tag:theconversation.com,2011:/us/topics/pleistocene-39595/articlesPleistocene – The Conversation2023-08-17T19:42:11Ztag: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/2057592023-06-07T00:49:44Z2023-06-07T00:49:44ZGiant tree-kangaroos once lived in unexpected places all over Australia, according to major new analysis<figure><img src="https://images.theconversation.com/files/529536/original/file-20230601-28-j6qu5h.jpg?ixlib=rb-1.1.0&rect=287%2C296%2C5236%2C3565&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dendrolagus goodfelowi, or Goodfellow's tree-kangaroo.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Kangaroos are an enduring symbol of Australia’s uniqueness. To move, they do what no other large mammals do: they hop along on oversized hind legs. So you may be surprised to learn that some kangaroos live in trees, and are among the most endearing and threatened of all marsupials.</p>
<p>Today, biologists recognise ten tree-kangaroo species, all in the genus <em>Dendrolagus</em>. Two species inhabit tropical forest in far northern Queensland. The other eight live in New Guinea.</p>
<p>Studying them is difficult because their habitats are hard to access, they live high in trees and are increasingly rare due to human impacts.</p>
<p>The evolutionary history of tree-kangaroos is even more obscure. In a new study <a href="https://doi.org/10.11646/zootaxa.5299.1.1">published today in Zootaxa</a>, we pull together all the evidence on fossil tree-kangaroos and show giant tree-kangaroo species were widespread across Australia, and lived in habitats that were a long way from tropical forest – their modern-day home.</p>
<figure class="align-center ">
<img alt="Illustration of several maruspials in an ancient landscape" src="https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=433&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=433&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=433&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=544&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=544&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527321/original/file-20230519-7659-rz8ynn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=544&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Reconstruction of the giant tree-kangaroo <em>Bohra illuminata</em>, Nullarbor region, 250,000 years ago.</span>
<span class="attribution"><span class="source">Peter Schouten, Author provided</span></span>
</figcaption>
</figure>
<h2>Tree-kangaroos from the Treeless Plain</h2>
<p>In 2002, a team of explorers found three new caves in the middle of the arid Nullarbor Plain of south-central Australia. The cave floors were littered with the bones of the extinct marsupial “lion” <em>Thylacoleo carnifex</em> and short-faced kangaroos, as well as those of several mammals, birds and reptiles that still live in drier parts of Australia.</p>
<p>Given the high diversity of herbivores, we <a href="https://doi.org/10.1038/nature05471">concluded</a> the Nullarbor had to have been more than just arid shrubland some 200–400 thousand years ago, even if it was still very dry. This is because a few shrubs would not have been enough for such a range of herbivores to live on.</p>
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Read more:
<a href="https://theconversation.com/we-found-out-when-the-nullarbor-plain-dried-out-splitting-australias-ecosystems-in-half-203052">We found out when the Nullarbor Plain dried out, splitting Australia's ecosystems in half</a>
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<p>In this light, it was hard to believe when we discovered partial skeletons of two new species of giant tree-kangaroo in <a href="https://doi.org/10.1671/0272-4634(2008)28%5b463:ANPTDM%5d2.0.CO;2">2008</a> and <a href="https://doi.org/10.18195/issn.0312-3162.25(2).2009.165-179">2009</a>. They belong to the extinct genus <em>Bohra</em>, first named in 1982 on the basis of <a href="https://doi.org/10.1071/AM82010">leg bones found in the Wellington Caves</a> in New South Wales.</p>
<p>Like the picture on a jigsaw box, we used the Nullarbor skeletons as a guide to search for isolated pieces in museum collections. We discovered more than 100 teeth and bones belonging to a total of at least seven species of extinct tree-kangaroos.</p>
<p>These come from fossil sites extending from southern Victoria to central Australia to the New Guinea highlands, and range in age from 3.5 million (late Pliocene) to a few hundred thousand years old (middle Pleistocene).</p>
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<img alt="Side by side image of two similar looking skulls" src="https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=296&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=296&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=296&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=372&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=372&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527324/original/file-20230519-21-9zk2gg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=372&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">Skull of the extinct <em>Bohra illuminata</em> alongside that of a modern tree-kangaroo (scaled to same length).</span>
<span class="attribution"><span class="source">Author provided</span></span>
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<h2>A big leap forwards – and then upwards</h2>
<p>Anatomical and molecular evidence shows that, among living marsupials, kangaroos are <a href="https://doi.org/10.1093/sysbio/syx076">most closely related to possums</a>. No one is sure exactly when the kangaroo ancestor made the descent to the forest floor, due to big gaps in the Australian fossil record.</p>
<p>Similarly, we do not know whether the distinctive “bipedal” hopping mode of locomotion originated in the trees or on the ground – but we do know it became the enduring hallmark of the kangaroo family. They have longer hind legs and longer feet than their possum ancestors, and the foot bones lock together in such a way as to limit sideways foot movement.</p>
<p>Combined with high tendon elasticity and a large muscular tail, these adaptations make kangaroos among the most <a href="https://doi.org/10.1242/jeb.161661">energy-efficient</a> movers on the planet.</p>
<p>The foot bones of tree-kangaroos reveal three stages in the evolutionary “reversal” of these adaptations. Pliocene species of <em>Bohra</em> evolved a broader heel bone and upper ankle joint, allowing them greater mobility. Later, Pleistocene species of <em>Bohra</em> evolved a smoother joint at the front of that heel bone, giving them the ability to roll the soles of their feet inward to wrap around tree trunks and limbs.</p>
<p>As well as shorter feet, modern tree-kangaroos (<em>Dendrolagus</em>) have shorter hindlimbs, in conjunction with powerful forelimbs and claws for grasping and climbing. They can even walk with their hind legs while climbing, whereas ground-dwelling kangaroos only move their hind legs alternately while swimming.</p>
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<img alt="Diagram of a shorter, more splayed foot skeleton and a longer, more focused one" src="https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527327/original/file-20230519-21-yaf53y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&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">Comparison of tree-kangaroo (Dendrolagus) and grey kangaroo (Macropus) foot bones.</span>
<span class="attribution"><span class="source">Author provided</span></span>
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<h2>Why return to the trees?</h2>
<p>As Australia dried out over the past 10 million years, more open vegetation became widespread. This trend was interrupted by a greenhouse phase 5–3.5 million years ago. We speculate that the temporary expansion of <a href="https://doi.org/10.1073/pnas.1520188113">forest habitats</a> during this period would have opened new ecological niches that early tree-kangaroos evolved to exploit. </p>
<p>By the time climatic drying returned, tree-kangaroos had become established members of the Australian fauna, with species adapting to expanding woodland and savannah habitats.</p>
<p>As some larger monkeys do today, species of <em>Bohra</em> probably divided their time between living in trees and on the ground, whereas modern tree-kangaroos spend most of their time in the canopy.</p>
<p>So, although we might now think of tree-kangaroos as quintessential rainforest animals, this is because the <em>Bohra</em> species that lived in other habitats have become extinct.</p>
<p>Despite everything we can learn about evolution from studies of modern species, the fossil record holds the potential to flip the script with one discovery. </p>
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Read more:
<a href="https://theconversation.com/an-exciting-possibility-scientists-discover-markedly-different-kangaroos-on-either-side-of-australias-dingo-fence-206752">'An exciting possibility': scientists discover markedly different kangaroos on either side of Australia's dingo fence</a>
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<img src="https://counter.theconversation.com/content/205759/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gavin Prideaux is a palaeontologist at Flinders University, and receives research grant funding from the Australian Research Council, Australia Pacific Science Foundation, Hermon Slade Foundation, National Geographic and Australian Geographic.</span></em></p><p class="fine-print"><em><span>Natalie Warburton receives funding from Australia Pacific Science Foundation and has previously received funding from the Australian Research Council. She is a researcher in the Harry Butler Institute at Murdoch University, a Research Associate of the Western Australian Museum and the current Vice President of the Australian Mammal Society.</span></em></p>The ancestors of kangaroos once lived in the trees – but their evolutionary history is murky. Here’s everything we know so far.Gavin Prideaux, Professor, Flinders UniversityNatalie Warburton, Associate Professor in Anatomy, Murdoch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2048882023-05-04T19:06:29Z2023-05-04T19:06:29ZReconstructing ancient bacterial genomes can revive previously unknown molecules – offering a potential source for new antibiotics<figure><img src="https://images.theconversation.com/files/523906/original/file-20230502-2182-swsnio.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C8256%2C5499&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ancient DNA preserved in the tooth tartar of human fossils encodes microbial metabolites that could be the next antibiotic.</span> <span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/983784?">Werner/Siemens Foundation</a></span></figcaption></figure><p>Microorganisms – in particular bacteria – are skillful chemists that can produce an impressive diversity of chemical compounds known as <a href="https://theconversation.com/nature-is-the-worlds-original-pharmacy-returning-to-medicines-roots-could-help-fill-drug-discovery-gaps-176963">natural products</a>. These metabolites provide the microbes major evolutionary advantages, such as allowing them to interact with one another or their environment and helping defend against different threats. Because of the diverse functions bacterial natural products have, many have been <a href="https://doi.org/10.1021/acs.jnatprod.5b01055">used as medical treatments</a> such as antibiotics and anti-cancer drugs.</p>
<p>The microbial species alive today represent only a tiny fraction of the vast diversity of microbes that have inhabited Earth over the past <a href="https://theconversation.com/were-viruses-around-on-earth-before-living-cells-emerged-a-microbiologist-explains-197880">3 billion years</a>. Exploring this microbial past presents exciting opportunities to recover some of their lost chemistry. </p>
<p>Directly studying these metabolites in archaeological samples is virtually impossible because of their <a href="https://doi.org/10.1007/s11306-017-1270-3">poor preservation</a> over time. However, reconstructing them using the genetic blueprints of long-dead microbes could provide a path forward. </p>
<p>We are a team of <a href="https://scholar.google.com/citations?user=cDFcc3cAAAAJ&hl=en">anthropologists</a>, <a href="https://scholar.google.de/citations?user=trnMQ7MAAAAJ&hl=en">archaeogeneticists</a> and <a href="https://scholar.google.com/citations?user=26MgwRgAAAAJ&hl=en">biochemists</a> who study ancient microbes. By <a href="https://www.science.org/doi/10.1126/science.adf5300">generating previously unknown chemical compounds</a> from the reconstructed genomes of ancient bacteria, our newly published research provides a proof of concept for the potential use of fossil microbes as a source of new drugs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Researcher weighing tooth fossil on a scale" src="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=565&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=565&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=565&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=710&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=710&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=710&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 single ancient tooth preserves the genomes of millions of ancient bacteria.</span>
<span class="attribution"><span class="source">Felix Wey/Werner Siemens Foundation</span></span>
</figcaption>
</figure>
<h2>Reconstructing ancient genomes</h2>
<p>The cellular machinery producing bacterial natural products is encoded in genes that are typically in close proximity to one another, forming what are called <a href="https://doi.org/10.1016/j.tim.2016.07.006">biosynthetic gene clusters</a>. Such genes are difficult to detect and reconstruct from ancient DNA because very old genetic material breaks down over time, fragmenting into thousands or even millions of pieces. The end result is numerous tiny DNA fragments <a href="https://doi.org/10.1038/s43586-020-00011-0">less than 50 nucleotides long</a> all mixed together like a jumbled jigsaw puzzle.</p>
<p>We sequenced billions of such ancient DNA fragments, then improved a bioinformatic process called <a href="https://doi.org/10.1007/s40484-019-0166-9">de novo assembly</a> to digitally order the ancient DNA fragments in stretches of up to 100,000 nucleotides long – a 2,000-fold improvement. This process allowed us to identify not only what genes were present, but also their order in the genome and the ways they differ from bacterial genes known today – key information to uncovering their evolutionary history and function. </p>
<p>This method allowed us to take an unprecedented look at the genomes of microbes living up to 100,000 years ago, including species not known to exist today. Our findings push back the <a href="https://doi.org/10.1038/s41586-021-03532-0">previously oldest</a> <a href="https://doi.org/10.1186/s40168-021-01132-8">reconstructed microbial genomes</a> by more than 90,000 years.</p>
<p>In the microbial genomes we reconstructed from DNA extracted from ancient tooth tartar, we found a gene cluster that was shared by a high proportion of Neanderthals and anatomically modern humans living during the <a href="https://www.britannica.com/event/Stone-Age/Middle-Paleolithic">Middle and Upper Paleolithic</a> that lasted from 300,000 to 12,000 years ago. This cluster bore the <a href="https://doi.org/10.1038/s43586-020-00011-0">molecular hallmarks of very ancient DNA</a> and belonged to the bacterial genus <em>Chlorobium</em>, a group of green sulfur bacteria capable of photosynthesis.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chemical structure of paleofurans produced using ancient microbial DNA." src="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=280&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=280&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=280&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=351&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=351&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=351&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These paleofurans were produced from ancient microbial DNA.</span>
<span class="attribution"><span class="source">Pierre Stallforth</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We inserted a synthetic version of this gene cluster into a “modern” bacterium called <em>Pseudomona protegens</em> so it could produce the chemical compounds encoded in the ancient genes. Using this method, we were able to isolate two previously unknown compounds we named <a href="https://www.science.org/doi/10.1126/science.adf5300">paleofuran A and B</a> and determine their chemical structure. Resynthesizing these molecules in the lab from scratch confirmed their structure and allowed us to produce larger quantities for further analysis.</p>
<p>By reconstructing these ancient compounds, our findings highlight how archaeological samples could serve as new sources of natural products. </p>
<h2>Mining ancient natural products</h2>
<p>Microbes are constantly evolving and adapting to their surrounding environment. Because the environments they inhabit today differ from those of their ancestors, microbes today likely produce different natural products than ancient microbes from tens of thousands of years ago.</p>
<p>As recently as <a href="https://www.doi.org/10.1007/978-1-4613-1145-4_1">25,000 to 10,000 years ago</a>, the Earth underwent a major climate shift as it transitioned from the colder and more volatile <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene Epoch</a> to the warmer and more temperate <a href="https://www.britannica.com/science/Holocene-Epoch">Holocene Epoch</a>. Human lifestyles also dramatically changed over this transition as people began living outside of caves and increasingly experimented with food production. These changes brought them into contact with different microbes through agriculture, animal husbandry and their new built environments. Studying Pleistocene-era bacteria may yield insights into bacterial species and biosynthetic genes no longer associated with humans today, and perhaps even microbes that have gone extinct.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/JfX06NINZpk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Changes in human lifestyles changed our genomes.</span></figcaption>
</figure>
<p>While the amount of data collected by scientists on biological organisms has exponentially increased over the past few decades, the <a href="https://theconversation.com/antibiotic-resistance-is-at-a-crisis-point-government-support-for-academia-and-big-pharma-to-find-new-drugs-could-help-defeat-superbugs-169443">number of new antibiotics has stagnated</a>. This is particularly problematic when bacteria are able to evade existing antibiotic treatments faster than researchers can develop new ones. </p>
<p>By reconstructing microbial genomes from archaeological samples, scientists can tap into the hidden diversity of natural products that would have otherwise been lost over time, increasing the number of potential sources from which they can discover new drugs.</p>
<h2>Scaling up ancient molecules</h2>
<p>Our study has shown that it is possible to access natural products from the past. To tap into the vast diversity of chemical compounds encoded in ancient DNA, we now need to streamline our methodology to be less labor-intensive. </p>
<p>We are currently optimizing and automating our process to identify biosynthetic genes in ancient DNA more quickly and reliably. We are also implementing robotic liquid handling systems to complete the time-consuming pipetting and bacterial cultivation steps in our methods. Our goal is to scale up the process to be able to translate a vast amount of data on ancient microbes into the discovery of new therapeutic agents. </p>
<p>Although we can recreate ancient molecules, their biological and ecological roles are difficult to decipher. Since the bacteria that originally produced these compounds no longer exist, we cannot culture or genetically manipulate them. Further study will need to rely on similar bacteria that can be found today. Whether or not the functions of these compounds have remained the same in the modern relatives of ancient microbes remains to be tested. Although the original functions of these compounds for ancient microbes may be unknown, they still have the potential to be repurposed to treat modern diseases.</p>
