tag:theconversation.com,2011:/us/topics/primates-1240/articlesPrimates – The Conversation2024-03-20T14:19:34Ztag:theconversation.com,2011:article/2243932024-03-20T14:19:34Z2024-03-20T14:19:34ZChimpanzees stayed in an ‘invisible cage’ after zoo enclosure was enlarged – South African study<p>Captive chimpanzees are one of the most popular species kept in zoos because of their <a href="https://www.mdpi.com/2076-2615/13/3/424">charismatic appeal and similarity to humans</a>. They are the closest living relatives of humans because of the shared genes and behavioural and psychological <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(04)00328-8">similarities</a>.</p>
<p>Zoos are ethically bound to care for the animals <a href="https://www.taylorfrancis.com/chapters/edit/10.4324/9781315688718-52/defense-zoos-aquariums-ethical-basis-keeping-wild-animals-captivity-michael-hutchins-brandie-smith-ruth-allard">they house</a>. Many provide environments that care for animals’ welfare needs. However, the impact of zoo environment on the behaviour, psychology and welfare of animals is sometimes overlooked or poorly understood.</p>
<p>Historically, zoos have been criticised and labelled as “animal prisons”. But based on my experience and <a href="https://www.tandfonline.com/doi/abs/10.2752/089279314X14072268687808">research</a>, it’s clear that modern zoos play an important multifaceted role as centres of education, recreation, conservation and research.</p>
<p>Chimpanzees have been the focus of much zoo-based research, including research on their welfare. Most people – researchers, zoo workers and the public alike – assume that providing animals with larger, more “naturalistic” spaces to live in improves their welfare and existing evidence suggests that this is usually the case.</p>
<p>Few studies have focused on the long-term effects of these enclosures, however. </p>
<p>A <a href="https://www.mdpi.com/2076-2615/12/17/2207">recent paper</a> I co-authored with colleagues fills this gap. We observed a stable group of eight chimpanzees at Johannesburg Zoo in South Africa five years after their outdoor housing was given a revamp to a more naturalistic design. The chimpanzees benefited from the new enclosure. But they appeared to use the space in an unusual way. </p>
<p>We found that the chimpanzees preferred to spend time in the space that was their original enclosure and that they formed groups that were remarkably tightly spaced. </p>
<p>We suggest that the chimpanzees’ perception of space had been altered by their experience of the previous, smaller, barren housing and that this limited their space use in the naturalistic enclosure through what appears to be a self-imposed “invisible cage”. </p>
<p>The role that the “invisible cage” might play in other settings is unclear. However, we believe our findings have implications for animal welfare, husbandry and broader conservation of endangered species. </p>
<p>Our paper shows that zoo-based research can teach us about the needs of animals in our care, and how their environment and experiences shape their biology and behaviour. It can even give us a glimpse into their minds and perceptions. </p>
<h2>Enclosures</h2>
<p>The Johannesburg Zoo turns 120 years old in 2024. Located in Saxonwold in Johannesburg, the zoo covers an area of 55 hectares and is the <a href="https://www.jhbcityparksandzoo.com/services-facilities/zoo/about">second-largest zoo in South Africa</a>. It hosts 320 species of animals and is a member of the <a href="https://www.waza.org/">World Association of Zoos and Aquariums</a>. </p>
<p>In 2004, the chimpanzee outdoor enclosure at the Johannesburg Zoo which was built in the 1970s was extensively upgraded. The chimpanzee space was increased from a pair of concrete and wood enclosures, each measuring 10 metres by 10 metres, to a large, naturalistic enclosure encompassing about 2,500 square metres of grass, shrubs, trees, rocks and streams, occupying the same site as the previous housing. Most of the chimpanzees had lived their entire lives in the old enclosures while two had only lived there for a few years.</p>
<p>Upgrades to naturalistic designs have become <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/zoo.20404">the standard for zoos</a>. They are often followed by evaluations to determine how the new space affects the welfare of the animals. Such evaluations typically find that welfare is improved with <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/zoo.20404">naturalistic enclosures</a>. This was true at the Johannesburg Zoo too. Chimpanzees exhibited persistent beneficial changes in behaviour, such as decreased abnormal or repetitive behaviour, suggesting improved welfare in their <a href="https://www.sciencedirect.com/science/article/pii/S0168159113001585">naturalistic enclosure</a>.</p>
<p>Our study started <a href="https://www.mdpi.com/2076-2615/12/17/2207">in 2009</a>, five years after the overhaul of the enclosure. In this study, the chimpanzees appeared to use all of the enclosure to some degree but showed a preference for the area where the previous enclosure had been. </p>
<p>Curiously, the chimpanzees also appeared to exhibit a strong tendency to form tightly spaced groups which matched the exact dimensions of the previous housing. These groups formed regardless of when or where in the enclosure the chimpanzees were, the environmental conditions at the time or which individual chimpanzees were involved. </p>
<p>This unusual pattern had not previously been reported and appeared contrary to what might be expected for a group of animals which had lived in such a large space for five years. This space-use behaviour appeared to reflect a perceived, self-imposed, intangible barrier to the spacing of the chimpanzees, as if an invisible cage surrounded the groups.</p>
<h2>Animal welfare and the use of space</h2>
<p>Space use is difficult to interpret in terms of animal welfare because it is often context-dependent and so is usually ignored when doing evaluations after an enclosure overhaul. When an animal chooses to use a small amount of space it may be because the space is attractive and meets their welfare needs. However, an animal may choose to remain in a small area because the larger space is perceived as unpleasant or even dangerous. </p>
<p>For the chimpanzees, nothing suggested that the spacing pattern indicated distress or compromised welfare. Other aspects of the chimpanzees’ behaviour suggested improved welfare in the naturalistic enclosure. Instead, it appeared that the invisible cage reflected a persistent psychological barrier, learned in the previous housing and then imposed in the naturalistic enclosure years later.</p>
<p>These findings mirror a psychological effect termed <a href="https://scholar.google.com/scholar_url?url=https://psycnet.apa.org/journals/xge/105/1/3/&hl=en&sa=T&oi=gsb&ct=res&cd=1&d=6387435864426922977&ei=vuvuZb3nKcfTy9YPt6iP6AU&scisig=AFWwaeZ9sUMBtIlV5VGbEbKfQw3U">“learned helplessness”</a> seen in many species, including <a href="https://www.researchgate.net/publication/318280261_Learned_Helplessness">humans</a>. In situations where individuals are helpless or lack control, they learn that their actions <a href="https://scholar.google.com/scholar_url?url=https://psycnet.apa.org/journals/xge/105/1/3/&hl=en&sa=T&oi=gsb&ct=res&cd=1&d=6387435864426922977&ei=vuvuZb3nKcfTy9YPt6iP6AU&scisig=AFWwaeZ9sUMBtIlV5VGbEbKfQw3U">cannot affect the outcome</a>. This perception is carried into later situations where they can affect the outcome, acting as though still helpless.</p>
<p>Further research is needed to understand the welfare implications and broader application of these findings. However, they highlight some important issues around the role of zoos and how zoos affect species conservation.</p>
<h2>The importance of zoos</h2>
<p>Zoos help raise awareness around conservation issues. They also provide a haven for species under threat. Many facilities breed and reintroduce these species into nature. The <a href="https://www.jhbcityparksandzoo.com/services-facilities/zoo/about">Johannesburg Zoo</a> particularly has several <a href="https://www.jhbcityparksandzoo.com/services-facilities/zoo/conservation">conservation programmes</a>, including a breeding programme for the endangered Pickersgill’s reed frog.</p>
<p>As sanctuaries sustaining threatened populations, zoos actively conserve biodiversity on many ways (creating gene banks, breeding animals and conserving biological and behavioural diversity) while providing critical access to rare species for observation and research.</p><img src="https://counter.theconversation.com/content/224393/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luke Mangaliso Duncan received funding from the Jane Goodall Institute and the National Research Foundation (NRF) of South Africa. </span></em></p>Zoo-based research can teach us about the needs of animals in our care.Luke Mangaliso Duncan, Postdoctoral Fellow, University of WarwickLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2255962024-03-13T15:03:15Z2024-03-13T15:03:15ZIt’s a myth that male animals are usually larger than females – new study<p>Males are bigger than females, right? Generally, this is true of humans – imagine the extremes of Dwayne “The Rock” Johnson and singer Kylie Minogue. It is also true of other familiar mammals including pets, such as cats and dogs, and livestock such as sheep and cows.</p>
<p>But <a href="https://www.nature.com/articles/s41467-024-45739-5">a new study</a> by US scientist Kaia Tombak and colleagues found that, in many mammal species, males are not larger than females. In fact, in a comparison of 429 species in the wild, 50% of species including rodents and some bats – which make up <a href="https://news.mongabay.com/2022/04/of-rats-and-bats-hundreds-of-mammal-species-still-unidentified-study-says/">a large proportion</a> of all mammal species – showed no difference in body size between the sexes. Male-biased size dimorphism (where males are larger than females) was found in only 28% of mammal species.</p>
<p>So, why do a lot of people have a misconception that males are normally larger than females? </p>
<p><a href="https://www.nature.com/scitable/students-page/160/">Anisogamy</a> is the term used to describe the difference in sex cells – small, numerous, sperm, compared to relatively large eggs. Males can produce sperm throughout most of their lifespan, whereas females are born with a finite number of eggs. Therefore, females (or rather, their eggs), are a scare resource for which males compete for access. Generally, in species where females are a limited resource that males need to fight over, males are larger than females.</p>
<p>In terms of evolution, most males have been shaped to be larger, bolder, heavier, more adorned and have more weaponry than females. This is due to males fighting to acquire females – a larger stag with bigger antlers would do much better in a fight, <a href="https://www.discoverwildlife.com/animal-%20facts/mammals/understand-the-british-deer-rut">known as a rut</a>, than a small stag with tiny antlers. So, bigger usually wins.</p>
<p>This includes species such as lions and baboons, where size is an advantage when competing physically for mates. Male northern elephant seals, who fight for access to harems of females, show the largest male-biased size dimorphism, being over 3.2 times heavier than females. These are the animals that tend to attract research</p>
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<h2>The strange world of fish</h2>
<p>But, what happens in species where males don’t fight for access to females? Generally, females are larger than males. This is because larger females usually produce more offspring. Indeed, Tombak’s study noted that larger female rabbits usually have multiple litters each mating season. Being a larger female is much more advantageous in terms of reproductive success. But more so when offspring do not need extended parental care and when gestation periods are short.</p>
<p>The most extreme sexual size dimorphism is found outside of mammals. Cichlid fish (<em>Lamprologus callipterus</em>) males are up to 60 times larger than females. The males protect empty snail shells for the females to breed in. <a href="https://link.springer.com/article/10.1007/s12038-010-0030-6">Larger females</a> can produce more offspring but they need larger shells and therefore a larger male to defend those shells.</p>
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<p>In mammals, the largest female-biased size dimorphism is found in peninsular tube-nosed bats, where females are 1.4 times the size of males. However, more dimorphism in body size is seen in fish, reptiles and insects. For example, the female orb-weaving spider (<em>Nephila plumipes</em>) has a much larger body size than the male, reaching up to ten times his size. Size dimorphism also shows a correlation with cannibalism, where larger females are more likely to eat their male partner.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large spider and small one in a web" src="https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581306/original/file-20240312-22-e1nldo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A female golden orb weaving spider and the smaller male.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-photograph-female-golden-orb-weaving-1692871246">Cassandra Madsen/Shutterstock</a></span>
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<p>Anglerfish that typically live at the bottom of oceans, are an example of extreme sexual dimorphism in body size. While the females look like typical fish, the males are tiny, basic organisms. In order to survive, the male needs to fuse with a female, tapping into her nutrients to produce enough sperm to fertilise her. Female deep-sea anglerfish (<em>Ceratias
holboelli</em>) are <a href="https://www.livescience.com/49330-animal-sex-anglerfish.html">60 times longer</a> and half a million times heavier than males.</p>
<p>But, the most extreme sexual size dimorphism is found in rhizocephala, types of barnacle where the male looks like a larvae. Once a male finds a mate, he <a href="https://www.wired.com/2015/07/absurd-creature-of-the-week-rhizocephalan/">inserts himself into the females</a>, transforming into nothing more than a mass of cells.</p>
<h2>What about mammals?</h2>
<p>So, why isn’t sexual size dimorphism seen in more mammals? Mammals tend to have fewer offspring than other species such as fish or spiders. They only have a few offspring at a time, and often have long gestation periods or extended periods of parental care. In addition, the majority of mammals are monogamous, so there is less need for males to fight over females. That’s why species such as lemurs, golden moles, horses, zebra and tenrecs, usually have similar sized males and females.</p>
<p>It is thought that biases in the scientific literature may have led to the misconception that males are normally bigger as research historically focused on <a href="https://wwf.panda.org/discover/our_focus/wildlife_practice/flagship_keystone_indicator_definition/">species considered “charismatic”</a>, such as primates and carnivores, that attract funding. These are some of the few mammalian species where males compete for mates, and so gain an evolutionary advantage if they are larger. </p>
<p>There was also a bias of <a href="https://www.nationalgeographic.co.uk/science-and-technology/2019/10/once-most-famous-scientists-were-men-thats-changing">male scientists</a> conducting research. And, although a study in 1977 <a href="https://www.journals.uchicago.edu/doi/epdf/10.1086/283223">by a female scientist</a> found that species with little sexual size dimorphism were frequent in mammals, the research was drowned out by studies on charismatic species with a bias towards large males. Perhaps if there had been more female scientists at the time, we might have had a different preconception about body size in the animal kingdom.</p><img src="https://counter.theconversation.com/content/225596/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Gentle works for Nottingham Trent University. </span></em></p>Does size matter? In the animal kingdom, yes.Louise Gentle, Principal Lecturer in Wildlife Conservation, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2224752024-02-20T14:31:08Z2024-02-20T14:31:08ZDefying expectations, disabled Japanese macaques survive by adjusting their behaviours and receiving support<figure><img src="https://images.theconversation.com/files/576169/original/file-20240216-30-6btxw6.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5184%2C3453&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A disabled young female macaque named Monmo at the Awajishima Monkey Center in Japan.</span> <span class="attribution"><span class="source">(Sarah E. Turner)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Nina is a Japanese macaque, one of the red-faced monkeys famous for sitting in hot springs in Japan. Nina lives wild in the forest, but most days, along with her group, she visits the <a href="https://monkey-center.jp/english.php">Awajishima Monkey Center</a> to eat the food people provide for the monkeys. </p>
<p>Nina was born without hands, <a href="https://doi.org/10.1007/s10329-008-0083-4">an unusually common occurrence in this group of macaques</a>. While no one knows for sure why these malformations of the limbs and digits occur, many researchers have suggested a potential link to pesticides or <a href="https://doi.org/10.1007/%20s10329-014-0405-7">other environmental contaminants</a>. </p>
<p>Nina survived because of a combination of factors: her ability to modify her behaviours to compensate for her physical impairments; the extra care provided by her mother when she was little; and living in a group of monkeys who treat her much <a href="https://doi.org/10.1016/j.jhevol.2014.01.002">the same way they do non-disabled group members</a>.</p>
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<a href="https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an infant and older macaque in the middle of the road" src="https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=657&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=657&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=657&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=826&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=826&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576171/original/file-20240216-18-i4irp6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=826&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">Nina, a juvenile disabled female Japanese macaque at the Awajishima Monkey Center, sitting with an older Juvenile.</span>
<span class="attribution"><span class="source">(Brogan M. Stewart)</span></span>
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<p>Over the years, we have spent many hours observing Nina and other disabled and non-disabled monkeys, as they live their lives — moving through the forest, socializing with others in their group and finding novel ways of adjusting their behaviours to compensate for physical impairments. </p>
<p>Disability is a <a href="https://www.un.org/development/desa/disabilities/resources/factsheet-on-persons-with-disabilities.html">normal part of human experience</a>, with at least <a href="https://www.who.int/news-room/fact-sheets/detail/disability-and-health">16 per cent of people experiencing some form of disability</a>. However, while conducting research at Awajishima, we have noticed that many people expect that disabled animals would be unlikely to survive. However, Nina and other disabled macaques in her group can survive and reproduce, and are far from being alone among primates of the world. </p>
<h2>Primates and disability</h2>
<p>In a recently published review of the literature on non-human primates and disability in the <em>American Journal of Primatology</em>, we found that <a href="https://doi.org/10.1002/ajp.23579">physical impairment is more common among wild and free-ranging primates than most people might think</a>. </p>
<p>We found 114 published papers on primates with disability, not including all the casual observations and field notes that were not published in the scientific literature. These papers included 37 species of non-human primates — monkeys, apes and lemurs — from 70 different study sites (38 of those with wild and free-ranging primates).</p>
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<a href="https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a group of monkeys in the middle of a path, three of them are grooming each other" src="https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576172/original/file-20240216-16-wcme8i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Disabled and non-disabled monkeys hanging out and socially grooming at the Awajshima Monkey Center in Japan.</span>
<span class="attribution"><span class="source">(Sarah E. Turner)</span></span>
</figcaption>
</figure>
<p>About 45 per cent of these disabilities, like Nina’s, were present from birth, while approximately 24 per cent came from injury, with similar frequency caused by a condition or illness. </p>
<p>Behavioural flexibility or plasticity (the ability to modify activities and actions in response to specific circumstances), the innovation of novel behaviours and extra maternal care stood out in the published research papers.</p>
<p>Seventy papers reported on ways that primates used behavioural flexibility and innovations to compensate for physical impairments, or provided examples of mothers who were able to support the needs of their physically impaired offspring. There were also some instances of other relatives and group members also providing support. </p>
<p>Overall, there was little evidence of social selection against disabled primates. There were also many examples of undifferentiated treatment for disabled individuals, and a few examples of disability-associated care behaviours.</p>
<h2>Human causes of primate disability</h2>
<p>Having studied disabled monkeys, we were not surprised to learn about the behavioural plasticity we found in this review. What was more surprising to us was just how many of these disabilities were linked to anthropogenic activities. </p>
<p>There are many ways that human activities can lead directly and indirectly to long-term disability in our closest animal relatives. Sixty per cent of the published examples of primate disability we surveyed were linked to human causes. </p>
<p>These included: injuries from <a href="https://doi.org/10.1046/j.1365-2028.2002.00356.x">hunting snares among chimpanzees and gorillas</a>; injuries sustained on <a href="https://doi.org/10.1007/s10764-014-9779-z">roads or from electrical wires in South African baboons</a> and <a href="https://doi.org/10.1896/044.014.0206">South American howler monkeys</a>; and the effects of <a href="https://doi.org/10.1098/rstb.1985.0020">diseases transmitted between human and non-human primates</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a monkey with a malformed hand in the foreground, other monkeys in the background" src="https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=713&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=713&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=713&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=896&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=896&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576599/original/file-20240219-21-gxzmo5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=896&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 disabled infant macaque with her mother in the background at the Awajishima Monkey Center in Japan.</span>
