimorphism seen in more mammals? Mammals tend to have fewer offspring than other species such as fish or spiders. They only have a few offspring at a time, and often have long gestation periods or extended periods of parental care. In addition, the majority of mammals are monogamous, so there is less need for males to fight over females. That’s why species such as lemurs, golden moles, horses, zebra and tenrecs, usually have similar sized males and females.</p>
<p>It is thought that biases in the scientific literature may have led to the misconception that males are normally bigger as research historically focused on <a href="https://wwf.panda.org/discover/our_focus/wildlife_practice/flagship_keystone_indicator_definition/">species considered “charismatic”</a>, such as primates and carnivores, that attract funding. These are some of the few mammalian species where males compete for mates, and so gain an evolutionary advantage if they are larger. </p>
<p>There was also a bias of <a href="https://www.nationalgeographic.co.uk/science-and-technology/2019/10/once-most-famous-scientists-were-men-thats-changing">male scientists</a> conducting research. And, although a study in 1977 <a href="https://www.journals.uchicago.edu/doi/epdf/10.1086/283223">by a female scientist</a> found that species with little sexual size dimorphism were frequent in mammals, the research was drowned out by studies on charismatic species with a bias towards large males. Perhaps if there had been more female scientists at the time, we might have had a different preconception about body size in the animal kingdom.</p><img src="https://counter.theconversation.com/content/225596/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Gentle works for Nottingham Trent University. </span></em></p>Does size matter? In the animal kingdom, yes.Louise Gentle, Principal Lecturer in Wildlife Conservation, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2223062024-03-11T17:18:48Z2024-03-11T17:18:48ZThe next pandemic? It’s already here for Earth’s wildlife<p>I am a conservation biologist who studies emerging infectious diseases. When people ask me what I think the next pandemic will be I often say that we are in the midst of one – it’s just afflicting a great many species more than ours.</p>
<p>I am referring to the highly pathogenic strain of avian influenza H5N1 (HPAI H5N1), otherwise known as bird flu, which has killed millions of birds and unknown numbers of mammals, particularly during the past three years. </p>
<p>This is the strain that emerged in domestic geese in China in 1997 and quickly jumped to humans in south-east Asia with a mortality rate of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1634780/">around 40-50%</a>. My research group <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1634780/">encountered the virus</a> when it killed a mammal, an endangered <a href="https://svw.vn/owstons-civet/">Owston’s palm civet</a>, in a captive breeding programme in Cuc Phuong National Park Vietnam in 2005.</p>
<p>How these animals caught bird flu was never confirmed. Their diet is mainly earthworms, so they had not been infected by eating diseased poultry like many captive tigers in the region.</p>
<p>This discovery prompted us to collate all confirmed reports of fatal infection with bird flu to assess just how broad a threat to wildlife this virus might pose.</p>
<p>This is how a newly discovered virus in Chinese poultry came to threaten so much of the world’s biodiversity.</p>
<figure class="align-center ">
<img alt="A person in white overalls operates a forklift carrying dead turkeys." src="https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580987/original/file-20240311-22-gzginr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">H5N1 originated on a Chinese poultry farm in 1997.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/western-negev-israel-march-18-2006-111241157">ChameleonsEye/Shutterstock</a></span>
</figcaption>
</figure>
<h2>The first signs</h2>
<p>Until December 2005, most confirmed infections had been found in a few zoos and rescue centres in Thailand and Cambodia. Our analysis in 2006 showed that nearly half (48%) of all the different groups of birds (known to taxonomists as “orders”) contained a species in which a fatal infection of bird flu had been reported. These 13 orders comprised 84% of all bird species. </p>
<p>We reasoned 20 years ago that the strains of H5N1 circulating were probably highly pathogenic to all bird orders. We also showed that the list of confirmed infected species included those that were globally threatened and that important habitats, such as Vietnam’s Mekong delta, lay close to reported poultry outbreaks.</p>
<p>Mammals known to be susceptible to bird flu during the early 2000s included primates, rodents, pigs and rabbits. Large carnivores such as Bengal tigers and clouded leopards were reported to have been killed, as well as domestic cats.</p>
<p>Our 2006 paper showed the ease with which this virus crossed species barriers and suggested it might one day produce a pandemic-scale threat to global biodiversity.</p>
<p>Unfortunately, our warnings were correct.</p>
<h2>A roving sickness</h2>
<p>Two decades on, bird flu is killing species from <a href="https://www.theguardian.com/environment/2024/jan/02/polar-bear-dies-from-bird-flu-age-of-extinction">the high Arctic</a> to <a href="https://www.cidrap.umn.edu/avian-influenza-bird-flu/avian-flu-reaches-antarcticas-mainland">mainland Antarctica</a>.</p>
<p>In the past couple of years, bird flu has spread rapidly across Europe and infiltrated North and South America, killing millions of poultry and a variety of bird and mammal species. <a href="https://wwwnc.cdc.gov/eid/article/30/3/23-1098_article">A recent paper</a> found that 26 countries have reported at least 48 mammal species that have died from the virus since 2020, when the latest increase in reported infections started.</p>
<p>Not even the ocean is safe. Since 2020, 13 species of aquatic mammal have succumbed, including American sea lions, porpoises and dolphins, often dying in their thousands in South America. A wide range of scavenging and predatory mammals that live on land are now also confirmed to be susceptible, including mountain lions, lynx, brown, black and polar bears.</p>
<p>The UK alone has <a href="https://www.rspb.org.uk/birds-and-wildlife/seabird-surveys-project-report">lost over 75%</a> of its great skuas and seen a 25% decline in northern gannets. Recent declines in sandwich terns (35%) and common terns (42%) were also <a href="https://maryannsteggles.com/wp-content/uploads/2024/02/Bird-flu-causing-%E2%80%98catastrophic-fall-in-UK-seabird-numbers-conservationists-warn-Bird-flu-The-G.pdf">largely driven by the virus</a>. </p>
<p>Scientists haven’t managed to <a href="https://wwwnc.cdc.gov/eid/article/30/3/23-1098_article">completely sequence</a> the virus in all affected species. Research and continuous surveillance could tell us how adaptable it ultimately becomes, and whether it can jump to even more species. We know it can already infect humans – one or more genetic mutations may make it more infectious.</p>
<h2>At the crossroads</h2>
<p>Between January 1 2003 and December 21 2023, 882 cases of human infection with the H5N1 virus were reported from 23 countries, of which <a href="https://cdn.who.int/media/docs/default-source/influenza/human-animal-interface-risk-assessments/influenza-at-the-human-animal-interface-summary-and-assessment--from-4-october-to-1-november-2023.pdf?sfvrsn=6c67e7df_2&download=true">461 (52%) were fatal</a>.</p>
<p>Of these fatal cases, more than half were in Vietnam, China, Cambodia and Laos. Poultry-to-human infections were first recorded in Cambodia in December 2003. Intermittent cases were reported until 2014, followed by a gap until 2023, yielding 41 deaths from 64 cases. The subtype of H5N1 virus responsible has been detected in poultry in Cambodia since 2014. In the early 2000s, the H5N1 virus circulating had a high human mortality rate, so it is worrying that we are now starting to see people dying after contact with poultry again.</p>
<p>It’s not just H5 subtypes of bird flu that concern humans. The H10N1 virus was originally isolated from wild birds in South Korea, but has also been reported in samples from China and Mongolia. </p>
<p><a href="https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1256090/full">Recent research</a> found that these particular virus subtypes may be able to jump to humans after they were found to be pathogenic in laboratory mice and ferrets. The first person who was confirmed to be infected with H10N5 <a href="https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON504">died</a> in China on January 27 2024, but this patient was also suffering from seasonal flu (H3N2). They had been exposed to live poultry which also tested positive for H10N5.</p>
<p>Species already threatened with extinction are among those which have died due to bird flu in the past three years. The first deaths from the virus in mainland Antarctica have just been <a href="https://www.cidrap.umn.edu/avian-influenza-bird-flu/avian-flu-reaches-antarcticas-mainland">confirmed in skuas</a>, highlighting a looming threat to penguin colonies whose eggs and chicks skuas prey on. Humboldt penguins have already been <a href="https://www.nytimes.com/2023/08/30/science/birds-flu-antarctica.html">killed by the virus</a> in Chile.</p>
<figure class="align-center ">
<img alt="A colony of king penguins." src="https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580982/original/file-20240311-26-mmf7j5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Remote penguin colonies are already threatened by climate change.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/king-penguin-colony-103683413">AndreAnita/Shutterstock</a></span>
</figcaption>
</figure>
<p>How can we stem this tsunami of H5N1 and other avian influenzas? Completely overhaul poultry production on a global scale. Make farms self-sufficient in rearing eggs and chicks instead of exporting them internationally. The trend towards megafarms containing over a million birds must be stopped in its tracks. </p>
<p>To prevent the worst outcomes for this virus, we must revisit its primary source: the incubator of intensive poultry farms.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
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<p class="fine-print"><em><span>Diana Bell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Bird flu is decimating species already threatened by climate change and habitat loss.Diana Bell, Professor of Conservation Biology, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2191402024-02-27T12:41:39Z2024-02-27T12:41:39ZCould a couple of Thai otters have helped the UK’s otter population recover? Our study provides a hint<p>Otter populations crashed in Britain around the 1960s from the lethal effects of chemical pollution in rivers and lakes – or so we thought. <a href="https://academic.oup.com/mbe/article/40/11/msad207/7275014">Our research</a> has looked more closely at what happened to otters in Britain over the last 800 years and has revealed a more complex picture. </p>
<p>Since Eurasian otters (<em>Lutra lutra</em>) are at the top of the aquatic food chain in Britain, any contamination consumed by their prey, and by the prey of their prey, <a href="https://pubs.acs.org/doi/10.1021/acs.est.1c05410">accumulates in otters</a>. So otters are particularly susceptible to any toxic chemicals in their environment. </p>
<p>Following the banning of many chemical pollutants, otter populations began to recover, and we now have otters in <a href="https://onlinelibrary.wiley.com/doi/10.1111/eva.13505">every county in Britain</a>. National otter surveys have been conducted in Wales, Scotland and England since 1977 and have helped to track population recovery. </p>
<p>However, we didn’t have a good grasp on what population sizes were like in the decades before this time. We only had anecdotal evidence that otter hunting was becoming less “successful” over time, and that both sightings and signs of otters were rarer. </p>
<h2>Otter population decline</h2>
<p>Our research shows that roughly between 1950 and 1970, an extreme population decline happened in the east of England, and a strong decline in south-west England. They were probably caused by chemical pollution. </p>
<p>In Scotland, otter populations showed a long-term, but smaller decline, which suggests less chemical pollution. There was a smaller population decline in Wales, which started around 1800, possibly linked to otter hunting and changes in how people shaped and used the landscape. </p>
<p>While both deal with DNA, genetics focuses on individual genes and their roles, while genomics examines the entire set of an organism’s DNA. Although there have been genetic studies of otters in Britain, our research was the first time genomics was used to study Eurasian otters anywhere in the world.</p>
<p>Working with scientists from the Smithsonian Conservation Biology Institute and the Wellcome Sanger’s Darwin Tree of Life project, we looked at the entire otter genome. The upgrade from genetics to genomics threw up a few surprises. </p>
<p>First, there was a mitochondrial DNA sequence found in the east of England, which was very different to the sequences in the rest of Britain. Mitochondrial DNA is a sequence of DNA found in a cell’s mitochondria, which is what generates the energy. Mitochondrial DNA is inherited only from the mother, while the rest of the DNA is a mix of both the mother’s and the father’s DNA.</p>
<p>Another <a href="https://www.tandfonline.com/doi/full/10.1080/19768354.2023.2283763">recent study</a> by our research group, in collaboration with colleagues in South Korea, suggested a divergence between these two lineages at least 80,000 years ago. Finding this mitochondrial lineage (that, based on our data, is otherwise restricted to Asia) in the UK was surprising. </p>
<p>Second, we found high levels of genetic diversity in the east of England. Normally, after an extreme population decline such as the one we identified in this area, genetic diversity decreases. Yet we saw much greater diversity here than in the population in Scotland, where there was no clear evidence for such a decline. </p>
<h2>Thai otters</h2>
<p>With a little detective work, we discovered that a pair of Eurasian otters (the same species that we have in the UK), were brought to Britain from Thailand in the 1960s. Populations of Eurasian otters range right across Europe and Asia. Although they are the same species, there are several genetically distinct subspecies, particularly in Asia. </p>
<p>It seems possible that these genetically different otters from Thailand bred with otters in the east of England. At the time of the population decline, when native UK populations were at their smallest, even a few individuals introduced into the population may have made a big difference. And they left unexpected marks on the genome. </p>
<p>We don’t know for sure if this is what happened, and we need to do more work to find out what effect this may have had on otters in the east of England. High genetic diversity is usually good for a population or species. But on the other hand, conservation often strives to maintain genetic differences between populations, rather than mixing distinct populations.</p>
<p>One way to find out more would be to compare the genome of a Eurasian otter from Thailand to the otters we see in the east of England. Unfortunately, it’s not that easy. Since the 1960s, otters in Thailand and across Asia have become increasingly rare. This is due to habitat loss, pollution and the illegal otter trade. So getting samples for genome sequencing is very difficult. It highlights the importance of conserving the species in Asia, despite population recoveries in Europe.</p>
<p>Our work shows the value of using modern genomic tools to look at the genetic diversity of a threatened species. The application of such tools can uncover surprising facts, even in supposedly well-studied species.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Frank Hailer receives funding from NERC and Dŵr Cymru Welsh Water. </span></em></p><p class="fine-print"><em><span>Elizabeth Chadwick receives funding from the UK Natural Environment Research Council and from the Environment Agency</span></em></p><p class="fine-print"><em><span>Sarah du Plessis receives funding from the UK Natural Environment Research Council and the Global Wales International Mobility Fund.</span></em></p>Research has revealed how British otters may have been able to recover from species loss in the 1950s with the help of otters from Asia.Frank Hailer, Senior Lecturer in Evolutionary Biology, Cardiff UniversityElizabeth Chadwick, Senior Lecturer at the School of Biosciences, Cardiff UniversitySarah du Plessis, PhD Candidate, Cardiff UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2233572024-02-26T03:17:26Z2024-02-26T03:17:26ZOur native animals are easy prey after a fire. Could artificial refuges save them?<figure><img src="https://images.theconversation.com/files/577816/original/file-20240226-24-d5noma.jpeg?ixlib=rb-1.1.0&rect=80%2C187%2C1816%2C1348&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A tawny-crowned honeyeater in an artificial refuge</span> <span class="attribution"><span class="source">Author provided</span></span></figcaption></figure><p>Australia is home to some of the most spectacular and enigmatic wildlife on Earth. Much of it, however, is being eaten by two incredibly damaging invasive predators: the feral cat and the red fox. </p>
<p>Each year in Australia, cats and foxes kill an estimated 697 million reptiles, 510 million birds, and 1.4 billion mammals, totalling a staggering <a href="https://doi.org/10.1111/ddi.13497">2.6 billion</a> animals. Since the predators were introduced more than 150 years ago, they have contributed to the extinction of more than 25 species – and are pushing <a href="https://researchers.cdu.edu.au/en/publications/degrees-of-population-level-susceptibility-of-australian-terrestr">many more to the brink</a>.</p>
<p>Research suggests cats and foxes can be <a href="https://link.springer.com/article/10.1186/s42408-023-00183-6">more active in areas</a> recently burnt by fire. This is a real concern, especially as climate change increases the <a href="https://www.nature.com/articles/s43247-020-00065-8">frequency and severity of fire</a> in south-eastern Australia.</p>
<p>We urgently need new ways to protect wildlife after fires. Our <a href="https://doi.org/10.1016/j.biocon.2024.110501">study</a> trialled one such tool: building artificial refuges across burnt landscapes. The results are promising, but researchers need to find out more.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/kkxYqW0-SZE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Video showing a buttonquail using an artificial refuge built by the researchers.</span></figcaption>
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<h2>Triple threat: cats, foxes and fire</h2>
<p>Many native animals are <a href="https://theconversation.com/surprisingly-few-animals-die-in-wildfires-and-that-means-we-can-help-more-in-the-aftermath-174392">well-adapted to fire</a>. But the changing frequency and intensity of fire is posing a <a href="https://doi.org/10.1111/conl.12905">considerable threat</a> to much of Australia’s wildlife.</p>
<p>Fire removes vegetation such as grass, leaf litter and shrubs. This leaves fewer places for native animals to shelter and hide, making it <a href="https://www.nature.com/articles/srep22559">easier</a> for cats and foxes to <a href="https://doi.org/10.1111/brv.12853">catch them</a>. </p>
<p>We conducted <a href="https://doi.org/10.1016/j.biocon.2024.110501">our experiment</a> in three Australian ecosystems: the forests of the Otway Ranges (Victoria), the sand dunes of the Simpson Desert (Queensland) and the woodlands of Kangaroo Island (South Australia). Each had recently been burnt by fire. </p>
<p>We built 76 refuges across these study areas. They were 90cm wide and up to 50m long – and backbreaking to install! They were made from wire mesh, mostly covered by shade cloth. Spacing in the mesh of 50mm allowed small animals to enter and exit from any point, while completely excluding cats, foxes and other larger animals. The shade cloth obstructed the vision of predators.</p>
<p>We then placed <a href="https://nesplandscapes.edu.au/wp-content/uploads/2015/10/5.2.4_a_guide_to_use_of_remote_cameras_for_wildlife_surveys_final_web.pdf">remote-sensing camera traps</a> both inside and away from each refuge, and monitored them for periods ranging from four months to four years.</p>
<p>The placement of the cameras meant we could compare the effect of the refuges with what occurred outside them.</p>
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Read more:
<a href="https://theconversation.com/a-season-in-hell-bushfires-push-at-least-20-threatened-species-closer-to-extinction-129533">A season in hell: bushfires push at least 20 threatened species closer to extinction</a>
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<h2>What we found</h2>
<p>Across the three study areas, the artificial refuges were used by 56 species or species groups. This included the critically endangered Kangaroo Island dunnart, the threatened white-footed dunnart and the threatened southern emu-wren. </p>
<p>For around half the species, we detected more individuals inside the refuges than outside. As we predicted, the activity of small birds and reptiles, in particular, was much higher inside the refuges. </p>
<p>But surprisingly, reptile activity was also generally higher inside the refuges, particularly among skinks. We had not predicted that, because the shade cloth likely made conditions inside the refuges cooler than outside, and reptiles require warmth to regulate their body temperature.</p>
<p>Over time, the number of animals detected inside the refuges generally increased. This was also a surprise. We expected detections inside the refuges to decline through time as the vegetation recovered and the risk of being seen by predators fell.</p>
<p>But there were also a few complicating factors. For example, in the Otway Ranges and Simpson Desert, similar numbers of the mammals were detected inside and away from the refuges. This suggests the species didn’t consider the refuges as particularly safe places, which means the structures may not reduce the risk of these animals becoming prey.</p>
<p>So what’s the upshot of all this? Our findings suggest that establishing artificial refuges after fire may help some small vertebrates, especially small birds and skinks, avoid predators across a range of ecosystems. However, more research is required before this strategy is adopted as a widespread management tool.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-critically-endangered-marsupial-survived-a-bushfire-then-along-came-the-feral-cats-185133">This critically endangered marsupial survived a bushfire – then along came the feral cats</a>
</strong>
</em>
</p>
<hr>
<h2>Important next steps</h2>
<p>Almost all evidence for an increase in cat and fox activity after fire comes from <a href="https://link.springer.com/article/10.1186/s42408-023-00183-6">Australia</a>, particularly the <a href="https://www.nature.com/articles/srep22559">tropical north</a>. But cats are an invasive species in more than <a href="https://www.gbif.org/species/2435035">120 countries and islands</a>.</p>
<p>That means there’s real potential for post-fire damage to wildlife to worsen globally, especially as <a href="https://www.nature.com/articles/s43017-020-0085-3">fire risk increases</a> with climate change. </p>
<p>Our results suggest artificial refuges may be a way to help animals survive after fire. But there are still important questions to answer, such as:</p>
<ul>
<li>can artificial refuges improve the overall abundance and survival of individuals and species?</li>
<li>if so, how many refuges would be required to achieve this?</li>
<li>in the presence of natural refuges – such as rocks, logs, burrows, and unburnt patches – are artificial refuges needed?</li>
<li>does their effectiveness vary between low-severity planned burns and high-severity bushfires?</li>
</ul>
<p>These questions must be answered. Conservation budgets are tight. After fires, funds must be directed towards actions that we know will work. That evidence is not yet there for artificial refuges.</p>
<p>Our team is busy trying to find out more. We urge other ecologists and conservationists to do so as well. We also encourage collaboration with designers and technologists to improve on our refuge design. For example, can such large refuges be made <a href="https://www.australianwildlife.org/biodegradable-flat-pack-homes-to-help-wildlife-survive-after-bushfires/">biodegradable and easier to deploy</a>?</p>
<p>Solving these problems is important. It’s almost impossible to rid the entire Australian continent of cats and foxes. So land managers need all the help they can get to stop these predators from decimating Australia’s incredible wildlife. </p>
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<figcaption><span class="caption">The impact of roaming pet cats on Australian wildlife.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/223357/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Darcy Watchorn receives funding from the Hermon Slade Foundation, Parks Victoria, the Conservation and Wildlife Research Trust, the Ecological Society of Australia, the Victorian Environmental Assessment Council, and the Geelong Naturalists Field Club. He is a member of the Ecological Society of Australia and the Society for Conservation Biology Oceania.</span></em></p><p class="fine-print"><em><span>Chris Dickman receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Don Driscoll receives funding from the ARC, Melbourne Water and Parks Victoria. He is affiliated with the Ecological Society of Australia and the Society for Conservation Biology.</span></em></p>We need every tool at our disposal to stop feral cats and foxes from decimating Australia’s incredible wildlife after fires. Artificial refuges show promise.Darcy Watchorn, PhD Candidate, Deakin UniversityChris Dickman, Professor Emeritus in Terrestrial Ecology, University of SydneyDon Driscoll, Professor in Terrestrial Ecology, Deakin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2232242024-02-21T13:04:38Z2024-02-21T13:04:38ZGut bacteria may explain why grey squirrels outcompete reds – new research<p>Across large parts of the UK, the native red squirrel has been replaced by the grey squirrel, a North American species. As well as endangering reds, grey squirrels pose a threat to our woodlands because of the damage they cause to trees. </p>
<p><a href="https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001793">New research</a> from my colleagues and I compared the gut bacteria of red and grey squirrels. We found that differences between the two may explain their competition and red squirrel decline, as well as why grey squirrels are so destructive to woodland.</p>
<p>Grey squirrels were introduced to the UK between 1876 and 1929 and have displaced reds in most areas of the UK. Greys carry a virus called “squirrelpox”, which doesn’t affect them but leads to sickness and often death in red squirrels.</p>
<p>Grey squirrels are bigger than red squirrels and compete with them <a href="https://www.frontiersin.org/articles/10.3389/fevo.2023.1083008/full">for food and habitat</a>.