<p>Ultimately, we aim to shed new light on microbial evolution and fight the current antibiotic crisis by providing a new time axis for antibiotic discovery.</p><img src="https://counter.theconversation.com/content/204888/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina Warinner receives funding from the Werner Siemens Foundation, the Francis Goelet Charitable Trust, the European Research Council, the United States National Science Foundation, and the Deutsche Forschungsgemeinschaft. She is affiliated with the Max Planck Institute for Evolutionary Anthropology, the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI), and the Biological Faculty of Friedrich Schiller University Jena. </span></em></p><p class="fine-print"><em><span>Alexander Hübner receives funding from the Werner Siemens Foundation, the European Research Council, and the Deutsche Forschungsgemeinschaft. He is affiliated with with the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI).</span></em></p><p class="fine-print"><em><span>Pierre Stallforth receives funding from the Werner Siemens Foundation, the Deutsche Forschungsgemeinschaft, and the Leibniz Association. He is affiliated with with the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI) and the Friedrich Schiller University, Jena, Germany.</span></em></p>Ancient microbes likely produced natural products their descendants today do not. Tapping into this lost chemical diversity could offer a potential source of new drugs.Christina Warinner, Associate Professor of Anthropology, Harvard UniversityAlexander Hübner, Postdoctoral Researcher in Archaeogenetics, Max Planck Institute for Evolutionary AnthropologyPierre Stallforth, Professor of Bioorganic Chemistry and Paleobiotechnology, Friedrich-Schiller-Universität JenaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1705252021-11-01T17:11:07Z2021-11-01T17:11:07ZHumanity is compressing millions of years of natural change into just a few centuries<figure><img src="https://images.theconversation.com/files/429578/original/file-20211101-19-hfkg25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The near future may be similar to the mid-Pliocene warm period a few million years ago.</span> <span class="attribution"><span class="source">Daniel Eskridge / shutterstock</span></span></figcaption></figure><p>Many numbers are swirling around the climate negotiations at the UN climate summit in Glasgow, COP26. These include global warming targets of 1.5°C and 2.0°C, recent warming of 1.1°C, remaining CO₂ budget of 400 billion tonnes, or current atmospheric CO₂ of 415 parts per million. </p>
<p>It’s often hard to grasp the significance of these numbers. But the study of ancient climates can give us an appreciation of their scale compared to what has occurred naturally in the past. Our knowledge of ancient climate change also allows scientists to calibrate their models and therefore improve predictions of what the future may hold.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=253&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=253&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=253&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=318&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=318&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429582/original/file-20211101-17-gr64rc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=318&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Recent climate changes in context.</span>
<span class="attribution"><a class="source" href="https://www.ipcc.ch/report/ar6/">IPCC AR6, chapter 2</a></span>
</figcaption>
</figure>
<p>Recent work, summarised in the <a href="https://www.ipcc.ch/report/ar6/wg1/">latest report</a> of the Intergovernmental Panel on Climate Change (IPCC), has allowed scientists to refine their understanding and measurement of past climate changes. These changes are recorded in rocky outcrops, sediments from the ocean floor and lakes, in polar ice sheets, and in other shorter-term archives such as tree rings and corals. As scientists discover more of these archives and get better at using them, we have become increasingly able to compare recent and future climate change with what has happened in the past, and to provide important context to the numbers involved in climate negotiations.</p>
<p>For instance one headline finding in the IPCC report was that global temperature (currently 1.1°C above a pre-industrial baseline) is higher than at any time in at least the past <a href="https://theconversation.com/the-last-time-earth-was-this-hot-hippos-lived-in-britain-thats-130-000-years-ago-53398">120,000 or so years</a>. That’s because the last warm period between ice ages peaked about 125,000 years ago – in contrast to today, warmth at that time was driven not by CO₂, but by changes in Earth’s orbit and spin axis. Another finding regards the rate of current warming, which is faster than at any time in the past 2,000 years – and probably much longer.</p>
<p>But it is not only past temperature that can be reconstructed from the geological record. For instance, tiny gas bubbles trapped in Antarctic ice can record atmospheric CO₂ concentrations back to 800,000 years ago. Beyond that, scientists can turn to microscopic fossils preserved in seabed sediments. These properties (such as the types of elements that make up the fossil shells) are related to how much CO₂ was in the ocean when the fossilised organisms were alive, which itself is related to how much was in the atmosphere. As we get better at using these “proxies” for atmospheric CO₂, recent work has shown that the current atmospheric CO₂ concentration of around 415 parts per million (compared to 280 ppm prior to industrialisation in the early 1800s), is greater than at any time in <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter_02.pdf">at least the past 2 million years</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="chart showing climate changes over history" src="https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=518&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=518&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=518&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=650&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=650&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429581/original/file-20211101-13-1buk2sp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=650&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 IPCC graphic showing climate changes at various points since 56 million years ago. Note most rows show changes over thousands or millions of years, while the top row (recent changes) is just a few decades.</span>
<span class="attribution"><span class="source">IPCC AR6, chapter 2 (modified by Darrell Kaufman)</span></span>
</figcaption>
</figure>
<p>Other climate variables can also be <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter_02.pdf">compared to past changes</a>. These include the greenhouse gases methane and nitrous oxide (now greater than at any time in at least 800,000 years), late summer Arctic sea ice area (smaller than at any time in at least the past 1,000 years), glacier retreat (unprecedented in at least 2,000 years) sea level (rising faster than at any point in at least 3,000 years), and ocean acidity (unusually acidic compared to the past 2 million years).</p>
<p>In addition, changes predicted by climate models can be compared to the past. For instance an “intermediate” amount of emissions will likely lead to global warming of between 2.3°C and 4.6°C by the year 2300, which is similar to the mid-Pliocene warm period of about 3.2 million years ago. Extremely high emissions would lead to warming of somewhere between 6.6°C and 14.1°C, which just overlaps with the warmest period since the demise of the dinosaurs – the “Paleocene-Eocene Thermal Maximum” kicked off by massive volcanic eruptions about <a href="https://theconversation.com/sudden-global-warming-55m-years-ago-was-much-like-today-35505">55 million years ago</a>. As such, humanity is currently on the path to compressing millions of years of temperature change into just a couple of centuries.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small animals in a forest" src="https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429485/original/file-20211101-15910-11cfiis.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"></a>
<figcaption>
<span class="caption">Many mammals, like these horse-ancestors ‘Eohippus’, first appeared after a sudden warm period 55 million years ago.</span>
<span class="attribution"><span class="source">Daniel Eskridge / shutterstock</span></span>
</figcaption>
</figure>
<h2>Distant past can help predict the near future</h2>
<p>For the first time in an IPCC report, the latest report uses ancient time periods to refine projections of climate change. In previous IPCC reports, future projections have been produced simply by averaging results from all climate models, and using their spread as a measure of uncertainty. But for this new report, temperature and rainfall and sea level projections relied more heavily on those models that did the best job of simulating known climate changes. </p>
<p>Part of this process was based on each individual model’s “climate sensitivity” – the amount it warms when atmospheric CO₂ is doubled. The “correct” value (and uncertainty range) of sensitivity is known from a number of different lines of evidence, one of which comes from certain times in the ancient past when global temperature changes were driven by natural changes in CO₂, caused for example by volcanic eruptions or change in the amount of carbon removed from the atmosphere as rocks are eroded away. Combining estimates of ancient CO₂ and temperature therefore allows scientists to estimate the “correct” value of climate sensitivity, and so refine their future projections by relying more heavily on those models with more accurate climate sensitivities.</p>
<p>Overall, past climates show us that recent changes across all aspects of the Earth system are unprecedented in at least thousands of years. Unless emissions are reduced rapidly and dramatically, global warming will reach a level that has not been seen for millions of years. Let’s hope those attending COP26 are listening to messages from the past. </p>
<hr>
<figure class="align-right ">
<img alt="COP26: the world's biggest climate talks" src="https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424739/original/file-20211005-17-cgrf2z.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>This story is part of The Conversation’s coverage on COP26, the Glasgow climate conference, by experts from around the world.</strong>
<br><em>Amid a rising tide of climate news and stories, The Conversation is here to clear the air and make sure you get information you can trust. <a href="https://page.theconversation.com/cop26-glasgow-2021-climate-change-summit/"><strong>More.</strong></a></em> </p>
<hr><img src="https://counter.theconversation.com/content/170525/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dan Lunt receives funding from NERC, the Leverhulme Trust, the EU, and SKB/Posiva. </span></em></p><p class="fine-print"><em><span>Darrell Kaufman receives funding from the US National Science Foundation.</span></em></p>What climate changes in the distant past can tell us about the near future.Dan Lunt, Professor of Climate Science, University of BristolDarrell Kaufman, Professor of Earth and Environmental Sciences, Northern Arizona UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1599292021-05-13T19:56:06Z2021-05-13T19:56:06ZHow climate change is erasing the world’s oldest rock art<figure><img src="https://images.theconversation.com/files/400229/original/file-20210512-18-1f30o5y.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C817%2C544&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This Warty Pig is part of a panel dated to more than 45,500 years in age.</span> <span class="attribution"><span class="source">Basran Burhan/Griffith University</span>, <span class="license">Author provided</span></span></figcaption></figure><p>In caves on the Indonesian island of Sulawesi, ancient peoples marked the walls with red and mulberry hand stencils, and painted images of large native mammals or <a href="https://theconversation.com/indonesian-cave-paintings-show-the-dawn-of-imaginative-art-and-human-spiritual-belief-128457">imaginary human-animal creatures</a>. </p>
<p>These are the oldest cave art sites yet known — or at least the oldest attributed to our species. One painting of a Sulawesi warty pig was recently dated as at least <a href="https://theconversation.com/we-found-the-oldest-known-cave-painting-of-animals-in-a-secret-indonesian-valley-153089">45,500 years old</a>.</p>
<p>Since the 1950s, archaeologists have observed these paintings appear to be blistering and peeling off the cave walls. Yet, little had been done to understand why. </p>
<p>So our research, <a href="http://nature.com/articles/s41598-021-87923-3">published today</a>, explored the mechanisms of decay affecting ancient rock art panels at 11 sites in Sulawesi’s <a href="https://www.worldheritagesite.org/tentative/id/5467">Maros-Pangkep</a> region. We found the deterioration may have gotten worse in recent decades, a trend likely to continue with accelerating climate change.</p>
<p>These Pleistocene (“ice aged”) cave paintings of Indonesia have only begun to tell us about the lives of the earliest people who lived in Australasia. The art is disappearing just as we’re beginning to understand its significance.</p>
<h2>Australasia’s rock art</h2>
<p>Rock art gives us a glimpse into the ancient cultural worlds of the artists and the <a href="https://youtu.be/3OLaNtKoJFk">animals</a> they may have hunted or interacted with. Even rare clues into early people’s <a href="https://theconversation.com/indonesian-cave-paintings-show-the-dawn-of-imaginative-art-and-human-spiritual-belief-128457">beliefs in the supernatural</a> have been preserved.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/mNiqamYP3Sc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Climate change could erase ancient Indonesian cave art.</span></figcaption>
</figure>
<p>We think humans have been creating art of some kind in Australasia — which includes northern Australia, Papua New Guinea and Indonesia — for a very long time. <a href="https://theconversation.com/buried-tools-and-pigments-tell-a-new-history-of-humans-in-australia-for-65-000-years-81021">Used pigments</a> are among the earliest evidence people were living in Australia more than 60,000 years ago. </p>
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Read more:
<a href="https://theconversation.com/buried-tools-and-pigments-tell-a-new-history-of-humans-in-australia-for-65-000-years-81021">Buried tools and pigments tell a new history of humans in Australia for 65,000 years</a>
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<p>Tens of thousands of distinctive rock art sites are scattered across Australasia, with Aboriginal people creating many <a href="https://www.nma.gov.au/defining-moments/resources/first-rock-art">styles of rock art</a> across Australia. </p>
<p>Until as recently as 2014, scholars thought the earliest cave art was in Europe — for example, in the Chauvet Cave in France or <a href="https://cuevas.culturadecantabria.com/el-castillo-2/">El Castillo</a> in Spain, which are 30,000 to 40,000 years old. We now know people were painting inside caves and rockshelters in Indonesia at the same time and even earlier. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400487/original/file-20210513-21-ie5v2q.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">Hand stencils in one of the study sites at Leang Sakapao cave.</span>
<span class="attribution"><span class="source">Linda Siagian</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Ongoing surveys throughout Australasia turn up new rock art sites every year. To date, more than 300 painted sites have been documented in the limestone karsts of Maros-Pangkep, in southern Sulawesi. </p>
<p>Cave paintings in Sulawesi and <a href="https://theconversation.com/borneo-cave-discovery-is-the-worlds-oldest-rock-art-in-southeast-asia-106252">Borneo</a> are some of the earliest evidence we have that people were living on these islands.</p>
<p>Tragically, at almost every new site we find in this region, the rock art is in an advanced stage of decay. </p>
<h2>Big impacts from small crystals</h2>
<p>To investigate why these prehistoric artworks are deteriorating, we studied some of the oldest known rock art from the Maros-Pangkep region, scientifically dated to between at least 20,000 and 40,000 years old.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400234/original/file-20210512-17-1811e0t.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">Expanding and contracting salt crystals are causing rock art to flake off the cave walls.</span>
<span class="attribution"><span class="source">Linda Siagian</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Given these artworks have survived over such a vast period, we wanted to understand why the painted limestone cave surfaces now appear to be eroding so rapidly. </p>
<p>We used a combination of scientific techniques, including using high-powered microscopes, chemical analyses and crystal identification to tackle the problem. This revealed that salts growing both on top of and behind ancient rock art can cause it to flake away. </p>
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Read more:
<a href="https://theconversation.com/indonesian-cave-paintings-show-the-dawn-of-imaginative-art-and-human-spiritual-belief-128457">Indonesian cave paintings show the dawn of imaginative art and human spiritual belief</a>
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<p>Salts are deposited on rock surfaces via the water they’re absorbed in. When the water solution evaporates, salt crystals form. The salt crystals then swell and shrink as the environment heats and cools, generating stress in the rock. </p>
<p>In some cases, the result is the stone surface crumbling into a powder. In other instances, salt crystals form columns under the hard outer shell of the old limestone, lifting the art panel and separating it from the rest of the rock, obliterating the art. </p>
<p>On hot days, geological salts can grow to more than three times their initial size. On one panel, for example, a flake half the size of a hand peeled off in under five months.</p>
<h2>Climate extremes under global warming</h2>
<p>Australasia has an <a href="https://www.sciencedirect.com/science/article/abs/pii/S027737911200529X?via%3Dihub">incredibly active atmosphere</a>, fed by intense sea currents, seasonal trade winds and a reservoir of warm ocean water. Yet, some of its rock art has so far managed to survive tens of thousands of years through major episodes of climate variation, from the cold of the last ice age to the start of the current monsoon.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Limestone karsts in a field" src="https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400437/original/file-20210513-23-abkixy.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">Limestone karsts of Maros and Pangkep Regencies, in South Sulawesi, Indonesia.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>In contrast, famous European cave art sites such as Altamira in Spain and Lascaux in France are found in deep caves, in more stable (temperate) climates, so threats to rock art are different and generally weathering is less aggressive. </p>
<p>But now greenhouse gases are magnifying climatic extremes. In fact, global warming can be up to <a href="https://theconversation.com/climate-explained-will-the-tropics-eventually-become-uninhabitable-145174">three times higher in the tropics</a>, and the wet-dry phases of the monsoon have become stronger in recent decades, along with more numerous La Niña and El Niño events.</p>
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<strong>
Read more:
<a href="https://theconversation.com/climate-explained-will-the-tropics-eventually-become-uninhabitable-145174">Climate explained: will the tropics eventually become uninhabitable?</a>