<span class="attribution"><span class="source">(Sarah E. Turner)</span></span>
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</figure>
<h2>Human pressure, increasing threats</h2>
<p>At a time when the majority of non-human primates are experiencing declining populations and <a href="https://doi.org/10.1126/sciadv.abn2927">are threatened with extinction</a>, this link between human activities and physical impairments in primates is a poignant reminder of how humans are impacting other life on Earth. </p>
<p>Wherever non-human primates are found in the world — throughout the tropics and as far north as Japan — they face compounding threats from human pressures. As humans increasingly convert forests and wild lands to agricultural and urban spaces, habitat loss is pushing many <a href="https://doi.org/10.1126/sciadv.1600946">primate species towards extinction</a>. </p>
<p>These pressures are exacerbated by resource extraction (often to meet market demand from the Global North), hunting, the exotic pet trade and disease. The threat of major impacts from <a href="https://doi.org/10.1007/s10584-020-02776-5">climate change is also looming on the horizon</a>. Even the most behaviourally flexible, smart, care-giving and innovative of individuals and species may not be able to navigate the scope and variety of these changes and pressures.</p>
<p>Physically impaired and disabled primates often find ways to behaviourally compensate for their impairments, survive and reproduce. </p>
<p>Nina and her friends show us an important side of non-human primate behaviour, giving us a model to examine the capacity for behavioural flexibility in nonhuman primates. Our research also underscores the critical role that humans have in shaping the futures of our closest animal relatives.</p><img src="https://counter.theconversation.com/content/222475/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah E. Turner receives funding from the Natural Sciences and Engineering Research Council of Canada - Leadership in Environmental and Digital innovation for Sustainability (LEADS-CREATE), Fonds de recherche du Québec ‐ Nature et technologies, MITACS Globalink Research Awards, the Quebec Centre for Biodiversity Science, and Concordia University.</span></em></p><p class="fine-print"><em><span>Brogan M. Stewart receives funding from NSERC - Alexander Graham Bell and CREATE in the Leadership in Environmental and Digital innovation for Sustainability (LEADS), FRQNT, Concordia University, Kyoto University, Quebec Centre for Biodiversity Science, and MITACS Globalink.</span></em></p><p class="fine-print"><em><span>Jack Creeggan receives funding from MITACS Globalink, Quebec Centre for Biodiversity Science, Concordia University, and NSERC-CREATE in Leadership in Environmental and Digital innovation for Sustainability (LEADS).</span></em></p><p class="fine-print"><em><span>Megan M. Joyce receives funding from MITACS Globalink, Quebec Centre for Biodiversity Science, Concordia University, and NSERC-CREATE in Leadership in Environmental and Digital innovation for Sustainability (LEADS).</span></em></p><p class="fine-print"><em><span>Mikaela Gerwing receives funding from Miriam Aaron Roland Graduate Fellowship, Concordia University, and NSERC - CGS M and CREATE in Leadership in Environmental and Digital innovation for Sustainability (LEADS).</span></em></p><p class="fine-print"><em><span>Stephanie Eccles receives funding from FRQSC and NSERC‐CREATE in Leadership in Environmental and Digital innovation for Sustainability (LEADS).</span></em></p>A community of macaques in Japan has a high rate of disabled individuals who survive with behavioural flexibility and maternal care. Globally, primate disabilities are often related to human causes.Sarah E. Turner, Associate Professor, Geography, Planning and Environment, Concordia UniversityBrogan M. Stewart, PhD Student in Environmental Science, Concordia UniversityJack Creeggan, Master's Student in Geography, Planning, and Environment, Concordia UniversityMegan M. Joyce, PhD Student in the Department of Geography, Planning and Environment, Concordia UniversityMikaela Gerwing, Wildlife Conservation Biologist and PhD Student, Concordia UniversityStephanie Eccles, PhD Candidate, Department of Geography, Planning, and Environment, Concordia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2202182024-02-04T22:56:09Z2024-02-04T22:56:09ZOur ancient primate ancestors had an appetite for soft fruits – and their diet shaped human evolution<p>The diet of early anthropoids – the ancestors of apes and monkeys – has long been debated. Did these early primates display behaviours and diets similar to modern species, or did they have much humbler beginnings? </p>
<p>Research on early anthropoids has often suggested a diet high in soft fruits. But some species seem to have had a more varied diet, containing harder foods such as seeds and nuts. </p>
<p>Our <a href="https://doi.org/10.1002/ajpa.24884">latest research</a> reveals a different story, one that highlights the dominant role of soft fruits. This likely encompassed various types that were ripe and high in sugar, as evidenced by the presence of tooth decay in some individuals.</p>
<p>This has important implications for understanding how our earliest ancestors adapted and evolved.</p>
<h2>Tracking anthropoid evolution</h2>
<p>When discussing the primate family tree, it is crucial to address the common confusion arising from the everyday use of terms such as “ape” and “monkey”. </p>
<p>Humans, for instance, are typically excluded from the ape category, and apes are not generally considered monkeys. Yet humans are nested within the ape family tree, which in turn is nested within the broader monkey group, however this is defined.</p>
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Read more:
<a href="https://theconversation.com/revelations-from-17-million-year-old-ape-teeth-could-lead-to-new-insights-on-early-human-evolution-187996">Revelations from 17-million-year-old ape teeth could lead to new insights on early human evolution</a>
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<p>All of these primates (humans, apes, and monkeys) are collectively called anthropoids, and we all share a common anthropoid ancestor that lived around 40 million years ago.</p>
<p><a href="https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1001342">Genetic and molecular studies</a>, along with <a href="https://www.pnas.org/doi/abs/10.1073/pnas.0908320107">fossil evidence</a>, indicate the period from 40 to 25 million years ago was a critical phase for the evolution and spread of anthropoid primates. </p>
<p>The early portion of this period marks when Afro-Eurasian monkeys and apes (Catarrhini) diverged from monkeys native to the Americas (Platyrrhini). The latter part of this period witnessed further divergence between Afro-Eurasian monkeys (Cercopithecoidea) and apes (Hominoidea).</p>
<h2>Fossils of our earliest ancestors</h2>
<p>The <a href="https://link.springer.com/chapter/10.1007/978-3-319-65661-8_12">Fayum Depression</a> in the Western Desert of Egypt offers one of the largest and best-preserved collections of fossil primates from this time frame. Between 35 and 29.2 million years ago (when the fossils used in this study were deposited), the Fayum sat on the lush northern coast of Africa. </p>
<p>The terrestrial rocks of the Fayum preserve the remnants of ecosystems that laid the groundwork for Africa’s modern biodiversity. They also capture a pivotal window in primate evolution. </p>
<p>Several of the anthropoid primates from the site may represent either the direct ancestors of all (or some) living anthropoids. Or they were close relatives of this common ancestor. </p>
<p>Fossils of these early anthropoids are relatively abundant in the Fayum, with some species known from dozens of partial skulls and jaws. Because of this, the Fayum offers a fascinating glimpse into the behaviour and life of our early ancestors.</p>
<h2>Dietary interpretations</h2>
<p>Dental evidence is a powerful tool in palaeontology. Our new study examined dental wear and disease in fossilised teeth from five Fayum anthropoid primates: <em>Aegyptopithecus</em>, <em>Parapithecus</em>, <em>Propliopithecus, Apidium</em> and <em>Catopithecus</em>. </p>
<p>We focused on tooth chipping patterns and dental caries (also known as cavities), key indicators in fossils of dietary habits.</p>
<p>Our findings indicate a predominantly soft fruit diet in early anthropoids, different to some earlier research suggesting a more varied diet, including hard foods. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/human-ancestors-had-the-same-dental-problems-as-us-even-without-fizzy-drinks-and-sweets-92546">Human ancestors had the same dental problems as us – even without fizzy drinks and sweets</a>
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<p>A mere 5% of teeth show chipping (minor enamel fractures). This is substantially lower than the frequency observed in most modern anthropoids, where chipping frequencies range from 4% to 40% of teeth. </p>
<p>Additionally, the presence of dental caries, notably in Propliopithecidae (the extinct primate family that includes <em>Aegyptopithecus</em> and <em>Propliopithecus</em>), is consistent with the regular consumption of soft, sugary fruits. </p>
<p>This research also lends support to previous studies suggesting an arboreal (tree-living) lifestyle for early anthropoids. Terrestrial primates often exhibit higher chipping prevalence due to more varied diets and accidental grit consumption when feeding on the ground, none of which was evident in our findings. </p>
<h2>Adaptation and evolution</h2>
<p>The preference for soft fruits likely had significant impacts on exploration of ecological niches, and even in the development of eyesight in anthropoid primates. This includes colour vision that likely evolved as a need for <a href="https://www.jstor.org/stable/3066998">finding ripe fruit among the foliage</a>. </p>
<p>It would have also influenced the shape of their teeth, social behaviours and foraging strategies, setting the stage for an adaptive radiation, leading to the global spread and diversification of monkeys and apes. </p>
<p>This rapid evolution of diverse species from humble anthropoid beginnings was likely in response to new ecological opportunities opening up.</p>
<p>Other primates more distantly related to us, in the primate suborder Strepsirrhini, which includes lemurs and lorises, split off from the ancestors of anthropoids millions of years earlier. </p>
<p>Unlike anthropoids, Strepsirrhini show a large variation in diet during the same time interval. The diets of fossil lemurs and lorises likely consisted of hard and tough foods, insects, gum, leaves and fruits. </p>
<p>In contrast, our own ancestors took a long time to move away from a diet based on soft fruits. Our journey into the past to unravel the lives of our ancestors continues, with each fossil adding a new piece to the puzzle of early primate evolution.</p><img src="https://counter.theconversation.com/content/220218/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Robert Borths receives funding from the United States National Science Foundation and the Institute for Museum and Library Services. </span></em></p><p class="fine-print"><em><span>Carolina Loch and Ian Towle do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New fossil studies tell us our ancient ancestors enjoyed a diet of soft, sweet fruits. This would have influenced where they lived and spread to – and even the evolution of colour vision.Carolina Loch, Senior Lecturer in Oral Biology, University of OtagoIan Towle, Postdoctoral researcher, Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)Matthew Robert Borths, Curator of the Duke Lemur Center Museum of Natural History, Duke UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2215472024-01-31T12:02:05Z2024-01-31T12:02:05ZWhy monkeys attack people – a primate expert explains<figure><img src="https://images.theconversation.com/files/570907/original/file-20240123-15-jwdv0w.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5159%2C3429&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/monkeys-open-mouth-see-horrible-teeth-1156580965">Witsawat.S/Shutterstock</a></span></figcaption></figure><p>Wildlife tourism thrives on our fascination with animals and primates are particularly attractive animals to tourists. With their human-like faces, complex family dynamics and acrobatic antics, they are a joy to behold.</p>
<p>But recent stories have emerged that portray monkeys in a more sinister light. Reports of <a href="https://www.theguardian.com/world/2022/jul/25/monkey-attacks-injure-people-japanese-city-yamaguchi-tranquilliser-gun">“monkey attacks”</a>, <a href="https://metro.co.uk/video/devil-monkeys-push-driver-160ft-hillside-attack-thailand-2994905/">“devil monkeys”</a>, or even <a href="https://www.dailystar.co.uk/news/latest-news/what-face-ripping-bone-biting-31631055">“face-ripping, bone-biting monkeys”</a> have become common in the media. Have our primate cousins turned on us?</p>
<p>The recent monkey attacks involve a variety of species in different countries. They include the <a href="https://metro.co.uk/2024/01/16/thailand-monkeys-turn-tourists-start-attacking-beach-20120135/">long-tailed macaque</a> and the <a href="https://metro.co.uk/2023/08/09/thailand-devil-monkeys-pushed-driver-down-hill-and-attacked-him-19307282/">pig-tailed macaque</a> in Thailand, <a href="https://www.theguardian.com/world/2022/jul/25/monkey-attacks-injure-people-japanese-city-yamaguchi-tranquilliser-gun">Japanese macaques</a> in Japan, and <a href="https://www.businessinsider.com/boy-killed-monkey-attack-india-intestines-ripped-2023-11?r=US&IR=T">Hanuman langurs</a> in India.</p>
<p>Most of these species are macaques, which are a diverse group of monkeys. But all macaques are sociable, intelligent, relatively large (between 4kg and 9kg), and comfortable travelling on the ground. They have a flexible diet, but prefer fruit. They also have cheek pouches that allow them to gather food quickly and carry it to a safe place to eat.</p>
<h2>Over-habituation</h2>
<p>Regardless of species or location, a major factor in monkey bites and attacks is “over-habituation”. Habituation is a process used by animal researchers to gain animals’ trust so they can follow and record their behaviour, with limited impact of the researchers’ presence. </p>
<p>But animals can become unintentionally habituated. Squirrels in a city park who have grown accustomed to handouts are one example, but others include urban foxes in the UK, bears in North America, and, in many parts of the tropics, monkeys.</p>
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Read more:
<a href="https://theconversation.com/three-surprising-reasons-human-actions-threaten-endangered-primates-197850">Three surprising reasons human actions threaten endangered primates</a>
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<p>When animals lose their fear of humans and become a nuisance, they are over-habituated. In nearly all cases of over-habituation, the main factor is human food. What people eat is irresistible to wildlife. It is nutrient-dense, easy to digest and is available in rubbish bins, unattended backpacks, or even directly from people. </p>
<p>From an ecological point of view, animals have every incentive to take advantage of this high-quality resource. So, it’s no surprise that animals will adjust their fear and natural behaviour accordingly.</p>
<p>While over-habituation due to associating tourists with food is certainly the main driver for the reported monkey attacks, that does not mean that every person bitten or threatened by a monkey is guilty of feeding or teasing them. </p>
<figure class="align-center ">
<img alt="A long-tailed macaque sits on a red footbridge while a cyclist rides past." src="https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572224/original/file-20240130-23-bkbzlc.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">
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<span class="caption">A contemplative long-tailed macaque in Singapore.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/long-tailed-macaques-crossing-bridge-singapore-2364831037">Tan Yong Lin/Shutterstock</a></span>
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</figure>
<p>Monkeys are very smart, have a long memory and learn from each other. Many groups have grown so accustomed to human foods that they have learned to harass tourists to get it. Some monkeys have become so adept at this that they know which items are valuable to tourists, which they will <a href="https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0677">“trade” for food</a>. In other words, they’ll steal your mobile phone but then drop it when you throw them some food. </p>
<p>Another important factor in monkey attacks at tourist sites is an unawareness of the animals’ body language, facial expressions and vocalisation. Even highly habituated monkeys will normally give a warning before attacking someone. But people inexperienced with monkey behaviour will often <a href="https://peerj.com/blog/post/115284879374/experience-based-human-perception-of-facial-expressions-in-barbary-macaques/">misinterpret</a> a threatening facial expression for a friendly one. This can lead to dangerous encounters.</p>
<h2>Advice</h2>
<p>Wildlife tourists cannot be expected to understand every species’ typical expressions and body postures. But some things can help tourists be more safe and responsible, regardless of the primate species they are viewing.</p>
<ol>
<li><p>Give them space. According to the <a href="https://human-primate-interactions.org/responsible-primate-watching-for-tourists/">International Union for Conservation of Nature</a>, a network of environmental organisations, keeping a distance of seven metres (23 feet) from the animals is recommended. This helps the animals not feel threatened and also reduces the risk of disease transmission.</p></li>
<li><p>Do not stand between the animals and their route to safety, or between adults and young.</p></li>
<li><p>Avoid direct eye contact or showing your teeth because monkeys may perceive this as aggressive.</p></li>
<li><p>For many primate species, common threats include bared teeth (including some yawns), direct stares with a lowered head, and short lunges or slapping the ground with the hands. If an animal does any of these things, quietly back away.</p></li>
<li><p>Do not feed the monkeys.</p></li>
</ol>
<p>Wildlife tourism contributes <a href="https://wttc.org/Portals/0/Documents/Reports/2019/Sustainable%20Growth-Economic%20Impact%20of%20Global%20Wildlife%20Tourism-Aug%202019.pdf">more than US$100 billion</a> (£786 billion) per year to the global economy. It is also immensely rewarding and can offer many benefits to wildlife and the communities of people who live near them. But we should all be <a href="https://theconversation.com/five-ways-to-be-a-responsible-wildlife-tourist-118869">responsible tourists</a>.</p><img src="https://counter.theconversation.com/content/221547/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tracie McKinney is affiliated with the IUCN SSC Primate Specialist Group's Section for Human-Primate Interactions (SHPI).</span></em></p>Tourists can do a number of things to avoid dangerous encounters with monkeys.Tracie McKinney, Senior Lecturer in Biological Anthropology, University of South WalesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2193042024-01-10T19:13:07Z2024-01-10T19:13:07ZGiant ‘kings of apes’ once roamed southern China. We solved the mystery of their extinction<figure><img src="https://images.theconversation.com/files/563807/original/file-20231206-15-lq4hvc.jpg?ixlib=rb-1.1.0&rect=4%2C9%2C3241%2C2087&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's impression of a group of Gigantopithecus blacki in a forest in southern China.</span> <span class="attribution"><span class="source">Garcia/Joannes-Boyau (Southern Cross University)</span></span></figcaption></figure><p>Giant creatures are usually associated with dinosaurs, woolly mammoths or mystical beasts. But if you go back though the human lineage you’ll find a very distant relative that stood three metres tall and weighed around 250 kilograms. This was <em>Gigantopithecus blacki</em>, the mightiest of all the primates and one of the biggest unresolved mysteries in palaeontology.</p>
<p>Despite surviving for nearly two million years in what is now the Guangxi Zhuang Autonomous Region of southern China, the entire species is represented in the fossil record only by a few thousand teeth and four jawbones. Nothing from the neck down. </p>
<p>Added to that is its mysterious disappearance from the fossil record at a time when other primates were flourishing. Where did the giants go and what brought them down?</p>
<p>Since 2015, a team of Chinese, Australian and US scientists <a href="https://www.wheregiantsroamed.com/">has been chasing</a> this mighty beast in <a href="https://education.nationalgeographic.org/resource/karst/">the distinctive terrains</a> of southern China. Our findings <a href="https://www.nature.com/articles/s41586-023-06900-0">are published in Nature today</a> and reveal a story of seasonality, stress and vulnerability.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A series of flat-topped tall cliffs covered in greenery set against a blue sky" src="https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=226&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=226&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=226&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=284&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=284&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566488/original/file-20231219-23-d6iweb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=284&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A karst landscape panorama in southern China.</span>
<span class="attribution"><span class="source">Renaud Joannes-Boyau</span></span>
</figcaption>
</figure>
<h2>Finding the window of extinction</h2>
<p>Extensive exploration and excavations in hundreds of caves over a five-year period has been narrowed down into evidence from 22 caves in two regions of Guangxi: Chongzuo, near the Vietnamese border, and Bubing Basin, close to Nanning. Eleven of these caves contain evidence of <em>G. blacki</em> and the other eleven – of a similar age range – do not. </p>
<p>Our team applied several dating techniques to sediments from the caves: <a href="https://www.thoughtco.com/luminescence-dating-cosmic-method-171538">luminescence dating</a> of feldspars (a common rock-forming mineral), <a href="https://en.wikipedia.org/wiki/Electron_spin_resonance_dating">electron spin resonance dating</a> of quartz, and <a href="https://www.britannica.com/science/dating-geochronology/Uranium-series-disequilibrium-dating">uranium series dating</a> of stalagmites and similar deposits, as well as fossils. Altogether we ended up with a staggering 157 radiometric ages.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark cave with light walls, with several people in hard hats looking through the sediment" src="https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566487/original/file-20231219-25-qvs2tg.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">Excavations in Ma Feng Cave in Guangxi Zhuang Autonomous Region of southern China.</span>