Acorns, a widespread food source, contain tannins, which are hard for red squirrels to digest. But greys can digest acorns easily, giving them an extra edge in competing for resources. </p>
<p>Grey squirrels frequently strip the bark from deciduous trees. In commercial plantations, the damage can lead to fungal infection and result in the tree producing low quality timber. The annual cost is an <a href="https://rfs.org.uk/insights-publications/rfs-reports/report-overview-the-cost-of-grey-squirrel-damage-to-woodland-in-england-and-wales/">estimated £37 million.</a> with sycamore, oak, birch and beech frequently targeted. </p>
<p>The grey squirrels select the strongest growing trees as these have bark containing the largest volume of sap. Intriguingly, grey squirrels do not select trees with the <a href="https://www.researchgate.net/publication/230344319_Bark-stripping_by_Grey_squirrels_Sciurus_carolinensis">highest sugar content</a>. This observation has led scientists to posit that the squirrels consume bark to obtain <a href="https://www.sciencedirect.com/science/article/pii/S0378112716300421?via%3Dihub">certain micro-nutrients</a>. </p>
<h2>Gut bacteria</h2>
<p>All mammals have microorganisms living in their intestines. For example, the typical human colon is host to at least <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847071/">160 bacterial species</a>, while in birds, research has found thousands of different bacterial species in <a href="https://pubmed.ncbi.nlm.nih.gov/33868800/">chicken intestines.</a></p>
<p>The bacteria break down foods and help synthesise vitamins, complementing the enzymes secreted by the body. The diversity of these microorganisms, known as the “microbiota”, can reflect the level of health and also the diet of an individual. But we don’t know enough about the microbiota living in squirrel intestines. </p>
<p>The types of microbes present vary between species, yet the extent to which they differ between grey and red squirrels is unclear. We explored this and investigated the potential for any differences to affect competition between the two squirrel species. We also examined whether gut bacteria might be playing a role in bark stripping behaviour.</p>
<p>We sampled bacterial DNA from red and grey squirrel intestinal contents and performed gene sequencing to identify the range of bacteria present in the samples. The results were analysed to compare any important differences between the two.</p>
<figure class="align-center ">
<img alt="A cute red squirrels with a large bushy tail stands on the branch of a tree." src="https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Ynys Môn off the north Wales coast is one of the few places in the UK where greys have been eradicated in favour of red squirrels.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-squirrel-views-around-north-wales-2232607907">Gail Johnson/Shutterstock</a></span>
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<h2>Calcium</h2>
<p>Calcium is an important nutrient in the body and is required for healthy bones, muscles and nerves. It is especially needed by lactating animals and ones that are young and growing.</p>
<p>We found that grey squirrels may have the capacity to obtain the calcium that exists in tree bark thanks to the presence of a bacteria called “oxalobacter” in their gut. The calcium in tree bark comes in an insoluble form and is hard for an animal to digest. But oxalobacter would be able to change this into a form that could be more digestible. </p>
<p>Calcium levels <a href="https://www.sciencedirect.com/science/article/pii/S0378112716300421?via%3Dihub">increase in trees</a> as active growth resumes after winter dormancy. This happens immediately before the main squirrel bark-stripping season of May to July. Our research may therefore help to explain the destructive behaviour of grey squirrels and why red squirrels appear to strip bark much less frequently.</p>
<p>Our research also identified a significantly higher diversity of bacteria in the intestines of grey squirrels compared to red squirrels. This could hold the key to further understanding why grey squirrels outcompete red squirrels in the UK. </p>
<p>A more diverse range of bacteria being sustained in the gut means that grey squirrels potentially may be able to access a broader range of resources than red squirrels in addition to acorns.</p>
<h2>Adenovirus</h2>
<p>The grey squirrel harbours not just the squirrelpox virus, but also another potential threat – adenovirus. While this virus causes severe intestinal lesions in some red squirrels, curiously, grey squirrels never exhibit the same symptoms.</p>
<p>This discrepancy underscores the fascinating and complex potential role of gut microbiota. Research increasingly reveals their influence on everything from digestion to immune response, and even susceptibility to disease.</p>
<p>In the context of red squirrels, understanding how variations in their gut bacteria might predispose them to adenovirus becomes crucial. This is especially pertinent for captive breeding programs, where adenovirus infections pose a hurdle to successful reintroductions of red squirrels into the wild.</p>
<p>Given we only sampled red and grey squirrels from north Wales, we hope that future studies will map the gut microbiota of other European populations too. Such future research will continue to improve our knowledge of the competition between red and grey squirrels.</p><img src="https://counter.theconversation.com/content/223224/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Craig Shuttleworth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research suggests the gut bacteria of red and grey squirrels differ significantly, potentially explaining the decline of the native red and the success of its grey counterpart.Craig Shuttleworth, Honorary Visiting Research Fellow, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2231822024-02-13T19:08:16Z2024-02-13T19:08:16ZNew logging rules in NSW put the greater glider closer to extinction. When will we start protecting these amazing animals?<p>Forty years ago when my colleagues and I did spotlighting surveys, the southern greater glider was the most common animal we’d see. Now, this amazing species is endangered. In many areas it is hard to find; in others it has been lost altogether.</p>
<p>Australia has a <a href="https://www.science.org/doi/10.1126/science.adg7870">disproportionately large</a> number of in-danger species, and their decline follows a well-trodden path. Common species become uncommon, then uncommon species become rare. Rare species become threatened or endangered. Then tragically, endangered species go extinct. </p>
<p>Australia leads the world in native mammal extinctions – roughly 10% have <a href="https://doi.org/10.1073/pnas.1417301112">become extinct</a> since British invasion. The southern greater glider is heading towards this fate.</p>
<p>That’s why ecologists were shocked by a recent announcement by New South Wales environment authorities that we believe loosens protections for southern greater gliders in logging areas. </p>
<h2>A marsupial to cherish</h2>
<p>The southern greater glider is an iconic marsupial. It’s one of three species of greater gliders found in eastern Australia. It was <a href="https://www.environment.gov.au/biodiversity/threatened/species/pubs/254-conservation-advice-05072022.pdf">listed</a> as vulnerable to extinction under national environment law in 2016, then <a href="https://www.theguardian.com/environment/2022/jul/05/greater-glider-now-endangered-as-logging-bushfires-and-global-heating-hit-numbers">uplisted</a> to endangered in 2022.</p>
<p>Greater gliders are amazing animals. Their diet is low on nutrients, comprised almost entirely of eucalypt leaves and buds. Yet they are the world’s largest gliding marsupial, weighing up to 1.3 kg and capable of gliding up to 100m through a forest. </p>
<p>Southern greater gliders have white bellies and thick back fur that ranges from pure white to jet black.</p>
<p>The species is highly dependent on forest habitat and, in particular, large trees with hollows where they shelter and breed. But sadly, <a href="https://www.environment.vic.gov.au/conserving-threatened-species/threatened-species-fact-sheets/greater-glider">extensive glider habitat</a> has been burnt, logged or both. Climate change poses a <a href="https://doi.org/10.1016/j.biocon.2011.02.022">further</a> risk. </p>
<p>We have <a href="https://doi.org/10.1016/j.biocon.2011.02.022">long been concerned</a> for the southern greater glider. In the wet forests of Victoria, for example, their numbers have <a href="https://doi.org/10.1111/acv.12634">declined</a> by 80% since 1997. In 2007, the species became <a href="https://doi.org/10.1016/j.biocon.2018.03.007">regionally extinct</a> at Booderee National Park, south of Sydney.</p>
<p>When the southern greater glider was upgraded to endangered, Federal Environment Minister Tanya Plibersek <a href="https://www.theguardian.com/environment/2022/jul/05/greater-glider-now-endangered-as-logging-bushfires-and-global-heating-hit-numbers">said</a> the new listing would “ensure prioritisation of recovery actions to protect this iconic species”. She noted that habitat protection and land clearing were “primarily the responsibility of state governments”.</p>
<p>You might think, then, that state governments would now be working harder to protect greater glider habitat. But a recent decision in NSW suggests little has changed.</p>
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<h2>What the changes mean</h2>
<p>The NSW Environment Protection Authority this month <a href="https://www.epa.nsw.gov.au/news/media-releases/2024/epamedia240202-new-protections-for-endangered-southern-greater-gliders">announced</a> changes to rules in logging operations. It claims the amendments constitute “new protections” for greater gliders. But many ecologists, us included, believe the changes are designed to make logging easier and will leave the species at greater risk.</p>
<p>At present, Forestry Corporation staff undertake pre-logging habitat searches for trees that might contain hollows. They must retain eight of these trees per hectare but can log right up to the tree base. The staff must also look for den trees (where an animal is actually seen entering or leaving a tree hollow) – although this is problematic as gliders are active at night and the surveys take place during the day. If a den tree is found, it must be protected and a 50m area around it retained.</p>
<p>Under the proposed new rules, Forestry Corporation will have to keep more large hollow-bearing trees per hectare – 14 instead of the current eight in high-density glider areas, and 12 instead of the current eight in low-density areas. A 50m exclusion zone will remain around known recorded locations of greater glider dens, but there will no longer be a requirement to specifically find or protect den trees. </p>
<p>This means actual habitat where greater gliders currently occur, and occupy den trees, may not be protected. We believe this will increase the gliders’ rate of decline and fast-track it towards extinction. </p>
<p>The new rules were due to begin on February 9, but were <a href="https://www.epa.nsw.gov.au/news/media-releases/2024/epamedia240209-forestry-protocol">postponed</a> by a week. In a statement, the authority said it was “consulting with stakeholders and considering their feedback to ensure we find the most appropriate way to address concerns while achieving long-term protections for this endangered species”.</p>
<p>If the authority is serious about protecting greater gliders, it will move to strengthen not weaken protections for greater glider habitat.</p>
<h2>Logging glider habitat is nonsensical</h2>
<p>Since the southern greater glider was listed as vulnerable in 2016, its habitat continued to be <a href="https://theconversation.com/australia-has-failed-greater-gliders-since-they-were-listed-as-vulnerable-weve-destroyed-more-of-their-habitat-164872">destroyed</a>. This is poor management for many reasons:</p>
<ul>
<li><p>gliders often <a href="https://www.jstor.org/stable/3041">die on site</a> when their habitat is disturbed</p></li>
<li><p>young forests recovering after disturbances tend to be <a href="https://doi.org/10.1016/j.foreco.2022.120101">hotter and drier</a>, which is bad for gliders because they are <a href="https://doi.org/10.1007/BF00683223">heat-sensitive</a> </p></li>
<li><p>removing <a href="https://doi.org/10.1016/j.foreco.2017.02.014">hollow-bearing trees</a> not only destroys a key part of glider habitat immediately, but it can take decades (if not centuries) for forest to become suitable again </p></li>
<li><p>logging makes forests <a href="https://doi.org/10.1111/brv.13041">more flammable</a> and gliders are particularly <a href="https://doi.org/10.1111/acv.12634">sensitive</a> to fire</p></li>
<li><p>logging can <a href="https://doi.org/10.1016/j.foreco.2019.117585">change</a> the composition of tree species in a forest, reducing the availability of quality food for gliders. </p></li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australia-has-failed-greater-gliders-since-they-were-listed-as-vulnerable-weve-destroyed-more-of-their-habitat-164872">Australia has failed greater gliders: since they were listed as 'vulnerable' we’ve destroyed more of their habitat</a>
</strong>
</em>
</p>
<hr>
<h2>The choice is ours</h2>
<p>Human activity has left few remaining refuges for the southern greater glider. Any remaining habitat should be subject to the highest protections.</p>
<p>Logging those refuges is nonsensical given the large body of scientific work demonstrating its negative effects. And tinkering around the edge of logging rules will have limited benefits. </p>
<p>Australia has already lost so many wonderful mammal species. Do we want the southern greater glider to suffer the same fate? If not, let’s stop destroying the forests our species need to survive.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/greater-gliders-are-hurtling-towards-extinction-and-the-blame-lies-squarely-with-australian-governments-186469">Greater gliders are hurtling towards extinction, and the blame lies squarely with Australian governments</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/223182/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Lindenmayer receives funding from the Australian and Victorian Governments and the Australian Research Council. He is a member of the Biodiversity Council and Birdlife Australia. </span></em></p><p class="fine-print"><em><span>Kita Ashman works for WWF Australia and is an Ambassador for Paddy Pallin.</span></em></p>Australia has already lost so many wonderful mammal species. Do we want the southern greater glider to suffer the same fate?David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National UniversityKita Ashman, Adjunct research associate, Charles Sturt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2213522024-02-05T13:34:48Z2024-02-05T13:34:48ZHow bats ‘leapfrog’ their way home at night – new research<figure><img src="https://images.theconversation.com/files/572171/original/file-20240130-27-o1vlrb.jpg?ixlib=rb-1.1.0&rect=0%2C10%2C3413%2C2539&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The greater horseshoe bat is one of the UK's 18 bat species. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/flying-bat-hunting-forest-greater-horseshoe-1494098204">Rudmer Zwerver/Shutterstock</a></span></figcaption></figure><p>A silent ballet takes place above our heads at night as Britain’s bat populations leave their roosts to forage for food. Although their initial movement away from roosts is fairly well understood, until recently little was known about how they returned home. </p>
<p>But our <a href="https://link.springer.com/article/10.1007/s11538-023-01233-5">new research</a> shows how bats may use a “leap-frogging” motion to make their way home, something which could help conservationists in future.</p>
<p>As they flit through the darkness, bats play a crucial role in the health of our ecosystems. From keeping insect populations in check to dispersing seeds and pollinating plants, they provide a multitude of benefits. </p>
<p>In the UK alone, the 18 bat species devour agricultural pests such as cockchafers with impressive efficiency. So, it is imperative that we not only understand and appreciate bats, but also actively support and safeguard their populations for the wellbeing of our planet.</p>
<p>But bat populations are vulnerable to pollution, climate change and loss of roosting locations. Habitat fragmentation and light pollution can also interrupt how bats feed. This is particularly important during the maternity season <strong>in early summer</strong>, when bats gather together to have and raise their young.</p>
<p>An integral aspect of effective bat conservation lies in unravelling the mysteries of how bats move. This not only helps us understand how bats navigate and use their environment, but also helps in identifying and protecting their roosts. </p>
<h2>Radio-tracking</h2>
<p>Conventional methods for pinpointing bat roosts primarily hinge on radio-tracking surveys. This arduous process involves capturing bats, attaching small radio transmitters to them before releasing them and following the signals throughout the night. </p>
<p>Our team conducted a radio-tracking survey in Devon which monitored 12 greater horseshoe bats over 24 nights. The trajectories of seven of those bats over 14 nights were extracted from the data for analysis, ensuring that in each case, a bat’s beginning and ending roost were the same.</p>
<p>Using this data, we measured the population’s average distance from the roost. We found two distinctive patterns in the data we analysed: an initial spread of bats within the first one to two hours after sunset and a gradual return to the roost afterwards.</p>
<p>The initial spread reflects the expected random dispersal of bats leaving their roosts to forage after sunset. The return to the roost, occurring two to eight hours after sunset, is more complicated. </p>
<p>This prompted us to explore two potential mechanisms influencing the bats’ return. First, a “pull mechanism”, where the roost attracts the bats home, and second, a mechanism pushing the bats who range furthest away back to the roost.</p>
<p>We modelled the pushing mechanism as a leapfrog process. Imagine this as a cascade effect, where the outermost bats begin their return. Once the “outer” bats have passed or “leapt over” bats that are closer to the roost, the “inner” bats become the furthest out causing them to return too.</p>
<p>This motion unfolds systematically, like a synchronised dance, as each bat from the periphery of the foraging range follows suit in returning to the roost after being “leapfrogged”.</p>
<p>But what causes the bats to return in this manner? One plausible explanation underscores how bats rely on each other for effective navigation, like tiny radar signals. If a bat experiences prolonged silence or predominantly hears calls from one direction, it might decide to move closer to the roost, anticipating the presence of other colony members. </p>
<p>But a bat might return more slowly, prolonging foraging, if it perceives the presence of bats beyond its current location. So, it is the outer bats that would drive the return as they would not be surrounded by calls.</p>
<h2>How does this research help bats?</h2>
<p>The significance of these findings extends beyond just describing the movements of bats. They have laid the foundation for work that promises easier discovery of new bat roosts, potentially reducing the need for labour-intensive bat tracking surveys in the future. </p>
<p>One of the immediate effects of our research includes informing a measurement of the “core sustenance zone” for greater horseshoe bats. This is where most of their foraging occurs, so it’s important in bat ecology, conservation and construction planning.</p>
<p>The leapfrogging mechanism also allows us to ascribe intention to bat movements. Namely, through using surrounding bat calls they can identify where the population is relative to their position, suggesting whether or not they are on the periphery of the group, which is an indicator of their vulnerability. Should they be furthest from the roost they move back towards the bulk of the population and closer to the roost.</p>
<p>While these interpretations hold promise, further rigorous testing is essential. And we need to think about the safety and wellbeing of the bat population.</p>
<p>Our observations are also specific to greater horseshoe bats during the summer months. Different bat species have distinct flight patterns and habitat preferences, with the same species displaying diverse behaviours at different times of the year. </p>
<p>So, while we have taken some crucial first steps, we still have a lot of work to do in unravelling the characteristics of bat motions in general.</p><img src="https://counter.theconversation.com/content/221352/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fiona Mathews receives funding from Devon Area of Outstanding Natural Beauty, Devon County Council and the Natural Environment Research Council. She is affiliated with the UK Mammal Society, Mammal Conservation Europe, Ecotype Genetics and Ecology Search Services Ltd. </span></em></p><p class="fine-print"><em><span>Thomas Woolley does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Maths plays a crucial role in new research which finds that bats “leapfrog” their way home at night.Thomas Woolley, Senior Lecturer in Applied Mathematics, Cardiff UniversityFiona Mathews, Professor of Environmental Biology, University of SussexLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2210092024-01-17T23:33:35Z2024-01-17T23:33:35ZThese fierce, tiny marsupials drop dead after lengthy sex fests – and sometimes become cannibals<p>If you are exploring our beautiful Australian wilderness this year, keep an eye out for animals behaving in interesting ways. You never know what you might see, as our research team discovered.</p>
<p>In 2023, our colleague from Sunshine Coast Council, Elliot Bowerman, took a two-night trip to <a href="https://www.nationalparks.nsw.gov.au/visit-a-park/parks/new-england-national-park">New England National Park</a> – its 1,500 metre-high mountain peaks are some of the loftiest on Australia’s mid-east coast.</p>
<p>On the afternoon of 17 August, Elliot trekked the path to Point Lookout. While inspecting some plants on the trail, he heard a rustle in the bushes ahead and peering more closely, saw something of interest. A small mammal had abruptly appeared, dragging the carcass of another mammal, which it then began to devour.</p>
<p>At first glance, this was not so strange. Mammals eat each other all the time. However, it <em>is</em> unusual to see small mammals during the day at such close quarters, so Elliot recorded the scene, taking a video on his mobile phone.</p>
<p>It was only several days later when looking over the footage that our research team realised it featured something rarely seen in the wild, the record of which is now published <a href="https://doi.org/10.1071/AM23042">in the journal <em>Australian Mammalogy</em></a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-5-of-australias-tiniest-mammals-who-tread-a-tightrope-between-life-and-death-every-night-159239">Meet 5 of Australia’s tiniest mammals, who tread a tightrope between life and death every night</a>
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<h2>A native marsupial… cannibal</h2>
<p>The furry critter on film was an <a href="https://animalia.bio/dusky-antechinus">antechinus</a>, a native marsupial denizen of forested areas in eastern, south-western and northern Australia. Antechinuses usually eat a range of insects and spiders, occasionally taking small vertebrates such as birds, lizards, or even other mammals. </p>
<p>But this <a href="https://www.youtube.com/watch?v=dd1nlIdIsK8">camera footage</a> clearly showed a mainland dusky antechinus (<em>Antechinus mimetes mimetes</em>), and it was eating a dead member of its own species!</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/dd1nlIdIsK8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>Antechinuses are perhaps best known for exhibiting <a href="https://daily.jstor.org/death-and-mating/">semelparity</a>, or “suicidal reproduction”. This is death after reproducing in a single breeding period. The phenomenon is known in a range of plants, invertebrates and vertebrates, but it is rare in mammals. </p>
<p>Each year, all antechinus males drop dead at the end of a one to three week breeding season, poisoned by their own raging hormones.</p>
<p>This is because the stress hormone cortisol rises during the breeding period. At the same time, surging testosterone from the super-sized testes in males causes a failure in the biological mechanism that mops up the cortisol. The flood of unbound cortisol results in systemic organ failure and the inevitable, <a href="https://link.springer.com/article/10.1007/s00360-007-0250-8">gruesome death of every male</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark grey marsupial with a pointy snout tearing at pink flesh" src="https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=747&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=747&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=747&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=939&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=939&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569221/original/file-20240115-15-2bu24v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=939&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A mainland dusky antechinus during the mating period, with fur loss visible on the shoulder, eating another antechinus.</span>
<span class="attribution"><span class="source">Elliot Bowerman</span></span>
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</figure>
<p>Mercifully, death occurs only after the males have unloaded their precious cargo of sperm, <a href="https://theconversation.com/doing-it-to-death-suicidal-sex-in-marsupial-mice-18884">mating with as many promiscuous females</a> as possible in marathon, energy-sapping sessions lasting up to 14 hours. The pregnant females are then responsible for ensuring the survival of the species.</p>
<p>So, exactly what was happening that day at Point Lookout – why had an antechinus turned cannibal? </p>
<h2>Cheap calories</h2>
<p>August is the breeding period for mainland dusky antechinuses at that location. Intense mating burns calories, and at the end of winter it is cold and there isn’t as much invertebrate food about.</p>