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<p>The net effect is that temperatures are higher, there are more hot days in a row, droughts are lasting longer, and other extreme weather such as storms (and the flooding they cause) are more <a href="https://www.ipcc.ch/sr15/chapter/spm/">severe and frequent</a>. </p>
<p>What’s more, monsoonal rains are now captured in rice fields and aquaculture ponds. This promotes the growth of art-destroying salt crystals by raising humidity across the region and especially in nearby caves, prolonging the shrink and swell cycles of salts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three people hold a torch to cave wall" src="https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400446/original/file-20210513-17-ahrr86.jpeg?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">Makassar’s culture heritage department, Balai Pelestarian Cagar Budaya, undertaking rock art monitoring in Maros-Pangkep.</span>
<span class="attribution"><span class="source">Rustan Lebe/Griffith University</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>What happens now?</h2>
<p>Apart from the direct threats associated with industrial development — such as <a href="https://theconversation.com/rio-tinto-just-blasted-away-an-ancient-aboriginal-site-heres-why-that-was-allowed-139466">blasting away archaeological sites</a> for <a href="https://www.theguardian.com/science/2020/feb/21/worlds-oldest-art-under-threat-from-cement-mining-in-indonesia-sulawesi">mining and limestone quarrying</a> — our research makes it clear global warming is the biggest threat to the preservation of the trpoics’ ancient rock art.</p>
<p>There’s a pressing need for further research, monitoring and conservation work in Maros-Pangkep and across Australasia, where cultural heritage sites are under threat from the destructive impacts of climate change.</p>
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Read more:
<a href="https://theconversation.com/rio-tinto-just-blasted-away-an-ancient-aboriginal-site-heres-why-that-was-allowed-139466">Rio Tinto just blasted away an ancient Aboriginal site. Here’s why that was allowed</a>
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<p>In particular, we urgently need to document the remaining rock art in great detail (such as with 3D scanning) and uncover more sites before this art disappears forever.</p>
<p>If humans are ultimately causing this problem, we can take steps to correct it. Most importantly, <a href="https://theconversation.com/the-1-5-global-warming-limit-is-not-impossible-but-without-political-action-it-soon-will-be-159297">we need to act now</a> to stop global temperature increases and drastically cut emissions. Minimising the impacts of climate change will help preserve the incredible artworks Australasia’s earliest people left to us.</p>
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<p>
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<strong>
Read more:
<a href="https://theconversation.com/indonesian-cave-paintings-show-the-dawn-of-imaginative-art-and-human-spiritual-belief-128457">Indonesian cave paintings show the dawn of imaginative art and human spiritual belief</a>
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<img src="https://counter.theconversation.com/content/159929/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jillian Huntley receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Adam Brumm receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Adhi Oktaviana is a PhD student at Griffith University and researcher at Pusat Penelitian Arkeologi Nasional, Indonesia. </span></em></p><p class="fine-print"><em><span>Basran Burhan is a PhD student at Griffith University</span></em></p><p class="fine-print"><em><span>Maxime Aubert receives funding from the Australian Research Council and the National Geographic Society.</span></em></p>The ancient cave paintings have only begun to tell us about the lives of the earliest people who lived in Australasia. The art is disappearing just as we are beginning to understand its significance.Jillian Huntley, Research Fellow, Griffith UniversityAdam Brumm, Professor, Griffith UniversityAdhi Oktaviana, PhD Candidate, Griffith UniversityBasran Burhan, PhD candidate, Griffith UniversityMaxime Aubert, Professor, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1593472021-04-25T08:35:07Z2021-04-25T08:35:07ZWhat triangular patterns on rocks may reveal about human ancestors<figure><img src="https://images.theconversation.com/files/395950/original/file-20210420-15-1xixsaq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The larger of the two triangular geometric features (scale bar = 10 cm.)</span> <span class="attribution"><span class="source">Charles Helm</span></span></figcaption></figure><p>The <a href="https://www.livescience.com/40311-pleistocene-epoch.html">Pleistocene epoch</a>, which started 2.6 million years ago and lasted until about 11,700 years ago, was crucially important for our hominin ancestors. </p>
<p><em>Homo sapiens</em> first evolved in this era, about 200,000 years ago. Then, in the latter period of the Pleistocene, our ancestors started to display signs of <a href="https://doi.org/10.1080/0067270X.2015.1039236">cognitive complexity</a>: among other innovations, they made more sophisticated tools, began to harvest seafood, used compound paints and adhesives, engraved objects with geometric designs and strung shell beads.</p>
<p>Some of these ancient humans lived in and travelled through what is today South Africa’s Cape south coast. They, like the many animals that occupied this space, left their tracks in aeolianites, the cemented remains of dune surfaces; the oldest of these surfaces are around 400,000 years old and the youngest are about 35,000 years old. One hominin tracksite that our research team found, at Brenton-on-Sea on the Cape south coast, <a href="https://doi.org/10.1038/s41598-018-22059-5">contained 40 human footprints</a> dating back around 90,000 years. Since then we have <a href="https://doi.org/10.17159/sajs.2020/8156">identified</a> a further three hominin tracksites. <a href="http://dx.doi.org/10.1080/10420940802470482">Previously reported sites</a> from the Cape’s east and west coasts bring the total number of reported Pleistocene hominin tracksites in southern Africa to six.</p>
<p>These rock surfaces don’t just show where and how our ancestors walked or jogged. They also reveal how they foraged or <a href="https://doi.org/10.17159/sajs.2020/6542">left stone tools</a> – and made patterns in the sand. The patterns that we have found consisted of circles, grooves, “hashtags”, fan shapes and even what appeared to be a sand sculpture that resembled a sting-ray. In our <a href="https://doi.org/10.1016/j.pgeola.2019.08.004">research paper</a> about these discoveries, we introduced the term “ammoglyph” to describe a pattern created by humans in sand that is now evident in rock. </p>
<p>Now we’ve <a href="http://www.ifrao.com/wp-content/uploads/2021/04/38-1-Helm-et-al.pdf">discovered</a> two new triangular patterns that we believe are ammoglyphs. This is yet <a href="https://www.sciencedirect.com/science/article/abs/pii/S0047248404001307?via%3Dihub">more evidence</a> that South Africa’s coastline is a place where our human forebears became <a href="https://science.sciencemag.org/content/325/5942/859">truly modern</a>.
Here they developed the complex cognition that defines us today. </p>
<p>It appears that the area’s dunes and beaches formed a vast canvas of sand on which our ancestors could leave their mark, perhaps in the same way that today we enjoy inscribing patterns on the beach or making sandcastles with our kids. Remarkably, those surfaces are now amenable to our inspection and interpretation, if we know where to look.</p>
<h2>Surprise discoveries</h2>
<p>This newest discovery came in 2019. Three members of our research team were exploring a rugged and remote stretch of coastline at low tide, searching for newly exposed tracksites. As we clambered over a bunch of rocks and looked up, we could hardly believe our eyes. Ahead of us, on a large rock that had tumbled down from the cliffs above, was an arrangement of linear groove features that formed a near-isosceles triangle, complete with an almost perfect bisector. </p>
<p>The sides of the triangle were close to a metre in length. Our first question was whether this could be <a href="https://theconversation.com/graffiti-threatens-precious-evidence-of-ancient-life-on-south-africas-coast-157777">modern graffiti</a>. Fortunately we were easily able to exclude that possibility, as disturbance of the underlying layers of rock implied that this triangular feature had been created when the surface was sand, not rock. </p>
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Read more:
<a href="https://theconversation.com/graffiti-threatens-precious-evidence-of-ancient-life-on-south-africas-coast-157777">Graffiti threatens precious evidence of ancient life on South Africa's coast</a>
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<p>We documented the site and took photos for photogrammetry, so we could generate digital 3D images. </p>
<figure class="align-right ">
<img alt="A scale bar in blue and red is visible to the right of a smooth piece of stone, also in blue and red, that features a triangular shape." src="https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=470&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=470&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=470&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=591&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=591&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395947/original/file-20210420-23-njdwzx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=591&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Photogrammetry of the larger geometric feature; horizontal and vertical scales are in metres.</span>
<span class="attribution"><span class="source">Authors supplied</span></span>
</figcaption>
</figure>
<p>When we returned a few weeks later we were amazed to find a similar but smaller rock right beside the rock we had initially identified. It also contained a triangular feature, but this time a near-right-angled triangle. It likely came from the same original surface, and high tides must have overturned it since our initial visit.</p>
<p>These triangular features, we argue in <a href="http://www.ifrao.com/wp-content/uploads/2021/04/38-1-Helm-et-al.pdf">our new paper</a>, are probably ammoglyphs. Geological correlation to a dated site about 2km to the east suggests an age range of between 130,000 and 80,000 years, but we don’t yet know exactly when they were made; we have submitted rock samples for dating studies and hope to have these results soon. </p>
<h2>Palaeo-art</h2>
<p>The area where we found the triangular features is relatively close to <a href="https://theconversation.com/south-africas-blombos-cave-is-home-to-the-earliest-drawing-by-a-human-103017">Blombos Cave</a>. This site is internationally famous because of what can be termed its “palaeo-art”, epitomised by <a href="https://doi.org/10.1126/science.1067575">an engraved piece of ochre</a> and an <a href="https://doi.org/10.1038/s41586-018-0514-3">abstract drawing</a>. </p>
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Read more:
<a href="https://theconversation.com/south-africas-blombos-cave-is-home-to-the-earliest-drawing-by-a-human-103017">South Africa's Blombos cave is home to the earliest drawing by a human</a>
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<p>The engraving pattern at Blombos Cave has been analysed by numerous experts, with varying interpretations. However, it can clearly be regarded as a series of triangles. Could what we have found and described represent a version of this pattern on an unprecedented, large scale? After all, it may have been easier for our ancestors to inscribe a large pattern in sand using a stick than to have to carry ochre a long distance to a cave and then meticulously get to work on engraving. For now, until we find more examples, this is pure speculation. But it is an intriguing possibility.</p>
<p>It is also exciting to think that the record of ancient art could be deepened by these sorts of finds. Examples of palaeo-art become less common with increasing distance in time, partly because some materials like bone or wood or rock art deteriorate faster than others, like stone. Some researchers have lamented how much ancient art must have been created in perishable materials and, so, been <a href="https://doi.org/10.1111/j.1469-7580.2009.01160.x">lost to the archaeological record</a>.</p>
<p>With the emergence of possible ammoglyphs on South Africa’s Cape south coast, it appears that such a lament may have been premature. The addition of sand as another medium through which palaeo-art can potentially be recognised is an unexpected development in the understanding of our human origins – and is something to be cherished.</p><img src="https://counter.theconversation.com/content/159347/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Helm 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>It appears that the South African Cape south coast’s dunes and beaches formed a vast canvas of sand on which our ancestors could leave their mark.Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1476562020-10-07T19:10:21Z2020-10-07T19:10:21ZIt was growing rainforests, not humans, that killed off Southeast Asia’s giant hyenas and other megafauna<figure><img src="https://images.theconversation.com/files/362096/original/file-20201007-14-1ciu27.jpeg?ixlib=rb-1.1.0&rect=56%2C56%2C4159%2C3148&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>Thinking of Southeast Asia today may conjure up images of dense tropical rainforests teeming with iconic jungle animals such as orangutans, tigers and monkeys.</p>
<p>Perhaps less well known, but just as important to these ecosystems, are a host of other large-bodied creatures: the goat-like <a href="https://en.wikipedia.org/wiki/Serow">serows</a> and <a href="https://en.wikipedia.org/wiki/Goral">gorals</a>, <a href="https://www.wwf.org.uk/learn/wildlife/asian-rhinos">three species of Asian rhino</a> and the only species of <a href="https://en.wikipedia.org/wiki/Malayan_tapir">tapir</a> still living in the “Old World”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tapir sitting in a green forest." src="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362098/original/file-20201007-16-10up6pm.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"></a>
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<span class="caption">The endangered Malayan tapir is the largest of four widely-recognized tapir species and the only one native to Asia.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Together, these creatures comprise Southeast Asia’s megafauna, second only to Africa’s in diversity. These two continental ecosystems are the last vestiges of a world largely lost – one where giants roamed the Earth. But what caused so many megafauna species to go extinct?</p>
<p>Several theories have suggested either humans, climate change, or both drove Southeast Asia’s megafauna to extinction. However, our newest research published today in <a href="https://www.nature.com/articles/s41586-020-2810-y">Nature</a> indicates it was actually the rise and fall of savannah environments that drove this extinction event.</p>
<h2>Southeast Asia’s megafauna extinctions</h2>
<p>Southeast Asia has lost many large mammal species over the Quaternary period, the past 2.6 million years. They included the world’s largest ever ape, <em><a href="https://en.wikipedia.org/wiki/Gigantopithecus">Gigantopithecus</a></em>, elephant-like creatures known as <a href="https://en.wikipedia.org/wiki/Stegodon">stegodons</a> and large water buffaloes.</p>
<p>These extinctions also include one of our closest relatives, <em>Homo erectus</em>, and two island offshoots of the human family tree – <em>Homo floresiensis</em> (the “Hobbit”) and <em>Homo luzonensis</em>. One final human species is also recorded in the genes of Southeast Asians today: the Denisovans, who were once <a href="https://cosmosmagazine.com/palaeontology/southeast-asia-was-crowded-long-before-we-turned-up/">likely widespread throughout the region</a>.</p>
<p>According to <a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">previous research</a>, the lead antagonist in the megafauna extinction story is humans. Some have suggested the arrival of people to new lands over the past 60,000 years or more – who then overhunted and altered this new habitat – is what led to the loss of giant mammals. </p>
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Read more:
<a href="https://theconversation.com/new-analysis-finds-no-evidence-that-climate-wiped-out-australias-megafauna-53821">New analysis finds no evidence that climate wiped out Australia's megafauna</a>
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<p>Others researchers have contended <a href="https://theconversation.com/humans-coexisted-with-three-tonne-marsupials-and-lizards-as-long-as-cars-in-ancient-australia-138534">changes in climate</a> resulted in the extinction of the megafauna. While others suggest a <a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">combination</a> of both human and climate influences. </p>
<h2>Toothy insights into past environments</h2>
<p>For our research, we examined environmental changes in Southeast Asia over the <a href="https://www.nationalgeographic.com/science/prehistoric-world/quaternary/">past 2.6 million years</a>, to determine how they may have impacted extinctions. </p>
<p>We analysed the <a href="https://www.futurelearn.com/courses/archaeology/0/steps/15267">stable isotopes</a> of the teeth of mammals found in the region today, as well as those from available published fossil records.</p>
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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>
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<p>Stable isotopes are the non-radioactive forms of many elements. Stable isotopes of carbon and oxygen preserved in mammal teeth record important information on what kinds of plants those animals ate, and how wet their environments were, respectively. </p>
<p>Stable carbon isotopes are particularly helpful in recording whether animals predominantly ate leaves and fruits in shaded forests, or grasses in more open settings. This insight lets us identify shifts in environments over time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ancient tooth fossils." src="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=456&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=456&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362110/original/file-20201007-14-1ux7jsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=456&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These fossil teeth from extinct Southeast Asian elephants are one example of the various teeth available in the fossil record.</span>
<span class="attribution"><span class="source">Julien Louys</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The fluctuating presence of forests</h2>
<p>During the first 1.5 million years or so of the Pleistocene (the geological epoch that lasted from about 2,580,000 to 11,700 years ago), the northern parts of Southeast Asia were largely forest, while the southern parts were woodlands or grasslands. </p>
<p>Later, from about one million years ago, forests retreated everywhere in the region and grasslands dominated. Coincident with these changes, large forest-adapted animals including <em>Gigantopithecus</em> and a giant panda relative disappeared from Southeast Asia’s northern parts.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Model recreation of Gigantopithecus blacki." src="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=831&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=831&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=831&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362105/original/file-20201007-20-1wpzz47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Gigantopithecus blacki</em> was a large extinct ape that lived during the Pleistocene in what is now Southern China. It’s believed to have gone extinct about 300,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/22077805@N07/5484933159/in/photostream/">Greg Williams/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Later still, around 400,000 years ago, the Southeast Asian Sunda Shelf began to submerge and climate cycles changed. Because of this, forest conditions returned.</p>