<span class="attribution"><span class="source">Kira Westaway</span></span>
</figcaption>
</figure>
<p>We used these data sets to establish exactly when <em>G. blacki</em> dropped out of the fossil record, to define a “window of extinction”. This window allowed us to target a period of time to look closely at the environmental changes.</p>
<p>Next, we looked at eight sources of environmental and behavioural evidence, including ancient pollen grains, other animal bones and micro details in the sediments.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close up of a dark faced ape with dark ginger hair, black eyes and a round muzzle" src="https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=679&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=679&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=679&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=853&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=853&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567028/original/file-20231221-15-f2uwk9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=853&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 closest primate relative of <em>G. blacki</em> is the critically endangered orangutan.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/brown-monkey-on-green-grass-during-daytime-Sn9t1C7AhXQ">Bob Brewer/Unsplash</a></span>
</figcaption>
</figure>
<p>Furthermore, we gained a wealth of information from <em>G. blacki</em> teeth themselves – from <a href="https://en.wikipedia.org/wiki/Isotopic_signature">isotopic signatures</a>, trace elements and the wear patterns on the surface of the teeth. This evidence can indicate diet, migration patterns, habitat preferences, diversity of food sources and stress. </p>
<p>This data represents the largest collection of well-dated evidence for the giant ape and for the first time is supported by well-documented environmental and behavioural changes. It reveals the rise and fall of <em>G. blacki</em> in comparison to its closest primate relative – the orangutans. </p>
<h2>Stronger seasons</h2>
<p>Surprisingly, <em>G. blacki</em> went extinct between 295,000 and 215,000 years ago, much more recently than previously assumed. Before this time, <em>G. blacki</em> flourished in a rich and diverse forest. </p>
<p>But between 600,000 and 300,000 years ago the environment became more variable. An increase in the strength of the seasons caused a change in the structure of the forest plant communities. By 200,000 years ago, the forests started to deteriorate.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=731&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=731&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=731&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=919&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=919&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566490/original/file-20231219-15-qvs2tg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=919&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">Differences in trace elements such as barium, strontium and calcium mapped across the inside of <em>G. blacki</em> and orangutan teeth. At earlier sites, clear banding in both species’ teeth suggests diverse food sources and a flourishing population. Diffuse or no banding in later <em>G. blacki</em> suggests less diverse food sources and chronic stress. The orangutan tooth suggests a less stressed population than <em>G. blacki</em> at this time.</span>
<span class="attribution"><span class="source">Nature</span></span>
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<p>Despite being a close relative of <em>G. blacki</em>, orangutans were able to adapt their size, behaviour and habitat preferences to accommodate to these forest changes. Their fossils display a flexible and balanced diet with very little stress during this period.</p>
<p>But <em>G. blacki</em> made the fatal mistake of relying on a less nutritious back-up food like twigs and bark when their favourite food sources such as fruit-bearing plants were unavailable. This meant the diversity of the giant apes’ food decreased and their less mobile body size compared to the more agile orangutans restricted their geographic range for foraging. </p>
<p>Surprisingly, <em>G. blacki</em> also increased in body size over this period, which further contributed to food source problems and caused immense chronic stress to the species. This stress can be seen in the trace element mapping of their teeth, providing an insight into a species on the brink of extinction.</p>
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<a href="https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph showing more arboreal plants and fewer ferns before the window of extinction, and a more even spread of plants afterward" src="https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=187&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=187&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=187&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=235&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=235&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566489/original/file-20231219-23-1rpdyk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=235&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pollen records from caves in the region showing the change in plant communities over time.</span>
<span class="attribution"><span class="source">Nature</span></span>
</figcaption>
</figure>
<h2>Failure to adapt</h2>
<p>As a direct consequence, <em>G. blacki</em> numbers dwindled as the species was placed under increasing environmental stress.</p>
<p>It would seem that by having such specific food and habitat preferences, <em>G. blacki</em> was vulnerable to environmental and habitat changes. Its size and choice of food hampered its adaptation compared to more agile and mobile species like orangutans.</p>
<p>The story of <em>G. blacki</em> is a lesson in extinction – how some species are more equipped to survive change and others are more vulnerable. This is a lesson we must take on board with the looming threat of a sixth mass extinction event. </p>
<p>Trying to understand past extinctions is a good starting point to understand primate resilience. It may offer clues to the fate of other large animals, both in the past and in the future.</p>
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Read more:
<a href="https://theconversation.com/what-is-a-mass-extinction-and-are-we-in-one-now-122535">What is a 'mass extinction' and are we in one now?</a>
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<img src="https://counter.theconversation.com/content/219304/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kira Westaway receives funding from The Australian Research Council</span></em></p><p class="fine-print"><em><span>Marian Bailey receives funding from the Australian Government RTP Stipend. </span></em></p><p class="fine-print"><em><span>Renaud Joannes-Boyau receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Simon Haberle receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Yingqi Zhang receives funding from Chinese Academy of Sciences and The Australian Research Council. </span></em></p>What happened to the three-metre tall apes that once lived alongside orangutans? A new study suggests they were too slow to adapt to a changing world.Kira Westaway, Associate Professor, School of Natural Sciences, Macquarie UniversityMarian Bailey, PhD Candidate, Geoarchaeology, Southern Cross UniversityRenaud Joannes-Boyau, Associate Professor, Southern Cross UniversitySimon Haberle, Professor, Australian National UniversityYingqi Zhang, Research professor in palaeontology, Chinese Academy of SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2119542023-09-07T14:58:27Z2023-09-07T14:58:27ZChimpanzees are not pets, no matter what social media tells you<figure><img src="https://images.theconversation.com/files/546731/original/file-20230906-27-bnebzz.jpg?ixlib=rb-1.1.0&rect=45%2C0%2C5111%2C3358&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Miriam, a rescued chimpanzee brought to the Chimfunshi Wildlife Orphanage in 2018.</span> <span class="attribution"><span class="source">Jake Brooker</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Trading wild <a href="https://www.worldwildlife.org/species/chimpanzee">chimpanzees</a>, including their meat and body parts, is <a href="https://www.iucnredlist.org/species/15933/129038584">illegal</a>. And yet, social media influencers and companies still reap profits from sharing “cute” images and videos of chimpanzees and other primates poached from the wild. All the while, sanctuaries worldwide continue to receive orphaned victims of this illicit trade. </p>
<p>As a comparative psychologist who studies the social and emotional behaviour of great apes, I have worked with chimpanzee populations both in the wild and in sanctuaries. Currently, I’m working at <a href="https://chimfunshiwildlife.org/">Chimfunshi Wildlife Orphanage Trust</a>, a sanctuary located in Zambia. Over the past 40 years, Chimfunshi has provided sanctuary to over 100 chimpanzees rescued from the pet and bushmeat trades.</p>
<p>In May 2023, Chimfunshi welcomed three new rescues. Following their rehabilitation, Abbie, Francis and Vanessa* will be integrated into a small community of eight other chimps who were rescued from similar conditions in 2018.</p>
<p>Chimpanzees are not native to Zambia. So, why do these animals still end up in these circumstances, and how can we help to keep them in their wild homes where they belong?</p>
<h2>Chimp trafficking</h2>
<p>Chimpanzees live across sub-Saharan Africa, in habitats ranging from savannah-woodland mosaics to tropical rainforests. These habitats that chimps depend on are threatened by the expansion of agricultural activities, alongside the encroachment of the logging, mining and oil industries. </p>
<p>The fragmentation of chimpanzee habitats makes it easier for poachers to hunt them. Chimpanzees are now listed as endangered by the <a href="https://www.iucnredlist.org/species/15933/129038584">International Union for the Conservation of Nature’s Red List</a>.</p>
<p>Chimfunshi is home to chimpanzees stolen from the wild and sold for sums as high as US$10,000 (£7,900). Prior to their rescue, some of Chimfunshi’s chimps were forced to surf for tourists (nearly drowning in the process) and smoke cigarettes. One was even taught to masturbate on circus stages in front of families.</p>
<p>In these conditions, they are in an environment alien to their species. The chimpanzees’ natural inclinations are inhibited by chains or harsh training to keep them on their best behaviour for social media or tourists. Typically, “pet” chimps are unable to even interact with their own kind, preventing these incredibly social animals from knowing how to be themselves. </p>
<p>María Laura Cordonet Castagneto, a University of Girona researcher I have worked with at Chimfunshi, told me that one nine-year-old does not even know how to play or groom, as she was not raised among other chimps. Part of this chimp’s rehabilitation is to help her learn such crucial social behaviours from watching and engaging with her new peers.</p>
<p>Most of Chimfunshi’s rescues are physically or emotionally scarred from beatings by their previous captors to keep them disciplined. Many will have watched their mothers and peers try to protect them from capture, and being slaughtered in the process. </p>
<p>Like most primates that are imprisoned in human homes or used by the entertainment industry, chimpanzees quickly outgrow their attraction as “pets” as they age. Their canines grow, they become uncontrollably strong and their behaviour more erratic. For every chimp that is saved, many more are abandoned or <a href="https://www.nbcnews.com/video/bodycam-shows-oregon-police-kill-pet-chimpanzee-after-attacking-owners-115336261793">killed</a> when they can no longer be controlled.</p>
<h2>Not so cute</h2>
<p>For a chimp to wear human clothing, play the piano, ride a skateboard or hang out with <a href="https://theconversation.com/before-you-hit-share-on-that-cute-animal-photo-consider-the-harm-it-can-cause-126182">tourists paying US$700</a> (£560) for a ten-minute session, so much suffering must occur. This is the cruel reality that “cute” TikTok videos and Instagram reels neglect. </p>
<p>Such content is pushed virally to our newsfeeds, regardless of whether the animal is a family dog or a creature illegally poached from the wild. Research has found that depicting wild animals in human contexts can <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235451">increase the desire</a> of a viewer to buy their own exotic pet.</p>
<p>But social media companies ignore this problem because this type of content drives considerable online engagement. The Instagram account for <a href="https://www.instagram.com/limbanizwf/?hl=en">Limbani</a>, a chimpanzee who lives in Miami, has nearly 800,000 followers and a <a href="https://www.speakrj.com/audit/">1.5% engagement rate</a> (a measure of how much of your audience actively engages with the content). To put this in context, Kim Kardashian’s Instagram account has an engagement rate of around 0.65%.</p>
<h2>What can be done?</h2>
<p>We can all individually make choices towards the future we want to support. Only sharing responsible online content of wild animals in their natural habitats is one option. But you can take a more active role in wildlife conservation by <a href="https://www.nationalgeographic.co.uk/travel/2018/11/hot-topic-how-to-avoid-unethical-wildlife-tours">avoiding unethical wildlife tourism activities</a>.</p>
<p>However, the long-term survival of endangered species can only be guaranteed through a systemic shift in how we perceive and treat the natural world. First and foremost, we must start by making it socially undesirable to own wild animals as pets.</p>
<p>Steps have been taken in recent years to reduce and restrict the trade of exotic animals. More than 50 countries <a href="https://www.four-paws.org/campaigns-topics/topics/wild-animals/worldwide-circus-bans">have banned (or have announced impending bans on)</a> the use of wild animals in circuses. And the UK government has <a href="https://www.gov.uk/government/news/government-sets-out-proposals-to-ban-the-keeping-primates-as-pets">set out proposals</a> to finally outlaw primate pet ownership in 2024.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/putting-primates-on-screen-is-fuelling-the-illegal-pet-trade-91995">Putting primates on screen is fuelling the illegal pet trade</a>
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<p>Even Hollywood – which has a long history of using trained monkey or ape “actors” – is <a href="https://theconversation.com/putting-primates-on-screen-is-fuelling-the-illegal-pet-trade-91995">shifting to the use of computer-generated imagery</a> to depict primates on screen. Social media must catch up, and recognise that holding exotic animals in human contexts represents a grizzly and exploitative industry – and thus reflects animal abuse.</p>
<p>Chimpanzees are our closest living relatives. They are thoughtful, emotional and have complex social needs. They belong in their wild homes where they can be themselves. Primates are not pets.</p>
<p><em>*The names of Chimfunshi’s new rescues have been changed to protect the identities of the chimpanzees and those who rescued them.</em></p><img src="https://counter.theconversation.com/content/211954/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jake Brooker's salary is funded by a grant from the Templeton World Charity Foundation.
</span></em></p>Why wild chimpanzees end up as pets and how we can keep them in the wild.Jake Brooker, Research Associate in the Department of Psychology, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2094262023-07-13T14:06:55Z2023-07-13T14:06:55ZMale rhesus macaques often have sex with each other – a trait they have inherited in part from their parents<figure><img src="https://images.theconversation.com/files/536818/original/file-20230711-17-aibxh5.jpg?ixlib=rb-1.1.0&rect=941%2C102%2C3853%2C3154&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Male same-sex sexual behaviour was widespread in a population of rhesus macaques.</span> <span class="attribution"><span class="source">Sam Edwards</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Homosexual behaviour is not limited to humans. Biologists have reported homosexual behaviour in many species of wild animal, ranging from <a href="https://doi.org/10.1371/journal.pone.0166024">bats</a> and <a href="https://doi.org/10.1016/j.anbehav.2010.05.009">birds</a> to <a href="https://doi.org/10.1016/j.tree.2009.03.014">dolphins</a> and <a href="https://doi.org/10.1163/1568539X-bja10062">primates</a>. </p>
<p>When animals engage in homosexual behaviour, one might assume that they invest less time and energy on reproduction. This suggests that there may be strong reproductive costs associated with such behaviour, such as having fewer offspring. So it raises the question of how homosexual behaviour manages to evolve and continue to exist within a population.</p>
<p>The underlying presumption is that there is not only a cost associated with engaging in homosexual activity, but also that variation in such behaviour is passed down from one generation to the next. Called heritability, this is essential for any evolution by natural selection to occur. </p>
<p>We set out to investigate these issues by studying 236 male <a href="https://www.britannica.com/animal/rhesus-monkey">rhesus macaques</a> living freely in a colony of 1,700 monkeys on the tropical island of Cayo Santiago, Puerto Rico. We observed these monkeys for three years and <a href="https://doi.org/10.1038/s41559-023-02111-y">found that</a> male same-sex sexual behaviour (SSB) was widespread. In fact, 72% of the males we observed mounted other males, while only 46% mounted females.</p>
<p>Critically, male SSB is not unique to this population of macaques. We saw similar behaviour in wild rhesus macaque populations in northern Thailand. And there have been <a href="https://www.google.com/books/edition/Primate_Behavior/QingBAAAQBAJ?hl=en&gbpv=0">previous reports</a> of SSB in this species from India, too.</p>
<figure class="align-center ">
<img alt="A rhesus macaque colony." src="https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536787/original/file-20230711-30-f7j44b.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">
<figcaption>
<span class="caption">A rhesus macaque colony in Rajasthan, India.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rhesus-monkey-colony-alwar-rajasthan-india-159063821">Attila JANDI/Shutterstock</a></span>
</figcaption>
</figure>
<h2>From one generation to the next</h2>
<p>We also had access to pedigree records that traced the parentage of each macaque back to 1956. This allowed us to explore the effect of relatedness (heritability) on their behaviour, taking into account other factors that could influence the results, such as age and social group structure.</p>
<p>We found that the heritability of male SSB was 6.4%, meaning genetics do account for a small proportion of SSB – the rest is environmental.</p>
<p>We calculated “evolvability” to be 14.9%, giving the potential rate at which the trait can evolve per generation through natural selection. Evolvability is thought to be a more reliable indicator than heritability of the degree to which genetics can respond to evolutionary pressure, and provides us with further evidence that SSB can evolve through selection.</p>
<p>Our estimates align with what we would expect for a behavioural trait that is probably influenced by multiple genetic factors and environmental effects. They are also consistent with heritability values reported in studies of other social behaviour in primate species, including <a href="https://doi.org/10.1093/evolut/qpad066">social grooming in baboons</a> and <a href="https://doi.org/10.1038/s41437-022-00558-6">social proximity in capuchins</a>. </p>
<p>We also found a genetic correlation between the number of times a male was observed mounting another male and the number of times he was mounted by other males. This suggests that different forms of SSB in these monkeys share a common genetic basis.</p>
<figure class="align-center ">
<img alt="Two grooming chacma baboons on a tree." src="https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536773/original/file-20230711-25-fgafa9.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">Two chacma baboons grooming eachother. Caprivi, Namibia.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/two-grooming-chacma-baboons-papio-ursinus-2250991039">Fotografie-Kuhlmann/Shutterstock</a></span>
</figcaption>
</figure>
<h2>What underpins this behaviour?</h2>
<p><a href="https://doi.org/10.1126/science.aat7693">Previous studies</a> on the heritability of SSB have primarily focused on humans. However, these studies often rely on self-reported data, which can introduce complications. The cultural stigma surrounding homosexuality, for instance, could lead to the underreporting of homosexual activity.</p>
<p>Heritability of SSB has also been found in some invertebrate species, including <a href="https://doi.org/10.1186/s12862-016-0658-4">seed beetles</a> and <a href="https://doi.org/10.1098/rspb.2015.0429">fruit flies</a>. However, the pathways through which SSB develops in these species are thought to be different from those observed in social vertebrates like primates. For example, factors such as <a href="https://doi.org/10.1007/s00265-013-1610-x">imperfect sex recognition</a> are believed to influence the development of SSB in invertebrates.</p>
<p>Demonstrating that SSB is heritable and its potential for evolutionary response to natural selection is an important first step towards understanding the factors that influence variation in this behaviour. </p>
<p>Many evolutionary theories for SSB in animals exist. But they all depend on the behaviour showing a degree of heritability. </p>
<p>One theory suggests that in some species, animals may engage in SSB because it serves a <a href="https://doi.org/10.1016/j.anbehav.2007.02.001">beneficial social function</a>. For example, it may strengthen the bonds between males, ultimately benefiting them during competition for mates and food. </p>
<p>In support of this theory, our research found that male rhesus macaques involved in SSB partnerships were more likely to support each other in conflicts with other individuals. This effect could be a way in which SSB benefits a macaque and its chances of producing offspring, thereby allowing the behaviour and the genes associated with it to persist within a population.</p>
<figure class="align-center ">
<img alt="A group of macaques fighting." src="https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=335&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=335&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536779/original/file-20230711-15-ln4ks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=335&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Rhesus macaques involved in SSB partnerships were more likely to support each other in conflicts.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/group-macaques-fighting-1998316622">Di Qin/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Learning from primates</h2>
<p>So what can we learn from these findings about SSB across primate species, including humans?</p>