<p>If there are male antechinuses dropping dead from sex-fuelled exhaustion, our thinking is that still-living male and female antechinuses are taking advantage of the cheap energy boost via a hearty feast of a fallen comrade.</p>
<p>After all, animal flesh provides plenty of energetic bang for the buck, particularly if its owner does not have to be pursued or overpowered before being devoured.</p>
<p>In many areas of Australia, two antechinus species (of the known fifteen) occur together, and usually their breeding periods <a href="https://doi.org/10.1111/j.1095-8312.2006.00571.x">are separated by only a few weeks</a>. One can imagine a scenario where individuals may not only feed on the carcasses of their own species but consume the other species as well.</p>
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<a href="https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=567&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=567&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=567&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=713&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=713&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569229/original/file-20240115-15-pri0fh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=713&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An endangered silver-headed antechinus, <em>Antechinus argentus</em>.</span>
<span class="attribution"><span class="source">Andrew Baker</span></span>
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</figure>
<p>Each species may benefit from eating the dead males of the other. For the earlier-breeding species, females may be pregnant or lactating, which is a huge energy drain.</p>
<p>For the later-breeding species, both sexes need to pack on weight and body condition before their own breeding period commences. </p>
<p>Plausibly then, antechinus engage in orgiastic breeding and, when opportune, cannibalistic feeding. </p>
<p>So, the next time you are out and about in the bush, keep your eyes and ears peeled – you never know what secrets nature might reveal to you just around the next corner.</p>
<hr>
<p><em>The author would like to acknowledge the co-authors of the paper, Elliot Bowerman from Sunshine Coast Council, and Ian Gynther from the Queensland Department of Environment, Science and Innovation.</em></p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/torpor-a-neat-survival-trick-once-thought-rare-in-australian-animals-is-actually-widespread-146409">Torpor: a neat survival trick once thought rare in Australian animals is actually widespread</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/221009/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew M. Baker receives funding from the Federal Government, State Governments, Australian Biological Resources Study and various Industry sources. </span></em></p>Antechinuses are tiny marsupials famous for their intense sex lives. Now, researchers have documented another unusual behaviour – the cannibalism of their own species.Andrew M. Baker, Associate Professor in Ecology and Environmental Science, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2203182024-01-08T23:41:27Z2024-01-08T23:41:27ZWhen polar bears hunt snow geese, hunger justifies the means<figure><img src="https://images.theconversation.com/files/567181/original/file-20231220-19-d2je5g.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C989%2C745&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The adaptations that polar bears will have to make to meet the challenges brought about by climate change are numerous and unpredictable.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Polar bears (<em>Ursus maritimus</em>) take advantage of the winter to build up their <a href="https://doi.org/10.1086/physzool.69.2.30164186">fat reserves</a>. Intensive hunting of seals, <a href="https://doi.org/10.1139/z75-117">a resource rich in fat</a>, allows bears to store up enough energy to get through the summer.</p>
<p>As the climate warms, hunting opportunities on the ice pack are <a href="https://doi.org/10.1111/1365-2656.12685">diminishing</a>. Experts believe that as a result, there is not sufficient food resources on the land to allow bears to build up <a href="https://doi.org/10.1890/140202">the energy reserves they require</a>.</p>
<p>Faced with these changes, some polar bears are taking advantage of colonies <a href="https://doi.org/10.1098/rspb.2013.3128">of nesting birds and their eggs</a>, one of the few resources readily available on land, to compensate for their energy deficits. The adaptations that bears will have to make to meet the challenges brought about by climate change are numerous and unpredictable.</p>
<p>As a student researcher in ecology, I was going to take advantage of a short trip north of Baffin Island, in Nunavut, to do some work on the small fauna of Bylot Island. One afternoon, a polar bear decided otherwise. Here we report on his exploits, which led to observations of unprecedented behaviour.</p>
<h2>An unusual sighting – a polar bear in fresh water</h2>
<p>It was Aug. 8, 2021. Some 80 km from the Inuit community of Mittimatalik, the Bylot Island field station was bustling with activity.</p>
<p><a href="https://doi.org/10.1139/as-2023-0029">Established 30 years ago</a>, the field station is located in the heart of the breeding grounds of the largest known colony of snow geese (<em>Anser caerulescens caerulescens</em>). Today, scientists from a variety of backgrounds scour the Quarliktuvik valley floor, which is generally flat, to study the soil, water, plants and wildlife.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bylot Island main research station TimMoser x" src="https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=246&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=246&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=246&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=310&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=310&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566995/original/file-20231220-25-jybcic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=310&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Bylot Island research camp.</span>
<span class="attribution"><span class="source">(Tim Moser)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>Coming out of a ravine, one of the few landforms in the area, I was scanning the valley with my binoculars when two pairs of legs in the distance caught my eye. The image was foggy, but what I initially thought were two colleagues walking side by side, turned out to be the distinctive shape of a polar bear. Everyone in our group had the necessary protective equipment — bear spray, anti-bear cartridges and sometimes even a rifle — but I alerted them by radio and immediately returned to the field station.</p>
<p>Several colleagues had gathered on a small hill to keep an eye on the newcomer. In fact, by the time I’d covered the kilometre distance to the camp, the bear had walked three kilometres and was moving around a pond where geese were gathered. At this time of year, <a href="https://doi.org/10.1111/jav.00982">the geese are moulting</a> — and therefore unable to fly — so they congregate near ponds to avoid the <a href="https://doi.org/10.14430/arctic604">Arctic fox (<em>Vulpes lagopus</em>)</a>, which is reluctant to jump into the water. With a bear in the vicinity, we ceased our field activities and took advantage of the radiant afternoon to watch the king of the ice pack.</p>
<p>True to form, the geese took refuge in the nearest pond at the first sight of danger. They waded in quickly enough to keep the bear, who was swimming on the surface, at a safe distance.</p>
<p>But the bear was about to use a new hunting technique: he dove under the water, disappeared from the eyes of the geese who had stopped fleeing, and emerged from underneath one of them.</p>
<p>My colleague Mathilde Poirier recorded the behaviour in her notebook:</p>
<blockquote>
<p>1:45 p.m. - 2:00 p.m.: the bear swims in the lake […], makes 4 dives to try to catch a goose. Succeeds in its 4th attempt (catches the goose from below, during a dive).</p>
</blockquote>
<p>During the afternoon, the bear used this technique two more times, once failing and once with success.</p>
<h2>What are the benefits of this behaviour for bears?</h2>
<p>Two months later, back at Laval University, we were still fascinated by this observation. Nowhere in the scientific literature is there any mention of such behaviour. At best, there are reports of <a href="https://doi.org/10.33265/polar.v41.8176">attacks on murres in the ocean</a> near the coasts, an environment very different from the calm, shallow ponds where we observed the bear’s attacks.</p>
<p>Being aware of the <a href="https://doi.org/10.1890/140202">energy challenges</a> bears face during the summer, our research group — led by Matthieu Weiss-Blais — wanted to answer the following question: would this hunting technique allow polar bears to benefit from eating snow geese?</p>
<p>The information recorded in the field, i.e. the time the bear spent swimming and its success in hunting, allowed us to answer this question. By combining our observations with <a href="https://doi.org/10.1007/s00300-017-2209-x">estimates of the energy cost</a> of swimming in bears and <a href="https://doi.org/10.1093/conphys/cow045">the energy contained in a snow goose</a>, we were able to model the energy efficiency of the technique.</p>
<p><a href="https://doi.org/10.1139/AS-2023-0036">These calculations reveal</a> that this hunting technique could allow bears to acquire more energy than they expend, particularly for smaller bears, and if they manage to catch a goose quickly.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="polar bear" src="https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566994/original/file-20231220-25-lint0u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The bear was moving around near a pond occupied by geese.</span>
<span class="attribution"><span class="source">(Yannick Seyer)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<h2>An energy boost, but far from sufficient</h2>
<p>However, this energy contribution would be very limited in scope.</p>
<p>First of all, a goose provides relatively little energy — around 200 times less than a <a href="https://doi.org/10.1139/z75-117">ringed seal weighing 45 kilograms</a>.</p>
<p>What’s more, the geese are rarely available as prey: they lose the ability to fly for only three or four weeks each summer and they only have colonies in <a href="http://dx.doi.org/10.1002/jwmg.879">a few places</a> in the Arctic.</p>
<p>Hunting geese could therefore be of benefit to certain bears from time to time, but on a population-wide scale, it will not alleviate the energy deficits caused by the melting ice pack.</p>
<p>Although our observation highlights the range of behaviours bears can adopt in order to exploit terrestrial resources, this type of interaction between snow geese and polar bears should have no impact on the populations of either species.</p><img src="https://counter.theconversation.com/content/220318/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Bolduc received funding from the NSTP and the Canadian Association for Humane Trapping.</span></em></p><p class="fine-print"><em><span>Matthieu Weiss-Blais received funding from NSERC, FRQNT and NSTP.
</span></em></p>Researchers have made a fascinating observation: a polar bear used a diving hunting technique, never before reported, to capture large moulting snow geese.David Bolduc, Étudiant au doctorat en écologie animale, Université LavalMatthieu Weiss-Blais, Étudiant la maîtrise en biologie, Université LavalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2194352023-12-20T16:05:40Z2023-12-20T16:05:40ZCould dinosaurs be the reason humans can’t live for 200 years?<figure><img src="https://images.theconversation.com/files/565275/original/file-20231212-17-7baa92.jpg?ixlib=rb-1.1.0&rect=0%2C23%2C4000%2C2640&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/human-hand-compare-real-dinosaur-footprint-1205774944">Rattana/Shutterstock</a></span></figcaption></figure><p>All human beings age. It is part of our biology and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4010874/">limits our lifespan</a> to slightly over 120 years.</p>
<p>Not all animals <a href="https://www.sciencedirect.com/science/article/pii/S0925443917302193">experience ageing</a> during their lives. Some animals’ bodies do not gradually degenerate as they get older the way our bodies do.</p>
<p>But for humans once they reach about age 30 their <a href="https://www.smithsonianmag.com/smart-news/your-probability-of-dying-doubles-every-eight-years-180948228/">chance of dying</a> <a href="https://arxiv.org/PS_cache/q-bio/pdf/0411/0411019v3.pdf">doubles roughly</a> every eight years. So even if you are fortunate enough to become a centenarian, your chance of dying each year will be high. </p>
<p>This high mortality reflects numerous other health problems, such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2804956/#R4">loss of muscle mass</a> and general frailty, <a href="https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0035-1555115">cognitive decline</a>, loss of vision and hearing and many other degenerative changes that characterise the <a href="https://www.ncbi.nlm.nih.gov/books/NBK10041/#:%7E:text=Aging%20is%20the%20time%2Drelated,disease%20(which%20affect%20individuals).">human ageing process</a>. </p>
<p>And the reason humans age so markedly may be due to the fact our ancestors evolved during the <a href="https://www.embopress.org/doi/full/10.15252/embr.202051617">time of the dinosaurs</a>.</p>
<p>Compared to other mammals, humans have a long life. We have the longest lifespan of all land-based mammals, and of all mammals <a href="https://news.liverpool.ac.uk/2015/01/06/scientists-sequence-genome-longest-lived-mammal/">only whales probably</a> outlive us. I say “probably” because you need to keep animals in captivity to do a detailed study on lifespan, which for whales is virtually impossible due to their size and longevity. </p>
<p>We know that species of whales and dolphins <a href="https://www.pnas.org/doi/10.1073/pnas.1903844116">exhibit menopause</a>, and all mammals show some form of reproductive decline with age. In fact, all studied mammals show physiological ageing and increased mortality with age, even if some species – like mice and voles – age much faster than others – such as humans, whales, and elephants. </p>
<p>But many species of reptiles, amphibians and fish do not show signs of ageing. <a href="https://genomics.senescence.info/species/nonaging.php">Examples include</a> turtles and tortoises, salamanders and rockfishes. </p>
<p>One study of 77 species of reptiles and amphibians published in Science in 2022 showed that age-related increases in mortality <a href="https://www.science.org/doi/10.1126/science.abm0151">are not seen</a> in many species of reptiles and amphibians. It is as if these animals do not age at all. Some of these animals, such as turtles, probably live longer than humans.</p>
<p>Perhaps if we study these apparently non-ageing species for long enough they will show signs of ageing. But good luck studying animals such as the <a href="https://www.science.org/doi/10.1126/science.aaf1703">Greenland shark</a>, which has been estimated to live nearly 400 years. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/H3al2YI_128?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>For now we can at least say that among reptiles, amphibians and fish, some species not only live longer than the longest living mammals, but they age substantially slower. Besides, some of these non-ageing species grow throughout their lives, which means that older females <a href="https://www.sciencedirect.com/science/article/pii/S0531556500002424">lay more eggs</a>, again in stark contrast to what happens in mammals. </p>
<p>These animals die mainly from being eaten by predators and diseases. Indeed, most animals in the wild do not die of old age and, until the 20th century, of course, most people died of infectious diseases.</p>
<p>Some reptiles, amphibians and fish are also known for their <a href="https://www.mdpi.com/2221-3759/9/3/36">ability to regenerate</a> tissue. </p>
<h2>Pressure on mammals</h2>
<p>Amphibians evolved from fish about 370 million years ago, and about 50 million years later reptiles evolved from amphibians. <a href="https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/12%3A_Vertebrates/12.07%3A_Vertebrate_Evolution">Mammals then evolved</a> from reptiles about 250-300 million years ago. </p>
<p>We are all products of evolution, which we see in relics such as <a href="https://www.biorxiv.org/content/10.1101/2021.09.14.460388v1">our tailbone</a>. Our evolutionary history can have a profound influence in modern times. For example, humans maintain evolutionary traits from when our ancestors roamed the savannah that are no longer fit for the modern world, from <a href="https://theconversation.com/the-science-of-sugar-why-were-hardwired-to-love-it-and-what-eating-too-much-does-to-your-brain-podcast-175272">craving sugar</a> to <a href="https://theconversation.com/how-morbid-curiosity-can-lead-people-to-conspiracy-theories-214532">behaviour</a> that leads to prejudices. </p>
<p>About 200 million years ago, massive volcanic eruptions <a href="https://www.britannica.com/science/end-Triassic-extinction">wiped out 76%</a> of marine and land species. Afterwards, the dinosaurs became the dominant predators in the land. To survive and avoid being hunted to extinction by dinosaurs, mammals became small, nocturnal and short-lived. </p>
<p>Our ancestors of this time were not like us at all. They were more like <a href="https://www.livescience.com/60888-rat-creatures-were-earliest-eutherian-mammal-ancestors.html">voles and mice</a>, small animals going out in the dark to catch insects. Under the pressure from the dinosaurs, ancestral mammals had to reproduce rapidly, just like mice and rats do now. And just like mice, rats and voles, our ancestors had short lifespans. </p>
<p>For 100 million years, during the time of the dinosaurs, mammals were at or near the bottom of the food chain. Mammals were more often prey than predators. During this time there was no reason for mammals to keep processes and genes related to long life, such as DNA repair and tissue regeneration systems. </p>
<p>My <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/bies.202300098">longevity bottleneck hypothesis</a> proposes that repair and regeneration systems were lost, mutated or inactivated by the evolution of early mammals. This imposed biological constraints that shape how mammals age to this day. </p>
<p>After the dinosaurs disappeared when an asteroid hit the Earth <a href="https://www.nhm.ac.uk/discover/how-an-asteroid-caused-extinction-of-dinosaurs.html">66 million years</a> ago, mammals conquered the world. An astonishing diversity of species evolved with a variety of lifespans. Some species, like humans, evolved a long lifespan, but they may have done it under constraints, remnants from the time of the dinosaurs.</p>
<h2>Why dinosaurs made a difference</h2>
<figure class="align-center ">
<img alt="Lizard rests on the ground" src="https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=362&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=362&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=362&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=455&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=455&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564332/original/file-20231207-15-xjtuw7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=455&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Tuatara lives for over a hundred years.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tuatara-310936394">BeautifulBlossoms/Shutterstock</a></span>
</figcaption>
</figure>
<p>We can take a guess by looking at species that did not undergo the same evolutionary pressures as early mammals. For example, the tuatara, a reptile endemic to New Zealand, may look like a lizard but it diverged from snakes and lizards about 250 million years ago. It is sometimes referred to as a “living fossil”, due to its slow evolution. </p>
<p>Tuataras are thought to live for more than 100 years and age much slower than human beings, as a <a href="https://www.science.org/doi/10.1126/science.abm0151">2022 DNA analysis study showed</a>. Perhaps they have kept their anti-ageing genes, unlike even the longest lived mammals. </p>
<p>Our lifespan may be limited because of our evolutionary history.</p><img src="https://counter.theconversation.com/content/219435/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joao Pedro de Magalhaes receives funding from the Wellcome Trust, Longevity Impetus Grants, LongeCity, and the Biotechnology and Biological Sciences Research Council.</span></em></p>Our mammal ancestors evolved to compete with dinosaurs but may have lost something in the process.Joao Pedro de Magalhaes, Chair of Molecular Biogerontology, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2199612023-12-20T00:06:41Z2023-12-20T00:06:41Z19-million-year-old fossil jaw bone hints the biggest whales first evolved somewhere unexpected<figure><img src="https://images.theconversation.com/files/566527/original/file-20231219-15-u7qnu9.jpg?ixlib=rb-1.1.0&rect=68%2C0%2C1773%2C1279&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The baleen whale fossil at Museums Victoria Research Institute.</span> <span class="attribution"><span class="source">Eugene Hyland, Museums Victoria</span></span></figcaption></figure><p>Baleen whales are the titans of the ocean, the largest animals to have ever lived. The record holder is the blue whale (<em>Balaenoptera musculus</em>), which can reach <a href="https://www.worldwildlife.org/stories/meet-the-biggest-animal-in-the-world">lengths of up to 30 metres</a>. That’s longer than a basketball court.</p>
<p>However, throughout their evolutionary history, most baleen whales <a href="https://www.science.org/content/article/why-whales-grew-such-monster-sizes">were relatively much smaller</a>, around five metres in length. While still big compared to most animals, for a baleen whale that’s quite small.</p>
<p>However, new fossil discoveries from the Southern Hemisphere are beginning to disrupt this story. The latest is an unassuming fossil from the banks of the Murray River in South Australia.</p>
<p>Roughly 19 million years old, this fossil is the tip of the lower jaws (or “chin”) of a baleen whale estimated to be around nine metres in length, which makes it the new record holder from its time. This find has been published today in the journal <a href="https://doi.org/10.1098/rspb.2023.2177">Proceedings of the Royal Society B: Biological Sciences</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a whale with a piece of yellow bone superimposed on its lower jaw" src="https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566189/original/file-20231218-23-ajfj29.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The roughly 19-million-year-old fossil ‘chin’ bone superimposed on a Murray River whale illustration.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan</span></span>
</figcaption>
</figure>
<h2>What are baleen whales?</h2>
<p>Most mammals have teeth in their mouth. Baleen whales are a strange exception. While <a href="https://theconversation.com/ancient-whales-had-more-bite-than-todays-gentle-giants-82907">their ancestors had teeth</a>, today’s baleen whales instead have baleen – a large rack of fine, hair-like keratin used to filter out small krill from the water.</p>
<p>This structure enabled baleen whales to feed efficiently on <a href="https://www.scientificamerican.com/article/why-are-blue-whales-so-gigantic/">enormous shoals of tiny zooplankton</a> in productive parts of the ocean, which facilitated the evolution of larger and larger body sizes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a large dark humpback whale with its mouth open, showing off what looks like a solid filter at the top of its mouth" src="https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=325&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=325&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=325&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566194/original/file-20231218-21-bvvl3z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The bristle-like baleen, as shown on a humpback whale.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan</span></span>
</figcaption>
</figure>
<h2>The ‘missing years’ of whale evolution</h2>
<p>Various groups of <a href="https://www.telegraph.co.uk/news/2023/08/02/whale-heaviest-animal-ever-lived-perucetus-colossus/">toothed whales</a> terrorised the ocean for millions of years, including some that were the <a href="https://theconversation.com/ancient-ancestors-of-modern-baleen-whales-were-toothy-not-so-gentle-giants-96338">ancestors of the toothless baleen whales</a>. Yet at some time between 23 and 18 million years ago these ancient “toothed baleen whales” went extinct.</p>
<p>We aren’t exactly sure when, as fossil whales from this episode in Earth’s history <a href="https://museumsvictoria.com.au/media-releases/mystery-of-whale-fossil-dark-age-solved-in-new-palaeontology-research/">are exceedingly rare</a>. What we do know is immediately after this gap in the whale fossil record, only the relatively small, toothless ancestors of baleen whales remained. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark silhouette of a whale next to a smaller figure of a whale and even smaller human figure" src="https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566198/original/file-20231218-25-dshb8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The newly described extinct Murray River whale (9 metres) next to a fin whale (26 metres) and a human diver (2 metres).</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan, graphic by Rob French</span></span>
</figcaption>
</figure>
<p>Scientists previously thought baleen whales kept to relatively small proportions until the ice ages (which began from about 3–2.5 million years ago). But the majority of research on trends in the evolutionary history of whales is based on the reasonably well-explored fossil record from the Northern Hemisphere – a notable bias that likely shaped these theories.</p>
<p>Crucially, new fossil finds from the Southern Hemisphere are starting to show us that at least down south, whales got bigger much earlier than previous theories suggest.</p>
<h2>An unexpected find</h2>