<p>At the same time, grassland-adapted creatures that had filled the region, including giant hyenas, <a href="http://www.eartharchives.org/articles/stegodon-the-elephant-with-sideways-trunk/">stegodons</a>, <a href="https://www.britannica.com/animal/bovid">bovids</a> and <em>Homo erectus</em> began to disappear – and largely went extinct by the end of the Pleistocene. The remainder were driven into the rainforests. </p>
<p>By the last few tens of thousands of years, we see the first evidence of <a href="https://en.wikipedia.org/wiki/Stratification_(vegetation)">stratified</a>, closed-canopy rainforests in Southeast Asia. These have dominated the region for the past 20,000 years or so.</p>
<p>Rainforest-adapted species should have been advantaged by the return of the rainforests, but one interloper changed that. <em>Homo sapiens</em> appears to be the only species in our family tree that was able to successfully adapt to and exploit rainforest environments. </p>
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Read more:
<a href="https://theconversation.com/old-teeth-from-a-rediscovered-cave-show-humans-were-in-indonesia-more-than-63-000-years-ago-82075">Old teeth from a rediscovered cave show humans were in Indonesia more than 63,000 years ago</a>
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<p>And although humans lived in Southeast Asian rainforests as early as 73,000 years ago, it was probably only <a href="https://advances.sciencemag.org/content/4/6/e1701422">in the last 10,000 years</a> that <em>Homo sapiens</em> began to fundamentally alter these habitats and exploit the mammals within. </p>
<h2>A vanishing world</h2>
<p>Southeast Asia continues to preserve some of the most critically endangered megafauna on the planet. </p>
<p>Megafauna grassland specialists were the greatest loss as a result of disappearing savannahs 400,000 years ago. Today, rainforest megafauna are also at great risk of extinction. </p>
<p>Luckily for us, our own species’ fortunes changed for the better with the emergence of typical Southeast Asian rainforests. But we’re now the very thing threatening to <a href="https://theconversation.com/guns-snares-and-bulldozers-new-map-reveals-hotspots-for-harm-to-wildlife-113361">destroy them forever</a>.</p><img src="https://counter.theconversation.com/content/147656/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Patrick Roberts receives funding from the Max Planck Society and the European Research Council.</span></em></p>Several theories have suggested either humans, climate change or both drove megafauna extinctions in Southeast Asia. Our newest work suggests otherwise.Julien Louys, ARC Future Fellow, Griffith UniversityPatrick Roberts, Research Group Leader, Max Planck Institute of GeoanthropologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1471992020-10-04T07:26:09Z2020-10-04T07:26:09ZFossil tracks reveal which birds once roamed South Africa’s Cape south coast<figure><img src="https://images.theconversation.com/files/360741/original/file-20200930-20-m0bjts.JPG?ixlib=rb-1.1.0&rect=6%2C27%2C603%2C423&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">These fossil trackways resemble the tracks left by flamingos today, but are bigger. Just above the scale bar one can see (more faintly) the 'tramline traces' made by the ancient birds' stomping action.</span> <span class="attribution"><span class="source">Charles Helm</span></span></figcaption></figure><p>If you visit a particular stretch of South Africa’s Cape South coast, about 400km east of Cape Town, you are stepping back in time – in more ways than one. That’s because hundreds of fossil tracksites dot the area. These sites date back to between 400,000 and 35,000 years ago, during the <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene</a> Epoch. They occur in aeolianites (cemented dunes) and cemented foreshore deposits, the remains of dune and beach surfaces on which animals left their tracks.</p>
<p>Since 2007 our research team has identified more than 250 fossil tracksites on the Cape south coast, revealing unexpected findings that were not apparent in the traditional body fossil record. For example, <a href="http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532018000100017">giraffe</a>, <a href="https://theconversation.com/first-fossil-trails-of-baby-sea-turtles-found-in-south-africa-122434">hatchling sea turtles</a> and <a href="https://theconversation.com/fossil-track-sites-tell-the-story-of-ancient-crocodiles-in-southern-africa-134410">crocodiles</a> once inhabited this coastline.</p>
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Read more:
<a href="https://theconversation.com/first-fossil-trails-of-baby-sea-turtles-found-in-south-africa-122434">First fossil trails of baby sea turtles found in South Africa</a>
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<p>Our latest work has centred on avian tracksites, revealing evidence for the first time from this period of some of the bird species that once roamed the Cape south coast. In <a href="https://www.tandfonline.com/doi/abs/10.2989/00306525.2020.1789772">an article</a> recently published in the journal Ostrich, we summarised our findings from 29 sites on that coast. </p>
<p>One avian track, probably made by a large gull or a small goose, was found in sediments that have been <a href="https://doi.org/10.1016/j.epsl.2012.09.006">dated to about 400,000 years</a>. That makes it the oldest avian track reported from southern Africa.</p>
<p>Six of the tracksites we identified showed evidence of large avian trackmakers. For example, tracks at one site that appear to have been made by a crane were larger than any extant crane species in Africa, and a trackway at another site closely resembled that of a flamingo – except that the tracks were larger than those of the extant Greater Flamingo. </p>
<p>At this site, which was remarkably well preserved, we also documented flamingo feeding traces for the first time in the global fossil record. The creation of these traces can be readily observed in flamingo behaviour today: the birds stir up their food supply by “rhythmic stomping” or “marking time” while moving slowly backwards, resulting in “tramline traces”.</p>
<figure class="align-center ">
<img alt="A flock of pink flamingos in blue water" src="https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360760/original/file-20200930-16-alakkp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Flamingos stir up their food supply by ‘rhythmic stomping’ or ‘marking time’ while moving slowly backwards, resulting in ‘tramline traces’.</span>
<span class="attribution"><span class="source">Vera Larina/Shutterstock</span></span>
</figcaption>
</figure>
<p>These tracksites have the potential to complement the traditional body fossil record and offer more insights into what flora and fauna occurred in the region during the Pleistocene, mostly in the 130,000 to 80,000 year age range. They can also help us understand which of these species may have become extinct, perhaps driven by climatic shifts. This finding was unexpected, as there was no previous evidence of Pleistocene avian extinctions in Southern Africa. </p>
<h2>Tracing the tracks</h2>
<p>Avian tracks tend to be less common and less obvious than mammal and reptile tracks. This is partly because birds fly and perch, so many species left few tracks to be interpreted today. Our findings of bird tracks on what were beaches and dunes is extremely unusual – globally, most fossil bird tracks <a href="https://www.tandfonline.com/doi/abs/10.1080/10420940601006826">are found</a> on the margins of lakes and lagoons. </p>
<p>Some of our sites were tough to reach. For example, one site was among high, brittle cliffs on the under-surface of the ceiling of a tiny overhang.</p>
<figure class="align-center ">
<img alt="A man steadies himself on a cliff." src="https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360748/original/file-20200930-14-u1jtbl.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">
<figcaption>
<span class="caption">Some tracks were found high up in the cliffs, under an overhang.</span>
<span class="attribution"><span class="source">Author supplied</span></span>
</figcaption>
</figure>
<p>Initially only two tracks were visible. But, following some excavation we identified a total of five tracks and created enough space to take photos for <a href="https://www.researchgate.net/publication/316515978_Close-range_photogrammetry_for_3-D_ichnology_The_basics_of_photogrammetric_ichnology">photogrammetric studies</a> that enabled us to create a 3D digital model of the trackway which otherwise could not be adequately studied. </p>
<p>What do these large tracks tell us? Their outer digits showed some curvature, strongly suggesting that the trackmaker had webbed feet. But the tracks couldn’t be definitively linked to those of any member of southern Africa’s existing avifauna. </p>
<p>These findings raise two possibilities. The first, in line with <a href="http://www.dinosauria.org/documents/2011/07_20_tyrberg.pdf">evidence</a> from elsewhere in the world, is that some Pleistocene bird species were larger than their modern counterparts – they got smaller over time.</p>
<p>The second possibility is of previously unsuspected Pleistocene avian extinctions. We could postulate, for example, that a large freshwater bird species may have been driven to extinction by a change in climate that <a href="https://www.sciencedirect.com/journal/quaternary-science-reviews/vol/235/suppl/C">we know</a> inundated the abundant wetland habitat that previously existed on the adjacent Palaeo-Agulhas Plain. </p>
<p>The Pleistocene body record fossil does not provide any such evidence. It extends back to about 80,000 years ago and most of the tracksites we have documented appear to be from the 130,000 to 90,000 year range. So it’s plausible that Pleistocene avian extinctions predated any evidence that may be available through the skeletal record.</p>
<h2>Easily lost</h2>
<p>Though the sites we’re exploring are ancient, they are also ephemeral. Tracks are made on a dune, covered by another layer of sand, and then buried by 100,000 years or more. Once exposed through the forces of erosion they are destined to disappear within a very short period of time, also through erosion or other natural forces – and sometimes, regrettably, through graffiti on the rocks.</p>
<p>The splendid fossil flamingo tracksite is an unfortunate example of this. It was obliterated by a powerful storm surge in the winter of 2020. Nonetheless, the photogrammetric record that we obtained ensures that this unique surface has not been lost to science, and it would be feasible to create an exact replica. </p>
<p>Still, the message is clear: we need to be vigilant, and to keep on searching, exploring, and documenting – because like their mammal and reptile counterparts, fossil bird tracks have a lot to teach us.</p><img src="https://counter.theconversation.com/content/147199/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Helm 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>One avian track, probably made by a large gull or a small goose, was found in sediments that have been dated to about 400,000 years. That makes it the oldest avian track reported from southern Africa.Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1326272020-04-29T15:48:10Z2020-04-29T15:48:10ZHow bison, moose and caribou stepped in to do the cleaning work of extinct mammoths<figure><img src="https://images.theconversation.com/files/330714/original/file-20200427-145560-nibdjc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3777%2C2050&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Unlike mammoths, bison survived in Alaska at the end of the last ice age.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/QvCcqTHlLCE">Hans Veth/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The extinction of one species can create ripples that transform an ecosystem. That’s particularly true for so-called “ecosystem engineer” species. Beavers are one example – they dam rivers, creating ponds and channels that <a href="https://theconversation.com/beavers-are-set-to-recolonise-the-uk-heres-how-people-and-the-environment-could-benefit-132116">offer refuge for spawning fish and small mammals</a>.</p>
<p>Large herbivores such as <a href="http://thinkelephants.blogspot.com/2012/10/elephants-ecosystems-engineers.html">elephants, horses and reindeer</a> are engineers too – they break down shrubs and trees to create open grasslands, habitats that benefit a wealth of species.</p>
<p>We know that their ancestors – such as the woolly mammoth – shaped the world around them in a similar way, but what happened to those ancient ecosystems when they died out?</p>
<p>Our <a href="https://www.cambridge.org/core/journals/quaternary-research/article/tracking-latequaternary-extinctions-in-interior-alaska-using-megaherbivore-bone-remains-and-dung-fungal-spores/BD3C13789FBB262EDCA8432CBB47067E">new research published in the journal Quaternary Research</a> studied the extinction of mammoth, wild horse and saiga antelope towards the end of the last ice age in interior Alaska, analysing fossilised <a href="https://methodsblog.com/2016/07/19/european-bison/">dung fungal spores</a> recovered from the bottom of lakes and <a href="https://www.nps.gov/articles/aps-17-1-4.htm">ancient bones recovered from buried</a> sediments.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-effect-did-the-asteroid-that-wiped-out-the-dinosaurs-have-on-plants-and-trees-132386">Curious Kids: What effect did the asteroid that wiped out the dinosaurs have on plants and trees?</a>
</strong>
</em>
</p>
<hr>
<p>We wanted to know how ancient ecosystems responded to these species dying out so that it might teach us more about mass extinctions today. What we discovered could offer hope for modern ecosystems facing biodiversity loss.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=435&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=435&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330716/original/file-20200427-145536-v86bx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=435&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A museum replica of a woolly mammoth. Mammoths helped maintain open habitats by grazing herbs, trees and bushes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dvur-kralove-czech-republic-08132013-big-1024532596">Noska Photo/Shutterstock</a></span>
</figcaption>
</figure>
<h2>How ancient ecosystems coped with extinctions</h2>
<p>The late-Quaternary extinctions occurred towards the end of the last ice age. In North America, they saw the loss of large herbivores and carnivores, whose relatives still roam other continents as elephants, wild horses and tigers. This was a period of rapid climate change and growing pressure from humans.</p>
<p><a href="https://www.researchgate.net/publication/269820457_Late_Quaternary_megafaunal_extinctions_on_the_continents_A_short_review">Previous research showed that 69% of large mammals</a> were lost from North America around this time. Similar losses were seen on other continents, <a href="https://www.discovermagazine.com/planet-earth/dung-fungus-reveal-that-humans-not-climate-change-killed-australias-giant-beasts">including Australia</a>. The diversity of mammal species shrank, but more significant was the <a href="https://doc.rero.ch/record/210391/files/PAL_E4398.pdf">crash in numbers of all mammals</a>, including species that survived the extinction event.</p>
<p><a href="https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.12576">Previous research</a> showed that elsewhere in the Americas, the loss of ecosystem engineers like the woolly mammoth led to an explosion in plant growth, as trees and shrubs were no longer grazed and browsed so intensively. In turn, there were larger and more frequent wildfires.</p>
<p>But in Alaska, our results revealed that other species of wild herbivores, including bison, moose, caribou and musk ox, increased in abundance, making up for the loss of mammoths, saiga antelopes and wild horses.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=509&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=509&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=509&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=639&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=639&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330718/original/file-20200427-145499-105esni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=639&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Saiga antelopes used to roam North America, but they are now only found in scattered pockets of Asia.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Saiga_antelope#/media/File:Saiga_antelope_at_the_Stepnoi_Sanctuary.jpg">Andrey Giljov/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This suggests that as extinctions occurred, other large herbivores were able to fill the gap, partially taking over the lost role of ecosystem engineer. This insight from 13,000 years ago could offer hope for modern conservationists. Substituting an extinct ecosystem engineer with a similar species still living today may work to revive lost ecological processes.</p>
<p>Reintroducing large herbivores in this way is often referred to as “<a href="https://www.esf.edu/efb/parry/Invert_Cons_14_Readings/Seddon_etal_2014.pdf">rewilding</a>”. Today’s landscapes on most continents are <a href="https://www.chrispackham.co.uk/news/what-is-rewilding">empty of large vertebrate animals</a>, largely because of the late Quaternary extinctions we studied. <a href="https://www.researchgate.net/publication/257973653_Rewilding_North_America">One of the key arguments</a> behind rewilding is that bringing some of those species back to landscapes could boost biodiversity more broadly and create more diverse, resilient ecosystems.</p>
<p>But without resurrecting the woolly mammoth, our research indicates it may be possible to bring back some of the ecosystem engineering benefits of extinct species by reintroducing their living relatives or substitute species, ultimately helping surviving plants and animals to thrive.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/could-resurrecting-mammoths-help-stop-arctic-emissions-95956">Could resurrecting mammoths help stop Arctic emissions?</a>
</strong>
</em>
</p>
<hr>
<p>Our work in Alaska shows that the consequences of engineer extinctions are not always overwhelmingly negative. Studying this rare instance when ecosystems coped better with extinctions can help us design more effective conservation measures for megaherbivores today. </p>
<p>A good example of creative thinking in conservation can be found in Columbia. Here, pet hippos that escaped from Pablo Escobar’s private collection have multiplied in the wild and now appear to be recreating processes that were <a href="https://www.theguardian.com/environment/2020/mar/24/pablo-escobars-cocaine-hippos-show-how-invasive-species-can-restore-a-lost-world-aoe">lost thousands of years ago</a> when native megaherbivores died out. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330721/original/file-20200427-145499-1a33zx6.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">These hippos are technically invasive species in Colombia and are wild descendants of Pablo Escobar’s pets.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hippopotamus-colombia-1351698167">Perla Sofia/Shutterstock</a></span>
</figcaption>
</figure>