<p>A <a href="https://doi.org/10.1126/science.aat7693">previous study</a> examining SSB heritability in humans found significant reproductive costs associated with this behaviour. In contrast, we found no such costs in macaques. </p>
<p>This suggests that the costs associated with human SSB might arise from specific social factors unique to humans. However, more research is needed to explore this idea further.</p>
<p>Today, some people still believe that SSB is rare or the product of extreme and unusual environmental conditions, and selectively look to examples in nature to validate their view. Our results may help to challenge these beliefs and combat prejudice against homosexuality and bisexuality. However, society’s moral obligation to strive for more inclusivity and acceptance of different sexual orientations ultimately does not rely on observations from the natural world.</p><img src="https://counter.theconversation.com/content/209426/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jackson Clive received funding for this work from the UK Natural Environment Research Council, the American Institute of Bisexuality and the Genetics Society.</span></em></p><p class="fine-print"><em><span>Ewan Flintham receives funding from the UK Natural Environment Research Council
. </span></em></p><p class="fine-print"><em><span>Vincent Savolainen receives funding from NERC, the American Institute of Bisexuality and the Evolution, Education Trust. </span></em></p>Most of the males in a Puerto Rican monkey colony engaged in homosexual activity, a new study reveals.Jackson Clive, Postdoctoral Researcher, Imperial College LondonEwan Flintham, Postdoctoral Researcher, Université de LausanneVincent Savolainen, Professor of Organismic Biology, Imperial College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2071272023-06-07T17:56:17Z2023-06-07T17:56:17ZWhy we’re searching for the evolutionary origins of masturbation – and the results so far<figure><img src="https://images.theconversation.com/files/530596/original/file-20230607-23-51z6cg.JPG?ixlib=rb-1.1.0&rect=0%2C26%2C6000%2C3961&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This female rhesus macaque seems surprised at the idea not everyone thinks masturbation is natural. </span> <span class="attribution"><span class="source">Matilda Brindle</span>, <span class="license">Author provided</span></span></figcaption></figure><p>“Spanking the monkey”, “petting the poodle” and “pulling the python”: all fitting euphemisms for masturbation, and closer to the truth than you might imagine. Self-pleasure is common across the animal kingdom: from dogs humping unwitting teddy bears to dolphins thrusting their penises into decapitated fish (<a href="https://www.dailymotion.com/video/x34uowk">yes, really</a>), animal masturbation is a raucous affair.</p>
<p><a href="https://doi.org/10.1098/rspb.2023.0061">In my team’s new paper</a>, my colleagues and I tested the hypotheses that primate masturbation could increase reproductive success and help avoid sexually transmitted infections (STIs). </p>
<p>We focused our research on primates (the group of animals humans belong to) because, if there were a prize for the most inventive onanists in the animal kingdom, they would win.</p>
<p>Young chimpanzees <a href="http://mahale.main.jp/PAN/25_1/PAN25_1.pdf">fashion DIY sex toys </a> from bits of chewed-up fruit. Female Sulawesi crested macaques <a href="https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1977.tb04141.x?casa_token=WPyuKgF-VugAAAAA:wy7WU34Nq5flmQTiF3M1xwsSntqVFEV6WL-xTSsEOhAxmWAP4g5dxBQaayPUf7BX5r8hOOXt9DUX4fXE">slap their rumps</a> while repeatedly inserting their fingers into their vaginas. In one study, <a href="https://link.springer.com/article/10.1007/BF02735782">captive male chacma baboons</a> masturbated while ogling females sporting large prosthetic bottoms, attached by researchers to replicate the natural swellings females develop when at their most fertile. </p>
<figure class="align-center ">
<img alt="Male baboon with mane touches the swollen bottom of a female" src="https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530603/original/file-20230607-17-xzw1xp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Female chacma baboons develop sexual swellings, like the female in this picture of hamadryas baboons.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/adult-male-hamadryas-baboon-papio-female-2159615143">Prashanth Bala/Shutterstock</a></span>
</figcaption>
</figure>
<p>Despite masturbation being such common behaviour, there is very little research in this area. So – in a career move I did not anticipate when I was growing up – I spent my PhD researching the evolution of masturbation.</p>
<p>In evolutionary terms, masturbation is a puzzler because, by definition, it excludes reproductive partners and it’s hard to think of a scenario in which masturbating could aid survival. Many people have dismissed it as an <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/1468-0424.12594">abnormal and deviant behaviour</a>, or a byproduct of sexual arousal. And masturbation can be costly in terms of both time and <a href="https://link.springer.com/article/10.1007/s10329-005-0171-7">energy</a>.</p>
<h2>Mapping masturbation across the primate order</h2>
<p>My colleagues and I started by compiling a “who’s who” of masturbators across the primate order. We collated every detail we could find from published research, and supplemented this with questionnaires dutifully filled out by accommodating, if slightly bewildered, colleagues who are experienced working with primates.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Primate sitting on the ground with its paws in its lap" src="https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530638/original/file-20230607-15-42jgyt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rhesus macaques often masturbate several times a day during the mating season.</span>
<span class="attribution"><span class="source">Matilda Brindle</span></span>
</figcaption>
</figure>
<p>If you know how different animals are related to one another, you can compare data from living species to infer how a trait may have evolved. We combined information on the evolutionary relationships between different primates (think of it like an extensive family tree) with our new data on their masturbatory behaviours (or lack thereof). </p>
<p>For some analyses, we added information on other traits, such as their mating system and whether the species typically had a <a href="https://www.understandinganimalresearch.org.uk/news/sti-day">high exposure to STIs</a>.</p>
<p>It turns out that masturbation occurs in all age groups, in both females and males, in the wild and in captivity. We discovered that masturbation is an ancient behaviour within primates, and concluded that the ancestor of all monkeys and apes, including humans, probably masturbated. It’s unlikely masturbation is a habit that different species of monkeys and apes have picked up along the way. </p>
<h2>Can masturbation increase reproductive success?</h2>
<p>Previous research has shown that marine iguanas <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspb.1996.0066">have an ingenious secret</a>. Bigger males monopolise females, physically separating small males from their partner if they spot them copulating. To get around this, small males masturbate and store their ejaculate in a special pouch at the tip of their penis. Next time there’s an opportunity to mate, they quickly deposit their pre-prepared ejaculate. Amazingly, this method improves small males’ fertilisation success by 41%.</p>
<p>Primates don’t have a special pouch for storing semen, but getting aroused before sex is still a good strategy for low-ranking males, as they are likely to be interrupted by those at the top of the pecking order. Hovering close to orgasm means they can ejaculate faster if they do get the opportunity to mate, before making a speedy exit. </p>
<p>Male masturbation can also <a href="https://edoc.ub.uni-muenchen.de/105/">keep sperm fighting fit</a>, since ejaculation allows males to replenish their semen with fresh, high-quality sperm that are more likely to outcompete those of other males.</p>
<p>Our study found support for the theory that masturbation increases male – but not female – reproductive success. Mating systems with lots of competition between males have coevolved with masturbation across the course of evolution.</p>
<p>Previous studies have showed that arousal in females <a href="https://www.tandfonline.com/doi/abs/10.1080/01614576.2000.11074323?casa_token=bsMUtcOesQsAAAAA:Mi9gJeYErprE0mQ4i3l1npkSFGgRa6rOgrB6Uzkxu4HfLK-n5CZ3wLXUPrcM-2fjSGKNe6MkTDFeog">increases vaginal pH</a>, creating a more welcoming environment for sperm, while <a href="https://www.google.com/url?sa=D&q=https://academic.oup.com/humupd/article/12/1/23/607817%3Flogin%3Dfalse&ust=1686131220000000&usg=AOvVaw2iXFjDr3bpxxNVFZULLd_d&hl=en&source=gmail">vaginal mucus filters out inferior sperm</a> and fast-tracks high-quality semen towards the uterus. <a href="https://www.cambridge.org/core/journals/twin-research-and-human-genetics/article/evolution-of-female-orgasm-adaptation-or-byproduct/C90552B9D074471C93C6F53E11E094BC">Orgasmic contractions</a> can also help sperm on their journey. </p>
<h2>Masturbation as a means of genital grooming</h2>
<p><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0013060">Male Cape ground squirrels</a> masturbate after they’ve had sex – and the more partners they have, the more they do it. If their partner has had a lot of previous sex, they masturbate even more.</p>
<p>It’s thought that, among males, this practice of ejaculating via masturbation after sex is a form of genital cleansing. It’s unlikely that female masturbation evolved for STI prevention, though, because the higher vaginal pH associated with arousal is <a href="https://www.sciencedirect.com/science/article/pii/S0010782414000250?casa_token=AWVf3OR4f_IAAAAA:YOW1PwNAWCdKQPw0sZak9t88dsHQ6PWE2QZ6R4IcsiKBj5JDPnPD5eCIUj9i3pzUMrTbfWi8JlQ">more hospitable for pathogens</a> as well as sperm.</p>
<p>Our research supports the hypothesis that masturbation can be a pathogen avoidance strategy in males, having coevolved with higher risk of STIs. And in species with a high risk of contracting an STI, once masturbation evolved it was maintained. </p>
<h2>So what about females?</h2>
<p>At first glance, our data seems to suggest that female masturbation is less prevalent than its male counterpart. We didn’t find evidence for an evolutionary function of female masturbation. </p>
<p>However, I’m not convinced these results reflect what’s really going on. This is in part because female arousal and masturbation are often far less obvious than in males. But it also reflects a broader trend in the sciences – a shocking lack of information on female sexual behaviour and anatomy.</p>
<p>In the past, females have been pushed to the side in favour of research on males, which has the benefit of a back-catalogue of previous scientific effort. We set out to explore the evolution of masturbation in both females and males, but our analyses of females were hampered because we couldn’t collect as much data.</p>
<p>Our research highlights how masturbation is a normal part of the behavioural repertoire of many different species – both in females and males, in the wild and in captivity. Those who condemn masturbation as unnatural or wrong should have a look at our primate cousins, and take a walk on the wild side.</p><img src="https://counter.theconversation.com/content/207127/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matilda Brindle receives funding from the Natural Environment Research Council</span></em></p>Masturbation seems like an evolutionary conundrum. New research has found an explanation.Matilda Brindle, Associate Researcher, Department of Anthropology, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2056732023-05-18T06:49:33Z2023-05-18T06:49:33ZBaboon bonds: new study reveals that friendships make up for a bad start in life<figure><img src="https://images.theconversation.com/files/526176/original/file-20230515-12435-66xt42.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Two juvenile baboons passively share information about a food source when one sniffs the other’s muzzle while feeding.</span> <span class="attribution"><span class="source">Susan C. Alberts</span></span></figcaption></figure><p>Childhoods can predict a great deal about how adult lives might play out. For instance, <a href="https://www.sciencedirect.com/science/article/abs/pii/S0749379798000178?via%3Dihub">research</a> has shown that people whose childhoods involve poverty, abuse and neglect have poorer health and shorter lives than those who have happy, stable childhoods.</p>
<p>Is there a way to overcome a bad start? The <a href="https://www.science.org/doi/10.1126/science.aax9553">evidence</a> suggests that strong social ties may be one way to make up for adversity in early life. <a href="https://pubmed.ncbi.nlm.nih.gov/25910392/">People</a> (and other animals such as <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2017.1313">killer whales</a>, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022375">hyraxes</a> and <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2014.1261">baboons</a>) with strong adult friendships are healthier and live longer than those without such bonds.</p>
<p>I am a biologist working on how social environments affect development and lifespan. I <a href="https://www.science.org/doi/10.1126/sciadv.ade7172">recently collaborated</a> with statisticians and other biologists to understand whether harsh conditions in early life led to weak social relationships and poor health, or if close friendships could develop in adulthood in spite of a tough childhood. We also wondered if having close friends could potentially even make up for a poor early life. </p>
<p>To answer these questions, we studied a population of wild baboons in Kenya. Scientists often use <a href="https://academic.oup.com/emph/article/2017/1/162/4835137">animal models</a> to test hypotheses that are difficult to study in humans. <a href="https://elifesciences.org/articles/50989">Baboons are a useful proxy for humans</a> because they are similar in their life cycle, social relationships, physiology and behaviour. And research has shown that the effects of early adversity and social bonds on lifespan in <a href="https://www.sciencedirect.com/science/article/pii/S0145213419303047">humans</a> are <a href="https://www.pnas.org/doi/10.1073/pnas.2015162117">paralleled</a> in <a href="https://www.nature.com/articles/ncomms11181">baboons</a>.</p>
<p>The most important result of <a href="https://www.science.org/doi/10.1126/sciadv.ade7172">our research</a> is that early life adversity and adult social relationships have independent effects on survival. That is, both early life environments and adult social bonds have strong effects, but they don’t depend on each other. </p>
<p>This has been an important question for social scientists, because one possibility is that the effects of adult social bonds on survival are solely a result of the fact that early life adversity tends to lead to poor social bonds in adulthood and also to poor survival. In that scenario, the two effects are not independent. Everything is driven by early life adversity. </p>
<p>But our data shows that both effects matter. What’s more, our results suggest that strong social bonds can make up for some of the negative effects of early adversity for baboons. If that’s true for human too – we don’t know that yet – interventions early in life and in adulthood could improve human health.</p>
<h2>Baboons’ lives</h2>
<p>Baboons live in social groups with many <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.12887">complex relationships and interactions</a>. They have an accelerated life cycle compared to humans (they mature at around 4.5 years and females live about 18 years). Like humans, they evolved in a savannah environment and are highly adaptable and behaviourally flexible. These traits make them an ideal species for exploring our research questions and linking results to humans.</p>
<p>We study the baboons of the Amboseli ecosystem in Kenya. The lives of these baboons have been documented since 1971 as part of the <a href="https://amboselibaboons.nd.edu/">Amboseli Baboon Research Project</a>. We have complete lifespan data for many individuals and can track families across generations. Direct observation also offers a complete picture of their development and behaviour.</p>
<p>We used data collected by the <a href="https://amboselibaboons.nd.edu/people/">senior field team of biologists</a> in Amboseli between 1983 and 2019 and examined six sources of early life adversity in the baboons: </p>
<ul>
<li>experiencing a drought in the first year of life</li>
<li>being born into an unusually large social group (“crowding”)</li>
<li>having a low-ranking mother</li>
<li>having a socially isolated mother</li>
<li>having a younger sibling born soon after them</li>
<li>losing their mother when they are young. </li>
</ul>
<p>These events are like adverse childhood experiences in humans that are associated with poverty or family trauma.</p>
<figure class="align-center ">
<img alt="One baboon grooms another with its hands" src="https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526739/original/file-20230517-23-na6y4i.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">A mother grooms her infant daughter during a nursing bout. The mother is wearing a radio collar, which researchers use to locate the study groups.</span>
<span class="attribution"><span class="source">Susan C. Alberts</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/thriving-in-the-face-of-adversity-resilient-gorillas-reveal-clues-about-overcoming-childhood-misfortune-205184">Thriving in the face of adversity: Resilient gorillas reveal clues about overcoming childhood misfortune</a>
</strong>
</em>
</p>
<hr>
<p>Once the study subjects grew up, we measured their social bonds and their survival as adults.</p>
<h2>Independent effects</h2>
<p>Our results showed that the effects of early life adversity and adult social relationships on survival were largely independent. Early life environments and adult social bonds both had strong effects on survival, but adult social bonds were not as heavily influenced by early life adversity as we’d thought. And the effect of bonds on survival didn’t depend in any way on whether the baboon experienced early life adversity. </p>
<p>This rules out the possibility that being born into a poor environment destines a baboon to both poor social relationships and poor survival.</p>
<p>Our results also suggest that strong social bonds in baboon adulthood can buffer some negative effects of early adversity: friends can make up for a bad start. </p>
<p>For the baboons, this is especially true if a female loses her mother but can maintain strong social ties to other members of the group after she grows up. Because <a href="https://www.google.com/books/edition/Baboon_Mothers_and_Infants/7x6i9RAgSGAC?hl=en&gbpv=1&dq=mother+baboons&pg=PR15&printsec=frontcover">mothers</a> are an important source of resources, learning and social support in baboons, maternal loss is a particularly strong source of adversity. </p>
<p>If this result holds for humans, it means that interventions early in life and in adulthood could help improve lifespan.</p>
<h2>Human adversity</h2>
<p>Our results raise the possibility that human health and survival could be improved if people with adverse childhood experiences were identified and helped to improve their social relationships in adulthood. </p>
<p>Researchers working with humans are asking similar questions to determine whether early life adversity and social bonds affect survival in the same way as in baboons. Future work should also ask if there are other links between a poor early life environment and survival. For example, <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2019.01668/full">genetics</a>, <a href="https://www.pnas.org/doi/abs/10.1073/pnas.2004524117">physiology</a>, <a href="https://www.pnas.org/doi/abs/10.1073/pnas.0902971106">immune responses</a>, and <a href="https://www.sciencedirect.com/science/article/abs/pii/S2352154615001588">other behaviours</a> likely play a role.</p>
<p>Our study also shows that some of our most important human traits – including the importance of social relationships for survival – evolved long ago. Looking to the animals can help us learn about ourselves. </p>
<p><em>Shuxi Zeng, Fernando Campos, Fan Li, Jenny Tung, Beth Archie and Susan Alberts co-authored the research and collaborated on the project on which this article is based.</em></p><img src="https://counter.theconversation.com/content/205673/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work was supported by NIH grant R01AG053308 (S.C.A.), NSF Integrative Organismal Systems grant 1456832 (S.C.A.), NIH grant P01AG031719 (S.C.A.), NIH grant R01AG053330 (E.A.A.), NIH grant R01AG071684 (E.A.A.), NIH grant R01HD088558
(J.T.), and NIH grant R01AG075914 (J.T.).</span></em></p>Early life environments and adult social bonds both have strong effects on survival.Elizabeth Lange, Assistant Professor, State University of New York OswegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2051842023-05-15T15:01:07Z2023-05-15T15:01:07ZThriving in the face of adversity: Resilient gorillas reveal clues about overcoming childhood misfortune<figure><img src="https://images.theconversation.com/files/525949/original/file-20230512-23918-udbd4r.jpeg?ixlib=rb-1.1.0&rect=837%2C1234%2C5222%2C3305&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A lot of bad things can happen to young mountain gorillas in the wild.</span> <span class="attribution"><span class="source">Dian Fossey Gorilla Fund</span></span></figcaption></figure><p>In 1974, an infant mountain gorilla was born in Volcanoes National Park in Rwanda. Researchers named him Titus. As is typical for young gorillas in the wild, Titus spent the first years of his life surrounded by his mother, father and siblings, as well as more distant relatives and unrelated gorillas that made up his social group.</p>
<p>In 1978, however, tragedy struck. Poachers killed Titus’ father and brother. In the chaos that followed, his younger sister was killed by another gorilla, and his mother and older sister fled the group. Juvenile Titus, who was at a developmental stage similar to that of an 8- or 9-year-old human, <a href="https://www.imdb.com/title/tt1922764/">experienced more tragedy</a> in his first four years of life than many animals do in a lifetime.</p>
<p>In people, <a href="https://doi.org/10.1016/j.neuron.2017.09.027">a rough start in life</a> is often associated with significant problems later on. <a href="https://www.npr.org/sections/health-shots/2015/03/02/387007941/take-the-ace-quiz-and-learn-what-it-does-and-doesnt-mean">Early life adversity</a> can take a wide variety of forms, including malnutrition, war and abuse. People who experience these kinds of traumas, assuming they survive the initial event, are <a href="https://doi.org/10.1542/peds.2011-2663">more likely to suffer health problems</a> and social dysfunction in adulthood and to have shorter life spans. Often, <a href="https://doi.org/10.1111/nyas.13928">these outcomes trace back at least in part</a> to what public health researchers call health risk behaviors – things like smoking, poor eating habits and a sedentary lifestyle.</p>