<p>More than 100 years ago, palaeontologist Francis Cudmore found the very tips of a large pair of fossil whale jaws eroding out of the banks of the Murray River in South Australia. These 19-million-year-old fossils made their way to Museums Victoria and remained unrecognised in the collection until they were rediscovered in a drawer by one of the authors, Erich Fitzgerald.</p>
<p>Using equations derived from measurements of modern-day baleen whales, we predicted the whale this fossilised “chin” came from was approximately nine metres long. The previous record holder from this early period of whale evolution was only six metres long.</p>
<p>Together with <a href="https://www.nationalgeographic.co.uk/animals/2019/05/fossil-of-85-foot-blue-whale-is-largest-ever-discovered">other fossils</a> from Peru in South America, this suggests larger baleen whales may have emerged much earlier in their evolutionary history and the large body size of whales evolved gradually over many more millions of years than previous research suggested.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's reconstruction of the extinct whale, showing where the fossil is located, and a map of Australia showing the location it was found" src="https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566195/original/file-20231218-30-l3q7vz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The fossilised baleen whale ‘chin’ was found along the banks of the Murray River in South Australia.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan, photo by Eugene Hyland</span></span>
</figcaption>
</figure>
<h2>The Southern Hemisphere as the cradle of gigantic whale evolution</h2>
<p>The large whale fossils from Australasia and South America seem to suggest that for most of the evolutionary history of baleen whales, whenever a large baleen whale shows up in the fossil record, it is in the Southern Hemisphere.</p>
<p>Strikingly, this pattern persists despite the fact the Southern Hemisphere contains less than 20% of the known fossil record of baleen whales. While this is an unexpectedly strong signal from our research, it doesn’t come as a complete surprise when we consider living baleen whales.</p>
<p>Today, the temperate seas of the Southern Hemisphere are connected by the chilly Southern Ocean, which surrounds Antarctica and is <a href="https://niwa.co.nz/productivity-of-the-southern-ocean-antarctica">extremely productive</a>, supporting the greatest biomass of marine megafauna on Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph, showing that baleen whales in the Southern Hemisphere were larger than Northern Hemisphere whales throughout most of the last 23 million years" src="https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566197/original/file-20231218-19-6xezc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fossils from the Southern Hemisphere, including the Murray River whale fossil, are demonstrating that whales may have evolved large body sizes first in the Southern Hemisphere.</span>
<span class="attribution"><span class="source">Art by Ruairidh Duncan</span></span>
</figcaption>
</figure>
<p>Around the time baleen whales started evolving from big to gigantic, the strength of the Antarctic Circumpolar Current was intensifying, eventually leading to the present day powerhouse Southern Ocean. </p>
<p>Today, baleen whales are ecosystem engineers, their huge bodies consuming tremendous amounts of energy. <a href="https://oceanservice.noaa.gov/facts/whale-fall.html">Upon death</a>, these whales provide an abundance of nutrients to deep-sea ecosystems.</p>
<p>As we learn more about the evolutionary history of whales, such as when and where their large size evolved, we can begin to understand just how ancient their role in the ocean ecosystem may have been and how it could shift in tune with global climate change.</p>
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Read more:
<a href="https://theconversation.com/the-true-origins-of-the-worlds-smallest-and-weirdest-whale-208279">The true origins of the world's smallest and weirdest whale</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/219961/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Patrick Rule currently receives funding from an Engineering and Physical Sciences Research Council UKRI Fellowship, and previously received funding from an Australian Research Council Discovery Project.</span></em></p><p class="fine-print"><em><span>Erich Fitzgerald received funding from an Australian Research Council Linkage Project that supported part of this research.</span></em></p>A newly described fossil from South Australia is making waves in our understanding of where and when whales evolved titanic body sizes.James Patrick Rule, Research Affiliate, Monash UniversityErich Fitzgerald, Senior Curator, Vertebrate Palaeontology, Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2152222023-11-21T13:27:15Z2023-11-21T13:27:15ZClimate change is already forcing lizards, insects and other species to evolve – and most can’t keep up<figure><img src="https://images.theconversation.com/files/558259/original/file-20231108-29-upppm0.jpg?ixlib=rb-1.1.0&rect=2%2C2%2C1615%2C1069&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Temperature sensitivity makes western fence lizards vulnerable to climate change.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/blmoregon/47961427128">Greg Shine/BLM</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Climate change is threatening the survival of plants and animals around the globe as temperatures rise and habitats change.</p>
<p>Some species have been able to meet the challenge with rapid evolutionary adaptation and other changes in behavior or physiology. Dark-colored dragonflies are <a href="https://doi.org/10.1073/pnas.2101458118">getting paler</a> in order to reduce the amount of heat they absorb from the sun. Mustard plants are <a href="https://doi.org/10.1098/rspb.2012.1051">flowering earlier</a> to take advantage of earlier snowmelt. Lizards are <a href="https://doi.org/10.1098/rsbl.2020.0625">becoming more cold-tolerant</a> to handle the extreme variability of our new climate.</p>
<p>However, scientific studies show that climate change is occurring much faster than species are changing.</p>
<figure class="align-center ">
<img alt="A tiny, royal blue fish with gold stripes looks into the camera. The downward slant of its mouth and shadow at the top of its eye give it an annoyed look." src="https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&rect=8%2C8%2C5599%2C3724&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558243/original/file-20231108-23-xs3oy9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Zebrafish have evolved to thrive in water a degree or so warmer than normal, but they struggle to survive at higher temperatures.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/brachydanio-rerio-royalty-free-image/154930602?adppopup=true">isoft/E+ Getty Images</a></span>
</figcaption>
</figure>
<h2>What is evolutionary adaptation?</h2>
<p>The word “adaptation” is used in many ways by climate scientists, but it has a very specific meaning to biologists: It refers to genetic changes that are passed on from one generation to the next and improve a species’ ability to survive in its environment.</p>
<p>These genetic modifications make evolutionary adaptation different from “acclimation” or “acclimatization,” which involve advantages that are not passed on to offspring. For example, when people move to high-altitude cities, they <a href="http://dx.doi.org/10.1136/bjsports-2013-092840">start producing more red blood cells</a> as they acclimate to the low oxygen.</p>
<p>All over the world, plants and animals have adapted to many different warm and dry habitats, prompting scientists to <a href="https://doi.org/10.1098/rstb.2018.0176">question</a> <a href="https://doi.org/10.1038/s41586-019-1520-9">whether</a> <a href="https://doi.org/10.1111/gcb.14881">species</a> <a href="https://doi.org/10.1073/pnas.1406314111">might</a> <a href="https://doi.org/10.1111/evo.13862">also</a> <a href="https://doi.org/10.1126/science.1063656">adapt</a> <a href="https://doi.org/10.1073/pnas.0608379104">to</a> <a href="https://doi.org/10.1111/ele.14072">our</a> <a href="https://doi.org/10.1126/science.aba9287">rapidly</a> <a href="https://doi.org/10.1126/science.abj7484">changing</a> <a href="https://doi.org/10.1126/science.aaf3343">climate</a>, <a href="https://doi.org/10.1038/nclimate2628">too</a>.</p>
<p>Thus far, the answer <a href="https://doi.org/10.1002/wcc.852">seems to be no</a> for most species.</p>
<h2>Evolving, fast and slow</h2>
<p>A <a href="https://doi.org/10.1038/s41467-019-10924-4">recent study</a> of the populations of 19 bird and mammal species, including owls and deer, shows one potential barrier to adaptation. </p>
<p>In animals that take several years to reach breeding age, the climate has already shifted by the time their offspring are born. Genes that gave the parents an advantage – like hatching at exactly the right time or growing to the best size – are no longer as beneficial for the offspring.</p>
<p>Populations of these slow-maturing animals are adapting to climate change, but not enough during each generation to thrive in the changing conditions. In fact, the rate of evolution is so mismatched to the rate of global warming that the study’s authors estimate that nearly 70% of the local populations they studied are already vulnerable to climate-driven extinction over the coming decades.</p>
<figure class="align-center ">
<img alt="A dragonfly with dark bands on its wings." src="https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558246/original/file-20231108-27-yipcvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Black bands on dragonflies heat up their bodies. Research shows some dragonflies have evolved smaller black bands as the climate warms.</span>
<span class="attribution"><span class="source">Michael P. Moore</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A heat map clearly shows that the dark bands on the wings absorb more heat." src="https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558248/original/file-20231108-27-nr1728.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In this heat map of the same dragonfly, white areas are the warmest and purple areas are cooler. The dark bands on the wings stand out.</span>
<span class="attribution"><span class="source">Michael P. Moore</span></span>
</figcaption>
</figure>
<p>Small-bodied animals, such as many fish, insects and plankton, typically mature quickly. Yet, recent research on <a href="https://doi.org/10.1073/pnas.2011419117">small fish</a> and a type of <a href="https://doi.org/10.1098/rspb.2011.0542">fast-maturing plankton called a copepod</a> revealed another hurdle for rapid genetic adaptation to climate change.</p>
<p>Many species possess genes that permit them to live in environments that are 1 to 2 degrees Celsius (about 2 to 4 Fahrenheit) warmer than today, but new genetic mutations must arise to enable survival if climates reach 4 to 5 C (about 7 to 9 F) warmer, as is possible in some regions, particularly if greenhouse gas emissions continue at a high rate.</p>
<p>To test species’ resilience, scientists warmed populations of these fast-maturing species over many generations to observe their genetic changes. They found that both the copepods and the small fish were able to adapt to the first couple degrees of warming, but populations soon went extinct above that. This was because genetic mutations that increased their ability to live in hotter conditions occurred at a slower rate than the temperatures rose.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tiny nearly translucent oval creature with a tail and egg sacks trailing behind it." src="https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558242/original/file-20231108-29-dkylc9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A live copepod with egg sacs at 10 times magnification. These ocean creatures produce new generations quickly, allowing for speedier evolution.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/copepod-micrograph-royalty-free-image/170025374?adppopup=true">NNehring/E+ Getty Images</a></span>
</figcaption>
</figure>
<p>Cold-blooded species, such as lizards, frogs and fish, are especially vulnerable to climate change because they have a limited capacity to regulate their own body temperatures. Their ability to evolve in response to climate change is expected to be critical for their survival.</p>
<p>However, rapid adaptation to climate change often comes <a href="https://doi.org/10.1007/BF02984069">at a cost</a>: Populations get smaller due to the deaths of individuals that cannot tolerate new, hotter temperatures. Therefore, even if species do evolve to survive with climate change, their smaller populations may still go extinct due to problems such as inbreeding, harmful new mutations or plain old bad luck, such as a disease epidemic.</p>
<p><a href="https://doi.org/10.1126/science.1184695">In a now-classic study</a>, researchers studying lizards in Mexico discovered that the high death rates of just the heat-sensitive individuals – representing only a subset of the entire population – caused 12% of all lizard populations in Mexico to go extinct between 1975 and 2009. Even with some heat-tolerant adult lizards surviving in each population under the warmer conditions, the researchers estimated climate change would kill so many heat-sensitive adults within each population that 54% of all populations would go extinct by 2080.</p>
<h2>Evolutionary adaptation isn’t species’ only option</h2>
<p>Another way species adjust to rising temperatures is acclimation, sometimes called “phenotypic plasticity.” For example, <a href="https://doi.org/10.1126/science.1157174">great tits in the U.K.</a> – small birds that are common in yards and forests – lay their eggs earlier in warmer years so that their nestlings hatch right as the winter weather ends, no matter when that happens.</p>
<figure class="align-center ">
<img alt="A small bird with a yellow body and black head with white cheeks sits on a branch." src="https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558258/original/file-20231108-21-3e6t6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A great tit – <em>Parus major</em>. In the U.K., these common birds have been laying their eggs earlier in warm years.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/hedera_baltica/49433487712/in">Hedera.Baltica via Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>However, a <a href="https://www.nature.com/articles/s41467-022-32953-2">recent analysis</a> of more than 100 beetle, grasshopper and other insect species all over the world found that acclimation may not help those species enough. The study’s authors found that the species they reviewed gained an average of only 0.1 C (about 0.2 F) greater heat tolerance when acclimating to 1 C (about 2 F) warmer air temperatures during their development. Thus, the rate of global warming seems to be outstripping species’ abilities to acclimate, too.</p>
<p>Plants and animals could also escape the impacts of global warming by migrating to cooler habitats. A <a href="https://doi.org/10.1038/s41559-020-1198-2">global analysis</a> of more than 12,000 different plants and animal species recently showed that many species are migrating toward the poles fast enough to keep pace with rising temperatures, and many <a href="https://doi.org/10.1111/ele.13762">tropical species are moving upslope</a> to higher elevations as well.</p>
<p>Nonetheless, migration has its limits. Research shows that <a href="https://doi.org/10.1073/pnas.1804224115">tropical birds that already live high in the mountains could be doomed</a> because there is no room for them to migrate any farther upward. Tropical species, therefore, may be on what the authors call an “escalator to extinction.”</p>
<figure class="align-center ">
<img alt="A yellow-and-black moth sits on a yellow flower in an alpine field with snow-covered mountains in the background." src="https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=789&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=789&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=789&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=992&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=992&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558253/original/file-20231108-21-ad3ofx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=992&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Police car moths living at high elevations have little room to migrate to escape increasing heat.</span>
<span class="attribution"><span class="source">Michael P. Moore</span></span>
</figcaption>
</figure>
<p>High-latitude and high-elevation habitats also present numerous challenges for species to overcome besides temperature. Our own research across 800 species of insects all over the Earth shows that butterflies, bees and other flying insects are <a href="https://doi.org/10.1038/s41558-023-01794-2">especially hindered from migrating to higher elevations</a> because there is not enough oxygen for them to survive. </p>
<h2>Many species lack obvious climate strategies</h2>
<p>Overall, evolutionary adaptation appears to help lessen the impacts of global warming, but the evidence thus far shows that it is insufficient to overcome current rates of climate change. Acclimation and migration provide faster solutions, but research shows that those may not be enough, either.</p>
<p>Of course, not all evolution is driven by warming temperatures. Plant and animal species appear to be also gradually adapting to other kinds of environments, including <a href="https://doi.org/10.1111/evo.14191">human-created ones like cities</a>. But the fast pace of global warming makes it <a href="https://nca2023.globalchange.gov/chapter/8#fig-8-2">one of the major threats</a> that species must respond to immediately.</p>
<p>The <a href="https://nca2023.globalchange.gov/chapter/8#fig-8-2">evidence indicates</a> that humanity cannot simply assume that plants and animals will be able to save themselves from climate change. To protect these species, humans will have to stop the activities that are fueling climate change.</p><img src="https://counter.theconversation.com/content/215222/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>From dark dragonflies becoming paler to plants flowering earlier, some species are slowly evolving with the climate. Evolutionary biologists explain why few will evolve fast enough.Michael P. Moore, Assistant Professor of Biology, University of Colorado DenverJames T. Stroud, Assistant Professor of Ecology and Evolution, Georgia Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2123082023-10-17T15:29:28Z2023-10-17T15:29:28ZHow animal traits have shaped the journey of species across the globe<p>The devastating <a href="https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/event-more-info/5413">tsunami</a> that hit Japan in March 2011 set off a series of events which have long fascinated scientists like me. It was so powerful that it caused 5 million tonnes of debris to <a href="https://marinedebris.noaa.gov/japan-tsunami-marine-debris/monitoring-tsunami-debris-north-american-shorelines">wash</a> into the Pacific – 1.5 million tonnes remained afloat and started drifting with the currents. </p>
<p>One year later, and half a world away, debris began washing ashore on the west coast of North America. More than 280 Japanese coastal species such as mussels, barnacles and even some species of fish, had <a href="https://www.science.org/doi/full/10.1126/science.aao1498?casa_token=YwHfCNElf14AAAAA:zJj4eY3uUm2_m4ZH5YzIO6ecvSWdVa_53yZk0ycnxm1Ga3bPLTl5Z6hCbUhvsmA4d0KSPHFPKz84nQ">hitched a ride</a> on the debris and made an incredible journey across the ocean. These species were still alive and had the potential to establish new populations. </p>
<p>How animals cross major barriers, such as oceans and mountain ranges, to shape Earth’s biodiversity is an intriguing topic. And a new <a href="https://www.nature.com/articles/s41559-023-02150-5">study</a> by my collaborators and I has shed light on this process, revealing how animal characteristics such as body size and life history can influence their spread across the globe.</p>
<p>We know that such dispersal events occur in terrestrial species as well. For instance, at least 15 green iguanas <a href="https://www.nature.com/articles/26886">journeyed</a> more than 200km (124 miles) from Guadeloupe to Anguilla in the Caribbean in 1995. They arrived on a mat of logs and trees (likely uprooted through a hurricane), some of which were more than 9 metres (20 feet) long. </p>
<h2>The role of animal characteristics in dispersal</h2>
<p>When animals move across major barriers it can have a big impact on both the new and old locations. For example, an invasive species can arrive in a new area and compete with native species for resources. However, those consequences can be even greater over longer periods of time.</p>
<p>The movement of monkeys from Africa to South America around 35 million years ago led to the evolution of more than 90 species of <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-anthro-102116-041510?casa_token=CZtEoQ5Z9bMAAAAA%3AX9JrgVyGxxegDXgVTUPNHZboMldBec1egagn5S4pLwx4yudreF4L6Q6zG4jUeB9tMxJEIy4q67iX&journalCode=anthro">New World monkeys</a>, including tamarins, capuchins and spider monkeys. And a few chameleons rafting on vegetation from Africa to Madagascar is why we find half of all living <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2013.0184">chameleon</a> species there today.</p>
<p>These events were long thought to be determined by chance – the coincidence of some chameleons sitting on the right tree at the right time. However, <a href="https://www.jstor.org/stable/pdf/24529638.pdf?casa_token=NyxiUsFXod0AAAAA:9aBvrCPO0om98AjWOfs482QWf5eQxRUwKt95p4S3trPy1CQ2CM4K0AJeMBtsNKwKST8ILswcwdjQBRq8ZpdR5-3KL3gOn9uYZHOjzDdPyTm4R3Dom1o">some scientists</a> have suggested there might be more to it. They hypothesised there could be more general patterns in the animals that reach their destination successfully, related to certain characteristics.</p>
<p>Could body size affect how far a species can travel? Animals with more fat reserves may be able to travel longer distances. Or could it be how a species reproduces and survives? For example, animals that lay many eggs or mature early may be more likely to establish a new population in a new place.</p>
<p>But despite a vigorous theoretical debate, the options to test these hypotheses were limited because such dispersal events are rare. Also, the right statistical tools were not available until recently.</p>
<p>Thanks to the recent development of new <a href="https://academic.oup.com/sysbio/article/69/1/61/5490843">biogeographical models</a> and the great availability of data, we can now try to answer questions about how tetrapod species (amphibians, reptiles, birds and mammals) have moved around the globe over the past 300 million years and whether successful species share any common characteristics.</p>
<p>These models allow us to estimate the movements of species’ ancestors while also considering their characteristics. We used these models to study 7,009 species belonging to 56 groups of tetrapods.</p>
<h2>What we found</h2>
<p>For 91% of the animal groups we studied, models that included species characteristics were better supported than models that didn’t. This means that body size and life history are closely linked to how successful a species is at moving to and establishing itself in a new location.</p>
<p>Animals with large bodies and fast life histories (breeding early and often, like water voles) generally dispersed more successfully, as expected. However, there were some exceptions to this rule. In some groups, smaller animals or animals with average traits had higher dispersal rates.</p>
<p>For example, small hummingbirds dispersed better than larger ones, and poison dart frogs with intermediate life histories dispersed better than those with very fast or very slow life histories.</p>
<p>We investigated this variation further and found that the relationship between body size and movement depended on the average size and life history of the group. Our results show that the links between characteristics and dispersal success depend on both body size and life history, and that these cannot be considered separately. </p>
<p>Groups in which small size was an advantage were often already made up of small species (making the dispersal-prone species even smaller), and these species also had fast life histories. We found this to be true for the rodent families <a href="https://www.britannica.com/animal/Muridae"><em>Muridae</em></a> and <a href="https://nhpbs.org/wild/cricetidae.asp"><em>Cricetidae</em></a>. </p>
<p>But groups in which dispersers had intermediate body sizes generally had slow life histories (meaning they had low reproductive output but long lifespans). This means the combination of small body size and slow life history is very unlikely to be an advantage for dispersal across major barriers such as oceans.</p>
<h2>It’s not just chance</h2>
<p>It is amazing to think that rare dispersal events, which can lead to the rise of many new species, are not completely random. Instead, the intrinsic characteristics of species can shape the histories of entire groups of animals, even though chance still may play an important role.</p>
<p>At the same time, two of the most important <a href="https://zenodo.org/record/3553579">environmental challenges</a> of our time are related to movement across major barriers: biological invasions and species’ responses to climate change. On a planet facing rapid changes, understanding how animals move across barriers is therefore crucial.</p><img src="https://counter.theconversation.com/content/212308/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>While working on this study, Sarah-Sophie Weil was affiliated with Université Grenoble Alpes (France) and Swansea University (Wales, UK) who supported her through Initiative d’excellence (IDEX) International Strategic Partnership and Swansea University Strategic Partner Research (SUSPR) scholarships.</span></em></p>New research looks at how different species have managed to cross geographic barriers throughout history and whether their individual traits played a crucial role in these journeys.Sarah-Sophie Weil, PhD candidate, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2141012023-09-29T12:39:31Z2023-09-29T12:39:31ZHow the age of mammals could end<figure><img src="https://images.theconversation.com/files/551158/original/file-20230929-25-bq05kz.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C4928%2C3245&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When Pangea Ultima forms, conditions on Earth will be too inhospitable for most mammals to survive. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sand-dunes-sahara-algeria-390895972">Maurus Spescha/Shutterstock</a></span></figcaption></figure><p>Throughout the past 500 million years, our planet has experienced a total of five mass extinctions. One of these – the Permo-Triassic mass extinction event – led to the <a href="https://www.nature.com/articles/ngeo1649">demise of roughly 90%</a> of Earth’s species. </p>