<p>This includes the creation of well trodden hippo paths between wetlands and feeding areas on firmer ground, which help deepen water channels, disperse seeds and fertilise wetlands. Over 13,000 years ago, these processes would have been carried out by the now extinct <a href="https://prehistoric-fauna.com/Macrauchenia-patagonica">giant llama</a>, and semi-aquatic <a href="https://dcpaleo.org/notoungulata/">notoungulata</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/330738/original/file-20200427-145544-1ud4ur2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Notoungulata were hoofed, sometimes heavy-bodied grazing mammals that inhabited South America from 57 million years to 11,000 years ago.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Notoungulata#/media/File:Toxodon.jpg">ArthurWeasley/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Although it may seem an eternity since mammoths walked the Earth, our research suggests that some of the effects they had on the world around them can be resurrected without a Jurassic Park-style breakthrough in <a href="https://www.thoughtco.com/the-resurrection-of-extinct-animals-1091999">de-extinction</a>.</p><img src="https://counter.theconversation.com/content/132627/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maarten van Hardenbroek van Ammerstol receives funding from UKRI/NERC. </span></em></p><p class="fine-print"><em><span>Ambroise Baker 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>The historical record is full of surprises – and it could encourage conservationists to think more creatively.Ambroise Baker, Lecturer in Biology, Teesside UniversityMaarten van Hardenbroek van Ammerstol, Lecturer in Physical Geography, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1287992020-01-03T09:36:46Z2020-01-03T09:36:46ZHow the extinction of ice age mammals may have forced us to invent civilisation<figure><img src="https://images.theconversation.com/files/307690/original/file-20191218-11900-s0uqmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Hunting_Woolly_Mammoth.jpg">Wikimedia Commons/Cloudordinary</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Why did we take so long to invent civilisation? Modern <em>Homo sapiens</em> first evolved roughly <a href="https://theconversation.com/modern-humans-evolved-100-000-years-earlier-than-we-thought-and-not-just-in-east-africa-78875">250,000 to 350,000</a> years ago. But initial steps towards civilisation – harvesting, then domestication of crop plants – began only <a href="https://science.sciencemag.org/content/288/5471/1602?ijkey=3c1b653d8a610f044ce71bd2e41594fe7be12060&keytype2=tf_ipsecsha">around 10,000 years ago</a>, with the first civilisations appearing <a href="https://link.springer.com/article/10.1007/s10814-010-9041-y">6,400 years ago</a>.</p>
<p>For 95% of our species’ history, we didn’t farm, create large settlements or complex political hierarchies. We lived in small, nomadic bands, hunting and gathering. Then, something changed. </p>
<p>We transitioned from hunter-gatherer life to plant harvesting, then cultivation and, finally, cities. Strikingly, this transition happened only after the ice age megafauna – mammoths, giant ground sloths, giant deer and horses – disappeared. The reasons humans began farming still <a href="https://phys.org/news/2019-04-food-thought-farming.html">remain unclear</a>, but the disappearance of the animals we depended on for food may have forced our culture to evolve. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=494&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=494&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306925/original/file-20191214-85428-1rtscoo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=494&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Humans hunted wild cattle, horses, and deer in France 17,000 years ago.</span>
<span class="attribution"><span class="source">Wikipedia</span></span>
</figcaption>
</figure>
<p>Early humans were smart enough to farm. All groups of modern humans have similar levels of intelligence, suggesting our cognitive capabilities evolved before these populations separated <a href="https://science.sciencemag.org/content/358/6363/652/tab-pdf">around 300,000 years ago</a>, then changed little afterwards. If our ancestors didn’t grow plants, it’s not that they weren’t clever enough. Something in the environment prevented them – or they simply didn’t need to. </p>
<p>Global warming at the end of the last glacial period, 11,700 years ago, probably <a href="https://www.cambridge.org/core/journals/american-antiquity/article/was-agriculture-impossible-during-the-pleistocene-but-mandatory-during-the-holocene-a-climate-change-hypothesis/246B240BFFFBE904B1AC31296AD72949">made farming easier</a>. Warmer temperatures, longer growing seasons, higher rainfall and <a href="https://www.journals.uchicago.edu/doi/pdfplus/10.1086/605359">long-term climate stability</a> made more areas suitable for cultivation. But it’s unlikely farming had been impossible everywhere. And Earth saw <a href="https://science.sciencemag.org/content/292/5517/686">many such warming events</a> – 11,700, 125,000, 200,000 and 325,000 years ago – but earlier warming events didn’t spur experiments in farming. Climate change can’t have been the only driver.</p>
<p>Human migration probably contributed as well. When our species expanded from southern Africa throughout <a href="https://science.sciencemag.org/content/358/6363/652/tab-pdf">the African continent</a>, into <a href="https://www.nature.com/articles/nature22968">Asia</a>, Europe and then <a href="https://science.sciencemag.org/content/365/6456/891">the Americas</a>, we found new environments and <a href="https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2012.04253.x">new food plants</a>. But people occupied these parts of the world long before farming began. Plant domestication lagged human migration by tens of millennia.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306927/original/file-20191214-85376-sg48bc.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">
<figcaption>
<span class="caption">Rye, one of the first crops.</span>
<span class="attribution"><span class="source">Wikipedia</span></span>
</figcaption>
</figure>
<p>If opportunities to invent farming already existed, then the delayed invention of agriculture suggests our ancestors didn’t need, or want, to farm.</p>
<p>Agriculture has significant disadvantages compared to foraging. Farming <a href="https://www.discovermagazine.com/planet-earth/the-worst-mistake-in-the-history-of-the-human-race">takes more effort and offers less leisure time and an inferior diet</a>. If hunters are hungry in the morning, they can have food on the fire at night. Farming requires hard work today to produce food months later – or not at all. It requires storage and management of temporary food surpluses to feed people year round. </p>
<p>A hunter having a bad day can hunt again tomorrow or seek richer hunting grounds elsewhere, but farmers, tied to the land, are at the mercy of nature’s unpredictability. Rains arriving too soon or too late, droughts, frosts, blights or locusts can cause crop failure – and famine. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307696/original/file-20191218-11900-14xokd4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Agriculture has many disadvantages over hunting.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Ancient_Egyptian_agriculture#/media/File:Maler_der_Grabkammer_des_Sennudem_001.jpg">Wikipedia</a></span>
</figcaption>
</figure>
<p>Agriculture has military disadvantages as well. Hunter-gatherers are mobile and can travel long distances to attack or retreat. Constant practice with spears and bows made them <a href="https://theconversation.com/were-other-humans-the-first-victims-of-the-sixth-mass-extinction-126638">deadly fighters</a>. Farmers are rooted to their fields, their schedules dictated by the seasons. They are predictable, stationary targets, whose food stockpiles tempt hungry outsiders.</p>
<p>And having evolved to the lifestyle, humans may simply have loved being nomadic hunters. The Comanche Indians <a href="https://www.amazon.com/dp/B003KN3MDG/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1">fought to the death</a> to preserve their hunting lifestyle. The Kalahari Bushmen of southern Africa <a href="https://www.bbc.co.uk/news/world-africa-24821867">continue to resist</a> being turned into farmers and herders. Strikingly, when Polynesian farmers encountered New Zealand’s abundant flightless birds, they largely abandoned agriculture, creating the Maori <a href="https://teara.govt.nz/en/1966/maori-material-culture">moa-hunter culture</a>.</p>
<h2>Hunting abandoned</h2>
<p>Yet something changed. From 10,000 years ago onward, humans repeatedly abandoned the hunter-gatherer lifestyle for farming. It may be that after the extinction of mammoths and other megafauna from the Pleistocene epoch, and the overhunting of surviving game, the hunter-gatherer lifestyle became less viable, pushing people to harvest and then cultivate plants. Perhaps civilisation wasn’t born out of a drive to progress, <a href="https://www.penguinrandomhouse.com/books/112492/plagues-and-peoples-by-william-h-mcneill/">but disaster</a>, as ecological catastrophe forced people to abandon their traditional lifestyles.</p>
<p>As humans left Africa to colonise new lands, large animals disappeared everywhere we set foot. In Europe and Asia, megafauna like wooly rhinos, mammoths, and Irish Elk vanished <a href="https://www.researchgate.net/profile/Adrian_Lister/publication/264785182_Patterns_of_Late_Quaternary_megafaunal_extinctions_in_Europe_and_northern_Asia/links/53f0e69f0cf2711e0c431517.pdf">around 40,000 to 10,000 years ago</a>. In Australia, giant kangaroos and wombats disappeared <a href="https://science.sciencemag.org/content/292/5523/1888">46,000 years ago</a>. In North America, horses, camels, giant armadillos, mammoths and ground sloths declined and disappeared from <a href="https://science.sciencemag.org/content/326/5956/1100.full">15,000 to 11,500 years ago</a>, followed by extinctions in South America <a href="https://www.sciencedirect.com/science/article/pii/S1040618209004236">14,000 to 8,000 years ago</a>. After people spread to the Caribbean Islands, <a href="https://www.pnas.org/content/100/19/10800.short">Madagascar</a>, <a href="https://www.sciencedirect.com/science/article/pii/S0277379114003734">New Zealand</a> and <a href="https://science.sciencemag.org/content/217/4560/633">Oceania</a>, their megafauna vanished as well. Megafaunal extinctions inevitably followed humans.</p>
<p>Harvesting big game like <a href="https://www.pnas.org/content/112/14/4263.short">horses, camels</a> and <a href="https://science.sciencemag.org/content/334/6054/351">elephants</a> produces <a href="https://www.researchgate.net/publication/24107608_The_Primitive_Hunter_Culture_Pleistocene_Extinction_and_the_Rise_of_Agriculture/link/57dd854f08ae4e6f1849a954/download">a better return</a> than hunting small game like rabbits. But large animals like elephants reproduce slowly, and have few offspring compared to small animals like rabbits, <a href="https://www.researchgate.net/publication/24107608_The_Primitive_Hunter_Culture_Pleistocene_Extinction_and_the_Rise_of_Agriculture/link/57dd854f08ae4e6f1849a954/download">making them vulnerable to overharvesting</a>. And so everywhere we went, our human ingenuity – hunting with spear-throwers, herding animals with fire, stampeding them over cliffs – meant we harvested large animals faster than they could replenish their numbers. It was arguably the first sustainability crisis. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308109/original/file-20191220-11929-1gc4m3g.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">With our hunting prey gone, we were forced to invent civilisation.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/egypt-sakkara-step-pyramid-king-djoser-109821740">WitR/Shutterstock</a></span>
</figcaption>
</figure>
<p>With the old way of life no longer viable, humans would have been forced to innovate, increasingly focusing on <a href="https://www.researchgate.net/publication/24107608_The_Primitive_Hunter_Culture_Pleistocene_Extinction_and_the_Rise_of_Agriculture/link/57dd854f08ae4e6f1849a954/download">gathering, then cultivating plants to survive</a>. This let human populations expand. Eating plants rather than meat is <a href="https://www.google.com/search?q=jared+diamong+third+chimpanzee&rlz=1C5CHFA_enGB841GB841&oq=jared+diamong+third+chimpanzee&aqs=chrome..69i57j35i39l2j0l4j69i60.4797j0j7&sourceid=chrome&ie=UTF-8">a more efficient use of land</a>, so farming can support more people in the same area than hunting. People could settle permanently, build settlements, then civilisations. </p>
<p>The archaeological and fossil records tell us our ancestors could have pursued farming, but did only so after they had little alternative. We probably would have continued hunting horses and mammoths forever, but we were just too good at it, and likely wiped out our own food supply.</p>
<p>Agriculture and civilisation may have been invented not because they were an improvement over our ancestral lifestyle, but because we were left no choice. Agriculture was desperate attempt to fix things when we took more than the ecosystem could sustain. If so, we abandoned the life of ice age hunters to create the modern world, not with foresight and intent, but by accident, because of an ecological catastrophe we created thousands of years ago.</p><img src="https://counter.theconversation.com/content/128799/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas R. Longrich 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>Overhunting of megafauna such as mammoths may have force us to take up farming, ultimately leading to modern societyNicholas R. Longrich, Senior Lecturer, Paleontology and Evolutionary Biology, University of BathLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1254202019-10-21T21:58:07Z2019-10-21T21:58:07ZMonkey fossils found in Serbia offer clues about life in a warmer world millions of years ago<figure><img src="https://images.theconversation.com/files/297698/original/file-20191018-56198-c3d7uz.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2074%2C1418&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Two monkey teeth: the first monkey fossils found in Serbia.</span> <span class="attribution"><span class="source">Predrag Radović</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Sparse trees cast long shadows as the morning sun rises over the grassy woodland clearing. Elephants and rhinos gather around a quiet watering hole. A troop of baboons starts chattering as they wake up, preparing for the sweltering heat the day will bring. </p>
<p>The scene is straight out of <em>The Lion King</em>, but this isn’t Africa — this is Eastern Europe at the end of the <a href="https://www.thoughtco.com/the-pliocene-epoch-1091372">Pliocene epoch</a>, three million years ago.</p>
<p>It’s a world that’s familiar to <a href="https://www.researchgate.net/profile/Predrag_Radovic2">Predrag Radović</a>, a paleontologist at the <a href="http://nmkv.rs/">National Museum in Kraljevo</a>, Serbia. Radović has studied fossils from extinct European elephants like <a href="https://doi.org/10.2298/GABP1802001R"><em>Zygolophodon</em></a>, a large mastodon with three-metre-long tusks, and <a href="https://www.researchgate.net/profile/Predrag_Radovic2/publication/289184303_Deinotherium_giganteum_from_Adrani_Central_Serbia/links/568a1b8708aebccc4e191299.pdf"><em>Deinotherium</em></a>, which looked like a modern African elephant, except that its tusks grew from its bottom jaw and curved downwards. </p>
<p>Radović has identified the remains of a <a href="https://doi.org/10.13130/2039-4942/9751">12.5 million-year-old whale</a> from the Miocene epoch (5.3 million to 23 million years ago), when much of Europe was submerged beneath a vast inland sea. Now Radović is writing a report about a tooth from <em>Stephanorhinus</em>, an extinct rhinoceros from the Ice Age.</p>
<h2>Monkey teeth</h2>
<p>Recently, Radović invited me to collaborate on a paper about a new fossil tooth he was studying. Compared to rhinos and whales this tooth was small and unassuming, but that’s why it was so interesting: it belonged to a monkey! </p>
<p>The tooth came from a very rich paleontological site in the village of Ridjake, western Serbia. Soon afterwards, researchers from the <a href="http://www.nhmbeo.rs/home.195.html">Natural History Museum in Belgrade</a> found a second, better-preserved tooth from the same kind of monkey. We analyzed the teeth and <a href="https://doi.org/10.1016/j.jhevol.2019.102681">published our results in the <em>Journal of Human Evolution</em></a>. </p>
<p>The teeth belonged to <em>Paradolichopithecus</em>, a large, baboon-like monkey that lived during the Pliocene epoch, between 2.6 million and 5.3 million years ago. This is the first monkey fossil ever found in Serbia, but monkeys were common in Europe during the Pliocene. <em>Paradolichopithecus</em> fossils have already been found in Spain, France, Greece and Romania, and their range extended as far as China. Studying fossil monkeys like these can help us understand how ancient climates shaped primate evolution</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=556&fit=crop&dpr=1 600w, https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=556&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=556&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=699&fit=crop&dpr=1 754w, https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=699&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/297608/original/file-20191018-98674-1t9ho9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=699&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Two primate teeth from Ridjake, Serbia identified as <em>Paradolichopithecus</em>.</span>
<span class="attribution"><span class="source">Predrag Radović</span></span>
</figcaption>
</figure>
<h2>Primate paradise</h2>
<p>In many ways, the Pliocene epoch was a paradise for primates. The global climate was two to four degrees Celsius warmer and sea level was much higher. There was no permanent ice cap at the North Pole and boreal forests extended to the high Arctic. </p>
<p>European monkeys lived in humid, subtropical forests. This warmth was due in part to higher levels of atmospheric carbon dioxide — more than 400 parts per million, a number we’ve just recently reached again for the first time in three million years. In fact, some <a href="https://phys.org/news/2018-02-global-lessons-pliocene-epoch.html">scientists have begun studying the Pliocene</a> to help understand what our climate might look like if we fail to slow our current rate of global warming.</p>
<p>But for Europe’s Pliocene monkeys, a different kind of climate change was looming. The South American continent, which had been drifting northwards for millions of years, finally collided with the Caribbean plate, setting off <a href="http://doi.org/10.1038/srep39842">a chain reaction that would permanently change the global climate</a>. With North and South America connected for the first time, the flow of ocean water between the Atlantic and Pacific was cut off, redirecting global ocean currents. </p>
<p>The newly formed Gulf Stream began carrying warm water straight to Northern Europe, where it evaporated and then fell as rain and snow, diluting the salty Arctic Ocean enough that it was able to freeze. By three million years ago, the Arctic ice cap had begun to form, driving the global climate into an Ice Age. </p>
<h2>The last primate</h2>
<p>In continental Europe, the humid, subtropical environments began to get drier. <a href="https://doi.org/10.1016/j.jhevol.2004.08.003"><em>Paradolichopithecus</em> was able to weather the climate changes</a> pretty well: the earliest fossils from Romania came from a humid, forested environment, but later fossils from France and Spain show that the animals were able to adapt to drier grassland conditions.</p>
<p>But when the Pliocene ended and the Pleistocene epoch began, 2.6 million years ago, the <a href="https://www.livescience.com/40311-pleistocene-epoch.html">Ice Age took hold of the planet</a>. The global climate settled into a cycle of glacial and interglacial periods, during which giant ice sheets would repeatedly expand and retreat over much of the northern continents. The Pleistocene drove all the primates in Europe to extinction — except one.</p>
<p><a href="http://doi.org/10.1126/science.aac6182"><em>Homo</em>, the human genus,</a> emerged in Africa around the beginning of the Pleistocene and quickly spread out across the Old World. Early humans were able to adapt to environments other primates could not by creating tools, developing seasonal strategies for finding food and controlling fire. By the Middle Pleistocene, several different species of humans were living all across Africa, Asia and Europe. </p>