<p>But researchers have documented the same kinds of <a href="https://doi.org/10.1073/pnas.1205340109">problems in adulthood in nonhuman animals</a> <a href="https://doi.org/10.1016/j.cobeha.2020.06.006">that experienced early life adversity</a>. For example, female baboons who have the hardest childhoods have <a href="https://doi.org/10.1038/ncomms11181">life spans that are on average only half as long</a> as their peers that have the easiest. Activities like smoking and unhealthy food choices can’t be the whole story, then, since animals don’t engage in typical human health risk behaviors.</p>
<p>Given the connection between adverse events while young and poor health later in life, one might expect that Titus’ unlucky early years would predict a short, unhealthy adulthood for him. However, there are interesting hints that things <a href="https://doi.org/10.1016/j.cub.2023.04.051">might work differently in mountain gorillas</a>, which are one of humans’ closest living relatives.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="juvenile gorilla seated" src="https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525945/original/file-20230512-23-8omdyq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers analyzed decades of observational data to determine how life turned out for young gorillas that had faced adversity.</span>
<span class="attribution"><span class="source">Dian Fossey Gorilla Fund</span></span>
</figcaption>
</figure>
<h2>Decades of gorilla observations</h2>
<p><a href="https://scholar.google.com/citations?user=GxpHf-AAAAAJ&hl=en&oi=ao">As scientists who have spent</a> <a href="https://scholar.google.com/citations?user=1I9_QM0AAAAJ&hl=en&oi=ao">many years studying wild gorillas</a>, we have observed a wide variety of early life experiences and an equally wide variety of adult health outcomes in these great apes. Unlike other primates, mountain gorillas don’t appear to suffer any long-term negative effects of <a href="https://doi.org/10.7554/eLife.62939">losing their mothers at an early age</a>, provided that they reach the age at which they are old enough to have finished nursing.</p>
<p>Losing your mother is only one of many bad things that can happen to a young gorilla, though. We wanted to investigate whether a pattern of resilience was more generalized. If so, could we gather any insight into the fundamental question of how early life experiences can have long-lasting effects?</p>
<p>To do this, we needed exceptionally detailed long-term data on wild gorillas across their lifetimes. This is no mean feat, given <a href="https://doi.org/10.1038/sdata.2016.6">gorillas’ long life spans</a>. Primatologists know that males can survive into their late 30s and females into their mid-40s.</p>
<p>The best data in the world to conduct such a study comes from the <a href="https://gorillafund.org/">Dian Fossey Gorilla Fund</a>, which has been following individual mountain gorillas in Rwanda almost daily for 55 years. We conducted doctoral and postdoctoral research with the Fossey Fund and have collaborated with other scientists there for more than 20 years.</p>
<p>From their database, which stretches back to 1967, we extracted information on more than 250 gorillas tracked from the day they were born to the day they died or left the study area.</p>
<p>We used this data to identify six adverse events that gorillas younger than age 6 can endure: maternal loss, paternal loss, extreme violence, social isolation, social instability and sibling competition. These experiences are the gorilla equivalent of some kinds of adversity that are linked with long-term negative effects in humans and other animals.</p>
<p>Many young gorillas didn’t survive these challenges. This is a strong indication that these experiences were indeed adverse from the perspective of a gorilla.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Adult female gorilla seated tightly together with two young gorillas" src="https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525946/original/file-20230512-15-ldzmn2.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">Ubufatanye experienced the loss of her mother and father and the disintegration of her family group before the age of 5. Now 20, she has become a successful mother, raising three offspring.</span>
<span class="attribution"><span class="source">Dian Fossey Gorilla Fund</span></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1016/j.cub.2023.04.051">We were surprised to discover</a>, however, that most of the repercussions of these hardships were confined to early life: animals that survived past the age of 6 did not have the shorter life spans commonly associated with early life adversity in other species.</p>
<p>In fact, gorillas that experienced three or more forms of adversity actually had better survival outcomes, with a 70% reduction in the risk of death across their adult years. Part of this hardiness, especially for males, may be due to a phenomenon called <a href="https://www.biologyonline.com/dictionary/viability#:%7E:text=Viability%20selection%20can%20be%20defined,on%20the%20road%20for%20it.">viability selection</a>: Only the strongest animals survive early adversity, and thus they are also the animals with the longest life spans.</p>
<p>While viability selection may be part of the story, the patterns in our data strongly suggest that as a species, mountain gorillas are also remarkably resilient to early adversity.</p>
<h2>Where do gorillas get their resilience?</h2>
<p>Although our findings corroborate previous research on maternal loss in gorillas, they contrast with other studies on <a href="https://doi.org/10.1037/pag0000394">early adversity in humans</a> and <a href="https://doi.org/10.1111/1365-2656.13785">other long-lived mammals</a>. Our study indicates that the negative later-life consequences of early adversity are not universal.</p>
<p>The absence of this connection in one of our closest relatives suggests there might be protective mechanisms that help build resiliency to early-life knocks. Gorillas may provide valuable clues to understand how early life experiences have such far-reaching effects and how people can potentially overcome them.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="two adult and one young gorilla seated together" src="https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525944/original/file-20230512-20526-7wom64.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Young gorillas live with their parents as part of larger social groups.</span>
<span class="attribution"><span class="source">Dian Fossey Gorilla Fund</span></span>
</figcaption>
</figure>
<p>While there is still much left to explore, we suspect that gorillas’ food-rich habitat and cohesive social groups could underpin their resiliency. When young gorillas lose their mothers, <a href="https://doi.org/10.7554/eLife.62939">other social group members fill in</a> the companionship hole she leaves behind. Something similar may happen for other types of early adversity as well. A supportive social network combined with plentiful food may help a young gorilla push through challenges.</p>
<p>This possibility underscores the importance of ensuring that human children who experience early adversity are <a href="https://doi.org/10.1001/jamapediatrics.2016.1559">supported in multiple ways</a>: socially, but also economically, especially since early adversity is particularly prevalent among children living in poverty – itself a form of adversity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&rect=436%2C0%2C3845%2C2702&q=45&auto=format&w=1000&fit=clip"><img alt="large adult male gorilla against leafy background" src="https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&rect=436%2C0%2C3845%2C2702&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525223/original/file-20230509-25-vqm6q4.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Titus, pictured here as an adult, survived more adversity before age 4 than many animals confront in a lifetime.</span>
<span class="attribution"><span class="source">Dian Fossey Gorilla Fund</span></span>
</figcaption>
</figure>
<p><a href="https://www.imdb.com/title/tt1922764/">And what became of Titus</a>? Despite his difficult start in life, Titus went on to lead his group for two decades, siring at least 13 offspring and surviving to his 35th birthday, making him one of the most successful gorillas the Dian Fossey Gorilla Fund has ever studied.</p>
<p>Though Titus’ story is only a single anecdote, it turns out that his resilience is not so unusual for a member of his species.</p><img src="https://counter.theconversation.com/content/205184/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stacy Rosenbaum receives funding from the National Institutes of Health (NIH) and the University of Michigan. </span></em></p><p class="fine-print"><em><span>Robin Morrison receives funding from the Dian Fossey Gorilla Fund and the Swiss National Science Foundation. </span></em></p>In many animals, including humans, adverse events in youth have lasting negative health effects over the life span. But new research suggests something different is going on in mountain gorillas.Stacy Rosenbaum, Assistant Professor of Anthropology, University of MichiganRobin Morrison, Postdoctoral Fellow in Animal Behavior, University of ExeterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2022652023-04-04T10:55:19Z2023-04-04T10:55:19ZBonobos and chimps: what our closest relatives tell us about humans<figure><img src="https://images.theconversation.com/files/519318/original/file-20230404-897-1b84fi.png?ixlib=rb-1.1.0&rect=1%2C21%2C1059%2C577&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/banner-portrait-happy-adult-chimpanzee-smiling-1931769623">Oleg Senkov/Shutterstock</a></span></figcaption></figure><p>Humans are an interesting mixture of altruism and competition. We work together well at times and at others we will fight to get our own way. To try to explain these conflicting tendencies, researchers have turned to the chimpanzees and the bonobos for insight.</p>
<p>Among the great apes, the chimpanzees and the bonobos are the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0959437X16301162">most genetically related</a> to us as we share about 98.7% of our DNA with them. We share a common ancestor with them as well as <a href="https://sunypress.edu/Books/E/Evolution-of-Human-Behavior2">anatomical features, complex social hierarchies and problem-solving skills</a>.</p>
<p>Bonobos may be one of our closest cousins but chimpanzees dominated research after <a href="https://www.nature.com/articles/2011264a0">Jane Goodall discovered in the 1960s</a> that chimpanzees make and use tools. This finding paved the way for research on chimpanzees as a lens to understand which human aspects are natural rather than socially conditioned. An array of human characteristics, including <a href="https://link.springer.com/article/10.1007/BF02382862">empathy</a>, <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2020.0370">playfulness</a> and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010625">respect for elders</a> have since been attributed to our shared ancestry with chimpanzees. </p>
<h2>The aggressive chimp in us</h2>
<p>However, one disturbing characteristic stands out. Chimpanzees “go ape” and attack each other in coordinated assaults. Dutch primate expert Frans de Waal’s 1982 book <a href="https://www.goodreads.com/en/book/show/389530">Chimpanzee Politics</a> included a colourful description of how Luit and Nikkie, two young male chimpanzees, allied to violently usurp Yeroen, the alpha male. They bit and ripped out Yeroen’s testicles and the loss of blood killed him.</p>
<p>One argument scientists have made is that these warlike tendencies are hardwired in us the same way they are hardwired in chimpanzees, which challenges the view that <a href="https://www.scientificamerican.com/article/war-is-not-part-of-human-nature/">wars are a man-made phenomenon</a>. Chimps can also help us learn about the circumstances that might encourage aggression, such as <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2001.1926">when rivals are outnumbered</a> or when positions in the status hierarchy <a href="https://nyaspubs.onlinelibrary.wiley.com/doi/full/10.1196/annals.1330.015">are being negotiated</a>.</p>
<p>Nevertheless, J. B. Mulcahy, co-director at the Chimpanzee Sanctuary Northwest in the US, believes aggression only <a href="https://chimpsnw.org/2023/02/conflict-and-reconciliation-2/">“makes up a very small part of their daily activity”</a>. So some scientists may have overemphasised this trait. Increasingly, research is actually showing how <a href="https://www.pnas.org/doi/full/10.1073/pnas.1611826113">cooperative</a> chimpanzees can be. </p>
<h2>The gentle bonobo</h2>
<p>Once overlooked, researchers are recognising bonobos as <a href="https://www.nature.com/articles/s41598-017-00548-3">more similar</a> than chimpanzees to humans. Which, considering their reputation as amicable apes, is good news for us.</p>
<p>Unlike the male-dominated groups of chimpanzees, bonobos live in peaceful communities where the chief is female. Indeed, human societies <a href="https://networks.h-net.org/node/73374/announcements/7798769/warfare-and-peacemaking-among-matricultural-societies">tend to be matriarchal</a> when there is little direct competition for resources.</p>
<p>In bonobo communities, sexual relations play an important role in maintaining relationships and resolving conflicts. For instance, the prospect of food can stir chimpanzees into a hostile frenzy, but bonobos <a href="https://www.jstor.org/stable/24980375">take a more harmonious approach</a> and will gather for what often turns into a polyamorous picnic. There is plenty of sexual play and grooming reminiscent of our own free love movements in hippie culture. While the alpha female is typically smaller than the males, all the females will rally around her to chase the males away should they turn aggressive. </p>
<figure class="align-center ">
<img alt="Two bonobo chimpanzees hugging in the wilderness" src="https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519022/original/file-20230403-26-yv16rm.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">Bonobos are known for their peace-loving nature.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bonobo-chimpanzees-hugging-wilderness-democratic-republic-2158575391">Wirestock Creators/Shutterstock</a></span>
</figcaption>
</figure>
<p>Bonobos are also rather eager to share. Experiments at Lola ya Bonobo, a bonobo sanctuary in the Democratic Republic of Congo, in 2010 show that <a href="https://www.sciencedirect.com/science/article/pii/S0960982209022015">when bonobos are put in adjacent rooms</a> and one is given food, that bonobo would rather share the food than eat alone. They have also been observed sharing food with those <a href="https://pubmed.ncbi.nlm.nih.gov/29619667/">outside of their group</a>, perhaps to <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051922">make new friends</a>. And they demonstrate a willingness to help others obtain food <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051922">even if they won’t get to share it</a>.</p>
<p>Bonobos may even have better social intelligence than chimpanzees. In experiments where various animals were presented with <a href="https://www.amazon.com/Survival-Friendliest-Understanding-Rediscovering-Humanity/dp/0399590668">upside-down cups</a> with a treat hidden under one of them, chimpanzees kept choosing the cups at random but bonobos (and dogs) looked to the human running the experiment for information on which cup was correct. <a href="https://link.springer.com/article/10.1007/s00429-018-1751-9">Bonobos also have brain circuits</a> that seem more predisposed to sharing, tolerance, negotiation and cooperation than chimpanzees.</p>
<p>So where exactly do humans stand? We seem to have incorporated the traits of both species, resulting in a tension between our aggressive and harmonious proclivities. Our tendency for conflict mirrors the competitiveness of chimpanzees, and yet the bonobos teach us that we have it in us to be altruistic and that society can be organised in more peaceful ways. This selflessness underlies the large-scale cooperation that has helped <em>Homo sapiens</em> share ideas, form nations, explore the universe and outlast other early humans such as <em>Homo erectus</em>.</p>
<p>And while the idea of societies built on free love may sound like a utopian fairytale, we do seem to be opening up to alternative mating practices such as <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2019.03033/full">consensual non-monogamy</a> in response to a world that is getting increasingly jaded with traditional notions of gender and relationship structures. The flexibility of human behaviour is after all the cornerstone of our remarkable adaptability. So it can’t hurt to be open to new possibilities.</p><img src="https://counter.theconversation.com/content/202265/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jose Yong 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>Chimpanzees have been the focus of primate research for decades. But their close cousins, the bonobos, can offer us important insights into human nature too.Jose Yong, Assistant professor of Psychology , Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2005542023-03-02T14:25:20Z2023-03-02T14:25:20ZRoads and power lines put primates in danger: South African data adds to the real picture<figure><img src="https://images.theconversation.com/files/511943/original/file-20230223-703-kx83eg.jpg?ixlib=rb-1.1.0&rect=11%2C17%2C3982%2C2886&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Samango monkey choosing to use a pole bridge instead of a ladder bridge.</span> <span class="attribution"><span class="source">Birthe Linden</span></span></figcaption></figure><p>About 25 million kilometres of new roads are expected to be built around the world by <a href="https://www.nature.com/articles/nature13717">2050</a>. Along with power lines and railways, roads cut through the landscape everywhere, disrupting ecosystems. This linear infrastructure prevents animals from moving safely around their habitat. It also reduces access to the resources they need, like food, sufficient space and mating partners. </p>
<p>This threat to biodiversity is a conservation issue globally, but especially in developing nations, where <a href="https://www.nature.com/articles/nature13717">90%</a> of new road construction is expected. </p>
<p>The African continent is home to unique biodiversity and extraordinary landscapes. Planned <a href="https://au.int/en/videos/20190101/agenda2063-infrastructure-and-energy-initiatives">infrastructure developments</a> will certainly <a href="https://theconversation.com/kenyas-huge-railway-project-is-causing-environmental-damage-heres-how-159813">threaten</a> some of the last, unspoilt wildernesses on the continent.</p>
<p>We’re particularly concerned about the future of primates. The International Union for Conservation of Nature (IUCN) lists <a href="http://www.primate-sg.org/primate_diversity_by_region/">half of the continent’s 107 primate species as threatened</a>.</p>
<p>According to the <a href="https://www.iucnredlist.org/search?query=Primates&searchType=species">IUCN</a> 18% of the world’s primates are directly affected by roads and railroads and 3% by utility and service infrastructure. These figures are based on limited research, though. The true impact is likely to be higher.</p>
<p>South Africa’s case shows why. None of the South African primate species currently have linear infrastructure listed as a threat under the IUCN. But this doesn’t mean they are not negatively affected. It just means that the lists need to be better informed.</p>
<p>South Africa is the only African country that has long-term, country-wide mortality datasets for both <a href="https://ewt.org.za/what-we-do/saving-species/wildlife-and-transport/">wildlife roadkill</a> and <a href="https://ewt.org.za/what-we-do/saving-species/wildlife-and-energy/">wildlife electrocution</a>. It’s collected by patrol staff, scientists and the general public (<a href="https://theconversation.com/tracking-science-a-way-to-include-more-people-in-producing-knowledge-159587">citizen scientists</a>). </p>
<p>Using this data, <a href="https://brill.com/view/journals/ijfp/93/3-6/article-p235_4.xml">we investigated</a> how roads and power lines affect South Africa’s five primate species: the chacma baboon (<em>Papio ursinus</em>), the vervet monkey (<em>Chlorocebus pygerythrus</em>), the samango monkey (<em>Cercopithecus mitis</em>), the lesser bushbaby (<em>Galago moholi</em>) and the greater or thick tailed bushbaby (<em>Otolemur crassicaudatus</em>).</p>
<p>All species were affected, mostly by roads. We found a total of 483 deaths captured in the databases between 1996 and 2021. The number of deaths is likely to be a lot higher, due to under-reporting. Targeted species- and area-specific surveys are needed to refine this dataset. </p>
<p>The more mortality data is available, the better we will understand impacts, know where to focus interventions and inform future infrastructure developments to lessen the human impact on biodiversity.</p>
<p>We recommend that infrastructure like roads and power lines be more prominently recognised as a direct threat when developing Red List assessments.</p>
<h2>Primate deaths</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Furry black body of monkey on the verge with trees on either side of the road" src="https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=433&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=433&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511944/original/file-20230223-24-c9wbuu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=433&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Samango monkey lying dead at the side of a road.</span>
<span class="attribution"><span class="source">Birthe Linden</span></span>
</figcaption>
</figure>
<p>Most of the electrocution data used in our study was accessed from the <a href="https://www.eskom.co.za/">Eskom</a> Central Incident Register.</p>
<p>Roadkill data for our study was available from two sources: the national database from the Endangered Wildlife Trust’s Wildlife and Transport Programme and our own observations. </p>
<p>Since 2011, the Endangered Wildlife Trust has received records from systematic patrols on certain highways and species -and area-specific expert research surveys. Citizen science data comes from all over the country including national and regional roads, with differing speed limits, widths and vehicle usage.</p>
<p>The area surveyed by systematic patrols amounts to 1,370 km, covering 0.2% of the country’s entire road network and 0.9% of the paved road network.</p>
<p>The highest number of deaths recorded was for vervet monkeys. This was to be expected as vervet monkeys have a much wider geographic range in South Africa than both bushbaby species and the samango monkey, so they have a greater chance of encountering roads and power lines. The greater (or thick tailed) bushbaby and the samango monkey are forest associated and forests cover only about 0.1% of South Africa’s land surface area.</p>