<p>Most of these events have coincided with the formation of a supercontinent, where Earth’s tectonic plates slowly come together and combine.</p>
<p>Scientists predict that Earth’s continents will again merge together in 250 million years to form a supercontinent called “Pangea Ultima”. It will be centred over the equator and it will be hot. According to <a href="https://www.nature.com/articles/s41561-023-01259-3">new research</a> that I carried out with several colleagues from the University of Leeds and Northwestern University in the US, conditions on Pangea Ultima will be too inhospitable for most mammals to survive. </p>
<p>The formation of this supercontinent will drive more volcanic activity, and an older sun will emit more radiation to Earth. This will result in exceedingly hot land surface temperatures, transforming much of the continent into a vast, hot desert reminiscent of the <a href="https://theconversation.com/dune-we-simulated-the-desert-planet-of-arrakis-to-see-if-humans-could-survive-there-170181">desert planet Arrakis</a> from the science-fiction epic Dune.</p>
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Read more:
<a href="https://theconversation.com/dune-we-simulated-the-desert-planet-of-arrakis-to-see-if-humans-could-survive-there-170181">Dune: we simulated the desert planet of Arrakis to see if humans could survive there</a>
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<p>During the hottest months of the year, temperatures could exceed 40°C across most of the supercontinent, with many areas experiencing temperatures surpassing 50°C.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An animation showing the projected monthly surface temperature average on Pangea Ultima." src="https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550018/original/file-20230925-26-w2m6yj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The projected monthly surface temperature average on Pangea Ultima.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41561-023-01259-3">Farnsworth et al. (2023)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>It’s going to get hot</h2>
<p>Currently, mammals are able to survive on roughly <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ddi.12369">two-thirds of Earth’s surface</a>. However, after rearranging the continents without altering other factors, our modelling revealed that the average annual land temperature would increase from the <a href="https://www.ipcc.ch/report/ar6/wg1/">pre-industrial average</a> (about 5°C) to approximately 24°C. This change would reduce the habitable areas on Earth to just 54%.</p>
<p>The primary reason behind this temperature rise is the projected location of Pangea Ultima, which would be centred on the equator. However, various other factors, such as differences in land elevation (higher ground tends to be cooler), the absence of ice sheets and alterations in vegetation patterns and abundance would also contribute to this warming.</p>
<p>Our estimates also indicate that when Pangea Ultima eventually forms, the Sun will be 2.5% brighter than its present state. This increased solar intensity would further elevate the average land temperature on Earth to around 25°C, leaving only a quarter of the planet’s surface habitable.</p>
<p>One uncertainty lies in the atmospheric CO₂ levels at the time of Pangea Ultima’s formation. Our modelling suggests that CO₂ concentrations could reach approximately 613 parts per million (ppm), compared to the typical background level of around <a href="https://climate.nasa.gov/vital-signs/carbon-dioxide/">420 ppm today</a>. This elevation in CO₂ levels would result in average land surface temperatures ranging from 30°C to 35°C, further reducing Earth’s habitability to between 8% and 16%.</p>
<p>If we consider daily maximum temperatures and <a href="https://theconversation.com/what-is-a-heat-dome-an-atmospheric-scientist-explains-the-weather-phenomenon-baking-texas-and-the-southwest-185569">extreme weather events</a>, then temperatures could potentially be pushed above 60°C in some regions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map showing the mean surface temperature on Pangea Ultima of the warmest month." src="https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=476&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=476&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550016/original/file-20230925-17-aytg7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=476&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mean surface temperature of the warmest month.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41561-023-01259-3">Farnsworth et al. (2023)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>Inhospitable conditions</h2>
<p>The key to the success of mammals since the time of the dinosaurs lies in their adaptability. They possess the ability to regulate their body temperature irrespective of changes in the external environment.</p>
<p>For instance, humans cool themselves down during hot weather by sweating, while dogs rely on panting to dissipate heat. Elephants radiate heat through their large ears.</p>
<p>However, when the surrounding air is hotter than the skin’s temperature, the body struggles to shed heat, leading to overheating. Prolonged exposure to such conditions can result in heatstroke, potentially causing <a href="https://www.annualreviews.org/doi/10.1146/annurev-earth-053018-060100">swelling in critical organs</a> like the brain.</p>
<p>Mammals can only endure a specific temperature range. When the dry-bulb temperature (as measured by a standard thermometer) exceeds 40°C, or when the wet-bulb temperature <a href="https://www.pnas.org/doi/10.1073/pnas.0913352107">surpasses 35°C</a> (a lower limit influenced by high humidity), the situation becomes dangerous. <a href="https://journals.physiology.org/doi/full/10.1152/japplphysiol.00738.2021">Recent research</a> even suggests that the wet-bulb temperature limit for humans and most mammals could be as low as 31.5°C. Exposure to such temperatures for just six hours, even when in the shade while wet and with a fan, could result in death.</p>
<p>Some mammals have even lower temperature thresholds. North American moose, for example, have a critical wet-bulb <a href="https://cdnsciencepub.com/doi/10.1139/cjz-2013-0175">temperature threshold of 17°C</a> under calm conditions or 24°C if it is windy.</p>
<h2>Do mammals stand a chance?</h2>
<p>Mammals have endured warm periods in the past, such as the Paleocene-Eocene Thermal Maximum (PETM) approximately 50 million years ago, when Earth’s surface temperature <a href="https://www.sciencedirect.com/science/article/pii/S0012825213001207">increased by about 5°C</a>. But there are some important differences to consider with the formation of Pangea Ultima.</p>
<p>First, the PETM was relatively brief, lasting around <a href="https://www.science.org/doi/10.1126/science.aba6853">100,000 years</a>. Following this, temperatures gradually dropped to more habitable levels. By contrast, Pangea Ultima is predicted to last for tens of millions of years or longer before breaking up. </p>
<p>Second, during the PETM, the continents were positioned in a way that allowed mammals to move more easily towards cooler regions near the poles to escape extreme heat. In Pangea Ultima, the majority of the planet will be concentrated in the tropics, with vast impassable deserts covering much of the supercontinent. This will make it challenging for mammals to travel long distances in search of cooler areas.</p>
<p>Tectonics play a fundamental role in shaping the evolution of life on our planet and will continue to do so. What life form will become dominant if mammals do perish is anyone’s guess. However, mammals will have had a good run.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Alex Farnsworth receives funding from UK Research and Innovation</span></em></p>A supercontinent could raise global temperatures to such a degree that it could wipe out mammals.Alex Farnsworth, Senior Research Associate in Meteorology, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2117122023-08-17T19:42:11Z2023-08-17T19:42:11ZA changing climate, growing human populations and widespread fires contributed to the last major extinction event − can we prevent another?<p>Over the past decade, deadly wildfires have become increasingly common because of both <a href="https://www.scientificamerican.com/article/climate-change-is-escalating-californias-wildfires/">human-caused climate change</a> and <a href="https://www.nytimes.com/2023/08/13/us/hawaii-wildfire-factors.html">disruptive land management practices</a>. Southern California, where the three of us live and work, has been <a href="https://ktla.com/news/the-cities-where-wildfires-threaten-the-most-homes-in-california/">hit especially hard</a>.</p>
<p>Southern California also experienced a wave of wildfires 13,000 years ago. These fires permanently transformed the region’s vegetation and <a href="https://www.science.org/doi/10.1126/science.abo3594">contributed to Earth’s largest extinction</a> in more than 60 million years.</p>
<p>As <a href="https://www.ioes.ucla.edu/person/emily-lindsey/">paleontologists</a>, <a href="https://nhm.org/person/dunn-regan">we have</a> a <a href="https://scholar.google.com/citations?user=_FveDz4AAAAJ&hl=en">unique perspective</a> on the long-term causes and consequences of environmental changes, both those linked to natural climate fluctuations and those wrought by humans. </p>
<p><a href="https://www.science.org/doi/10.1126/science.abo3594">In a new study</a>, published in August 2023, we sought to understand changes that were happening in California during the last major extinction event at the <a href="https://www.britannica.com/science/Pleistocene-Epoch">end of the Pleistocene</a>, a time period known as the Ice Age. This event wiped out <a href="https://www.smithsonianmag.com/science-nature/what-happened-worlds-most-enormous-animals-180964255/">most of Earth’s large mammals</a> between about 10,000 and 50,000 years ago. This was a time marked by dramatic climate upheavals and rapidly spreading human populations. </p>
<h2>The last major extinction</h2>
<p>Scientists often call the past 66 million years of Earth’s history the Age of Mammals. During this time, our furry relatives took advantage of the <a href="https://www.nhm.ac.uk/discover/how-an-asteroid-caused-extinction-of-dinosaurs.html">extinction of the dinosaurs</a> to become the dominant animals on the planet. </p>
<p>During the Pleistocene, Eurasia and the Americas teemed with enormous beasts like woolly mammoths, giant bears and dire wolves. Two species of camels, three species of ground sloths and five species of large cats <a href="https://tarpits.org/research-collections/tar-pits-collections/mammal-collections">roamed what is now Los Angeles</a>.</p>
<p>Then, abruptly, they were gone. All over the world, the large mammals that had characterized global ecosystems for tens of millions of years disappeared. North America <a href="https://www.doi.org/10.1146/annurev.ecolsys.34.011802.132415">lost more than 70%</a> of mammals weighing more than 97 pounds (44 kilograms). South America lost more than 80%, Australia nearly 90%. Only Africa, Antarctica and a few remote islands retain what could be considered “natural” animal communities today.</p>
<p>The reason for these extinctions remains obscure. For decades, paleontologists and archaeologists have debated potential causes. What has befuddled scientists is not that there are no obvious culprits but that there are too many. </p>
<p>As the last ice age ended, a warming climate led to altered weather patterns and the reorganization of <a href="https://doi.org/10.1016/j.quascirev.2015.08.029">plant communities</a>. At the same time, human populations were rapidly increasing and <a href="https://www.worldhistory.org/article/1070/early-human-migration/">spreading around the globe</a>. </p>
<p>Either or both of these processes could be implicated in the extinction event. But the fossil record of any region is usually too sparse to know exactly when large mammal species disappeared from different regions. This makes it difficult to determine whether habitat loss, resource scarcity, natural disasters, human hunting or some combination of these factors is to blame.</p>
<h2>A deadly combination</h2>
<p>Some records offer clues. <a href="https://tarpits.org/">La Brea Tar Pits</a> in Los Angeles, the world’s richest ice age fossil site, preserves the bones of thousands of large mammals that were trapped in viscous asphalt seeps <a href="https://resolver.caltech.edu/CaltechAUTHORS:20191203-160736818">over the past 60,000 years</a>. Proteins in these bones can be precisely dated <a href="https://doi.org/10.1016/j.quageo.2014.03.002">using radioactive carbon</a>, giving scientists unprecedented insight into an ancient ecosystem and an opportunity to illuminate the timing – and causes – of its collapse. </p>
<p>Our recent study from La Brea Tar Pits and <a href="https://en.wikipedia.org/wiki/Lake_Elsinore">nearby Lake Elsinore</a> has unearthed evidence of a dramatic event 13,000 years ago that permanently transformed Southern California’s vegetation and <a href="https://www.science.org/doi/10.1126/science.abo3594">caused the disappearance</a> of La Brea’s iconic mega-mammals. </p>
<p>Sediment archives from the lake’s bottom and archaeological records provide evidence of a deadly combination – a warming climate <a href="https://doi.org/10.1002/jqs.3018">punctuated by decadeslong droughts</a> and rapidly rising human populations. These factors pushed the Southern California ecosystem to a tipping point. </p>
<p><a href="https://www.doi.org/10.1126/sciadv.1501682">Similar combinations</a> of climate warming and human impacts have been blamed for ice age extinctions elsewhere, but our study found something new. The catalyst for this dramatic transformation seems to have been an unprecedented increase in wildfires, which were probably set by humans. </p>
<p>The processes that led to this collapse are familiar today. As California warmed coming out of the last ice age, the landscape became drier and forests receded. At La Brea, herbivore populations declined, probably from a combination of human hunting and habitat loss. Species associated with trees, like camels, disappeared entirely. </p>
<p>In the millennium leading up to the extinction, mean annual temperatures in the region <a href="https://doi.org/10.1016/j.epsl.2019.03.024">rose 10 degrees Farenheit</a> (5.5 degrees Celsius), and the lake began evaporating. Then, 13,200 years ago, the ecosystem entered a 200-year-long drought. Half of the remaining trees died. With fewer large herbivores to eat it, dead vegetation built up on the landscape. </p>
<p>At the same time, human populations began expanding across North America. And as they spread, people brought with them a powerful new tool – fire. </p>
<p>Humans and our ancestors have used fire for <a href="https://www.science.org/content/article/artificial-intelligence-may-have-unearthed-one-world-s-oldest-campfires">hundreds of thousands of years</a>, but fire has <a href="https://www.firescience.gov/projects/09-2-01-9/supdocs/09-2-01-9_Chapter_3_Fire_Regimes.pdf">different impacts in different ecosystems</a>. Charcoal records from Lake Elsinore reveal that before humans, fire activity was low in coastal Southern California. But 13,200 to 13,000 years ago, as human populations grew, fire in the region increased by an order of magnitude. </p>
<p>Our research suggests that the combination of heat, drought, herbivore loss and human-set fires had pushed this system to a <a href="https://www.nature.com/articles/nature11018">tipping point</a>. At the end of this period, Southern California was covered in chaparral plants, which thrive after fires. A new fire regime had become established, and the iconic La Brea megafauna had disappeared.</p>
<h2>Lessons for the future</h2>
<p>Studying the causes and consequences of the Pleistocene extinctions in California can provide valuable context for understanding today’s climate and biodiversity crises. A similar combination of climate warming, expanding human populations, biodiversity loss and human-ignited fires that characterized the ice age extinction interval in Southern California are <a href="https://www.doi.org/10.1126/science.abb0355">playing out again today</a>.</p>
<p>The alarming difference is that temperatures today are rising <a href="https://www.scientificamerican.com/article/todays-climate-change-proves-much-faster-than-changes-in-past-65-million-years/">10 times faster</a> than they did at the end of the ice age, primarily because of the burning of fossil fuels. This human-caused climate change has contributed to a fivefold increase in fire frequency and intensity and the amount of area burned in the state of California in the <a href="https://doi.org/10.1029/2019EF001210">past 45 years</a>. </p>
<p>While California is now <a href="https://earthobservatory.nasa.gov/images/148908/whats-behind-californias-surge-of-large-fires">famous for extreme fires</a>, our study reveals that fire is a relatively new phenomenon in this region. In the 20,000 years leading up to the extinction, the Lake Elsinore record shows very low incidence of any fire even during comparable periods of drought. Only after human arrival does fire become a regular part of the ecosystem. </p>
<p>Even today, <a href="https://www.businessinsider.com/pge-caused-california-wildfires-safety-measures-2019-10">downed power lines</a>, campfires and <a href="https://www.nytimes.com/2020/09/07/us/gender-reveal-party-wildfire.html">other human activities</a> start <a href="https://doi.org/10.1071/WF18026">over 90%</a> of wildfires in coastal California. </p>
<p>The parallels between the late Pleistocene megafaunal extinctions and today’s environmental crises are striking. The past teaches us that the ecosystems we depend upon are vulnerable to collapse when stressed by multiple intersecting pressures. Redoubling efforts to eliminate greenhouse gas emissions, prevent reckless fire ignitions and preserve Earth’s remaining megafauna can help avert another, even more catastrophic transformation.</p><img src="https://counter.theconversation.com/content/211712/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Lindsey receives funding from the National Science Foundation, which funded some of the research reported in this article. </span></em></p><p class="fine-print"><em><span>Lisa N. Martinez receives funding from the National Science Foundation and the UCLA Endowed Chair in Geography of California and the American West. </span></em></p><p class="fine-print"><em><span>Regan E. Dunn receives funding from National Science Foundation and NASA. </span></em></p>New findings from the La Brea Tar Pits in southern California suggest human-caused wildfires in the region, along with a warming climate, led to the loss of most of the area’s large mammals.Emily Lindsey, Associate Curator, La Brea Tar Pits; Adjunct Faculty, Institute of the Environment and Sustainability, UCLA, University of California, Los AngelesLisa N. Martinez, Ph.D. Candidate in Geography, University of California, Los AngelesRegan E. Dunn, Adjunct Professor of Earth Sciences, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2114552023-08-16T14:52:16Z2023-08-16T14:52:16ZMore than half of life on Earth is found in soil – here’s why that’s important<figure><img src="https://images.theconversation.com/files/542806/original/file-20230815-17-8wyoa2.jpeg?ixlib=rb-1.1.0&rect=93%2C67%2C1501%2C831&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Springtails (Fasciosminthurus quinquefasciatus) are found in any damp soil.</span> <span class="attribution"><a class="source" href="https://www.chaosofdelight.org/gallery/5kispkk47gfjazdxskbw7m04mgvga3">Andy Murray/chaosofdelight.org</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>A <a href="https://www.pnas.org/doi/abs/10.1073/pnas.2304663120">recent study</a> has found that soil is home to 59% of all life on Earth, from an insect feeding on the soil surface to a tiny microbe nestled in a soil pore. This discovery crowns soil as the most biodiverse habitat on the planet.</p>
<p>The paper estimates that around 2 million species of <a href="https://www.britannica.com/animal/arthropod">arthropod</a> (think insects and spiders) inhabit the soil – some 30% of all known arthropod species. There are far fewer species of soil specialists such as <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/enchytraeidae"><em>enchytraeidae</em></a> (resembling mini earthworms) and <a href="https://www.britannica.com/animal/oligochaete"><em>oligochaeta</em></a> (worms), with only 770 and 6,000 species respectively. That might not seem like a lot, but it still represents around 98% and 63% of these animal groups.</p>
<p>The variety of mammals living in soil is, by comparison, quite limited. Only 3.8% of mammal species are associated with this habitat. On the other hand, 85% of plants have their roots buried in the soil and around 43% of <a href="https://www.britannica.com/animal/nematode"><em>nematode</em></a> (tiny worms) species call soil their home, or reside within the plants and animals that inhabit it.</p>
<p>However, the number of animal and plant species that live in soil are dwarfed by microscopic organisms. The researchers estimate that a mind-blowing 430 million species (or more than 50%) of bacteria and 5.6 million species (or 90%) of fungi have made soil their home.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-melting-arctic-is-a-crime-scene-the-microbes-i-study-have-long-warned-us-of-this-catastrophe-but-they-are-also-driving-it-207785">The melting Arctic is a crime scene. The microbes I study have long warned us of this catastrophe – but they are also driving it</a>
</strong>
</em>
</p>
<hr>
<p>But perhaps more important than the raw numbers are the functions that this biodiversity performs. The life within the soil not only helps to produce the food we eat, it also plays a crucial role in holding the soil together and even gives us potential sources for new antibiotics and medicines.</p>
<h2>Helping plants grow</h2>
<p>Small animals, including <a href="https://www.britannica.com/animal/earthworm">earthworms</a> and <a href="https://www.britannica.com/animal/springtail">springtails</a>, break down plant material and other forms of organic matter, such as dead insects, and incorporate them into the soil. This process releases the nutrients that most plants rely on to grow. But it’s not the only way that soil organisms <a href="https://theconversation.com/tapping-the-plant-microbiome-to-improve-farming-and-plant-health-36288">help plants gain more nutrition</a>. </p>
<figure>
<iframe src="https://player.vimeo.com/video/222168889" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">How soil organisms break down plant remains and create soil pores.</span></figcaption>
</figure>
<p><a href="https://www.rhs.org.uk/biodiversity/mycorrhizal-fungi"><em>Mycorrhizal</em> fungi</a> (a species of fungi that grow in association with plant roots), for instance, embed themselves in the roots of plants where they extract energy-rich compounds. In return, the fungi help plants expand their reach in the soil, allowing them to access a greater amount of nutrients.</p>
<p>Other species that are vital for food production include <a href="https://www.britannica.com/science/nitrogen-fixing-bacteria">nitrogen-fixing bacteria</a>. They are commonly associated with legumes such as beans and clover. These bacteria convert nitrogen gas from the atmosphere into compounds that the plants can use – an undertaking that can otherwise only be done synthetically, using vast amounts of energy.</p>
<h2>Holding soil together</h2>
<p>As organisms penetrate the soil, whether by burrowing, creating nests or as a means of anchoring themselves, they engineer pathways through the soil and contribute to its structure. Notable examples include <a href="https://www.britannica.com/animal/termite">termites</a> rearranging the soil to create channels for air and water to filter through, as well as <a href="https://doi.org/10.1093/aob/mcab029">roots and root hairs enmeshing soil</a>.</p>
<p>The incorporation of decomposed plant material into the soil serves a similarly crucial purpose. It helps to hold the soil together and creates pores that protect the soil from erosion and increase its capacity to store water.</p>
<p>Some of this organic material is also locked away with soil minerals, leading to the <a href="https://theconversation.com/france-has-a-great-plan-for-its-soil-and-its-not-just-about-wine-47335">storage of carbon</a>. In fact, <a href="https://www.ipcc.ch/site/assets/uploads/2018/03/WGI_TAR_full_report.pdf">soils hold</a> three times as much carbon as vegetation and twice as much as the atmosphere. </p>
<figure class="align-center ">
<img alt="A termite mound on the Savanna." src="https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=546&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=546&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=546&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Termites create structures above and below ground for air and water to move through.</span>
<span class="attribution"><span class="source">John Quinton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Biodiversity increases resilience</h2>
<p>In many cases, these functions involve a variety of species. Having multiple species perform the same function offers a safety net if conditions change, such as during a drought or a flood. </p>
<p>Some species are more resilient to these events than others. When conditions change, unaffected organisms within the soil can step in to fulfil the same functions as those that might have suffered – a process ecologists call “functional redundancy”. This improves the ability of an ecosystem, such as soil, to withstand and recover from environmental shocks. </p>