<p>Of all the exotic animals that Radović studies, these are the most interesting. As part of an international team — led by <a href="https://fvm.academia.edu/DusanMihailovic">Dušan Mihailović</a>, an archaeology professor at the University of Belgrade, and <a href="https://www.uwinnipeg.ca/anthropology/faculty/mirjana-roksandic.html">Mirjana Roksandic</a>, a biological anthropologist at the University of Winnipeg — Radović and I helped to identify the first Neanderthal remains from Serbia and the Central Balkans.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-neanderthal-tooth-discovered-in-serbia-reveals-human-migration-history-115543">A Neanderthal tooth discovered in Serbia reveals human migration history</a>
</strong>
</em>
</p>
<hr>
<h2>Balkan refuge</h2>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=617&fit=crop&dpr=1 600w, https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=617&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=617&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=776&fit=crop&dpr=1 754w, https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=776&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/297697/original/file-20191018-56207-87fqxu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=776&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 village of Ridjake, western Serbia, where two fossil monkey teeth were found.</span>
<span class="attribution"><span class="source">Predrag Radović</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><a href="https://popular-archaeology.com/article/the-road-through-sicevo/">The Balkan region is critical</a> for understanding how humans and other animals responded to climate change during the Pleistocene because it served as a refuge during glacial periods. As the ice sheets expanded across northern parts of Europe, populations were funnelled into the valleys and floodplains of the Central Balkans where they were forced to adapt to new environments — or face extinction.</p>
<p>In the end, even the genus <em>Homo</em> succumbed to the Pleistocene. When the last glacial cycle ended and the Holocene epoch began, 12,000 years ago, every human species had disappeared except one. </p>
<p>It’s tempting to think there’s something special about us that allowed us to survive when others didn’t, but we were probably just lucky. The track record of primates in the Plio-Pleistocene should remind us how much climate change has influenced the course of human and primate evolution, and how precarious our relationship with the climate can be.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ldLBoErAhz4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">PBS: The Last Time the Globe Warmed.</span></figcaption>
</figure>
<p>Humans are a true Ice-Age animal. The northern ice cap has never melted since it formed three million years ago so the Ice Age hasn’t technically ended. But if the current rate of <a href="https://time.com/5680432/climate-change-history-carbon/">human-influenced climate change</a> keeps up, we will be thrust into a world our genus has never known. Studying our Pliocene relatives like <em>Paradolichopithecus</em> can offer us a perspective on what that world may be like.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/125420/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joshua Allan Lindal receives funding from the Natural Sciences and Engineering Research Council of Canada.</span></em></p>The rise and fall of monkeys in ancient Europe should remind us of our own species’ precarious relationship with changing climates.Joshua Allan Lindal, PhD student, Anthropology, University of ManitobaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1235462019-09-22T09:14:36Z2019-09-22T09:14:36ZAncient humans may have made patterns and sculptures on South Africa’s beaches<figure><img src="https://images.theconversation.com/files/293200/original/file-20190919-22446-voc66e.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A rock surface containing a circular pattern with a central depression. The scale bar = 10 cm.</span> <span class="attribution"><span class="source">Images modified from: Helm, C.W.; Cawthra, H.C.; De Vynck, J.C.; Helm, C.J.; Rust, R.; Stear. W. Patterns in the Sand: A Pleistocene hominin signature along the South African coastline? Proceedings of the Geologists’ Association (2019)</span></span></figcaption></figure><p>One of the first things many kids – or even adults – may do when they are on a beach or dune is to make patterns in the sand, or sculptures in the form of sandcastles.</p>
<p>Many generations of humans have enjoyed these activities. But until now there has been no reported evidence to suggest how far back in human history this may have occurred. Now my colleagues and I believe we may have <a href="https://doi.org/10.1016/j.pgeola.2019.08.004">found such evidence</a> at sites along South Africa’s Cape south coast. </p>
<p>Southern Africa boasts <a href="https://www.mdpi.com/2076-0752/2/1/6">an extensive record of palaeo-art</a>, and South Africa’s Cape south coast, stretching eastward along the coast from Cape Town, contains one of the richest <a href="https://www.researchgate.net/publication/285273001_Stone_Age_People_in_a_Changing_South_African_Greater_Cape_Floristic_Region">Middle Stone Age archaeological records</a> in the world. This includes <a href="https://science.sciencemag.org/content/334/6053/219">an engraved piece of ochre</a> and the <a href="https://www.nature.com/articles/s41586-018-0514-3">oldest reported example of rock painting</a>. Evidence suggests that the area may have been critical to <a href="https://www.nature.com/articles/nature06204">the survival</a> of the human species. </p>
<p>This coastal region now contains extensive aeolianites (cemented dune deposits) and cemented foreshore deposits. These rocks are the cemented remains of the dune and beach surfaces that existed when our distant ancestors and many other vertebrates were <a href="https://www.livescience.com/40311-pleistocene-epoch.html">making tracks</a> in the region in the Middle-Late Pleistocene, approximately 158,000 to 70,000 years ago. We know the ages of the rocks from <a href="https://doi.org/10.1016/j.quascirev.2010.10.003">the results</a> of previous <a href="https://www.sciencedirect.com/science/article/pii/S0031018207004476?">dating studies</a>. </p>
<p>It may seem that tracks and patterns made in the sand are ephemeral, destined to be covered by the effects of the next wind storm or tide. However, perhaps surprisingly, many of these records are preserved, ready to be identified when they are re-exposed through cliff collapse or through forces of erosion. Our team has identified more than <a href="https://doi.org/10.1016/j.quascirev.2019.07.039">140 vertebrate tracksites</a> along this coastline. For example, as many as 40 footprints made by hominins travelling down a dune surface, and estimated as being 90,000 years old, <a href="https://www.nature.com/articles/s41598-018-22059-5">were identified</a> at one site by members of our research team in 2016. </p>
<p>So, given that we know humans moved across these landscapes, we wondered whether there might also be evidence of other forms of human activity on these surfaces of sand, such as patterns, symbols, sculptures, or foraging. If so, could such ancient canvases have left evidence of human activity that can be discerned and interpreted today? Indeed, could such evidence form a previously undocumented form of Middle Stone Age hominin expression and activity? Our findings suggest the answer to these questions may be “yes”. </p>
<h2>A plethora of patterns</h2>
<p>At one site we found a large almost perfectly circular groove, along with a depression in the centre of the circle. Beside this feature was a pair of oval shapes that may represent knee impressions. If this circle was generated by a human, then a possible mechanism could have involved the use of a forked stick, in the same way that a compass is used by kids in maths classes. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=722&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=722&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=722&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=908&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=908&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293202/original/file-20190919-22408-r85cy1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=908&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The author demonstrates how a forked stick may have been used by a kneeling human to create a circular pattern in the sand.</span>
<span class="attribution"><span class="source">Linda Helm</span></span>
</figcaption>
</figure>
<p>Other patterns included groove features beside possible human footprints, and a “hashtag” pattern that <a href="http://dx.doi.org/10.1126/science.1211535">resembles known palaeo-art in the region</a>. We also identified two possible animal images, one of which may conceivably have taken the form of a sculpture of a sting-ray. We have proposed a new term to describe patterns made in sand by humans, which become lithified over time through a natural cementation process: ammoglyph (“ammos” being Greek for “sand”, and “glyph” being Greek for a carving, image or symbol).</p>
<p>If our interpretations are accurate, these findings represent two important things. Firstly, evidence of a human presence on these ancient dunes and beaches is more substantial than has been thought. Secondly, this evidence would buttress that of other avenues <a href="https://www.nature.com/articles/nature06204">of research</a> that <a href="https://www.sciencedirect.com/science/article/pii/S0047248404001307?via%3Dihub">attest to</a> the <a href="https://science.sciencemag.org/content/325/5942/859">cognitive abilities</a> of early humans <a href="https://www.ncbi.nlm.nih.gov/pubmed/23135405">in this region</a>.</p>
<h2>Varying interpretations</h2>
<p>There is a multitude of lines, grooves, patterns and shapes on these rock surfaces. </p>
<p>One of our challenges therefore lay in identifying whether a hominin “signature” could reasonably be inferred among this plethora of forms. We outlined other possible agents that may have caused such patterns (such as wind, water, fossil roots and branches, and traces made by invertebrates, reptiles, birds and other mammals). We also considered how to distinguish between ancient patterns made in sand and more recent patterns etched in rock – that is, graffiti.</p>
<p>In some of the cases we described we simply pointed out features that appeared puzzling, that may possibly have been created by humans, but where other causes could not be reasonably excluded. One site contained patterns that we had never encountered before, and that do not appear anywhere in the ichnological (trace fossil) literature. After due consideration we interpreted this as possibly representing a seal tracksite, and will be reporting on this elsewhere. </p>
<p>In other cases, such as the circular feature with the central depression, the presence of grooves beside possible human footprints, and the “hashtag” pattern, the evidence for a human origin appeared more compelling. However, we took a cautious approach, acknowledging that absolute certainty is elusive. </p>
<h2>Next steps</h2>
<p>Samples have been taken for dating, adjacent to a number of the sites we described. We eagerly await these results. Non-invasive imaging studies may aid in the investigation of the rocks with patterns that suggest foraging behaviour. </p>
<p>We hope that other scientists will critically examine the findings and interpretations that we have presented. Recognising that ancient sand surfaces were not all “perishable”, but that some of them have preserved an extraordinary record of what transpired on them, suggests a previously under-appreciated means of interpreting ancient human expression. </p>
<p>The resulting search for ammoglyphs on the Cape south coast has the potential to become a new field of study, at a meeting point of archaeology, art, ichnology, palaeoanthropology, pattern recognition and sedimentology.</p><img src="https://counter.theconversation.com/content/123546/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Helm 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>Given that we know humans moved across these landscapes, we wondered whether there might also be evidence of other forms of human activity on these surfaces of sand.Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1135042019-03-18T16:31:08Z2019-03-18T16:31:08ZIndian summer monsoon amplified global warming 130,000 years ago, helping end ice age<figure><img src="https://images.theconversation.com/files/264376/original/file-20190318-28505-1by2fua.jpg?ixlib=rb-1.1.0&rect=5%2C0%2C3988%2C2652&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Monsoon clouds approach in India.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/view-lake-distant-cloud-approaching-654600133">Manoj Felix/Shutterstock</a></span></figcaption></figure><p>The past may be a surprisingly useful guide for predicting responses to future climate change. This is especially important for places where extreme weather has been the norm for a long time, such as the Indian subcontinent. Being able to reliably predict summer monsoon rainfall is critical to plan for the devastating impact it can have on the 1.7 billion people who live in the region. </p>
<p><a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/97JC02719">The onset of India’s summer monsoon</a> is linked to heat differences between the warmer land and cooler ocean, which causes a shift in prevailing wind direction. Winds blow over the Indian Ocean, picking up moisture, which falls as rain over the subcontinent from June to September.</p>
<p>The monsoon season can bring drought and food shortages or severe flooding, depending on how much rain falls and in what duration. Understanding how the monsoon responded to an abrupt climate transition in the past can therefore help scientists better understand its behaviour in the future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=147&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=147&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=147&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=184&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=184&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264392/original/file-20190318-28479-cur6ci.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=184&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maharashtra, India on May 28 2010, during the dry season.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:MatheranPanoramaPointDrySeason.JPG">Arne Hückelheim/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>When we researched this weather system’s ancient past, we found it was highly sensitive to climate warming 130,000 years ago. <a href="https://www.nature.com/articles/s41561-019-0319-5">Our new study</a> published in Nature Geoscience showed that the Indian summer monsoon pulled heat and moisture into the northern hemisphere when Earth was entering a warmer climate around 130,000 years ago. This caused tropical wetlands to expand northwards – habitats that act as <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004GL021009">sources of methane, a greenhouse gas</a>. This amplified global warming further and helped end the ice age.</p>
<p>The rate at which today’s climate is changing is unprecedented in the geological record, but our study shows how sensitive the Indian summer monsoon was during a global transition into warming in the past and may still be.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=163&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=163&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=163&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=205&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=205&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264393/original/file-20190318-28483-e4zcsh.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=205&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 same view in Maharashtra, India on August 28 2010, during the monsoon season.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:MatheranPanoramaPointMonsoon.JPG">Arne Hückelheim/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The monsoon rains of yesteryear</h2>
<p>Over the last one million years, the climate fluctuated between a cold glacial – known as an ice age – and a warm interglacial as the Earth’s position relative to the sun <a href="http://ossfoundation.us/projects/environment/global-warming/milankovitch-cycles">wobbled in its orbit</a>. The last transition from an ice age into the warm climate of the present interglacial – known as the Holocene – occurred around 18,000 years ago. This period of Earth’s history is relatively well understood, but how Earth system processes responded to these climate changes deeper in time is <a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SR15_Chapter3_Low_Res.pdf">still something of a mystery</a>.</p>
<p>A recent expedition to <a href="https://iodp.tamu.edu/scienceops/expeditions/indian_monsoon.html">drill deep into the ocean floor</a> of the Bay of Bengal gave an opportunity to reconstruct past Indian monsoon behaviour over hundreds of years before the last ice age.</p>
<p>Our study used these deep sea sediments from the northern Bay of Bengal to capture a direct signal of the Indian summer monsoon from 140,000 to 128,000 years ago, hidden in the fossilised shells of tiny microscopic creatures called foraminifera. These plankton species once lived in the upper ocean water column and captured the environmental conditions of the surrounding seawater in the chemical make up of their shells.</p>
<p>We detected the ocean surface water freshening from river discharge induced by the rains of the Indian summer monsoon from 140,000 to 128,000 years ago – a sign of the strengthening monsoon system. This occurred when the Earth was coming out of a glacial state and into the interglacial which occurred before the one we live in, separated by a single ice age. During this period – which we’ll refer to as the penultimate deglaciation – <a href="http://science.sciencemag.org/content/349/6244/aaa4019">sea levels rose</a> from six to nine metres worldwide.</p>
<p>Ice-core records show that Antarctica began to <a href="http://science.sciencemag.org/content/317/5839/793">warm first during the penultimate deglaciation</a>. Southern Hemisphere warming provided a source of heat and moisture which fuelled the strengthening of the Indian summer monsoon, as seen in our records of surface freshening and river runoff from the northern Bay of Bengal.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264398/original/file-20190318-28496-1w7uxrb.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">Wetland in Leh Ladakh, India. The expansion of tropical wetlands further north released more methane to the atmosphere, accelerating global warming.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/swamp-green-field-blue-sky-summer-535948285">WATHIT H/Shutterstock</a></span>
</figcaption>
</figure>
<p>During this warming period around 130,000 years ago, the Indian summer monsoon responded to southern hemisphere warming while the northern hemisphere and other monsoon systems, such as the East Asian summer monsoon – which affects modern day China, Japan and the Far East – remained in a glacial state.</p>
<p>The Indian summer monsoon pulled heat and moisture northwards, driving glacial melting in the northern hemisphere and helping tropical wetlands expand their range. These expanding tropical wetlands resulted in more methane release into the atmosphere which <a href="https://www.nature.com/articles/nature06950">caused even more warming</a>, setting changes in motion which ended the global ice age.</p>