<p>Although the total of 483 primate deaths over 25 years may not appear very high, we can assume that many remain undetected. For example scavengers might remove the dead animals, or they could be hidden by dense vegetation on road verges. They could be in remote places, in the case of power lines, or severely injured animals might die later, a distance away from the road. For roads, the actual mortality rate could be <a href="https://we.copernicus.org/articles/3/33/2002/we-3-33-2002.html">12–16 times higher</a> than the detection rate.</p>
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Read more:
<a href="https://theconversation.com/statistical-ecology-can-unlock-the-power-of-biodiversity-data-in-africa-171513">Statistical ecology can unlock the power of biodiversity data in Africa</a>
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<h2>Solutions</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Person facing away from the camera looks at a monkey walking along a pole in the tree canopy." src="https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511945/original/file-20230223-703-ly4rn4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Samango monkey using a pole canopy bridge while observer looks on.</span>
<span class="attribution"><span class="source">Horta Lacueva</span></span>
</figcaption>
</figure>
<p>Encouragingly, there is more and more <a href="https://brill.com/display/post/news/special-issue-of-folia-primatologica-highlights-the-importance-of-canopy-bridges-to-habitat-connectivity-globally.xml">research</a> showing that primates, as well as many other tree-dwelling species, accept man-made canopy bridges as a means to cross gaps in their habitat. </p>
<p>In South Africa we conducted an <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320719319172">experiment in the field</a> to test what kind of canopy bridge primates would use to cross gaps between trees. We found that all five South African primate species used the canopy bridges offered to them. The design they preferred was a solid pole bridge, rather than a ladder bridge. </p>
<p>More and more canopy bridges of various kinds are being provided in different countries. But <a href="https://brill.com/view/journals/ijfp/93/3-6/article-p197_1.xml">research</a> shows that Africa is lagging behind other continents in doing this, and there are no canopy bridges in South Africa. We suggest that all infrastructure development projects should try to give attention to maintaining the integrity of landscapes, for example by providing bridges for animals.</p>
<h2>Public participation</h2>
<p>We all need and use linear infrastructure in our day to day lives, so we all carry some level of responsibility. Hence, we encourage people to record wildlife mortalities and submit them to publicly available repositories such as <a href="https://www.inaturalist.org/">iNaturalist</a> or the <a href="https://www.gbif.org/">Global Biodiversity Information Facility</a>. </p>
<p>A new <a href="https://www.mdpi.com/2076-2615/13/10/1692">Global Primate Roadkill Database</a> has been developed by Laura Praill at Oxford Brookes University and colleagues and is <a href="https://gprd.mystrikingly.com/">available to the public</a>.</p>
<p>Public awareness and participation is essential to lessen the human impact on biodiversity.</p><img src="https://counter.theconversation.com/content/200554/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Birthe (Bibi) Linden is affiliated with the SARChI Chair on Biodiversity Value and Change in the Faculty of Science, Engineering and Agriculture at the University of Venda and the Lajuma Resesarch Centre. She receives funding from the South African National Research Foundation (NRF).</span></em></p><p class="fine-print"><em><span>Wendy Collinson is affiliated with The Endangered Wildlife Trust and the South African Research Chair in Biodiversity Value & Change, School of Mathematical and Natural Sciences, University of Venda, Thohoyandou, South Africa. She is also a member of the IUCN: Transport Working Group.</span></em></p>Researchers encourage citizen scientists to contribute to datasets on animal deaths caused by infrastructure. This will inform efforts to reduce the human impact on biodiversity.Birthe (Bibi) Linden, Postdoctoral Researcher (University of Venda) & Associated Researcher (Lajuma Research Centre), University of VendaWendy Collinson, Research Fellow: South African Research Chair in Biodiversity Value & Change, University of VendaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1978502023-02-06T12:20:00Z2023-02-06T12:20:00ZThree surprising reasons human actions threaten endangered primates<figure><img src="https://images.theconversation.com/files/506834/original/file-20230127-25-sl362z.jpg?ixlib=rb-1.1.0&rect=9%2C18%2C2994%2C1976&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A baby chimpanzee enjoys his food. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/little-gourmet-adorable-baby-chimpanzee-enjoying-1986791387">Michaela Pilch/Shutterstock</a></span></figcaption></figure><p>Monkeys, apes and lemurs are cute, familiar and lovable. But an estimated 60% of all primate species are listed as <a href="https://www.science.org/doi/10.1126/sciadv.1600946">vulnerable, threatened or endangered</a>, according to the International Union for Conservation of Nature, a network of environmental organisations. </p>
<p>You’ve probably heard about the main problems, like <a href="https://theconversation.com/deforestation-on-indonesian-island-of-sulawesi-destroys-habitat-of-endemic-primates-147189">deforestation</a> and the loss of habitat. But primates are a diverse group of animals with a wide geographical range, so there are many more subtle ways our actions as humans put these wonderful animals at risk.</p>
<h2>1. Dogs</h2>
<p>Everywhere we go, our best friends are likely to go with us. <a href="https://link.springer.com/book/10.1007/978-3-031-11736-7">Our review</a> shows that dogs are present in many primate habitats. These predators sometimes kill and injure primates, but they also may simply chase and harass them, disrupting their socialising or foraging. </p>
<p>Being on the lookout for harassing dogs is stressful and causes primates to use more energy. Reducing these potentially lethal encounters depends on conservationists communicating with dog owners, <a href="https://link.springer.com/chapter/10.1007/978-3-031-11736-7_5">who often don’t recognise</a> the danger their dogs pose to such wildlife.</p>
<figure class="align-center ">
<img alt="A black and white dog stands over a monkey in the street. The monkey has its mouth open." src="https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=373&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=373&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=373&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=469&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=469&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506836/original/file-20230127-7614-6vw6f7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=469&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Ma. Czarita A. Aguja/Shutterstock</span></span>
</figcaption>
</figure>
<p>When diseases jump between animal species, they can cause serious harm to a species that does not have the necessary resistance. Dog diseases such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9179186/">canine heartworm </a>and <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.2772">parvovirus</a> can be passed from dogs to primates, and could potentially be fatal. There’s also the possibility that pathogens – viruses, bacteria or parasites – could evolve to spread more easily or become more deadly. </p>
<h2>2. Depictions</h2>
<p>If you live outside a country where primates live, you may never see a live primate outside of a zoo. Nevertheless, your media choices can still affect their conservation. </p>
<p><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118487">Researchers have discovered</a> that our choices of what we watch on YouTube, Instagram or TikTok can end up fuelling the use of primates as pets or in entertainment. Primates are cute, and we love to watch videos of them. However, many of these pictures and videos show them in artificial contexts, such as primates wearing clothes or interacting with office equipment.</p>
<p>When people view such content, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022050">they often say</a> they want a primate as a pet and are less likely to believe that these animals are endangered. </p>
<p>We can help to protect primates by not viewing or sharing videos that show animals in unnatural situations. The <a href="https://human-primate-interactions.org/resources/">responsibility</a> for interacting with primates respectfully is even higher for those who live near primates or those who embark on <a href="https://theconversation.com/five-ways-to-be-a-responsible-wildlife-tourist-118869">wildlife tourism</a>.</p>
<p>People’s activities can affect where primates live, what food they eat, and how they live their lives. Many tourist destinations in these types of locations cater to people’s desire to interact and take pictures with primates by keeping them as pets or encouraging feeding or similar interactions. </p>
<p><a href="https://link.springer.com/book/10.1007/978-3-031-11736-7">Our research found</a> that these practices harm the animals, increase the poaching or the trade of primates, and can lead to dangerous situations for both the primates and people. Photographs that show monkeys posing with humans alarm primatologists because we understand the risks of being bitten or of passing on diseases. But the wider public may be unaware of these dangers.</p>
<h2>3. Disease</h2>
<p>The potential for disease transmission between humans and primates is high, partly because of our closely related biology. When diseases move from animals to humans they are known as “zoonoses”. And when they are transferred from animals to human beings, they are known as “anthroponoses”.</p>
<p>The African apes – chimpanzees, bonobos and gorillas – seem to be particularly <a href="https://www.science.org/content/article/primatologists-work-keep-great-apes-safe-coronavirus">vulnerable to human respiratory infections</a>. Protecting these endangered animals from infectious disease is an important conservation goal.</p>
<figure class="align-center ">
<img alt="A silverback gorilla sits within thick, green vegetation" src="https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506845/original/file-20230127-26-x0cl2i.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">An endangered silverback mountain gorilla.</span>
<span class="attribution"><span class="source">Denys Kutsevalov/Shutterstock</span></span>
</figcaption>
</figure>
<p>The risk of disease transmission between humans and nonhuman primates is worsened by close contact. Some primate species have always lived near people. But as human need for space grows and primate habitats become more fragmented, these encounters become more common. </p>
<p>Primate tourism also brings humans closer to wildlife, with people sometimes even holding the animals or sharing food with them. The <a href="https://theconversation.com/putting-primates-on-screen-is-fuelling-the-illegal-pet-trade-91995">pet trade</a> goes further and brings wild primates into our homes, where animals can contract illness from their owners and vice versa. </p>
<p><a href="https://humanprimateinteractions.files.wordpress.com/2022/10/primate-as-pets.pdf">Preventing the primate pet trade</a> and encouraging safe and respectful interactions with wildlife are vital for both human and nonhuman primate health.</p>
<p>These are only a few examples of the ways humans impact wild primates. And animal biologists are increasingly interested in such human-generated issues for wildlife conservation.</p><img src="https://counter.theconversation.com/content/197850/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tracie McKinney is affiliated with the IUCN SSC Primate Specialist Group's Section for Human-Primate Interactions (SHPI).</span></em></p><p class="fine-print"><em><span>Michelle Rodrigues is affiliated with the IUCN SSC Primate Specialist Group's Section for Human-Primate Interactions (SHPI).</span></em></p><p class="fine-print"><em><span>Sian Waters is affiliated with the IUCN SSC Primate Specialist Group's Section for Human-Primate Interactions (SHPI)</span></em></p>Most of us have heard of the dangers of deforestation but there are other more subtle ways that human beings can endanger monkeys, apes and lemurs.Tracie McKinney, Senior Lecturer in Biological Anthropology, University of South WalesMichelle Rodrigues, Assistant Professor, Marquette UniversitySian Waters, Honorary Research Fellow, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1982652023-01-30T11:58:23Z2023-01-30T11:58:23ZPrimates colonised the Arctic during a period of ancient global warming – their fate offers a lesson as climate change speeds up<figure><img src="https://images.theconversation.com/files/506318/original/file-20230125-16-h6irfh.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5455%2C3620&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers have found evidence that primates colonised northern Canada 52 million years ago.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hammer-tool-excavated-fossils-imprinted-on-711804889">Kaca Skokanova/Shutterstock</a></span></figcaption></figure><p>Two new species of prehistoric primate were recently <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0280114">identified</a> by scientists studying fossils from Canada’s <a href="https://en.wikipedia.org/wiki/Ellesmere_Island">Ellesmere Island</a> in the high Arctic. The primates are closely related and likely originated from a single colonisation event, following which they split into two species: <em>Ignacius dawsonae</em> and <em>Ignacius mckennai</em>. </p>
<p>At 52 million years old, they represent the most recent known members of their genus.</p>
<p>The primates colonised the high latitudes during a period of historic global warming called the <a href="https://www.sciencedirect.com/science/article/pii/S0012821X22002254">early Eocene climatic optimum</a> (EECO). During this period, the high Arctic, now cold and inhospitable, had a climate similar to the <a href="https://en.wikipedia.org/wiki/Cypress_dome">cypress swamps of the southeastern USA</a>. The primates shared the landscape with species that are today associated with warmer climates, including <a href="https://en.wikipedia.org/wiki/List_of_crocodilians">crocodilians</a> and <a href="https://www.nationalgeographic.com/animals/mammals/facts/tapirs">tapirs</a>.</p>
<p>This warmer period had a major impact on biodiversity. But it also has important implications for our understanding of climate change today. Human impact on the climate is so dramatic that scientists are calling for the acknowledgement of a new geological period called the <a href="https://www.nhm.ac.uk/discover/what-is-the-anthropocene.html">Anthropocene</a>.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/dawn-of-the-anthropocene-five-ways-we-know-humans-have-triggered-a-new-geological-epoch-52867">Dawn of the Anthropocene: five ways we know humans have triggered a new geological epoch</a>
</strong>
</em>
</p>
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<h2>New Arctic primate fossils</h2>
<p>The Ellesmere <em>Ignacius</em> species are known only from teeth and jaw fragments. But other species of <a href="https://en.wikipedia.org/wiki/Ignacius"><em>Ignacius</em></a> for which additional skeletal materials are available indicate a tree-living lifestyle similar to modern <a href="https://animaldiversity.org/accounts/Dermoptera/">colugos</a>, a gliding mammal native to southeast Asia. The new primates likely evolved from ancestral <a href="https://www.nature.com/articles/345340a0">paromomyids</a> (extinct gliding primates) from North America’s southerly latitudes. </p>
<figure class="align-center ">
<img alt="A green Colugo hanging upside down from a branch." src="https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505710/original/file-20230122-8930-qchj1f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Colugo, a gliding mammal native to southeast Asia.</span>
<span class="attribution"><span class="source">Nick Garbutt/ARKive</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Based on tooth size, <em>Ignacius dawsonae</em> at 1.17 kg was twice as large as <em>Ignacius clarkforkensis</em>, the biggest mid-latitude member of the genus (0.47 kg). <em>Ignacius mckennai</em> at 1.98 kg may have been four times as large as its biggest southern cousin. The new Ignacius were roughly the <a href="https://www.wildlifetrusts.org/wildlife-explorer/mammals/rabbit">size of a rabbit</a>.</p>
<p>These results support <a href="https://en.wikipedia.org/wiki/Bergmann%27s_rule">Bergmann’s Rule</a>, a theory that links the climate to animal anatomy. It states that the colder the climate, the larger the animal. While the high Arctic was warmer during the EECO than it is today, its climate was still cooler than the ancestral range of <em>Ignacius</em> species.</p>
<p>As a shape gets bigger, its relative surface area to volume ratio gets smaller. This means the surface area over which heat is lost is relatively smaller for larger animals. To minimise heat loss, animals that live in colder climates tend to be bigger than similar species in warmer climates.</p>
<p>Penguins, for example, broadly follow Bergmann’s rule. The <a href="https://www.penguins-world.com/emperor-penguin/">large emperor penguin</a> lives near the south pole, while smaller species such as the <a href="https://www.penguins-world.com/humboldt-penguin/https://www.penguins-world.com/emperor-penguin/">Humboldt penguin</a> inhabit regions closer to the equator.</p>
<p>The Ellesmere <em>Ignacius</em> also exhibits large teeth and jaw muscles. The <a href="https://en.wikipedia.org/wiki/Biomechanics">biomechanics</a> indicate a high bite force with relatively low and serrated molars. This suggests a diet that included harder objects such as seeds and nuts that provided a food source during the long dark winters of such northerly latitudes. </p>
<h2>The science of discovery</h2>
<p>The fossils were excavated at multiple locations over several decades before being examined and photographed using <a href="https://en.wikipedia.org/wiki/X-ray_microtomography">micro-computed tomography</a>. This is a modern technique that allows scientists to digitally map the anatomy of fossils embedded inside rocks.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Images of teeth and jaw fragments of the new primates against a black background." src="https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=706&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=706&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=706&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=887&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=887&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506320/original/file-20230125-20-12692e.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=887&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Micro-computed tomography images of the teeth and jaw fragments of Ignacius Dawsonae.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1371/journal.pone.0280114">Miller, Tietjen & Beard (2023)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The researchers then conducted <a href="https://en.wikipedia.org/wiki/Phylogenetics">phylogenetic analysis</a> of the teeth and jaw fragments to determine identity and evolutionary relatedness to previously described species. They also compared tooth topography (a 3D landscape map of the tooth surface) with living and other fossil primates to determine the new species’ likely diet. </p>
<h2>Implications for future evolution</h2>
<p>The EECO will have seen a turnover of animal species. As local climates warm, individual organisms have two options: move or die. At the species level, animals have a third option, to <a href="https://www.nature.com/scitable/definition/evolution-78/">evolve</a> over generations to adapt to changing environmental conditions. </p>
<p>The fact that mammals living in warmer climates colonised the changing Arctic habitat is likely because their own ancestral range was becoming too hot. This indicates the potential for migration, followed by <a href="https://www.digitalatlasofancientlife.org/learn/evolution/macroevolution/evolutionary-radiations/">evolutionary radiation</a>, to fill opening <a href="https://education.nationalgeographic.org/resource/niche">ecological niches</a> created by climate change. </p>
<p>But the colonisation was selective. Several mammal species, including deer, antelope, horses and small herbivore groups lived in warmer regions further south but did not inhabit such northerly latitudes. A much greater variety of primitive primates also did not make Ellesmere their home during the EECO. Biodiversity in the High Arctic therefore <a href="https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/124/1-2/3/125757/Life-at-the-top-of-the-greenhouse-Eocene-world-A?redirectedFrom=fulltext">remained lower</a> than at more southerly latitudes. </p>
<p>The researchers suggest that temperature was not the main barrier to successful colonisation. Instead it was probably the long winter darkness and the resultant effect on the availability of plant materials as food. Some mammal species were not capable of the transition.</p>
<p>History shows us that various mammals can move northwards and adapt, and that <a href="https://education.nationalgeographic.org/resource/biodiversity">biodiversity</a> can increase. But evolution needs two things: <a href="https://www.studysmarter.us/explanations/biology/genetic-information/genetic-diversity/">genetic diversity</a> and time. </p>
<p>However, expanding human populations are having increasingly destructive effects on nature. Persecution and habitat loss have, for example, reduced population sizes and <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12810">genetic diversity</a> across species. Pollution also means that the climate is changing <a href="https://www.metoffice.gov.uk/weather/climate-change/what-is-climate-change">faster than ever before</a>. It is thus harder for species to adapt. </p>
<figure class="align-center ">
<img alt="A polar bear cub standing on a patch of ice overlooking a melting snow landscape." src="https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506057/original/file-20230124-23-3wea8p.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">The climate is changing faster than ever before.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/polar-bear-standing-on-rests-ice-2000477978">foto.t-kress.de/Shutterstock</a></span>
</figcaption>
</figure>
<p>Ironically, climate change may also explain why the Arctic <em>Ignacius</em> species went extinct. As Arctic temperatures again cooled, <em>Ignacius</em> likely found itself maladapted to the cold and unable to migrate south or compete with mid-latitude species that were better adapted to their environment. </p>
<p>Humans cheat the climate by <a href="https://theconversation.com/most-humans-havent-evolved-to-cope-with-the-cold-yet-we-dominate-northern-climates-heres-why-195621">using technology</a> to evade environmental challenges. Air conditioning, central heating and clothes enable humans to survive in places that we would otherwise be unable to tolerate. </p>
<p>But we are vulnerable to climate change. If human-induced climate change continues, it is not just other animals that will experience the same fate as <em>Ignacius</em>. We will too.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