<p>Soil biodiversity is also a key reservoir for new drugs. Soil bacteria have produced <a href="https://doi.org/10.1016/j.cub.2009.04.001">most of our antibiotics</a>, including streptomycin, chloramphenicol and tetracycline. Unfortunately, the rise of antibiotic resistance has rendered many early antibiotics ineffective. However, searching through different soils is <a href="https://www.nature.com/articles/d41586-018-01931-4">yielding promising new antibiotics</a> with the potential to kill “superbugs” that are resistant to existing drugs.</p>
<figure class="align-center ">
<img alt="A soil animal eating mould." src="https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A peeudachorutes species eating a slime mould.</span>
<span class="attribution"><a class="source" href="https://www.chaosofdelight.org/gallery/m5bftdf81d97p7ib5tgiais5dymfb8">Andy Murray/ChaosofDelight.org</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Soil biodiversity plays an important role in producing the food we eat, sustaining soil health and helping to deliver a range of other services, from sourcing medicines to reducing the impact of floods and droughts. The importance of protecting our soils for future generations becomes ever clearer.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>John Quinton receives research funding from the Natural Environment Research Council, The Engineering and Physical Sciences Research Council and the European Commission</span></em></p>With more than one species for every person on the planet, soils are the most diverse habitat on Earth.John Quinton, Professor of Soil Science, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2090382023-08-10T01:17:41Z2023-08-10T01:17:41ZMeet 5 marvellous mammals of the South Pacific you’ve probably never heard of<figure><img src="https://images.theconversation.com/files/541646/original/file-20230808-21-gvt2ao.jpg?ixlib=rb-1.1.0&rect=20%2C37%2C2741%2C2086&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/waigeo-spotted-cuscus-relaxing-on-branch-1722987340">Arie de Gier, Shutterstock</a></span></figcaption></figure><p>Islands are renowned for their weird and wonderful wildlife. These isolated ecosystems present unparalleled opportunities to study evolution, and the archipelagos of the southwest Pacific are no exception. </p>
<p>This vast and diverse region encompasses 24 nations and territories. It also includes four “<a href="https://www.cepf.net/our-work/biodiversity-hotspots">biodiversity hotspots</a>”: the East Melanesian Islands, Polynesia-Micronesia, New Caledonia and New Zealand. Each contains at least 1,500 plant species found nowhere else on Earth. So their total land area may be small, but south-west Pacific islands punch well above their weight in terms of their contributions to global biodiversity.</p>
<p>Our <a href="https://www.publish.csiro.au/book/7928/">latest book</a> provides glimpses of more than 180 native mammals of the southwest Pacific, on islands that fall under the banners of Polynesia, Micronesia and Melanesia (but excluding the island of New Guinea). Indigenous species of marsupials, bats, rodents and a monotreme are among the animals found here. Not surprisingly, half of these are endemic. Many are found only on a single island or small group of islands.</p>
<p>Let’s meet five charismatic species you’ve probably never have heard of, but simply must get to know.</p>
<h2>1. Black dorcopsis or black forest wallaby (<em>Dorcopsis atrata</em>)</h2>
<p><strong>Conservation status: critically endangered</strong></p>
<p><strong>Distribution: Goodenough Island (Papua New Guinea)</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A drawing of the black dorcopsis or black forest wallaby, side view." src="https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541588/original/file-20230807-19-dbkg37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The black dorcopsis (<em>Dorcopsis atrata</em>) is an enigmatic wallaby from forests on the mountains of Papua New Guinea’s Goodenough Island.</span>
<span class="attribution"><span class="source">Madison Erin Mayfield</span></span>
</figcaption>
</figure>
<p>At the southeastern tip of Papua New Guinea is the gravity-defying Goodenough Island. It looms more than 2,500 metres above sea level, but it’s only about 3,900 metres wide – at the widest point. </p>
<p>Goodenough’s higher peaks are covered in rare forests. Here among the clouds is the only place you’ll find black dorcopsis.</p>
<p>Black dorcopsis often have very worn claws, suggesting they spend a great deal of time <a href="https://www.sciencedirect.com/science/article/abs/pii/S1754504811000195">digging for truffles</a> in the rocky soil. This probably plays an important role in dispersing fungi throughout their habitat. </p>
<p>Curiously, some appear to be wearing white gloves, on one or both front paws. Others do not. No one knows why. </p>
<h2>2. Waigeo cuscus (<em>Spilocuscus papuensis</em>)</h2>
<p><strong>Conservation status: vulnerable</strong></p>
<p><strong>Distribution: Waigeo (Indonesia)</strong></p>
<p>Waigeo cuscus have a remarkable coat. Irregular black splotches stand out against a background of almost pure white. In young animals these contrasting colours are subdued by the presence of blackish-grey tips to the hairs. </p>
<p>The cuscus have been photographed in the branches of fruiting fig (<em>Ficus</em> spp.) and breadfruit (<em>Artocarpus altilis</em>) trees, so they have a taste for fruit.</p>
<h2>3. Bougainville melomys (<em>Melomys bougainville</em>)</h2>
<p><strong>Conservation status: data deficient</strong></p>
<p><strong>Distribution: Bougainville (Papua New Guinea), Choiseul and Mono (Solomon Islands)</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of the native rodent Bougainville melomys standing on brown leaf litter" src="https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541590/original/file-20230807-23-tde9av.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Bougainville melomys (<em>Melomys bougainville</em>) occurs in a wide variety of habitat on the islands of Bougainville, Choiseul and Mono.</span>
<span class="attribution"><span class="source">Stephen Richards</span></span>
</figcaption>
</figure>
<p>Pacific Island native rodents have proven vulnerable to disturbance, but thankfully Bougainville melomys seems to remain relatively common. </p>
<p>The contrast between orange fur on the head and back, and crisp white fur on the belly is rather attractive. </p>
<p>An active climber, Bougainville melomys can be found tiptoeing along thin woody vines (lianas), in fruiting trees among Bismarck common cuscuses (<em>Phalanger breviceps</em>), or scaling the trunks of wild betel nut palms (<em>Areca</em> spp.). They’ll tolerate disturbance and have been known to visit village edges to nibble on cultivated bananas.</p>
<h2>4. Lesser sheath-tailed bat (<em>Mosia nigrescens</em>)</h2>
<p><strong>Conservation status: least concern</strong></p>
<p><strong>Distribution: Widespread throughout Indonesia, Papua New Guinea and Solomon Islands</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of three lesser sheath-tail bats huddled under a palm tree leaf" src="https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541591/original/file-20230807-675-za2v2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lesser sheath-tail bats (<em>Mosia nigrescens</em>) are endearing little animals that roost in ‘tents’ under palm tree leaves across parts of Melanesia.</span>
<span class="attribution"><span class="source">Stephen Richards</span></span>
</figcaption>
</figure>
<p>If you’re quiet and patient while walking through the palm-filled lowland forests of Melanesia, you might be lucky enough to spot one of the region’s smallest and most common echo locating bats. </p>
<p>Lesser sheath-tailed bats are alert little creatures with good eyesight. They rest in small groups huddled together under the cover of a palm leaf where they’re sheltered from the rain. Although watchful, they’ll stay in place if approached with caution, allowing time to view how neatly stacked they are. </p>
<p>Lesser sheath-tailed bats are among the first to emerge of an evening, leaving their palm tree tents while there is still plenty of twilight. They fly in sharp circles in the open spaces above forests and villages. Then as darkness falls, they move away to focus on other areas. </p>
<p>Later in the evening you can find them back in the same roosts, again lined up front to back, taking a breather from their busy schedule of hunting for insects on the wing.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/pacific-island-bats-are-utterly-fascinating-yet-under-threat-and-overlooked-meet-4-species-165765">Pacific Island bats are utterly fascinating, yet under threat and overlooked. Meet 4 species</a>
</strong>
</em>
</p>
<hr>
<h2>5. Palau flying-fox (<em>Pteropus pelewensis</em>)</h2>
<p><strong>Conservation status: vulnerable</strong></p>
<p><strong>Distribution: Ulithi, Yap (Federated States of Micronesia), Palau</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of a Palau flying-fox with outstretched wings, flying over a green landscape." src="https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541592/original/file-20230807-27645-ndrc99.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Palau flying-fox (<em>Pteropus pelewensis</em>) has suffered from hunting and international trade.</span>
<span class="attribution"><span class="source">Thibaud Aronson</span></span>
</figcaption>
</figure>
<p>The south-west Pacific supports an incredible diversity of endemic <em>Pteropus</em> flying-foxes. Over-harvesting and international trade for human consumption pushed most of Micronesia’s flying-foxes to the brink of extinction (and in fact did send two species extinct). </p>
<p>Thankfully the introduction of restrictions under the <a href="https://cites.org/eng">Convention on International Trade in Endangered Species</a> stabilised populations of the Palau fying-fox. However, it remains <a href="https://www.iucnredlist.org/species/118093652/206768055">vulnerable</a> and threatened by habitat loss and climate change.</p>
<h2>So much to learn</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustrated book cover for Mammals of the South-West Pacific" src="https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=865&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=865&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=865&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1087&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1087&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541608/original/file-20230808-25-kenxlv.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1087&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>The species showcased here represent just a small fraction of the diversity of south-west Pacific mammals. </p>
<p>So many unique species evolved here, on discrete areas of land separated by ocean. </p>
<p>Unfortunately islands are also vulnerable to human disturbance and extinctions have <a href="https://theconversation.com/pacific-island-bats-are-utterly-fascinating-yet-under-threat-and-overlooked-meet-4-species-165765">already occurred</a> here. </p>
<p>There is still much to learn about many of these mammals. We hope <a href="https://www.publish.csiro.au/book/7928/">this book</a> will inspire more research, including how we can keep these fascinating island inhabitants thriving in a time of such great environmental change. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-werent-to-blame-for-the-extinction-of-prehistoric-island-dwelling-animals-160092">Humans weren't to blame for the extinction of prehistoric island-dwelling animals</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/209038/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tyrone Lavery has received funding from the Critical Ecosystem Partnership Fund, The Australian Museum, The Field Museum of Natural History, Fondation Segre, The Australia Pacific Science Foundation, and the National Science Foundation.</span></em></p>From the cuscus with the fancy coat, to the wallaby often sporting a single white glove, a wide variety of life evolved on island homes in the south-west Pacific.Tyrone Lavery, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2090932023-07-13T13:35:01Z2023-07-13T13:35:01ZChildren have a skewed view of the natural world – but it doesn’t have to be that way<figure><img src="https://images.theconversation.com/files/536877/original/file-20230711-2328-hduubb.jpg?ixlib=rb-1.1.0&rect=1070%2C31%2C5214%2C4626&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/african-american-little-girls-friends-exploring-2187306085">KlingSup/Shutterstock</a></span></figcaption></figure><p>Children’s books and TV shows are full of animals, but how well do kids really know the natural world?</p>
<p>The vast majority of the world’s known animal species – <a href="https://ourworldindata.org/grapher/number-of-described-species?country=Fishes%7EInsects%7EReptiles%7EMammals%7EBirds%7EAmphibians%7EMolluscs%7ECrustaceans%7EArachnids%7EPlants%7EAll%2Bgroups%7EInvertebrates">96.9%</a> – are invertebrates, such as insects, snails, spiders and worms. But when my colleagues and I asked a large group of children to draw animals from their garden or local park, most of the <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0287370">resulting pictures</a> were of mammals or birds.</p>
<p>This suggests there’s a disconnect between children’s perception of the wildlife surrounding them and what is actually there. If we don’t address this, we risk leaving children with a skewed view of the natural world, which has implications for efforts to tackle biodiversity loss and climate change.</p>
<figure class="align-left ">
<img alt="Child's pencil drawing with animals such as an owl, hedgehog, blue tit and robin labelled." src="https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=817&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=817&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=817&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1027&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1027&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536543/original/file-20230710-17-etza9w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1027&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A child’s drawing of the animals in their garden.</span>
<span class="attribution"><span class="source">Kate Howlett</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We asked over 400 children aged between seven and 11, under the supervision of their teachers, to draw a picture of their garden or local park, and to label all the animals they thought lived there.</p>
<p>We collected 401 drawings in total. We counted how many different types of animal were drawn by each child, and which were drawn the most and least often.</p>
<p>We found that the children’s drawings did not reflect the make up of the natural world very well. We noticed that 80.5% of drawings contained at least one mammal and 68.6% featured at least one bird.</p>
<p>In the outside world, though, just <a href="https://ourworldindata.org/grapher/number-of-described-species?country=Fishes%7EInsects%7EReptiles%7EMammals%7EBirds%7EAmphibians%7EMolluscs%7ECrustaceans%7EArachnids%7EPlants%7EAll%2Bgroups%7EInvertebrates">4.7% of animal species described by science</a> are vertebrates, such as mammals, birds, reptiles, amphibians and fish.</p>
<figure class="align-right ">
<img alt="A child's drawing of the plants and animals in their garden." src="https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=819&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=819&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=819&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1029&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1029&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535765/original/file-20230705-15-ey6m80.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1029&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A child’s drawing of their garden.</span>
<span class="attribution"><span class="source">Howlett, Turner, 2023, PLOS ONE.</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>A third of the drawings contained no invertebrates at all. And when asked to name the creatures they’d drawn, the children were far less able to give detailed information about insects and other invertebrates. While they could often give specific species names for mammals and birds, this was not often the case for these smaller, overlooked animals.</p>
<p>For instance, many children were able to identify a bird as being a robin in particular. For insects, the equivalent might be being able to point to a red admiral butterfly. But the children mostly labelled butterflies simply as “butterfly”.</p>
<h2>Biases matter</h2>
<p>This bias mirrors <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1002/pan3.10431">those we previously found in nature documentaries</a>, which in turn reflect people’s tendency to <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/j.1755-263X.2012.00229.x">pay more attention to larger, more charismatic species</a> that are more similar to humans than invertebrates.</p>
<figure class="align-center ">
<img alt="Child's drawing of a fox, labelled as 'fox' with 'squirrle' crossed out" src="https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=290&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=290&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=290&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=364&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=364&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535766/original/file-20230705-21-m26a2j.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=364&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A drawing of a fox.</span>
<span class="attribution"><span class="source">Kate Howlett</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This can have knock-on effects for conservation funding. The animals we consider more attractive <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969717307726">receive higher levels of support</a>.</p>
<p>Insects and other invertebrates are crucial to the functioning of global ecosystems, and they will need our efforts to protect them as we attempt to combat climate change and biodiversity loss. </p>
<p>We know that when children spend <a href="https://www.jstor.org/stable/10.7721/chilyoutenvi.16.1.0001#metadata_info_tab_contents">time in nature</a> they become adults who care about the environment. But many <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1002/pan3.10128">children are growing up without</a> a <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1002/fee.1225">strong connection to the natural world</a>, even though we know spending time in nature is <a href="https://journals.sagepub.com/doi/abs/10.1177/0885412215595441">good for them</a>.</p>
<figure class="align-center ">
<img alt="A child's drawing of their back garden, with animals and plants labelled." src="https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&rect=7%2C3%2C2536%2C1602&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=476&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=476&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536548/original/file-20230710-23-pdyfuq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=476&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A child’s drawing of their back garden, with animals and plants labelled.</span>
<span class="attribution"><span class="source">Kate Howlett</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Children in many countries have <a href="https://www.tandfonline.com/doi/abs/10.1080/14733280500352912">dramatically less</a> freedom than they did in the past to roam and play freely in the area around their homes. In the UK, they now spend <a href="https://www.childinthecity.org/2018/01/15/children-spend-half-the-time-playing-outside-in-comparison-to-their-parents/?gdpr=accept">half as much time</a> playing outside as their parents did when they were young.</p>
<p>It also isn’t inevitable that children have a bias towards mammals, which probably stems from the wider cultural emphasis on mammals and birds. Parents and teachers can help children develop a good understanding of what nature is really like by helping them see more wildlife up close.</p>
<h2>How to introduce children to invertebrates</h2>
<p>When out with your child in your garden or local park, you can help them expand their understanding of the wildlife around them – and set them on the path to being the ecologists we’ll need in the future.</p>
<p>You may be able to spot black, hairy caterpillars on <a href="https://www.wildlifetrusts.org/wildlife-explorer/wildflowers/stinging-nettle">stinging nettles</a> around July. These are most likely the caterpillars of the <a href="https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/butterflies/red-admiral">red admiral</a>, <a href="https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/butterflies/peacock">peacock</a> or <a href="https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/butterflies/small-tortoiseshell">small tortoiseshell</a> butterflies. These are some of the UK’s largest, easiest-to-spot butterflies and caterpillars.</p>
<p>Turn over any brick or stone and you are more likely than not to find some <a href="https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/crustacea-centipedes-and-millipedes/common-woodlouse">woodlice</a>. The females carry their young around in a pouch on their undersides, just like a kangaroo. And children may be delighted to learn that woodlice can <a href="https://www.youtube.com/watch?v=SMB1UEEQwnM">drink through their bums</a>. </p>
<p><a href="https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/dragonflies">Dragonflies</a> and <a href="https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/damselflies">damselflies</a> are easy to spot and impressive, fast fliers. They are also excellent indicators of good water quality. This is because their nymphs – the young larval form – live underwater and need clear water to be able to hunt.</p>
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<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 20,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/209093/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Howlett does not work for, consult with or own shares in any company or organisation that would benefit from this article. She received funding from the Natural Environmental Research Council via grant NE/L002507/1. She is a member of the Green Party, the Women's Equality Party and the charity Pregnant Then Screwed.</span></em></p>Their drawings did not reflect the make up of the natural world.Kate Howlett, PhD candidate in Zoology, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2086942023-06-30T10:51:08Z2023-06-30T10:51:08ZDid our mammal ancestors live alongside dinosaurs? New research hopes to end long-running debate<figure><img src="https://images.theconversation.com/files/534772/original/file-20230629-25-yojgb1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4992%2C3113&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/scene-dinosaurs-asteroid-explosion-end-prehistoric-1944614881">david.costa.art/Shutterstock</a></span></figcaption></figure><p>If you were asked to think of a mammal, chances are high you would think of a placental mammal – horses, dogs, cats, humans, even bats and rats all fall into that category. It includes <a href="https://academic.oup.com/jmammal/article/99/1/1/4834091">some 6,000 species</a> who live in the oceans as well as on land. </p>
<p>Today placentals are by far the most abundant and widespread mammals, although there are two other groups, monotremes (echidnas and platypuses) and marsupials (pouched kangaroos and koalas).</p>
<p>Debate has raged for many years among palaeontologists (who study the earth through fossils) over whether placental mammals, evolved alongside dinosaurs or appeared only after they died out.</p>
<p>My team’s <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(23)00767-4">study used a new method</a> to investigate this question and our findings may help settle this debate. We think placental mammals may have evolved roughly 70 million years ago, meaning they would have walked the Earth at the same time as the dinosaurs.</p>
<h2>Estimating origins</h2>
<p>There are two main methods palaeontologists use to estimate when a group of animals first evolved. The first is reading the fossil record - the oldest fossil in a group determines the date when it first evolved. For placental mammals, there are a couple of fossils from around 65 million years ago, just after the mass extinction of dinosaurs. These include <em>Purgatorius</em>, considered <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.210050">an ancestor of primates</a> (and thus humans).</p>
<p>However, the <a href="https://royalsocietypublishing.org/doi/full/10.1098/rstb.2015.0130">fossil record is full of gaps</a>. Only a <a href="https://www.lyellcollection.org/doi/abs/10.1144/SP358.6">fraction of life has ever been fossilised</a>, and fossil hunters have probably only found a small percentage of the organisms preserved in Earth’s sediments. A species’ chance of featuring in a scientific study as a fossil are similar to winning the lottery. </p>
<p>Another way of estimating when groups first evolved is through <a href="https://theconversation.com/explainer-what-is-the-molecular-clock-46242">molecular clock</a> dating studies. Scientists can compare the DNA of organisms to work out when they emerged as distinct species. </p>
<p>Two species that are similar in their genetic makeup probably have family trees that split from each other fairly recently. Very different species diverge further back in time, allowing for the build-up of more genetic differences. </p>
<p>The genetic difference between two species is roughly proportional to their time of evolutionary divergence, or their origin.</p>
<p><a href="https://www.ucl.ac.uk/biosciences/news/2022/jan/species-level-timeline-mammal-evolution-integrating-phylogenomic-data">Molecular clock studies</a> of placental mammals suggest the group first evolved in the Cretaceous period, around 80 million years ago and nearly 20 million years before fossils of placental mammals first start to appear. So which is correct?</p>
<h2>Rocks or clocks?</h2>
<p>In our <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(23)00767-4">study, published in Current Biology</a>, my colleagues and I used a new method of interpreting the fossil record to estimate the age of placental mammals: statistical analysis.</p>