<p>The Indian summer monsoon is an incredibly dynamic system. Though confined to the tropics, the system is sensitive to climatic conditions in both hemispheres. Due to its role in contributing to methane emissions, the Indian summer monsoon also has an outsize impact on the global climate. Monsoons should not be viewed in isolation, just as the polar ice sheets shouldn’t. Earth’s internal climate system is intrinsically linked and abrupt changes at one place can have significant consequences over time elsewhere.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&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><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1113504">Climate change is inevitable. Our response to it isn’t. Click here to subscribe to our climate action newsletter.</a></em></p><img src="https://counter.theconversation.com/content/113504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katrina Nilsson-Kerr receives funding from CENTA NERC. </span></em></p><p class="fine-print"><em><span>Pallavi Anand receives funding from NERC, UK-IODP and Cushman Foundation. </span></em></p>The Indian summer monsoon rainfall affects the lives of over a billion people. By looking at how prehistoric climate changes affected it, scientists can contribute to its future prediction.Katrina Nilsson-Kerr, PhD Researcher in Climatology, The Open UniversityPallavi Anand, Lecturer in Ocean Biogeochemistry, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/959562018-05-11T14:45:22Z2018-05-11T14:45:22ZCould resurrecting mammoths help stop Arctic emissions?<figure><img src="https://images.theconversation.com/files/218613/original/file-20180511-34027-1cml58u.jpg?ixlib=rb-1.1.0&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/digital-illustration-mammoth-759825811?src=QiNqLwIPakxS_TRl5f54aQ-1-2">Shutterstock</a></span></figcaption></figure><p>If you managed to time travel back to Ice-Age Europe, you might be forgiven for thinking you had instead crash landed in some desolate part of the African savannah. But the chilly temperatures and the presence of six-ton shaggy beasts with extremely long tusks would confirm you really were in the Pleistocene epoch, otherwise known as the Ice Age. You’d be visiting the mammoth steppe, an environment that stretched from Spain across Eurasia and the Bering Strait to Canada. It was covered in grass, largely devoid of trees and populated by bison, reindeer, tigers and the eponymous “woolly” mammoth.</p>
<p>Unfortunately, both mammoth and most of the mammoth steppe ecosystem today have long but disappeared. But a group of <a href="https://www.theguardian.com/science/2017/feb/16/woolly-mammoth-resurrection-scientists">geneticists from Harvard</a> are hoping to change this by cloning living elephant cells that contain a small component of synthesised mammoth DNA. They claim that reintroducing such mammoth-like creatures to Arctic tundra environments could help stop the release of greenhouse gases from the ground and reduce future emissions as temperatures rise due to climate change. While this might sound like a far-fetched idea, scientists have actually been experimenting with something similar for over 20 years.</p>
<p>Arctic lands are covered by areas of ground known as permafrost that have been frozen since the Pleistocene. Permafrost contains <a href="https://www.nature.com/articles/ncomms13653">vast amounts of carbon</a> from dead plant life that is locked away by the extremely cold temperatures. The amount of carbon in these frozen stores is estimated to be about <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2013GL058088">twice as much as that currently in the atmosphere</a>. If it thaws out, microbes will break down soil organic material to release carbon dioxide and methane into the atmosphere.</p>
<p>As a result, permafrost and the associated carbon pools have been likened to “<a href="https://science.nasa.gov/sleeping-giant-arctic-permafrost-0">sleeping giants</a>” in our climate system. If they wake up, the resulting greenhouse gas emissions would raise global temperatures even further than currently projected, causing even greater global climate change (a process known as positive feedback).</p>
<h2>Natural geo-engineers</h2>
<p>This is where our shaggy friends may come in. Mammoths and other large herbivores of the Pleistocene continually trampled mosses and shrubs, uprooting trees and disturbing the landscape. In this way, they inadvertently acted as <a href="https://www.researchgate.net/publication/257110614_Mammoth_steppe_A_high-productivity_phenomenon">natural geo-engineers</a>, maintaining highly productive steppe landscapes full of grasses, herbs and no trees.</p>
<p>Bringing mammoth-like creatures back to the tundra could, in theory, help recreate the steppe ecosystem more widely. Because grass absorbs less sunlight than trees, this would cause the ground to absorb less heat and in turn keep the carbon pools and their greenhouse gases on ice for longer. Large numbers of the animals would also trample snow cover, stopping it from acting like insulation for the ground and allowing the permafrost to feel the effects of the bitter Arctic winters. Again, this would, in theory, keep the ground colder for longer.</p>
<p>This form of mammoth de-extinction and reintroduction could therefore promote grasslands and simultaneously slow the thawing of these frozen soils. So surely it’s worth it?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/218576/original/file-20180511-52177-gred5z.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">
<figcaption>
<span class="caption">Ukok Plateau, Siberia, is one of the last remnants of the mammoth steppe.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Ukok_Plateau#/media/File:Ukok_Plateau.jpg">Wikipedia/Kobsev</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p><a href="https://vimeo.com/207624364">Pleistocene Park</a> is an epic experiment in the Siberian Arctic that has been underway since 1996 and focused on investigating these processes. It is this park to which the Harvard team hope to deliver the first resurrected mammoth hybrid within the next decade.</p>
<p>Founded by Russian geophysicist <a href="http://reviverestore.org/projects/woolly-mammoth/sergey-zimovs-manifesto/">Sergei Zimov</a>, <a href="https://www.facebook.com/PleistocenePark/">the 16 square-kilometre park</a> is filled with <a href="http://science.sciencemag.org/content/308/5723/796.1.full?HITS=10&resourcetype=HWCIT&maxtoshow=&RESULTFORMAT=&FIRSTINDEX=0&firstpage=796&searchid=1&hits=10&volume=308&andorexacttitleabs=and&andorexactfulltext=and">around 100 animals</a> roaming free including bison, musk ox, moose, yaks, horses and reindeer. The park is designed to determine if the animals can disturb and fertilise the current ecosystem where little grows into highly productive pastures, as well as slowing or even reversing permafrost thaw. </p>
<p>I’ve been privileged to have visited the park a number of times, and have been amazed at the effort required to undertake such “big science” in this wilderness. We travelled for many hours along the massive Kolyma River to collect reindeer from the Arctic coast, and transported them by small boats to the park – no mean feat in these regions. Adding just another few animals to the experiment was exhausting. But it was totally exhilarating and made me question whether this was such a crazy idea after all.</p>
<p>The limited financial and personnel available to the park has made building and monitoring the project’s success difficult. Early evidence with extant species such as musk ox, reindeer and horse suggests animal presence is changing the park landscape structure and cooling the ground. </p>
<p>Recently, the park’s grasslands have <a href="https://agu.confex.com/agu/fm17/meetingapp.cgi/Paper/266991">been shown</a> to reflect more sunlight than the surrounding larch forest, which will reduce the heat penetrating the ground. Scientists have also taken 300 metre-long ground samples from across the landscape to measure the carbon storage in the park, and work out if it differs from that of the surrounding, non-disturbed landscape. </p>
<h2>Is it worth it?</h2>
<p>Much of the work relies on <a href="https://www.indiegogo.com/projects/bison-to-save-the-world--2#/">public crowdfunding</a> and the park is now seeking money to fill the park with temperature sensors and light sensors. It has already installed a 35-metre high <a href="https://www.esrl.noaa.gov/psd/iasoa/stations/cherskii#ui-tabs-2">flux tower</a> that continually monitors methane, carbon dioxide and temperature in the park’s atmosphere. Collecting convincing evidence to back up the theory clearly takes time and huge effort, but we should know soon if this bold plan could make a realistic solution to climate change.</p>
<p>Some scientists and conservationists <a href="https://www.nytimes.com/2017/03/20/science/revive-restore-extinct-species-dna-mammoth-passenger-pigeon.html">have questioned</a> whether resurrecting the mammoth is really worth it, comparing the high costs with the relative lack of funding for saving the world’s elephants. A key question is whether we need mammoth specifically to make these projects work? Could we not simply knock down trees manually, and then use existing animals? I guess this may depend on whether we decide to expand such an approach across far greater swathes of the Arctic, where human intervention will be costly or even near impossible in places.</p>
<p>Yet tackling global climate change needs ambitious, novel and often epic solutions, both to reduce emissions and to minimise the chance positive feedback from the Arctic that may cause untold damage to our climate system. I don’t know if bringing the mammoth back is the right approach, but at the moment we lack a decent solution for keeping the giant Arctic carbon deposits in the ground.</p><img src="https://counter.theconversation.com/content/95956/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Mann receives funding from the US National Science Foundation (NSF) and UK Natural Environmental Research Council (NERC). </span></em></p>A 20-year-old experiment is testing whether filling the Arctic tundra with animals could keep carbon trapped in the ground.Paul Mann, Senior Lecturer, Geography and Environmental Sciences, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/852542017-10-09T19:09:38Z2017-10-09T19:09:38ZNorthern exposure: fossils of a southern whale found for the first time in the north<figure><img src="https://images.theconversation.com/files/189137/original/file-20171006-25742-1708trv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The pygmy right whale, _Caperea marginata_, at sea.</span> <span class="attribution"><span class="source">Robert Pitman</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Ancient fossils of a whale species thought to be found only in southern waters have been discovered at northern sites in Japan and Italy.</p>
<p>The pygmy right whale <a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=39"><em>Caperea marginata</em></a> is a mystery in almost every regard. It’s the world’s smallest whale (up to 6.5 metres long), the only whale able to see colour, and its skeleton features enormous, overlapping ribs that give it the appearance of a tank.</p>
<p>Its evolutionary origins are still hotly debated. It has no close living relative and is the only major whale lineage that is entirely restricted to the Southern Hemisphere.</p>
<p>Fossils related to the pygmy right whale, some of them up to 10 million years old, have been found in Australia, Argentina and Peru. Together, they suggest that pygmy right whales have always been true southerners – as endemic to this part of the world as koalas and kangaroos are to Australia.</p>
<p>Or, at least, that’s what we thought until the northern find.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=342&fit=crop&dpr=1 600w, https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=342&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=342&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=430&fit=crop&dpr=1 754w, https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=430&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/188999/original/file-20171005-9767-fcv1d3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=430&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 smallest baleen whale, <em>Caperea marginata</em>, compared to the largest: the blue whale, <em>Balaenoptera musculus</em>.</span>
<span class="attribution"><span class="source">Drawings by Carl Buell</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-whales-had-more-bite-than-todays-gentle-giants-82907">Ancient whales had more bite than today's gentle giants</a>
</strong>
</em>
</p>
<hr>
<h2>Northern find</h2>
<p>In a paper published today in <a href="http://www.cell.com/current-biology/home">Current Biology</a>, our international team (spanning three continents) describes two <em>Caperea</em>-like fossils that completely turn the story of this bizarre whale on its head.</p>
<p>The new specimens - a partial skull from Okinawa in southern Japan, and an ear bone from Sicily, Italy - show that pygmy right whales once occurred in the Northern Hemisphere.</p>
<p>Finding <em>Caperea</em> in the north was truly unexpected. Imagine stumbling across a kangaroo in Scotland, or a polar bear in Antarctica! So how did <em>Caperea</em> end up in northern seas? Even more intriguingly, why is it no longer there?</p>
<p>The age of the northern fossils provides a vital clue. Compared to their southern counterparts, the northern specimens are relatively young: they lived about 1.8 million years ago in Italy and just 500,000-900,000 years ago in Japan.</p>
<p>These dates coincide with a time of pronounced global cooling - the ice age - starting about 2.5 million years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=294&fit=crop&dpr=1 600w, https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=294&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=294&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=370&fit=crop&dpr=1 754w, https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=370&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/189007/original/file-20171005-9757-pu9nm7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=370&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ear bones of a living pygmy right whale (left, mirrored for comparison), the fossil from Italy (centre) and the fossil from Japan (right).</span>
<span class="attribution"><span class="source">Adapted from Tsai et al. (2017) Current Biology 27, R1-R3</span></span>
</figcaption>
</figure>
<h2>Cooling waters</h2>
<p>Prior to the ice age, <em>Caperea</em> only lived in the south, just like today. To the north of its habitat lay warm, tropical seas that offered little in the way of food.</p>
<p>But as temperatures fell, waters near the equator cooled and became richer in nutrients. This would have made it easier for <em>Caperea</em> to spread into and, ultimately, beyond the tropics, into the Northern Hemisphere. Similar journeys were made by other marine mammals, including some dolphins, right whales and elephant seals.</p>
<p>But these good times would not last. As glacial gave way to interglacial, the tropical seas warmed and their nutrient bounty declined. What was once a tropical gateway became an impassable barrier, leaving populations trapped on either side of the equator in a warming world. </p>
<p>Whereas some divided marine mammal populations evolved into separate northern and southern species, such as elephant seals and right whales, others declined to extinction in one hemisphere. <em>Caperea</em> in the north had the latter fate.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=349&fit=crop&dpr=1 754w, https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=349&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/189004/original/file-20171005-9788-36jfp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=349&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">(Left) The distribution of the living pygmy right whale, compared to related fossils from the Southern (green) and Northern (red) hemispheres. (Right) Age of <em>Caperea</em>-like fossils, compared to global temperatures.</span>
<span class="attribution"><span class="source">Adapted from Tsai et al. (2017) Current Biology 27, R1-R3</span></span>
</figcaption>
</figure>
<p>So how did such a substantial, geologically recent change to the distribution and ecology of whales go unnoticed until now? </p>
<p>Unlike their cousins on land, fossils of marine mammals from the last 2 million years are relatively rare. In fact, we know more about marine mammals living 5 million years ago than we do about their descendants living a mere 100,000 years ago. </p>
<p>This is because the latter lived at a time when vast amounts of water were locked up in polar ice sheets, resulting in sea level drops of sometimes more than 100 metres. When the ice melted and sea levels rose, most of the remains of these marine mammals were buried deep below the sea, becoming inaccessible to palaeontologists. </p>
<p>Today, there are only a few places where ice age whale fossils have nonetheless come to light, often because geological forces caused some areas to rise upwards and, once again, out of the water. </p>
<p>The Northern Hemisphere pygmy right whales open a rare window on this most recent phase of marine mammal evolution, and suggest interesting times and unexpected histories. What might we find in future? Tasmanian walruses? Penguins in Alaska?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-alfred-the-whale-lost-its-teeth-to-become-a-giant-filter-feeder-69489">How 'Alfred' the whale lost its teeth to become a giant filter feeder</a>
</strong>
</em>
</p>
<hr>
<p>Fossils are powerful messengers from the past. That such a dramatic shift in the geographic range and ecology of pygmy right whales occurred so rapidly is a reminder of the profound influence of climate change on the ocean. </p>
<p>Our warming world may lead to tropical seas becoming ever more inhospitable to marine mammals, with the equator halting the movement of once widely distributed species, such as rorquals. </p>
<p>Only time will tell if climatic division into northern and southern populations leads to more evolution or extinction of marine mammals.</p><img src="https://counter.theconversation.com/content/85254/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Felix Georg Marx receives funding from a Marie Skłodowska-Curie Global Postdoctoral fellowship (656010/ MYSTICETI)</span></em></p><p class="fine-print"><em><span>Erich Fitzgerald receives funding from an ARC Linkage Project (LP150100403) </span></em></p>Fossils of a whale thought to be found only in southern waters have been discovered at two sites in the northern hemisphere.Felix Georg Marx, Post doctoral research fellow in evolutionary biology, Monash UniversityErich Fitzgerald, Senior Curator, Vertebrate Palaeontology, Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/809972017-07-19T17:01:16Z2017-07-19T17:01:16ZHere’s the three-pronged approach we’re using in our own research to tackle the reproducibility issue<figure><img src="https://images.theconversation.com/files/178674/original/file-20170718-31872-1uv1xdv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Step one is not being afraid to reexamine a site that's been previously excavated.</span> <span class="attribution"><span class="source">Dominic O'Brien. Gundjeihmi Aboriginal Corporation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>If you keep up with health or science news, you’ve probably been whipsawed between conflicting reports. Just days apart you may hear that “science says” coffee’s good for you, no actually it’s bad for you, actually red wine holds the secret to long life. As <a href="https://www.youtube.com/watch?v=0Rnq1NpHdmw">comedian John Oliver put it</a>:</p>
<blockquote>
<p>“After a certain point, all that ridiculous information can make you wonder: is science bullshit? To which the answer is clearly no. But there is a lot of bullshit currently masquerading as science.”</p>
</blockquote>
<p>A big part of this problem has to do with what’s been called a “<a href="https://theconversation.com/us/topics/reproducibility-5484">reproducibility crisis</a>” in science – many studies if run a second time don’t come up with the same results. <a href="https://doi.org/10.1038/533452a">Scientists are worried</a> about this situation, and <a href="https://www.nature.com/collections/byblhcfwhw">high-profile</a> international <a href="https://doi.org/10.1126/science.aab2374">research journals</a> have raised the alarm, too, calling on researchers to put more effort into ensuring their results can be reproduced, rather than only striving for splashy, one-off outcomes.</p>