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</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Jason Gilchrist 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>Close relatives of primates adapted to life in the High Arctic 52 million years ago – this may offer insight into future changes in the Arctic.Jason Gilchrist, Ecologist, Edinburgh Napier UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1882072022-08-31T12:27:02Z2022-08-31T12:27:02ZExpanding Alzheimer’s research with primates could overcome the problem with treatments that show promise in mice but don’t help humans<figure><img src="https://images.theconversation.com/files/481658/original/file-20220829-8371-fvt75z.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rhesus macaques experience an aging process similar to people's.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/rhesus-macaque-royalty-free-image/993621062">Goddard Photography/E+ via Getty Images</a></span></figcaption></figure><p>As of 2022, an estimated <a href="https://doi.org/10.1002/alz.12638">6.5 million Americans</a> have Alzheimer’s disease, an illness that robs people of their memories, independence and personality, causing suffering to both patients and their families. That number may double by 2060. The U.S. has made <a href="https://doi.org/10.1126/science.361.6405.838">considerable investments</a> in Alzheimer’s research, having allocated <a href="https://www.alz.org/news/2022/increase-in-federal-alzheimers-and-dementia-resear">US$3.5 billion in federal funding</a> this year. </p>
<p>Why, then, are researchers no closer to a cure today than they were 30 years ago? </p>
<p>Back in 1995, researchers created the <a href="https://doi.org/10.1038/373523a0">first transgenic mouse model</a> of Alzheimer’s disease, which involved genetically modifying mice to carry a gene associated with early-onset Alzheimer’s. Myriad studies have since focused on mouse models that accumulate <a href="https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease">abnormal proteins</a> in their brains, a hallmark of the disease. Although these studies made great strides in understanding specific mechanisms involved in the disease, they have <a href="https://doi.org/10.1002/trc2.12114">failed to translate</a> into effective treatments.</p>
<p>As <a href="https://scholar.google.com/citations?user=LWCllSsAAAAJ">research</a> <a href="https://scholar.google.com/citations?hl=en&user=0tW5idcAAAAJ">scientists</a> <a href="https://psych.wisc.edu/staff/bennett-allyson/">working</a> with nonhuman primates, we believe that part of the problem is that mice don’t reflect the full spectrum of Alzheimer’s disease. A more complementary animal model, however, could help researchers better translate the results from animal studies to humans. </p>
<h2>Why animal models?</h2>
<p>A critical aspect of understanding what goes awry in Alzheimer’s disease is the relationship between brain and behavior. Researchers rely heavily on animal models to do these types of studies because <a href="https://grants.nih.gov/grants/policy/air/why.htm">ethical and practical issues</a> make them impossible to conduct in people.</p>
<p>In recent years, researchers have developed <a href="https://doi.org/10.15252/embj.2021110002">alternative methods</a> to study Alzheimer’s, such as computer models and cell cultures. Although these options show promise for advancing Alzheimer’s research, they don’t supersede the need for animal models because of important limitations.</p>
<p>One is their inability to replicate the complexity of the human brain. The human brain has an estimated <a href="https://doi.org/10.1002/cne.21974">86 billion neurons</a> that perform highly complex computations. While computer models can simulate the workings of specific neural circuits, they are unable to fully capture these complex interactions and work best when used <a href="https://doi.org/10.1016/j.neuron.2021.07.015">in concert with animal models</a>.</p>
<p>Similarly, cell cultures and brain organoids – miniature brains derived from human stem cells – are <a href="https://doi.org/10.3389/fphar.2020.00396">unable to adequately mimic</a> the aging process and all the ways the components of the human body interact with one another.</p>
<p>As a result of these limitations, researchers turn to animal models that better reflect human biology and disease processes.</p>
<h2>The problem with mice</h2>
<p>According to the National Association for Biomedical Research, approximately <a href="https://www.science.org/content/article/how-many-mice-and-rats-are-used-us-labs-controversial-study-says-more-100-million">95% of lab research conducted in animals in the U.S.</a> is done in mice and rats. Alzheimer’s is no exception: For more than 25 years, research on Alzheimer’s has <a href="https://doi.org/10.1002/cpns.81">focused on using transgenic mice</a> to better understand the biological changes associated with the disease.</p>
<p>Because mice do not naturally get Alzheimer’s, they are genetically engineered to develop <a href="https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease">abnormal proteins</a> known as amyloid plaques and neurofibrillary tau tangles to mimic Alzheimer’s in their brains. These protein accumulations impair brain function and are associated with memory impairment. While studies on <a href="https://doi.org/10.1038/35050110">treatments that remove these proteins</a> have been able to improve cognition in mice, similar interventions have failed in people.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four white mice in a cage" src="https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481630/original/file-20220829-8838-qz7uav.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">Many Alzheimer’s studies have been conducted in transgenic mice.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/white-research-mice-royalty-free-image/170617385">filo/E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>This highlights the challenge of <a href="https://doi.org/10.1002/trc2.12114">translating animal research</a> in the lab to people in the clinic. Mouse studies often mirror only a single aspect of the disease that may not be directly relevant to people. For example, most transgenic mouse models focus on amyloid protein buildup while <a href="https://mitpress.mit.edu/9780262546010/how-not-to-study-a-disease/">neglecting other crucial aspects</a> of the disease, such as overall neurodegeneration. Such limitations have led some scientists to <a href="https://doi.org/10.3390/ijms222313168">question the value of using mouse models for Alzheimer’s research</a>. </p>
<p>It is important to recognize, however, that scientific knowledge often advances in <a href="https://www.statnews.com/2015/12/02/science-groundbreaking/">incremental steps</a> through the collective results of many studies using different methods and models. Rodent studies provide the necessary foundation for animal models that better mimic the full scope of Alzheimer’s – such as nonhuman primates.</p>
<h2>Nonhuman primates offer a closer model</h2>
<p>The specific features of a species – including brain structure, cognitive ability, life span and the extent to which they show the hallmarks of Alzheimer’s – determine how suitable it is for specific research questions. Based on these factors, we believe that nonhuman primates are particularly well suited for Alzheimer’s research.</p>
<p><a href="https://primate.wisc.edu/primate-info-net/pin-factsheets/">Primates</a> are a diverse group of mammals that includes humans, apes, monkeys and prosimians. Nonhuman primates are particularly valuable for understanding <a href="https://doi.org/10.1002/ajp.23309">human aging</a> and <a href="https://doi.org/10.1073/pnas.1912954116">Alzheimer’s disease</a> because their genetic makeup, brain, behavior, physiology and aging process closely resemble those of people. Aging monkeys experience cognitive, physical and sensory decline as well as a variety of illnesses, such as cancer and cardiovascular disease, much like aging people. Perhaps most critical for Alzheimer’s research, nonhuman primates live much longer than rodents and can <a href="https://doi.org/10.1002/ajp.23299">naturally develop some of the hallmarks associated with Alzheimer’s</a> as they get older. </p>
<p>Using nonhuman primates in research <a href="https://www.nature.com/articles/d41586-021-01894-z">faces some challenges</a>. Compared to mice, nonhuman primates are more expensive to house and feed, and face a growing shortage in research facilities. Nonhuman primates are also prime targets for activists seeking to stop the use of animals in research. Yet, in light of ongoing failures with rodent models, nonhuman primates could significantly help scientists better understand and treat Alzheimer’s. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist looking at brain MRIs on multiple computer screens" src="https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481632/original/file-20220829-8843-ucjkc0.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">Animal models pave the way for clinical research in humans.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/female-radiologist-analysing-the-mri-image-of-the-royalty-free-image/1326240246">simonkr/E+ via Getty Images</a></span>
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<p>Scientists study Alzheimer’s in nonhuman primates in a number of ways.</p>
<p>In one approach, researchers examine species with short life spans, such as <a href="https://doi.org/10.1002/ajp.23337">gray mouse lemurs</a> or <a href="https://doi.org/10.1002/ajp.23271">common marmosets</a>, to measure how brain and behavior naturally change with age and identify potential predictors of disease. Other researchers may instead accelerate the disease process by <a href="https://doi.org/10.1002/ajp.23289">inducing plaque</a> or <a href="https://doi.org/10.1002/alz.12318">tangle formation</a> in the brains of longer-lived species, like rhesus macaques. These approaches yield studies that are particularly promising for testing treatments in a short time frame.</p>
<p>A third approach takes advantage of recent advances in genomics to study marmosets <a href="https://doi.org/10.1002/alz.049952">born with genetic mutations</a> involved in Alzheimer’s. This method provides the opportunity to test preventive treatments during early life, well before any sign of the disease appears. </p>
<p>Lastly, <a href="https://doi.org/10.1002/ajp.23254">comparing Alzheimer-like patterns across primate species</a> may help reveal critical risk factors for developing the disease, which could be reduced to promote healthy aging.</p>
<p>We believe that research in nonhuman primates, when conducted with the highest <a href="https://doi.org/10.1016/j.neuroimage.2020.117700">ethical standards</a>, provides the best chance to understand how and why Alzheimer’s disease progresses, and to design treatments that are safe and effective in people.</p><img src="https://counter.theconversation.com/content/188207/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Agnès Lacreuse receives funding from NIH, serves on the American Psychological Association Committee for Animal Research and Ethics and volunteers for Speaking of Research</span></em></p><p class="fine-print"><em><span>Allyson Bennett serves on the Board of Directors for Public Responsibility for Medicine & Research and volunteers for Speaking of Research.
</span></em></p><p class="fine-print"><em><span>Amanda M. Dettmer volunteers for Speaking of Research.</span></em></p>Nonhuman primates like rhesus monkeys share certain characteristics with people that may make them better study subjects than mice for research on neurodegenerative diseases.Agnès Lacreuse, Professor of Behavioral Neuroscience, UMass AmherstAllyson J. Bennett, Professor of Psychology, University of Wisconsin-MadisonAmanda M. Dettmer, Associate Research Scientist, Yale UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1879962022-08-22T20:01:37Z2022-08-22T20:01:37ZRevelations from 17-million-year-old ape teeth could lead to new insights on early human evolution<figure><img src="https://images.theconversation.com/files/476868/original/file-20220801-60917-921i4s.JPG?ixlib=rb-1.1.0&rect=18%2C156%2C4007%2C2861&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fossilised jaws from the 17 million-year-old Kenyan ape _Afropithecus turkanensis_.</span> <span class="attribution"><span class="source">Tanya M. Smith/National Museums of Kenya</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The timing and intensity of the seasons shapes life all around us, including <a href="https://doi.org/10.1046/j.1461-0248.2002.00370.x">tool use</a> by birds, the <a href="https://doi.org/10.1371/journal.pone.0077191">evolutionary diversification</a> of giraffes, and the <a href="https://doi.org/10.1016/j.jhevol.2014.02.009">behaviour</a> of our close primate relatives. </p>
<p>Some scientists suggest early humans and their ancestors also evolved due to <a href="https://humanorigins.si.edu/research/climate-and-human-evolution/climate-effects-human-evolution">rapid changes</a> in their environment, but the physical evidence to test this idea has been elusive – until now.</p>
<p>After more than a decade of work, we’ve developed an approach that leverages tooth chemistry and growth to extract information about seasonal rainfall patterns from the jaws of living and fossil primates. </p>
<p>We share our findings in <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.2123366119">a collaborative study</a> just published in Proceedings of the National Academy of Sciences.</p>
<h2>Teeth are environmental time machines</h2>
<p>During childhood our teeth grow in <a href="https://doi.org/10.1002/evan.20176">microscopic layers</a> similar to the growth rings found in trees. Seasonal changes in the world around us, such as droughts and monsoons, influence our body chemistry. The evidence of such changes is recorded in our teeth. </p>
<p>That’s because the oxygen isotope composition of drinking water <a href="https://www.annualreviews.org/doi/10.1146/annurev.earth.24.1.225">naturally varies</a> with temperature and precipitation cycles. During warm or dry weather, surface waters accumulate more heavy isotopes of oxygen. During cool or wet periods, lighter isotopes become more common. </p>
<p>These temporal and climatic records remain locked inside fossilised tooth enamel, which can maintain <a href="https://www.degruyter.com/document/doi/10.1515/9781501509636-015/html">chemical stability</a> for millions of years. But the growth layers are generally so small that most chemical techniques can’t measure them. </p>
<p>To get around this problem, we teamed up with geochemist Ian Williams at the Australian National University, who runs the world-leading <a href="https://science.anu.edu.au/research/facilities/sensitive-high-resolution-ion-microprobe-shrimp">Sensitive High Resolution Ion Microprobe</a> (SHRIMP) facilities.</p>
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<p>In our study, we collected detailed records of tooth formation and enamel chemistry from slices of more than two dozen wild primate teeth from equatorial Africa.</p>
<p>We also analysed two fossil molars from an unusual large-bodied ape called <em>Afropithecus turkanensis</em> that lived in Kenya 17 million years ago. Diverse groups of apes inhabited Africa during this period, roughly 10 million years before the evolution of our early ancestors, the hominins.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=199&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=199&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=199&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=250&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=250&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476866/original/file-20220801-13732-4lab4s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=250&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Thin slice of a 17-million-year-old <em>Afropithecus</em> tooth illuminated with polarised light reveals progressive growth (right to left). We microsampled oxygen isotopes weekly for over three years, or 1148 days, in this tooth.</span>
<span class="attribution"><span class="source">Tanya M. Smith</span></span>
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<h2>Diving into an ancient African landscape</h2>
<p>Several aspects of our research are helpful for understanding the link between environmental patterns and primate evolution.</p>
<p>First, we observe a direct relationship between historic African rainfall patterns and primate tooth chemistry. This is the first test of a highly influential idea in archaeological and earth sciences applied to wild primates: that teeth can record fine details of seasonal environmental change.</p>
<p>We are able to document annual west African rainy seasons and identify the end of east African droughts. In other words, we can “see” the storms and seasons that occur during an individual’s early life.</p>
<p>And this leads into another important aspect. We provide the largest record of primate oxygen isotope measurements collected so far, from diverse environments in Africa that may have resembled those of ancestral hominins.</p>
<p>Lastly, we’ve been able to reconstruct annual and semi-annual climate cycles, and marked environmental variation, from information held within the teeth of the two fossil apes.</p>
<p>Our observations support the hypothesis that <em>Afropithecus</em> developed certain features to adapt to a seasonal climate and challenging landscape. For example, it had specialised dental traits for hard object feeding, as well as a longer period of molar growth compared with earlier apes and monkeys – consistent with the idea that it consumed more seasonally varied foods. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=245&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=245&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=245&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=308&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=308&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476867/original/file-20220801-44070-w6qtal.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=308&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">Oxygen isotopes from the teeth of <em>Afropithecus</em> reveal wet and dry seasons that occurred 17 million years ago in eastern Africa.</span>
<span class="attribution"><span class="source">Daniel R. Green & Tanya M. Smith</span></span>
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<p>We conclude our work by comparing data from <em>Afropithecus</em> to earlier studies of fossil hominins and monkeys from the same region in Kenya. Our detailed microsampling shows just how sensitive tooth chemistry is to fine-scale climate variation.</p>
<p>Previous studies of more than 100 fossil teeth have missed the most interesting part of oxygen isotope compositions in teeth: the huge seasonal variation on the landscape. </p>
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Read more:
<a href="https://theconversation.com/what-teeth-can-tell-about-the-lives-and-environments-of-ancient-humans-and-neanderthals-104923">What teeth can tell about the lives and environments of ancient humans and Neanderthals</a>
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<h2>Research potential closer to home</h2>
<p>This novel research approach, coupled with our fossil ape findings and modern primate data, will be crucial for future studies of hominin evolution – especially in Kenya’s famous Turkana Basin. </p>
<p>For example, some researchers have suggested that seasonal differences <a href="https://www.science.org/doi/full/10.1126/science.1133827">in foraging</a> and <a href="https://www.science.org/doi/full/10.1126/science.1135741">stone tool use</a> helped hominins evolve and coexist in Africa. This idea has been hard to prove or disprove, in part because seasonal climatic processes have been hard to tease out of the fossil record.</p>
<p>Our approach could also be extended to animal remains from rural Australia to gain further insight into historic climate conditions, as well as the prehistoric environmental changes that shaped Australia’s unique modern landscapes. </p>
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Read more:
<a href="https://theconversation.com/archaeology-can-help-us-prepare-for-climates-ahead-not-just-look-back-101823">Archaeology can help us prepare for climates ahead – not just look back</a>
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<img src="https://counter.theconversation.com/content/187996/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya M. Smith receives funding from the Australian Academy of Science and the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Daniel Green receives funding from Columbia University, the Leakey Foundation, the American National Science Foundation, and the Kenyan Turkana Basin Institute.</span></em></p>Cutting-edge analysis of fossil ape teeth reveals ancient seasonal change in Africa, long before human ancestors appeared. The method will be crucial for the future study of early hominins.Tanya M. Smith, Professor in the Australian Research Centre for Human Evolution & Griffith Centre for Social and Cultural Research, Griffith UniversityDaniel Green, Postdoctoral Research Scientist, Columbia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1838482022-05-27T13:10:03Z2022-05-27T13:10:03ZWhat is it about the human brain that makes us smarter than other animals? New research gives intriguing answer<figure><img src="https://images.theconversation.com/files/465475/original/file-20220526-14-cdnq58.jpg?ixlib=rb-1.1.0&rect=41%2C0%2C4608%2C3062&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">New research has compared the brains of chimps and macaques with those of humans.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/search/?license=2%2C3%2C4%2C5%2C6%2C9&text=person%20and%20macaque">CherylRamalho/Shutterstock</a></span></figcaption></figure><p>Humans are unrivalled in the area of cognition. After all, no other species has sent probes to other planets, produced lifesaving vaccines or created poetry. How information is processed in the human brain to make this possible is a question that has drawn endless fascination, yet no definitive answers. </p>
<p>Our understanding of brain function has changed over the years. But current theoretical models describe the brain as <a href="https://mitpress.universitypressscholarship.com/view/10.7551/mitpress/9780262514620.001.0001/upso-9780262514620">a “distributed information-processing system”</a>. This means that it has distinct components, which are tightly networked through the brain’s wiring. To interact with each other, regions exchange information though a system of input and output signals. </p>
<p>However, this is only a small part of a more complex picture. In a study <a href="https://www.nature.com/articles/s41593-022-01070-0">published in Nature Neuroscience</a>, using evidence from different species and multiple neuroscientific disciplines, we show that there isn’t just one type of information processing in the brain. How information is processed also differs between humans and other primates, which may explain why our species’ cognitive abilities are so superior.</p>