<p>First, we gathered records of more than 15,000 fossils of placental mammals, focusing on those that are well-researched enough to place in the placental mammal family tree. The <a href="https://www.nature.com/articles/s41559-020-01387-8">Bayesian Brownian Bridge</a> (BBB) model is a scientific formula that uses the distribution of fossils through time to estimate the age of a group. We used the BBB to estimate the ages of 380 families within placental mammals.</p>
<p>Rather than comparing species directly to each other like in molecular clock studies, the BBB model allowed us to take a wider view and compare families. As well as following the pattern of a family’s diversity through time, the BBB model also estimates a sampling rate, or how frequently fossils appear in the fossil record.</p>
<p>This helped us to fill the gaps in the fossil record. </p>
<p>For young lineages that evolved only a few hundred thousand years ago, this sampling rate may be quite high, because we have more fossils from <a href="https://thesedimentaryrecord.scholasticahq.com/article/31399-we-need-a-global-comprehensive-stratigraphic-database-here-s-a-start">younger rocks</a>. Younger rocks are more intact, and often closer to the surface. But for older groups, the sampling rate may be quite low because geological processes degrade and destroy rocks and fossils over time. </p>
<p>Additionally, a species needs to be fairly widespread and abundant to be fossilised, otherwise it has very little chance of winning that lottery. Which means the age of a group will always be older than the oldest fossil in that group, but it doesn’t tell us by how much. </p>
<h2>The origins of placental mammals</h2>
<p>This is what the sampling rate helps with - families with low sampling rates likely had more of a gap between the oldest fossil and the true origin of that family.</p>
<p>The BBB model estimated the age of placental mammals to be within the Cretaceous period, around 70-80 million years ago – possibly up to 20 million years before the asteroid impact. </p>
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<p>Our results show that placental mammals co-existed with dinosaurs for several million years. Ancestors to rabbits and hares (<em>Lagomorpha</em>), cats and dogs (<em>Carnivora</em>) and primates probably all evolved in the time of dinosaurs. Early placental mammals were probably <a href="https://www.science.org/doi/10.1126/science.1229237">small and shrew-like</a>. </p>
<p>From an origin at the feet of dinosaurs, placental mammals have soared to become the most dominant animals on Earth.</p><img src="https://counter.theconversation.com/content/208694/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Carlisle receives funding from the University of Bristol. </span></em></p>New research shows that placental mammals survived the mass extinction that killed the
dinosaurs.Emily Carlisle, PhD student in Palaeobiology, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2073512023-06-08T19:17:59Z2023-06-08T19:17:59ZWhile humans were in strict lockdown, wild mammals roamed further – new research<p>At one point in 2020, 4.4 billion people – more than half of the world’s population – were under lockdown restrictions to stem the spread of COVID-19. This was such a sudden and substantial event that it has become known as the <a href="https://doi.org/10.1038/s41559-020-1237-z">anthropause</a>.</p>
<p>Many bustling cities fell silent, often with restaurants, shops and schools closing, and only essential services allowed to operate. It was around this time when people started to report animals appearing in unusual places. For example, <a href="https://www.reuters.com/article/uk-health-coronavirus-chile-puma-idUKKBN21K36U">cougars</a> were seen prowling through the suburbs of Santiago, Chile, <a href="https://www.timesofisrael.com/jackals-roam-deserted-tel-aviv-park-as-virus-forces-public-indoors/">golden jackals</a> became more active during the day in Tel Aviv, Israel, and dolphins appeared in the normally busy harbour of Trieste, Italy.</p>
<p>Meanwhile, scientists began to wonder whether this tragic event could provide an opportunity to learn how humans impact the behaviour of wildlife. A group of animal movement researchers came together in 2020 and formed the <a href="https://www.bio-logging.net/">COVID-19 Bio-Logging Initiative</a>, which I joined in 2021.</p>
<p>The initiative includes researchers who were already studying animals before the pandemic, and who were using bio-logging devices, such as GPS tags, to record animal movements. These devices – which use technology that you might find in a smartphone or watch – were still recording information while research teams were under lockdown.</p>
<h2>What animals did in lockdown</h2>
<p>We were interested in finding out how animal movements might have changed when human activities were restricted – were the animals really altering their behaviour because human mobility had changed, or was it that people had more time to notice animals in these apparently unusual places? The initiative includes several projects tackling this question from different angles, with our first findings now published. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small deer in deserted street beside shuttered shops" src="https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530958/original/file-20230608-17666-hfat5o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Japan, May 2020: no humans to be seen.</span>
<span class="attribution"><span class="source">worldlandscape / shutterstock</span></span>
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<p>My colleague Marlee Tucker, an ecologist from Radboud University in the Netherlands, led an international team of 174 scientists who focused on studying whether the behaviour of large land mammals changed during the pandemic. Our results are in the journal <a href="https://www.science.org/doi/10.1126/science.abo6499">Science</a>.</p>
<p>By pooling data from over 2,300 individual tracked mammals, from 43 species including elephants, giraffes, bears, deer and cougars, we were able to look at how their behaviour and movement patterns changed during the lockdowns in 2020 compared to the same period one year earlier.</p>
<p>Animal movements can be influenced both by human mobility – people and vehicles moving in the landscape – and the built environment. It is normally impossible to distinguish these two effects because they are closely matched with each other, but the lockdown provided a chance for us to do this.</p>
<h2>Exploring new areas</h2>
<p>We found that mammals were 36% closer to roads during lockdown, and that their movement distances over ten days were 73% longer during strict lockdowns compared to the same period one year earlier. It may be that mammals ventured closer to roads with reduced levels of traffic, while the absence of humans in the environment may have allowed them to explore new areas.</p>
<p><a href="https://doi.org/10.1016/j.cub.2021.06.050">For example</a>, a team led by ecologist Chris Wilmers found that cougars, which are typically secretive animals that avoid areas of human habitation, ventured far closer to the built-up areas of Santa Cruz, California, in 2020 than in previous years.</p>
<figure class="align-center ">
<img alt="Three cougars crossing a road." src="https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=378&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=378&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=378&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531097/original/file-20230609-9440-byp5nm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cougars – or mountain lions – moved nearer to urban areas during lockdown.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/three-wild-cougars-puma-concolor-torres-1283588818">Agami Photo Agency/Shutterstock</a></span>
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<p>Our results were quite variable across species, which may be a result of lockdown policies varying between countries, but it could also be related to other factors, such as differences between species in their ability to change behaviour. Perhaps some species are more flexible in how they respond to changes in human activities.</p>
<p>These findings are important as they tell us that humans moving in the environment directly influence animal movements and behaviour, in addition to the effects of the built environment. With this knowledge we can start to think of new ways to change our behaviour that will positively impact wildlife. For example, we could adjust traffic flows in areas important for animal movement – in some national parks you can only drive during the day to avoid disturbing animals at night.</p>
<p>The COVID-19 Bio-Logging Initiative continues to investigate how changes in human mobility impact animal movements, with ongoing work that includes a study focusing on birds of prey, another on the marine environment, and a project comparing responses of birds and mammals in North America. Some members of the team recently had the chance to meet in-person for the first time at a workshop to discuss our projects and it was so exciting to meet these people that I had only ever worked with online.</p>
<p>Of course, humans moving around the landscape is only one of many impacts we have on wildlife. But the information gained from this research gives us the opportunity to think of new approaches to improve human-wildlife coexistence, and there is no time to lose.</p><img src="https://counter.theconversation.com/content/207351/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Patchett is a member of the COVID-19 Bio-Logging Initiative, which is funded in part by the Gordon and Betty Moore Foundation (GBMF9881) and the National Geographic Society (NGS-82515R-20) (grants to C. Rutz).</span></em></p>Researchers tracked 2,300 wild mammals during the strict 2020 lockdowns and found they moved 73% further than in the previous year.Robert Patchett, Postdoctoral Research Fellow, Covid-19 Bio-Logging Initiative, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2051172023-05-12T04:59:07Z2023-05-12T04:59:07ZThese giant ‘drop bears’ with opposable thumbs once scaled trees in Australia. But how did they grow so huge?<figure><img src="https://images.theconversation.com/files/525778/original/file-20230512-19-51iaj3.JPG?ixlib=rb-1.1.0&rect=0%2C245%2C2444%2C1821&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Peter Schouten</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Although long dead, fossil skeletons provide an incredible window into the lifestyle and environment of an extinct animal.</p>
<p>By analysing the various features of fossil bones we can reveal not only the overall size and shape of the animal, but also what kind of movement the animal was capable of, its lifestyle, and the environment in which it lived.</p>
<p>But what if we looked <em>inside</em> fossil bones? What secrets would it reveal about the growth and development of an extinct animal? In a newly published paper in the <a href="https://doi.org/10.1017/jpa.2023.22">Journal of Paleontology</a>, we have done just that, using 15 million-year-old skeletons of a giant bear-like marsupial from the world-famous Riversleigh World Heritage Area (Boodjamulla) in Waanyi country of northwest Queensland. </p>
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Read more:
<a href="https://theconversation.com/fossils-reveal-australias-tree-top-heavyweight-herbivore-10888">Fossils reveal Australia's tree-top heavyweight herbivore</a>
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<h2>Tree-dwelling wombat relatives</h2>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A colourful drawing of a bear like animal and its young in a flowering tree branch" src="https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=879&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=879&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=879&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1105&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1105&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525576/original/file-20230511-23-cii6w1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1105&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reconstruction of a mother and baby <em>Nimbadon</em>. They had powerful arms, large hands and feet and huge claws to assist climbing through the rainforest tree tops.</span>
<span class="attribution"><span class="source">Peter Schouten</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The huge tree-dwelling herbivorous marsupials, known as <em>Nimbadon</em>, weighed about 70kg, making them the largest arboreal (tree dwelling) mammals known from Australia.</p>
<p><em>Nimbadon</em> belongs to a diverse group of long extinct, large-bodied marsupials <a href="https://theconversation.com/giant-marsupials-once-migrated-across-an-australian-ice-age-landscape-84762">known as diprotodontoids</a>, the likes of which include the largest marsupial to have ever lived, the 2.5 tonne megafaunal <em>Diprotodon</em>, and bizarre trunked marsupials reminiscent of modern-day tapirs.</p>
<p>Among living animals, <em>Nimbadon</em> is most closely related to wombats. Yet surprisingly, in terms of body size and lifestyle, they are more comparable to <a href="https://www.nationalgeographic.com/animals/mammals/facts/sun-bear">sun bears</a>, which today can be found scaling the rainforest canopies of Southeast Asia.</p>
<p>When we first uncovered jawbones of <em>Nimbadon</em> at Riversleigh in 1993, we thought we were looking at very large leaf-eating marsupials who foraged for food on the forest floor.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark brown animal shaped roughly like a bear with a yellow snout asleep on a tree with big curved claws visible" src="https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525776/original/file-20230512-19-8b7knt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Modern-day sun bears climb trees and lounge there much like sloths do.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/lazy-sun-bear-snoozes-on-tree-3229256">Shutterstock</a></span>
</figcaption>
</figure>
<p>But like many of the species we’ve unearthed from Riversleigh, the closer we look at these animals, the more bizarre and fascinating they become.</p>
<p><em>Nimbadon</em> is now known from its complete skeleton, including material representing developmental ages ranging from tiny pouch-young to mature adults. It had strong arms with very mobile shoulder and elbow joints. Its hands and feet had specially adapted opposable thumbs with huge curved claws for climbing, penetrating bark and grasping branches.</p>
<p>These animals were highly specialised climbers and lived vastly different lifestyles compared to their closest living relatives – the land-dwelling, burrowing wombats.</p>
<p>Our initial research showed that <em>Nimbadon</em> was not only a “tree-hugger”, but also a “tree-hanger”, spending some of its time suspended from tree branches like a sloth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="yellow bones of a skeleton of a bear like animal on a black background" src="https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=537&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=537&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525564/original/file-20230511-25-ixau5w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=537&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fossil skeleton of a mature adult <em>Nimbadon</em>.</span>
<span class="attribution"><span class="source">Karen Black</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><em>Nimbadon</em> lived 15 million years ago in the canopy of lowland Australian rainforests. These biodiverse, lush forests were home to some equally strange animals: flesh-eating kangaroos, tree-climbing crocodiles, ancestral thylacines, cat- to leopard-sized marsupial lions, huge anaconda-like snakes, giant toothed platypuses and mysterious marsupials so strange they have been called “Thingodonta”. It was a very different Australia than the one we see today.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-the-giant-wombat-relative-that-scratched-out-a-living-in-australia-25-million-years-ago-141296">Meet the giant wombat relative that scratched out a living in Australia 25 million years ago</a>
</strong>
</em>
</p>
<hr>
<h2>Sectioning the bones</h2>
<p>Despite the wealth of information we have gleaned from <em>Nimbadon</em> skeletons, until now we hadn’t fully understood the growth patterns of these ancient marsupials. </p>
<p>Were they affected by seasonality? How long did they take to grow to adult body size in the canopies of the ancient forest? Clues to these questions lay in the bones’ microscopic structure.</p>
<p>To look inside the fossil bones, we needed to select the right material. Long bones, such as the bones of the leg, are known to preserve a good record of growth, so we analysed ten long bones of several different-sized individuals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large pink and grey rock with outlines of bones visible in it" src="https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525578/original/file-20230511-9582-qqy2f5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Articulated fossilised Nimbadon skeletons in a large slab of limestone recovered from a 15 million year old fossil cave deposit in the Riversleigh World Heritage Area, northwestern Queensland.</span>
<span class="attribution"><span class="source">Anna Gillespie</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We began by removing a section from the shaft of the bone, and embedded it in resin. Using a diamond-edged blade, we cut our samples into thin sections and polished them further until light could pass through them. These thinned sections were mounted on glass microscope slides to be studied.</p>
<p>Remarkably, even after millions of years of fossilisation, the microscopic structure of the fossil bones had remained intact. We were amazed to discover that <em>Nimbadon</em> grew in periodic spurts. Individuals had fast growth periods, each followed by a slow growth period, often associated with a band of arrested growth.</p>
<h2>Seasonal growers</h2>
<p>Cyclical growth patterns have previously been documented for marsupials such as in the living western grey kangaroo. However, our results indicate that, overall, the limbs of <em>Nimbadon</em> had a much slower, more extenuated growth than kangaroo limbs.</p>
<p>One individual recorded at least seven to eight growth cycles, which suggests this arboreal giant needed at least this amount of time – and probably more – to become a fully-grown, sexually mature adult. </p>
<p>Based on these alternating cycles of fast and slow growth, <em>Nimbadon</em> may have been affected by seasonal conditions such as food availability. However, exactly how long it took for eight growth cycles to develop remains a mystery. If indeed they represent annual cycles, it would be at least eight years until sexual maturity, which is unusual in the modern marsupial world.</p>
<p>For example, kangaroos are sexually mature at one to two years. That being said, <em>Nimbadon</em> is an unusual beast and a very large one at that, so an extended developmental period (and lifespan) is not unlikely.</p>
<h2>Real-life drop bears</h2>
<p>We have come to think about these strange arboreal marsupials as real versions of the legendary “drop bears” of Australian folklore – mysterious tree-dwelling creatures that would drop down on unsuspecting animals below. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A drawing of a forest with large animals in trees and a cave visible underground" src="https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=586&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=586&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=586&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=736&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=736&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525574/original/file-20230511-10438-r2hri4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=736&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reconstruction of Nimbadon’s palaeoenvironment of lush rainforest with underground caves.</span>
<span class="attribution"><span class="source">Karen Black</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While moving in herds through the rainforest canopy, both young and adult <em>Nimbadon</em> would have occasionally lost their grip before dropping down from the treetops. Sometimes they would end up in forest floor caves, which is where we have been finding their still-articulated skeletons.</p>
<p>Given the constant surprises that research into this extraordinary, extinct Riversleigh mammal has already produced, we are eager and prepared for still more.</p>
<p>Currently we are looking into wear in the enamel microstructure of <em>Nimbadon</em>’s teeth to determine this legendary drop bear’s diet. We expect that what we find down the track will continue to upend our naïve first presumptions about the lifestyles of this and many of the other strange inhabitants of the ancient inland rainforests of Riversleigh.</p><img src="https://counter.theconversation.com/content/205117/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anusuya Chinsamy-Turanis is based at the University of Cape Town in South Africa, and receives funding from National Research Foundation, South Africa, grant number, 136510. </span></em></p><p class="fine-print"><em><span>Karen Black receives funding for the work at Riversleigh and preparation of the fossils in the University of New South Wales has in the main been provided by the Australian Research Council Discovery and Linkage Grants, as well as funding provided by the Phil Creaser CREATE Fund in UNSW, a grant from the National Geographic Society and donations from private individuals including Ken & Margaret Pettit, Doug & Anne Jeanes and Gary Johnston.</span></em></p><p class="fine-print"><em><span>Mike Archer received funding for the work at Riversleigh and preparation of the fossils in the University of New South Wales mainly from the Australian Research Council Discovery and Linkage Grants, as well as funding provided by the Phil Creaser CREATE Fund in UNSW, a grant from the National Geographic Society and donations from private individuals including Ken & Margaret Pettit, Doug & Anne Jeanes and Gary Johnston.</span></em></p><p class="fine-print"><em><span>Sue Hand received funding for the work at Riversleigh and preparation of the fossils in the University of New South Wales mainly from the Australian Research Council Discovery and Linkage Grants, as well as funding provided by the Phil Creaser CREATE Fund in UNSW, a grant from the National Geographic Society and donations from private individuals including Ken & Margaret Pettit, Doug & Anne Jeanes and Gary Johnston.</span></em></p>Nimbadon lived 15 million years ago, in forests with flesh-eating kangaroos and tree-climbing crocodiles. Our first look inside their fossilised bones has revealed how these giants grew.Anusuya Chinsamy-Turan, Professor, Biological Sciences Department, University of Cape TownKaren Black, Leading Education Professional, UNSW SydneyMike Archer, Professor, Pangea Research Centre, UNSW SydneySue Hand, Professor emeritus, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2036892023-05-02T14:05:28Z2023-05-02T14:05:28ZFrom enormous elephants to tiny shrews: how mammals shape and are shaped by Africa’s landscapes<figure><img src="https://images.theconversation.com/files/521021/original/file-20230414-26-p86mwp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The African elephant is the world’s largest terrestrial mammal.</span> <span class="attribution"><span class="source">Ara Monadjem</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Africa is the world’s most diverse continent for large mammals such as antelopes, zebras and elephants. The heaviest of these large mammals top the scales at over one ton, and are referred to as <a href="https://www.sciencedirect.com/science/article/pii/S2351989416300804?via%3Dihub">megafauna</a>. In fact, it’s the only continent that has not seen a mass extinction of these megafauna.</p>
<p>The continent’s megafauna community includes the world’s largest terrestrial mammal, the <a href="https://www.worldwildlife.org/species/african-elephant">African elephant</a>. Adult African bush elephants can weigh as much as 6 tons. Other giants across African continent include hippopotamuses, rhinoceroses and giraffes.</p>
<p>So, it is only in Africa that ecological interactions and dynamics can be studied as they would have been before the sudden and profound flourishing of <em>Homo sapiens</em> over the past 12 000 years; before then, megafauna would have dominated all terrestrial landscapes on all continents. A visit to Africa is, in other words, a visit to our planet’s past.</p>
<p>In my latest book, <a href="https://witspress.co.za/page/detail/African-Ark/?K=9781776147809">African Ark: Mammals, Landscape and the Ecology of a Continent</a>, I tell the story of how Africa’s mammal fauna arose. </p>
<p>It’s not just a tale of megafauna and other well-known large mammals. I pay particular attention to small mammals, such as mice, bats and shrews. That’s partly because I have been <a href="https://www.researchgate.net/profile/Ara-Monadjem">studying these creatures</a> for the past three decades.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1133&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1133&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521018/original/file-20230414-26-d5o9p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1133&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
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<p>These animals are also generally overlooked by both scientists and the public. But without them, and the ways in which they’ve interacted with each other and with their larger cousins over tens of thousands years, Africa wouldn’t have the richly varied landscapes it does today.</p>
<p>Africa’s mammals are a global treasure that must be protected. However, the lives of local communities are inextricably linked with these mammals and the remaining natural landscapes that harbour their dwindling populations; conservation solutions will require these communities’ active participation and blessing.</p>
<p>In some areas, nature-based tourism may be a viable solution. However, much of the rest of the continent – where no tourists go – will require other, perhaps novel, approaches. What we cannot afford is the extinction of any of these beautiful creatures or the continued loss and reduction of the ecosystem services that they freely provide.</p>
<h2>Early mammal history</h2>