<p><a href="https://www.nytimes.com/2016/05/29/opinion/sunday/why-do-so-many-studies-fail-to-replicate.html">Concerns about</a> <a href="https://www.theatlantic.com/science/archive/2016/03/psychologys-replication-crisis-cant-be-wished-away/472272/">irreproducible results</a> <a href="http://www.slate.com/articles/health_and_science/future_tense/2016/04/biomedicine_facing_a_worse_replication_crisis_than_the_one_plaguing_psychology.html">in science resonate</a> <a href="https://fivethirtyeight.com/features/science-isnt-broken/">outside the ivory tower</a>, as well, because a lot of this research translates into information that affects our everyday lives. </p>
<p>For example, it informs what we know about how to stay healthy, how doctors should look after us when we’re sick, how best to educate our children and how to organize our communities. If study results are not reproducible, then we can’t trust them to give good advice on solving our everyday problems – and society-wide challenges. Reproducibility is not just a minor technicality for specialists; it’s a pressing issue that affects the role of modern science in society.</p>
<p>Once we’ve identified that reproducibility is a big problem, the question becomes: How do we tackle it? Part of the answer has to do with changing incentives for researchers. But there are plenty of things we in the research community can do right now in the course of our scientific work.</p>
<p>It might come as a surprise that <a href="https://doi.org/10.1007/s10816-015-9272-9">archaeologists are at the forefront</a> of finding ways to improve the situation. Our <a href="https://doi.org/10.1038/nature22968">recent paper in Nature</a> demonstrates a concrete three-pronged approach to improving the reproducibility of scientific findings.</p>
<h2>Going back to where it all started</h2>
<p>In our new publication we describe recent work at an archaeological site in northern Australia. The results of our excavations and laboratory analyses show that <a href="http://theconversation.com/buried-tools-and-pigments-tell-a-new-history-of-humans-in-australia-for-65-000-years-81021">people arrived in Australia 65,000 years ago</a>, substantially earlier than the previous consensus estimate of 47,000 years ago. <a href="http://theconversation.com/buried-tools-and-pigments-tell-a-new-history-of-humans-in-australia-for-65-000-years-81021">This date has exciting implications</a> for our understandings of human evolution.</p>
<p>A less obvious detail about this study is the care we’ve taken to make our results reproducible. Our reproducibility strategy had three parts: fieldwork, labwork and data analyses.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=906&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=906&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=906&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1138&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1138&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178680/original/file-20170718-10320-1sapmfd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1138&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ben Marwick and colleagues excavating at Madjedbebe.</span>
<span class="attribution"><span class="source">Dominic O'Brien. Gundjeihmi Aboriginal Corporation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our first step toward reproducibility was our choice of what to investigate. Rather than striking out to someplace new, we reexcavated an archaeological site <a href="https://doi.org/10.1016/j.jhevol.2015.03.014">previously known to have very old artifacts</a>.</p>
<p>The rockshelter site Madjedbebe in Australia’s Northern Territory had been excavated twice before. Famously, excavations there in 1989 indicated that people had <a href="https://doi.org/10.1038/345153a0">arrived in Australia by about 50,000 years ago</a>. But this age was not accepted by many archaeologists, who refused to accept anything older than 47,000 years ago.</p>
<p>This age was controversial from its first publication, and our goal in revisiting the site was to check if it was reliable or not. Could that controversial 50,000-years age be reproduced, or was it just a chance result that didn’t indicate the true time period for human habitation in Australia?</p>
<p>Like many scientists, archaeologists are generally less interested in returning to old discoveries, instead preferring to forge new paths in search of novel results. The problem with this is that it can lead to many unresolved questions, making it difficult to build a solid foundation of knowledge. </p>
<h2>Double-check the lab tests</h2>
<p>The second part of our reproducibility strategy was to verify that our laboratory analyses were reliable.</p>
<p>Our team used <a href="https://www.thoughtco.com/luminescence-dating-cosmic-method-171538">optically stimulated luminescence</a> methods to date the sand grains near the ancient artifacts. This method is complex, and there are only a few places in the world that have the instruments and skills to date these kinds of samples.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=766&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=766&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=766&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=963&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=963&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178820/original/file-20170719-27696-r2h9i8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=963&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Zenobia Jacobs produced the new ages for the Madjebdebe site based on her work in the Luminescence Dating Laboratory at the University of Wollongong, Australia.</span>
<span class="attribution"><span class="source">University of Wollongong</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We first analyzed our samples in our laboratory at the <a href="http://smah.uow.edu.au/sees/facilities/UOW002889.html">University of Wollongong</a> to find their ages. Then we sent blind duplicate samples to another laboratory at the <a href="https://www.adelaide.edu.au/ipas/facilities/luminescence/">University of Adelaide</a> to analyze, without telling that lab our results. With both sets of analyses in hand, we compared them; it turned out in this case that they got the same ages as we did for the same samples.</p>
<p>This kind of verification is not a common practice in archaeology, but because this site was already controversial, we wanted to make sure the ages we obtained were reproducible.</p>
<p>While this extra work involved some additional cost and time, it’s vital to proving that our dates give the true ages of the sediments surrounding the artifacts. This verification shows that our lab results are not due to chance, or the unique conditions of our laboratory. Other archaeologists, and the public, can be more confident in our findings because we’ve taken these extra steps. This external checking should be standard practice in any science where controversial findings are at stake. </p>
<h2>Don’t let the computer be a black box</h2>
<p>After we completed the excavation and lab analyses, we analyzed the data on our computers. This stage of our research was very similar to what scientists in many other fields do. We loaded the raw data into our computers to visualize it with plots and test hypotheses with statistical methods.</p>
<p>However, while many researchers do this work by pointing and clicking using off-the-shelf software, we tried as much as possible to write scripts in the <a href="https://doi.org/10.1038/517109a">R programming language</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178686/original/file-20170718-10283-q6g5bg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Could be the enemy of reproducibility if it helps obscure the steps in data analysis.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/erinkohlenbergphoto/5353222369">Erin Kohlenberg</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Pointing and clicking generally leaves no traces of important decisions made during data analysis. Mouse-driven analyses leave the researcher with a final result, but none of the steps to get that result is saved. This makes it <a href="https://theconversation.com/how-computers-broke-science-and-what-we-can-do-to-fix-it-49938">difficult to retrace the steps</a> of an analysis, and check the assumptions made by the researcher.</p>
<p>On the other hand, our scripts contain a record of all our data analysis steps and decisions. They’re like an exact recipe to generate our results. Other researchers not using scripts for their data analysis don’t have these recipes, so their results are much harder to reproduce. </p>
<p>Another advantage of our choice to use scripts is that we can share them with the scientific community and the public. We follow <a href="https://doi.org/10.1038/nn.4550">standard practices</a> by making our script files and main data files <a href="https://osf.io/qwfcz/">freely available online</a> so anyone can inspect the details of our analysis, or explore new ideas using our data.</p>
<p>It’s easy to understand why many researchers prefer point-and-click over writing scripts for their data analysis. Often that’s what they were taught as students. It’s hard work and time-consuming to learn new analysis tools among the pressures of teaching, applying for grants, doing fieldwork and writing publications. Despite these challenges, there is an accelerating shift away from point-and-click toward scripted analyses in many areas of science.</p>
<h2>Combating irreproducibility one step at a time</h2>
<p>Our recent paper is part of a new movement emerging in many disciplines to improve the reproducibility of science. Examples of recent papers that have made a commitment to reproducibility similar to ours have come from <a href="https://doi.org/10.1038/nature22975">epidemiology</a>, <a href="https://doi.org/10.1038/s41559-017-0160">oceanography</a> and <a href="https://doi.org/10.7554/eLife.20470">neuroscience</a>.</p>
<p>We hope our example will inspire other scientists to be strategic about improving the reproducibility of their research. Some of these steps can be difficult for researchers: It means learning how to use unfamiliar software, and publicly sharing more of their data and methods than they’re accustomed to. But they’re important for generating reliable results – and for maintaining public confidence in scientific knowledge.</p><img src="https://counter.theconversation.com/content/80997/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Marwick receives funding from the Australian Research Council, the University of Wollongong, and the University of Washington. This work was supported in part by the University of Washington eScience Institute.</span></em></p><p class="fine-print"><em><span>Zenobia Jacobs receives funding from the Australian Research Council. </span></em></p>A team of archaeologists strived to improve the reproducibility of their results, influencing their choices in the field, in the lab and during data analysis.Ben Marwick, Associate Professor of Archaeology, University of WashingtonZenobia Jacobs, Professor, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/791112017-06-14T00:49:28Z2017-06-14T00:49:28ZTall turkeys and nuggety chickens: large ‘megapode’ birds once lived across Australia<figure><img src="https://images.theconversation.com/files/173094/original/file-20170609-20883-u9fj1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hypothetical reconstruction of the largest extinct megapode, _Progura gallinacea_ (right), with a modern Brush-turkey and a Grey Kangaroo</span> <span class="attribution"><span class="source">Artwork by E. Shute, from photos by Tony Rudd, Kim Benson and Aaron Camens</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene</a> epoch (2.5 million years ago to 12,000 years ago) was a time of ecological upheaval in Australia. The climate fluctuated between warmer/colder and wetter/dryer periods, humans made their entrance around 50,000 years ago, and many giant marsupials became extinct for reasons that are still being debated.</p>
<p>In our <a href="http://rsos.royalsocietypublishing.org/content/4/6/170233">new paper</a>, we describe five related species of extinct <a href="https://www.britannica.com/animal/megapode">megapodes</a> – a group of stocky, medium-large chicken-like birds with small heads and large feet – from various parts of Australia. We think at least one of these bird species was still around when humans arrived in Australia around 50,000 years ago. </p>
<p>All were chunky relatives of living megapodes such as the shy <a href="http://www.birdlife.org.au/bird-profile/malleefowl">Malleefowl</a> and the bold-as-brass <a href="http://www.birdsinbackyards.net/species/Alectura-lathami">Brush-turkey</a>. They were heavy, ranging from three to eight kilograms, while a modern Malleefowl only weighs around two kilograms.</p>
<p>Two were long-legged species in the genus <em>Progura</em> – the “tall turkeys”, and two were short-legged, stout-bodied species in the genus <em>Latagallina</em> – the “nuggety chickens”. There aren’t enough remains of the fifth species, in the genus <em>Garrdimalga</em>, to know how it was built.</p>
<p>Unlike some other large extinct birds like the <a href="https://www.britannica.com/animal/dodo-extinct-bird">dodo</a>, all five of the large megapodes had a strong flight apparatus, and they probably flew into trees to roost and to escape danger as living megapodes do.</p>
<p>One of the “tall turkeys”, <em>Progura campestris</em>, had an upturned pygostyle – the tail bone that sits inside the “parson’s nose” – indicating it sported a large, ornamental tail. This species also had a long, narrow tip to its beak, while <em>Latagallina</em> and <em>Garrdimalga</em> had wide, wedge-shaped beaks, so perhaps they were adapted to different diets.</p>
<h2>Widespread fossils</h2>
<p>The bones we studied come from widespread sites in Australia – from the Darling Downs in south-eastern Queensland, to caves in eastern New South Wales, the Naracoorte Caves in south-eastern South Australia, Curramulka Quarry on South Australia’s Yorke Peninsula, the Warburton River in northern South Australia, to the Thylacoleo Caves on the Nullarbor Plain, Western Australia.</p>
<p>It seems megapodes once thrived in diverse climatic and habitat zones.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=514&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=514&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=514&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=646&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=646&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173095/original/file-20170609-26099-1r2z8kn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=646&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of megapode fossil sites.</span>
<span class="attribution"><span class="source">E. Shute</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The largest fossils, belonging to the eight kilogram “tall turkey” <em>Progura gallinacea</em> from Queensland, were first described in 1888 by naturalist <a href="http://adb.anu.edu.au/biography/de-vis-charles-walter-3406">Charles De Vis</a>, who thought they belonged to a giant ancestral pigeon.</p>
<p>Fossils belonging to the “nuggety chicken” <em>Latagallina naracoortensis</em>, come from various sites, but most of its remains – around 500 bones – are from the <a href="https://theconversation.com/naracoorte-where-half-a-million-years-of-biodiversity-and-climate-history-are-trapped-in-caves-78603">Naracoorte Caves</a>. Originally described in the 1970s as a slightly smaller relative of <em>Progura gallinacea</em>, and later considered to be the same species, our analysis instead shows that these bones belong to a bird in a separate new genus.</p>
<p>The <a href="https://www.youtube.com/watch?v=GUgGWLZsBwM">Thylacoleo Caves</a>, beneath the Nullarbor Plain, have yielded two brand new species, <em>Progura campestris</em> and <em>Latagallina olsoni</em>. While their fossils are fewer in number, they include two near-complete associated skeletons of individual birds – <a href="https://theconversation.com/the-worlds-biggest-cuckoos-once-roamed-the-nullarbor-plain-54050">more treasures</a> from this remarkable site. </p>
<p>The remains of <em>Garrdimalga mcnamarai</em> from Curramulka Quarry are somewhat scrappy by comparison – but are well enough preserved to show that this was a fifth large species different from all the others. </p>
<h2>Extinctions</h2>
<p>The five extinct megapodes lived during the Pleistocene, alongside Australia’s extinct “<a href="http://www.bbc.co.uk/science/earth/water_and_ice/ice_age">ice age</a>” <a href="http://www.bbc.com/earth/story/20160208-the-lost-giants-that-prowled-the-australian-wilderness">giant marsupials</a> such as diprotodon, marsupial lions and short-faced kangaroos.</p>
<p>We also know that they lived alongside the Malleefowl that are still alive today, because we have found ancient fossilised Malleefowl bones in the Naracoorte Caves and the Thylacoleo Caves, in the same sediment layers as bones of the extinct giants.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1652&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1652&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173096/original/file-20170609-20873-zggjkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1652&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wing bone of a living Brush-turkey <em>Alectura lathami</em> (left) versus that of an extinct giant megapode, <em>Latagallina naracoortensis</em></span>
<span class="attribution"><span class="source">E. Shute</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Why did the large megapodes die out along with the marsupial megafauna while the smaller birds survived?</p>
<p>We don’t know for sure, but larger animals usually reproduce more slowly than smaller ones, making them vulnerable to changes in climate or to new predators.</p>
<p>There is circumstantial evidence that at least one of these large megapodes was still around by the time people arrived on the continent, only to go extinct within a few thousand years of their arrival.</p>
<p>Fossil eggshell has been discovered in sandy environments in various parts of Australia, and <a href="http://www.sciencedirect.com/science/article/pii/S027737911530192X">microscopic analysis</a> shows it matches the structure of megapode eggshell. Scorch marks show that the eggs, which were larger than those of living megapodes, were cooked and eaten by people, perhaps contributing to the demise of the birds.</p>
<p>The short, deeply curved claws of the extinct megapodes show that they were not specialised for raking together huge nest mounds like Malleefowl and Brush-turkeys. </p>
<p>Rather, they probably scraped a hole in the sand or soil, and laid their eggs directly in the warm ground like the <a href="http://www.arkive.org/maleo/macrocephalon-maleo/">Maleo</a> from the Moluccas. This would explain how the fossil eggshell accumulated in <a href="https://theconversation.com/a-case-of-mistaken-identity-for-australias-extinct-big-bird-52856">sandy places</a>.</p>
<h2>Dropping off the twig</h2>
<p>Our phylogenetic analysis shows that the “tall turkeys” and the “nuggety chickens” were each other’s closest relatives, and were also some of the most recently-evolved species of megapode.</p>
<p>While they belong to the same major branch of the megapode family tree as Malleefowl and Brush-turkeys, they weren’t ancestral to any living species.</p>
<p>Rather, they were an unlucky side branch that was forever pruned from the tree.
How many birds species died out in Australia during the late Pleistocene extinctions? Perhaps more than we thought. All the more reason to <a href="http://www.nationalmalleefowl.com.au/">protect what’s left</a>.</p><img src="https://counter.theconversation.com/content/79111/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elen Shute received funding from Flinders University and Birdlife Australia for this project.</span></em></p><p class="fine-print"><em><span>Gavin Prideaux receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Trevor Worthy received funding from Australian Research Council DE130101133 and Flinders University, SA for this project. </span></em></p>Large birds once lived across Australia, only to become extinct around the time that giant marsupials and other megafauna died out during the Pleistocene “ice ages”.Elen Shute, PhD candidate, Flinders UniversityGavin Prideaux, Associate professor, Flinders UniversityTrevor H. Worthy, Associate professor, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.