<p>The history of African mammals begins with an apparently unrelated group of creatures. They’re so dissimilar from each other today that taxonomists didn’t work out their true relationships until about two decades ago. These are the elephants, manatees, elephant shrews, African golden moles, hyraxes and tenrecs. Collectively they make up the super-order <em><a href="https://afrotheria.net/">Afrotheria</a></em>. </p>
<p>Today, this group accounts for only a small fraction of the mammal species on the continent. But that is only because Africa – which formed part of the prehistoric southern supercontinent of <a href="https://www.britannica.com/place/Gondwana-supercontinent">Gondwana</a> – was colonised, in stages and over millions of years, by ‘invaders’ from the northern supercontinent of <a href="https://www.britannica.com/place/Laurasia">Laurasia</a>. </p>
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<strong>
Read more:
<a href="https://theconversation.com/large-mammals-shaped-the-evolution-of-humans-heres-why-it-happened-in-africa-196398">Large mammals shaped the evolution of humans: here’s why it happened in Africa</a>
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<p>These colonists include nearly all the mammals that we normally associate with Africa, including rhinoceroses, zebras, antelopes, primates, bats and even rodents. In return, some Afrotherians, including elephants, roamed out of Africa to colonise other lands further north. </p>
<p>Other mammals, including monkeys and <a href="https://onlinelibrary.wiley.com/doi/10.1002/9781118846506.ch1">caviomorph rodents</a> (such as guinea pigs and capybaras), used Africa as a stepping stone to colonise South America, as did lemurs to colonise Madagascar.</p>
<h2>Shaped by geography</h2>
<p>The variables of physical geography have worked hand in hand with the tectonic forces of prehistory. </p>
<p>Africa is not a uniform landscape that enjoys the same climate and habitat throughout. Some parts, such as Madagascar, are not even connected to the mainland but appear as offshore islands. Terrestrial mammals typically reach islands in two ways: they either raft across the intervening sea, or cross by foot during periods of drier weather or lower sea levels that connect the islands to the mainland. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/kenyan-fossil-shows-chameleons-may-have-rafted-from-mainland-africa-to-madagascar-130814">Kenyan fossil shows chameleons may have 'rafted' from mainland Africa to Madagascar</a>
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<p>In the continent’s interior, other formidable barriers restrict and determine mammal movement. Long, deep, fast-flowing rivers, such as the Congo in central Africa, can be almost as effective a barrier as open oceans. Mountain ranges can form inland ‘islands’ that are as ecologically isolated as their ocean equivalents. </p>
<p>By providing barriers, geographical features limit the movement of animals across the landscape, thereby affecting the composition of mammal communities in different parts of the continent.</p>
<h2>Population shifts</h2>
<p>Another element that’s crucial to telling the story of Africa’s mammals is an understanding of how species and population groups are formed and fluctuate over time. </p>
<p>For example, megafauna play important roles in shaping the landscape and its plant communities. This in turn shapes many smaller animals’ habitats. Hippopotamuses in the Okavango Delta <a href="https://www.researchgate.net/figure/Components-of-the-Okavango-ecosystem-a-Hippo-trail-through-flooded-vegetation-in_fig1_247844833#:%7E:text=In%20the%20panhandle%20and%20permanent,channels%20usually%20lead%20to%20lagoons.">create and maintain open water channels</a>, which serve as critical habitat for fishes. And, by defecating in water, hippos also introduce vast amounts of organic fertiliser into this aquatic ecosystem, helping to enrich it.</p>
<p>Smaller animals, too, shape landscapes. </p>
<p>Some species of rats and mice, such as pouched mice in the genus <em>Saccostomus</em>, are granivores that feed on seeds, including those of trees responsible for bush encroachment in savannas such as the sicklebush. Colleagues and I have <a href="https://www.frontiersin.org/articles/10.3389/fevo.2021.676572/full">shown experimentally</a> that various species of mice in Eswatini actually prefer the seeds of this encroaching plant and hence can assist in controlling its spread. But these rodents require good grass cover for persistence, and hence can’t provide this ecological service in over-grazed, degraded landscapes.</p>
<p>The numbers of animals naturally fluctuate over time, typically reflecting fluctuations in food supply brought about by, for example, droughts or floods. A key determinant of these population fluctuations is also the inherent life history characteristics of a species: short-lived, fast reproducing species such as rats and mice will, by definition, experience greater fluctuations in their numbers than long-lived, slow reproducing species like elephants.</p>
<h2>Conservation</h2>
<p>My book concludes by looking at human interactions with African mammals and the need to conserve these mammals, both for their own sake and for ours. The ecosystem services provided by many mammals are crucial to a healthy environment for all species. Humans evolved in Africa and have interacted with other African mammals for millions of years here. </p>
<p>This is not true on other continents, where humans are – in geological timescales – a recent addition. It may well be that this long relationship between humans and other African mammals is the reason why, despite the losses wrought by humankind, so many large mammals persist on the continent: they have ‘learnt’ through natural selection how to survive with us.</p>
<p><em>The book was written in conjunction with wildlife journalist Mike Unwin and is published by <a href="https://witspress.co.za/page/detail/African-Ark/?K=9781776147809">Wits University Press</a>.</em></p><img src="https://counter.theconversation.com/content/203689/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ara Monadjem receives funding from Oppenheimer Generations. </span></em></p>Africa’s mammals are a global treasure that must be protected.Ara Monadjem, Full Professor in the Department of Biological Sciences, University of EswatiniLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1951622023-04-05T12:23:16Z2023-04-05T12:23:16ZInnies, outies and omphalophobia: 7 navel-gazing questions about belly buttons answered<figure><img src="https://images.theconversation.com/files/517462/original/file-20230324-1164-blenfn.jpg?ixlib=rb-1.1.0&rect=0%2C374%2C3564%2C2404&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your genes determine the look of your navel.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-girl-looking-at-her-belly-button-royalty-free-image/97766642">Mike Kemp/Tetra images via Getty Images</a></span></figcaption></figure><p><em>Everyone has one, but you might not know much about it. Here <a href="https://scholar.google.com/citations?user=iGYBbvEAAAAJ&hl=en&oi=ao">biologist Sarah Leupen</a>, who teaches human and comparative animal physiology, explains the ins and outs of belly buttons.</em></p>
<h2>1. Why do I even have a belly button?</h2>
<p>Your belly button, or navel – <a href="https://link.springer.com/chapter/10.1007/978-3-319-62383-2_1">clinically, your umbilicus</a> – is the permanent scar left from where your umbilical cord connected your circulatory system, when you were a fetus, to the placenta. Fetuses don’t breathe, eat or eliminate waste, so the placenta provides an exchange site for the mother to deliver oxygen and nutrients from her bloodstream to the fetus, as well as collecting its wastes to eliminate from her body.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="closeup of umbilical cord stump on infant" src="https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Once the umbilical cord is cut, the stump dries up and falls off, revealing the baby’s navel.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-umbilical-cord-royalty-free-image/525032060">Wacharaphong/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>After the baby is born, the physician or other attendant cuts the cord and clamps off the stub, which then dries and falls off after about a week, leaving the point of connection – your belly button – remaining.</p>
<p>If the cord is not cut, as has been the practice in some times and places and as is becoming trendy again in others, it will close off after an hour or so, then naturally detach a few days after birth. Some health care practitioners are <a href="https://www.med.umich.edu/1libr/Pediatrics/LotusBirthHandout.pdf">concerned that this “lotus birth”</a> could be an infection risk, since the umbilical cord remains attached to the placenta, which is dead tissue once out of the mother’s body.</p>
<h2>2. If it’s a scar, why doesn’t it disappear over time?</h2>
<p>If you injure just the outer layers of your skin, as in a cut or burn, the scar will soon completely disappear, especially in young people. And newborns are very young people. But unlike in those situations, the umbilicus involves more tissue layers — not just the skin but the connective tissue underneath – so it makes sense it doesn’t just blend in with the rest of your abdominal wall once it’s healed.</p>
<p>What about some pretty complicated surgeries that don’t leave scars? Doctors perform many operations in ways that deliberately avoid scarring, which is not nature’s way. In fact, one way to minimize scarring for surgeries uses this existing scar – surgeons can take advantage of the navel as an incision site for <a href="https://doi.org/10.1053/j.sempedsurg.2011.05.003">removing your appendix</a> or <a href="https://doi.org/10.3109/13645706.2011.649039">gall bladder</a> or for <a href="https://doi.org/10.1016/j.soard.2010.12.007">weight-loss surgery</a>.</p>
<p>But if you don’t like the way your umbilical scar looks, plastic surgery to change its appearance, <a href="https://www.nytimes.com/2002/12/15/magazine/the-year-in-ideas-umbilicoplasty.html">called umbilicoplasty</a>, is possible. People sometimes take this cosmetic option after pregnancy or the removal of a piercing, or just to make an “outie” into an “innie.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="smooth belly with an outie belly button" src="https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outies are much less common than innies.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/8kd8nw">Zeev Barkan/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>3. But why do some people have outies, anyway?</h2>
<p>The look of your belly button is not related to the location of the clamp or where your doctor cut the cord.</p>
<p>Outies are simply an example of <a href="https://learn.genetics.utah.edu/content/basics/observable/">normal human variation</a>, like the way some people have curly hair or dimples. When the tip of the umbilical cord’s remnant pokes out past the skin around it, you have an outie; <a href="http://dx.doi.org/10.1007/978-3-319-62383-2_22">about 10% of people have these</a>. Any concave navel is called an “innie” and a convex one an “outie.”</p>
<p>Sometimes outies can be caused by an umbilical hernia in the baby or another medical problem, but most of it is just due to what your genes encoded. You might also temporarily have an outie during late pregnancy, when the abdominal pressure from the growing fetus stretches your navel and may push it out.</p>
<h2>4. How deep does it go?</h2>
<p>You can probably easily probe the depth of your own navel – there are no hidden recesses there. What’s under it is the same as what’s under the skin of the rest of your abdomen: your abdominal muscles, to which the navel is attached by a short umbilical stalk, and the peritoneum, the membrane that lines the abdominal cavity. Under that lie your guts – that is, your intestines and other abdominal organs. If you keep following this imaginary journey back, you’ll get to your spine – the belly button is usually lined up <a href="http://dx.doi.org/10.1007/978-3-319-62383-2_22">between the third and fourth lumbar vertebrae</a> (L3 and L4).</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/WkgjK3Kp6Uw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Learn how to find your pet’s belly button.</span></figcaption>
</figure>
<h2>5. Do other animals have belly buttons?</h2>
<p>Because the navel is a scar from where the umbilical cord connected the fetus to the placenta, all placental mammals have them. That includes all mammals except <a href="https://www.britannica.com/animal/marsupial">marsupials</a> (like kangaroos and possums) and <a href="https://www.britannica.com/animal/monotreme">monotremes</a> (like platypuses and echidnas).</p>
<p>Your cat or dog or guinea pig does have a belly button, but because it’s a flatter scar than a person’s rather than a concave one, and is covered in fur, you might have missed it.</p>
<h2>6. Is there anything besides lint in there?</h2>
<p>Like any concave surface, if you have an innie, it probably gathers bits of debris occasionally. Your navel also has microbiota, just like the rest of your skin. Because it’s pretty protected from soap and abrasion, a more <a href="https://en.wikipedia.org/wiki/Skin_flora#Umbilical_microbiome">stable and diverse bacterial community</a> lives in your navel than elsewhere on your skin’s surface.</p>
<p>The innovative <a href="http://robdunnlab.com/projects/belly-button-biodiversity/">Belly Button Biodiversity project</a> at North Carolina State University has revealed a lot about these little friends. The researchers found <a href="https://doi.org/10.1371/journal.pone.0047712">over 2,000 species of bacteria</a> in the first 60 belly buttons they investigated.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1422846688276979715"}"></div></p>
<p>It looks like most people have a set of eight common belly button bacteria, but the project is discovering new ones all the time.</p>
<h2>7. Why do belly buttons gross out some people?</h2>
<p>There hasn’t really been much research into why some people find belly buttons to be repulsive.</p>
<p>It may overlap with <a href="https://healthresearchfunding.org/fear-bellybuttons/">omphalophobia</a>, the fear of belly buttons and touching them. There’s no specific treatment beyond the therapy or anti-anxiety medications a doctor might prescribe for any other phobia.</p>
<p>Whatever your feelings about belly buttons, they’re harmless. What’s more, they’re part of your evolutionary legacy as a mammal, the group of animals so invested in their offspring that they invented a way to deliver nutrients and oxygen, the mother’s bread and breath, straight into their developing young. Your navel can be a reminder of that first life-sustaining care you received from another person before you were even born.</p><img src="https://counter.theconversation.com/content/195162/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Leupen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>All mammals who get nutrients from their parent via a placenta before birth are left with a belly button. It’s a visual reminder of this original connection.Sarah Leupen, Principal Lecturer in Biological Sciences, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2016282023-04-03T12:28:42Z2023-04-03T12:28:42ZSabertooth cat skull newly discovered in Iowa reveals details about this Ice Age predator<figure><img src="https://images.theconversation.com/files/518845/original/file-20230401-22-bgasdm.jpg?ixlib=rb-1.1.0&rect=145%2C64%2C5246%2C3306&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Heavier than a modern lion, these big cats were fearsome predators.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/smilodon-sits-on-a-rock-surrounded-by-golden-royalty-free-illustration/168839739">Daniel Eskridge/Stocktrek Images via Getty Images</a></span></figcaption></figure><p>The <a href="https://iupress.org/9780253010421/sabertooth/">sabertooth cat is an Ice Age icon</a> and <a href="https://www.press.jhu.edu/books/title/11538/smilodon">emblem of strength, tenacity and intelligence</a>. These animals <a href="https://uofupress.lib.utah.edu/giant-sloths-and-sabertooth-cats/">shared the North American landscape</a> with other large carnivores, including short-faced bears, dire wolves and the American lion, as well as megaherbivores including mammoths, mastodons, muskoxen and long-horned bison. Then at the end of the Pleistocene, between 50,000 and 10,000 years ago, <a href="https://doi.org/10.1073/pnas.2015032117">they all vanished</a>. The only place to see them now is in the fossil record.</p>
<p>Carnivore fossils are extremely rare, though, in comparison to those of their prey. Prey are always more abundant than predators in a healthy ecosystem. So the probability of burial, storage and discovery of carnivore bones and teeth is therefore slim compared to those belonging to herbivores.</p>
<p>Scientists have a relatively small and scattered inventory of sabertooth fossils. The exception comes from Rancho La Brea in downtown Los Angeles, where over <a href="https://archive.org/details/biostor-215051">1,000 individual sabertooths</a> were mired in tar-seep death traps.</p>
<p>That’s why the recent discovery of an exquisite sabertooth cat skull in southwestern Iowa is so exciting. The <em>Smilodon fatalis</em> skull was collected from late Pleistocene sand and gravel exposed along the East Nishnabotna River. My colleague, <a href="https://www.nwmissouri.edu/naturalsciences/directory/easterla.htm">biologist David A. Easterla</a>, <a href="https://scholar.google.com/citations?user=SvSuuIcAAAAJ&hl=en&oi=ao">and I</a> are <a href="https://doi.org/10.1016/j.quascirev.2023.108045">studying this specimen to learn more</a> about the life history, prey selection and eventual extinction of this ancient predator. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="side view of a fossil skull with one long tooth on the animal's left" src="https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518601/original/file-20230330-24-fohkrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The recent sabertooth find is a complete cranium, albeit missing one of its namesake sabers.</span>
<span class="attribution"><span class="source">Chris Gannon, ISU News Service</span></span>
</figcaption>
</figure>
<h2>Clues from a cranium</h2>
<p>The animal’s common name – sabertooth cat – comes from its highly distinctive, saberlike canine teeth that poke out of the mouth as much as 5 or 6 inches (13 to 15 centimeters).</p>
<p>Sabertooths are sexually dimorphic, with <a href="https://doi.org/10.1371/journal.pone.0048352">males generally larger than females</a>. The Iowa skull is larger than those of many adult males from Rancho La Brea. Several bones of the skull have not sealed together and the teeth are basically unworn, leading us to believe this individual was almost certainly a young male between 2 and 3 years old that was still growing.</p>
<p>We estimate he weighed 550 pounds (250 kilograms). That’s upwards of 110 pounds (50 kilograms) greater than the <a href="https://doi.org/10.1111/j.1469-7998.1980.tb01433.x">average adult male African lion</a>. Given a few years to mature and fill up loose skin, he might have tipped the scale at 650 pounds (300 kilograms).</p>
<p>Observations of the life cycles of <a href="https://press.uchicago.edu/ucp/books/book/chicago/S/bo42069173.html">modern lions</a> <a href="https://press.uchicago.edu/ucp/books/book/chicago/D/bo3635439.html">and tigers</a> suggest this sabertooth was newly independent or on the cusp of independent living.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="four lions attacking an African buffalo" src="https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518846/original/file-20230401-14-2med49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sabertooths might have lived and hunted together in groups like modern lions – but all other modern cats live more solitary lifestyles.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/the-chase-royalty-free-image/534361693">jez_bennett/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>However, whether sabertooths stuck together in groups or were loners is hotly debated. Disagreement revolves around just how much of a size difference there is between males and females. In many living animals, <a href="https://doi.org/10.1111/j.1469-7998.1997.tb02932.x">males are typically larger than females</a> in male-dominated harems, as in modern lions. In the case of sabertooths, some scholars identify this <a href="https://doi.org/10.1371/journal.pone.0048352">pronounced sexual dimophisim between the sexes</a> and contend these ancient cats lived in groups, akin to today’s lions. Other researchers see only minimal size differences and view sabertooth cats <a href="https://doi.org/10.1671/0272-4634(2002)022%5B0164:SDSBAI%5D2.0.CO;2">generally as solitary predators</a>, perhaps more like tigers and all other felines.</p>
<p>Whatever the case, at 2 or 3 years old the cat obviously possessed the weaponry – jaws and paws – and heft to take down large prey alone. He likely garnered experience hunting by first watching his mother locate, stalk, ambush and kill prey and defend the carcasses, then perhaps with her help, and finally, alone. His learning curve was probably a lot like lions and tigers as they mature physically and behaviorally. </p>
<p>Hunting for survival is high stakes. Repeated failure means death from starvation. And attacking large prey equipped with defensive gear like horns, antlers, hooves and trunks is always dangerous and sometimes lethal. For instance, a recent study of 166 modern lion skulls from Zambia revealed that 68 had healed or partially healed injuries associated with taking down prey. Put another way, <a href="https://doi.org/10.7717/peerj.11313">40% had survived major head trauma</a> to hunt another day.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="anterior view of sabertooth cat cranium, with only one long tooth on the right" src="https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=614&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=614&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=614&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=772&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=772&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518594/original/file-20230330-21-l5xqa8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=772&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of this cat’s distinctive sabers was broken off before it died.</span>
<span class="attribution"><span class="source">Chris Gannon, ISU News Service</span></span>
</figcaption>
</figure>
<p>One saber in the Iowa skull is broken off where the canine tooth emerges from the roof of the mouth. Morphological details of the fracture edges indicate the damage happened around this animal’s time of death. It’s possible the break may relate to a defense wound thanks to a prey animal’s well-placed hoof, antler, horn or swat. Since the stub is not worn, the encounter may have even caused the cat’s death. </p>
<h2>Additional technical analysis yields more info</h2>
<p>A technique called <a href="https://www.nature.com/scitable/knowledge/library/the-use-of-stable-isotopes-in-the-96648168/">stable isotope analysis</a> allows researchers to figure out what an animal ate and even where it lived based on ratios of isotopes in its teeth or bones. </p>
<p><a href="https://scholar.google.com/citations?user=oJ4ztXAAAAAJ&hl=en&oi=ao">Andrew Somerville</a>, a specialist in isotopic biogeochemistry, is leading this effort with the Iowa sabertooth. Our team suspects that sabertooth cats in this area would have focused their hunting on the <a href="https://iceage.museum.state.il.us/mammals/jefferson%E2%80%99s-ground-sloth">Jefferson’s ground sloth</a>, a massive, lumbering and solitary browser. With adults weighing around a ton, its size was probably a major deterrent to other predators – but not necessarily to sabertooths. Sharp sabers to the neck could have killed the sloth, size be damned.</p>
<p>My colleagues and I are also developing what natural science researchers call diet-breadth mixing models. Using stable isotopes of carbon and nitrogen preserved in Ice Age carnivore, herbivore and omnivore bones from southwest Iowa, our models should tell us if sabertooths, short-faced bears and dire wolves competed for the same prey, the habitats they searched for prey and, possibly, how these food-web connections collapsed at the end of the Ice Age.</p>
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<p><a href="https://www.britannica.com/science/carbon-14-dating">Radiocarbon dating</a> indicates this Iowa sabertooth lived between 13,605 and 13,455 years ago, making it <a href="https://doi.org/10.1016/j.quascirev.2023.108045">among the last of its kind</a> to walk the Western Hemisphere. Slightly younger dates – but not by much – come from Rancho La Brea, eastern Brazil and far southern Chile.</p>
<p>These dates mean sabertooths and the first people to infiltrate these places – <a href="https://doi.org/10.1017/aaq.2021.153">Clovis foragers in North America</a> and <a href="https://doi.org/10.7183/0002-7316.80.2.376">Fishtail foragers in South America</a> – shared the landscape for a short period of time. People probably chanced upon sabertooth tracks, scat and kills now and again. Maybe a few lucky people observed the magnificent animal going about its life. But neither knew what the future had in store. </p>
<p>The big cat vanished from both continents shortly after people arrived. The ultimate cause of the die-off is difficult to pinpoint, and multiple factors were certainly at play. However, at least with sabertooths, we can say extinction was a hemisphere-wide synchronous event that transpired in a geological instant, perhaps over just 1,000 or 2,000 years, which makes it difficult to directly or indirectly tie people to the die-off.</p>
<p>The Iowa skull, combined with other fossil evidence from the region and observations of modern large carnivores, has cast new light on the life history and behavior of sabertooth cats. Ongoing research promises to provide additional clues about the diet and ecology of this iconic predator.</p><img src="https://counter.theconversation.com/content/201628/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew G. Hill does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Researchers are analyzing the fossil cranium of a Smilodon fatalis that lived more than 13,000 years ago to learn more about the lifestyle of this iconic big cat.Matthew G. Hill, Associate Professor of Anthropology, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.