<p>We borrowed concepts from what’s known as the <a href="https://people.math.harvard.edu/%7Ectm/home/text/others/shannon/entropy/entropy.pdf">mathematical framework of information theory</a> – the study of measuring, storing and communicating digital information which is crucial to technology such as the internet and artificial intelligence – to track how the brain processes information. We found that different brain regions in fact use different strategies to interact with each other. </p>
<p>Some brain regions exchange information with others in a very stereotypical way, using input and output. This ensures that signals get across in a reproducible and dependable manner. This is the case for areas that are specialised for sensory and motor functions (such as processing sound, visual and movement information). </p>
<p>Take the eyes, for example, which send signals to the back of the brain for processing. The majority of information that is sent is duplicate, being provided by each eye. Half of this information, in other words, is not needed. So we call this type of input-output information processing “redundant”. </p>
<p>But the redundancy provides robustness and reliability – it is what enables us to still see with only one eye. This capability is essential for survival. In fact, it is so crucial that the connections between these brain regions are anatomically hard-wired in the brain, a bit like a telephone landline.</p>
<p>However, not all information provided by the eyes is redundant. Combining information from both eyes ultimately enables the brain to process depth and distance between objects. This is the basis for many kinds of 3D glasses at the cinema. </p>
<p>This is an example of a fundamentally different way of processing information, in a way that is greater than the sum of its parts. We call this type of information processing – when complex signals from across different brain networks are integrated – “synergistic”.</p>
<p>Synergistic processing is most prevalent in brain regions that support a wide range of more complex cognitive functions, such as attention, learning, working memory, social and numerical cognition. It is not hardwired in the sense that it can change in response to our experiences, connecting different networks in different ways. This facilitates the combination of information.</p>
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<img alt="MRI images of the human brain." src="https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465482/original/file-20220526-22-qp2590.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">
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<span class="caption">The human brain is extremely complex.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mri-brain-scan-background-magnetic-resonance-1054661900">Shutterstock</a></span>
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<p>Such areas where lots of synergy takes place – mostly in the the front and middle of the cortex (the brain’s outer layer) – integrate different sources of information from the entire brain. They are therefore more widely and efficiently connected with the rest of the brain than the regions which deal with primary sensory and movement related information. </p>
<p>High-synergy areas that support integration of information are also typically have lots of synapses, the microscopic connections that enable nerve cells to communicate.</p>
<h2>Is synergy what makes us special?</h2>
<p>We wanted to know whether this ability to accumulate and build information through complex networks across the brain is different between humans and other primates, which are close relatives of ours in evolutionary terms. </p>
<p>To find out, we looked at brain imaging data and genetic analyses of different species. We found that synergistic interactions account for a higher proportion of total information flow in the human brain than in the brains of macaque monkeys. In contrast, the brains of both species are equal in terms of how much they rely on redundant information. </p>
<p>However, we also looked specifically at the prefrontal cortex, an area in the front of the brain that supports more advanced cognitive functioning. In macaques, redundant information processing is more prevalent in this region, whereas in humans it is a synergy-heavy area.</p>
<p>The prefrontal cortex has also <a href="https://pubmed.ncbi.nlm.nih.gov/28162899/">undergone significant expansion with evolution</a>. When we examined data from chimpanzee brains, we found that the more a region of the human brain had expanded during evolution in size relative to its counterpart in the chimp, the more this region relied on synergy.</p>
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<img alt="Image of Rhesus macaques monkeys at Swayambhunath temple high above Kathmandu." src="https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465479/original/file-20220526-19-llc489.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">
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<span class="caption">Rhesus macaques monkeys at Swayambhunath temple in Nepal.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/kathmandu-nepal-april-202022-rhesus-macaques-2149794919">Shutterstock</a></span>
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<p>We also looked at <a href="https://www.nature.com/articles/nature11405">genetic analyses</a> from human donors. This showed that brain regions associated with processing synergistic information are more likely to express genes that are uniquely human and related to brain development and function, such as intelligence. </p>
<p>This led us to the conclusion that additional human brain tissue, acquired as a result of evolution, may be primarily dedicated to synergy. In turn, it is tempting to speculate that the advantages of greater synergy may, in part, explain our species’ additional cognitive capabilities. Synergy may add an important piece to the puzzle of human brain evolution, which was previously missing.</p>
<p>Ultimately, our work reveals how the human brain navigates the trade-off between reliability and integration of information – we need both. Importantly, the framework we developed holds the promise of critical new insights into a wide array of neuroscientific questions, from those about general cognition to disorders.</p><img src="https://counter.theconversation.com/content/183848/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emmanuel A Stamatakis receives funding from the Canadian Institute for Advanced Research and the Stephen Erskine Fellowship, Queens’ College, University of Cambridge.</span></em></p><p class="fine-print"><em><span>Andrea Luppi receives funding from a Gates Cambridge Scholarship.</span></em></p><p class="fine-print"><em><span>David Menon receives research funding from the National Institute for Health Research, UK; UK Research and Innovation (UKRI); the Medical Research Council (UK); the Canadian Institute for Advanced Research (CIFAR); Addenbrooke's Charitable Trust; the Brain Research Trust (UK). He has consultancy or research collaboration agreements with NeuroTrauma Sciences LLC, Gryphon Inc, GlaxoSmithKline Ltd; Lantmannen AB; Pressure Neuro Ltd; Integra NeuroSciences Ltd; Cortirio Ltd; and Calico LLC.</span></em></p>Human brains seem to be wired differently to those of chimps or macaques.Emmanuel A Stamatakis, Lead, Cognition and Consciousness Imaging Group, Division of Anaesthesia, University of CambridgeAndrea Luppi, PhD candidate in Neuroscience, University of CambridgeDavid Menon, Professor, Head of Division of Anaesthesia, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1767022022-02-09T13:31:25Z2022-02-09T13:31:25ZChimpanzees rub insects on open wounds – new research suggests treating others may not be uniquely human<p>The chimpanzees of the Rekambo community in Gabon, West Africa never fail to surprise. For a start, they are known to <a href="https://www.nature.com/articles/s41598-019-43301-8">kill and eat tortoises</a>, which sets them apart from any other community of chimpanzees. Now they have been seen displaying another unique behaviour – one which has never been seen before despite many years of painstaking research.</p>
<p>In their new study published in the journal Current Biology, researchers have described how they saw Rekambo chimpanzees <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(21)01732-2">applying insects</a> to their own open wounds, and, even more amazingly, to the wounds of other community members too. </p>
<p>Even by itself, treating wounds with insects is a groundbreaking observation – but until now no other animal, apart from humans, has been seen treating the wounds of others.</p>
<p>Humans have been <a href="https://www.phcogrev.com/sites/default/files/PhcogRev-6-11-1.pdf">using local remedies</a> (such as roots, leaves, bark and other animals) as medicines for at least 5,000 years, a practice that has been passed down over generations within societies all over the world. </p>
<p>There is some <a href="https://ethnobiomed.biomedcentral.com/articles/10.1186/s13002-017-0136-0">use of invertebrates</a> in traditional human medicine too. For example, leeches have been used <a href="https://ethnobiomed.biomedcentral.com/articles/10.1186/s13002-017-0136-0/tables/1">to clean wounds</a>, slugs and snails to treat inflammation, spider webs to dress wounds and termite pincers to inject medicine under the skin.</p>
<p>Is it possible, perhaps, that such cultural use of plants and animals to treat injuries and illness was inherited from a common ape-like ancestor millions of years ago?</p>
<h2>Self-medication in animals</h2>
<p>As in humans, <a href="https://www.science.org/doi/epdf/10.1126/science.1235824">self-medication in wild animals</a> is not uncommon –individuals from a diverse range of species, including chimpanzees, select particular plant foods that contain chemicals known to treat infection by parasites. </p>
<p>For example, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0004796">caterpillars</a> ingest plant toxins when infected by parasitic flies and <a href="https://repository.kulib.kyoto-u.ac.jp/dspace/handle/2433/68214">gorillas</a> consume a wide variety of plants that contain known compounds important in human traditional medicines. </p>
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<a href="https://theconversation.com/to-save-wild-chimpanzees-imagine-their-habitat-is-an-electrical-circuit-149761">To save wild chimpanzees, imagine their habitat is an electrical circuit</a>
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<p>Some species, such as wood ants, even <a href="https://serval.unil.ch/resource/serval:BIB_475BB8503A64.P001/REF">anticipate infection</a>, adding antimicrobial resin from nearby trees into their nests, which reduces the colony’s exposure to microbes. </p>
<p>To date however, this widespread behaviour almost always centres on self-medication with plant material. Never before has the use of insects on wounds been observed.</p>
<h2>The groundbreaking chimpanzees</h2>
<p>Over a 15-month period, beginning in November 2019, the team observed 76 open wounds on 22 different chimpanzees. There were 22 events of insect application by ten different chimpanzees. On 19 occasions, various individuals were seen applying an insect to one of their own wounds. </p>
<p>They caught an insect from the air, which they immobilised by squeezing between their lips. Then they placed it on an exposed surface of the wound and moved it around using their fingertips or lips. Finally, they extracted the insect from the wound.</p>
<p>But the use of insects didn’t stop there. In a remarkable act of “allocare” (caring for another individual) a mother was seen applying insects to her offspring’s wound, and a further two adult chimpanzees treated the wounds of another community member. </p>
<h2>Why it’s important</h2>
<p>The researchers do not yet know which insects were used, if they have any associated chemical properties or, most importantly, whether applying them to wounds has any health benefits. But what they do know is that the chimpanzees’ behaviour is extraordinary for a variety of reasons.</p>
<p>First, it’s likely an example of allo-medication behaviour (medicating others) in apes, which has never been seen before. </p>
<p>The authors think this is a possible prosocial behaviour – defined as one that benefits another individual. Humans are characterised by our propensity to volunteer, share and cooperate among others – but whether other species, especially our closely related cousins, also exhibit this type of behaviour remains unclear. </p>
<p>There is <a href="https://www.nature.com/articles/s41598-017-15320-w">evidence for prosociality</a> in captive bonobos (our other closest <a href="https://www.worldwildlife.org/species/bonobo">living relative</a>) who have been seen assisting an unfamiliar, non-group member to obtain food during an experimental task.</p>
<p>But up to now, its presence in chimpanzees is <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2014.1699?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed">contentious</a>. The current study undoubtedly pushes the needle towards their sharing some prosocial tendencies with humans.</p>
<p>Second, self-medication has long been associated with <a href="https://academic.oup.com/bioscience/article/51/8/651/220603">ingestion of plants</a> with specific medicinal properties. In a recent study, <a href="https://www.nature.com/articles/s41598-017-16621-w">orangutans were shown</a> to mix saliva with leaves from plants containing anti-inflammatory properties and apply it to various parts of their body – the first recorded case of topical self-medication in animals. </p>
<p>But never before have scientists observed chimpanzees (or any animal) essentially “treat” a wound, nor apply a different animal species to a wound. </p>
<p>In that sense, the observations stand out for what these chimpanzees are doing and how. Commonly known as “anointment”, rubbing a material, object or substance on a bodily surface has been observed in numerous species. </p>
<p>Mammals are especially known to rub themselves against trees and rocks or fruits and arthropods to <a href="https://www.karger.com/Article/Abstract/70649">pick up a particular scent</a>, and birds have been seen to capture and <a href="https://sora.unm.edu/node/119525">rub millipedes on their plumage</a>, probably to <a href="https://phys.org/news/2013-03-deterring-citrus-millipedes.html">deter ticks</a>. </p>
<p>In primates, anointing behaviour is also widespread. It’s not yet clear whether Rekambo chimpanzees are in fact rubbing the insects. But as they are uniquely targeting open wounds, it does suggest that it could well be an act of medication.</p>
<h2>What’s next?</h2>
<p>Identification and analysis of the insect species used by Rekambo chimpanzees will be key to revealing the purpose and effectiveness of this newly reported medication behaviour. Perhaps the insects from Gabon will be revealed to have wound-healing or anti-inflammatory properties, just like the plants used by orangutans. </p>
<p>Finally, although there can be little dispute about the <a href="https://www.nature.com/articles/s41467-020-18176-3">cultural diversity in chimpanzees</a>, the Rekambo chimpanzees continue to stand out for their uniqueness. It begs the question, what else do these chimpanzees have in store for us?</p><img src="https://counter.theconversation.com/content/176702/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>How Rekambo chimpanzees demonstrate a number of ground breaking behaviours never seen before in animals.Alexander Piel, Lecturer in Anthropology, University College London, UCLFiona Stewart, Lecturer in Wildlife Conservation, Liverpool John Moores UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1739512022-02-01T17:32:17Z2022-02-01T17:32:17ZWhy monkeys attack sick members of their troop – and don’t socially distance at all<p>Life in the wild can be tough, and sometimes animals don’t have the luxury of taking time out when they are sick. That’s certainly the reality of life for vervet monkeys living in Southern Africa, even though parasites and viruses are an ever-present <a href="https://pubmed.ncbi.nlm.nih.gov/3050629/">component of animal life</a>.</p>
<p>We know how people respond to infection. Loss of appetite and staying in bed or resting are some of the ways we adapt to being unwell. Being less active and eating less frees up energy to fight the infection – even digesting food uses energy. This behaviour may help us recover and is a key component of our survival.</p>
<p>My colleagues and I wanted to understand more about how monkeys respond to illness, and how a disease travels within and between animal groups. This is essential if we are to tackle the huge impact that infection can have on monkey population survival. While the causes of infection have been the <a href="https://oxford.universitypressscholarship.com/view/10.1093/acprof:oso/9780198565857.001.0001/acprof-9780198565857">focus of much attention</a>, until now we knew very little about the social consequences of infection in these monkeys. </p>
<p>For over ten years our international team of researchers have studied the behaviour and physiology of <a href="https://www.awf.org/wildlife-conservation/vervet-monkey">wild vervet monkeys</a> living in the Eastern Cape, South Africa. They live in large social troops – up to 40 monkeys per troop – and previous research has shown that they are routinely exposed to a <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.191078#d3e2732,%20https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.23962,%20https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2656.12329">range of environmental stressors</a> such as extreme heat and drought, as well as competition for food.</p>
<p>In our <a href="https://www.pnas.org/content/118/44/e2107881118">most recent study </a> of three groups of wild vervet monkey, we examined the effect of getting sick on individual vervet monkey’s social status.</p>
<h2>How we studied fever</h2>
<p>As with humans, when a monkey gets an infection, they can get feverish. </p>
<p>We implanted <a href="https://www.star-oddi.com/products/data-loggers/temperature-logger-implant-livestock-animals">miniature data loggers</a> - narrow cylinders about 3cm long – into each monkey’s abdomen and recorded core body temperature inside the stomach every five minutes. That allowed us to document for the first time the occurrence of fever in a wild monkey population. </p>
<p>After the study period, we returned to take the loggers out, with the help of a team of vets from the University of the Witwatersrand. We needed to do this to get the data, and obviously also for the sake of the monkeys.</p>
<p>In our study group of 59 vervet monkeys, we detected 128 fevers in 43 monkeys over seven years. Feverish monkeys reached an average (mean) daily body temperature of about 39°C, with the highest body temperature on record being nearly 42°C. Fevers lasted between two and 20 days.</p>
<p>At the same time, we kept a detailed account of the monkeys’ behaviour and social interactions. Just like us, they lose their appetite and spend more time resting. But they can’t stay out of action for too long. Even sick monkeys need to keep up with their troop if they are to keep themselves out of reach of predators, such as cheetah, jackal and caracal (a wild cat). Monkeys also rely on their group mates to help <a href="https://www.sciencedirect.com/science/article/abs/pii/S0003347216302858">fight off neighbouring troops</a> as they compete for food, water and sleep sites. </p>
<h2>The risk of attack</h2>
<p>In addition to the behavioural consequences of fever, we were able to show, for the first time, a hidden and previously unrecognised cost of social interactions – feverish monkeys were attacked while they were down. </p>
<p>Within a monkey troop, competition is rife – monkeys battle for food, status and mates. Although it’s unclear if a monkey knows that one of their troop is sick, they do recognise the weakened state of their troop mate, perhaps because they are out of sorts or are less responsive to more subtle exchanges of dominance. </p>
<p>Some individuals seemed to use this to their advantage.</p>
<p>We discovered that when monkeys were feverish they were twice as likely to be attacked by one of their group mates and six times more likely to become injured as a result. Sick animals were targeted with aggression when they were least able to fight back, potentially improving the attacker’s social status, access to resources, or position in the troop. </p>
<p>We saw a particularly unusual sequence of events in one of our troops of 25 monkeys. </p>
<p>Female vervets live in relatively stable hierarchies. But when Brie, the alpha female, fell ill she was subjected to a torrent of abuse from the troop’s beta female, Tyvara. Over seven days, Brie was attacked by her on 12 occasions and received four different injuries. Needless to say, Brie’s alpha dominance status was no more and she slipped down the hierarchy. </p>
<p>Bystanders also seemed to benefit from the weakened status of a sick individual, in this case by manoeuvring up the hierarchy, and these fever-induced social interactions are likely to have important long-term social and fitness consequences for the individuals involved. </p>
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<a href="https://theconversation.com/how-orangutan-mothers-help-their-offspring-learn-173959">How orangutan mothers help their offspring learn</a>
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<p>But that’s not all. The feverish monkeys spent just as much time grooming, or being groomed, by other group members even though they were sick. While it might seem common sense to avoid other sick individuals, our findings suggest that social engagement probably reflects a trade-off between the propensity to get infected by a contagious individual and the social value and other benefits that the relationship affords – such as the ability to cope in <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.12329">difficult environments</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0003347217300362?via%3Dihub">successfully raise offspring</a>. Or perhaps monkeys simply don’t know that their troop mates are ill or could pass them a nasty illness. </p>
<p>The response of vervet monkeys to infection suggests that the spread of disease among the troop is likely. Now we have seen that there is a cost of being sociable when feverish, where vulnerable individuals are open to attack, perhaps we should turn our attention to the question of the impact of social integration among monkeys on the spread of disease within and between groups.</p><img src="https://counter.theconversation.com/content/173951/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This research was funded by Faculty research grants from the University of the Witwatersrand, a Claude Leon Fellowship awarded to Richard McFarland, Natural Sciences and Engineering Research Council of Canada Discovery grants to Peter Henzi and Louise Barrett, a Canada Research Chair award to Louise Barrett, National Research Foundation of South Africa grants to Andrea Fuller, Robyn Hetem, Peter Henzi and Duncan Mitchell, a Carnegie Corporation of New York grant to Andrea Fuller, and a Harry Oppenheimer Fellowship to Duncan Mitchell.</span></em></p>Why social interaction isn’t always a good thing for primates, especially for individuals with a fever.Richard Mcfarland, Senior Lecturer in Evolution and Social Behaviour, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1736582022-01-07T09:50:18Z2022-01-07T09:50:18ZEven bushbabies get stressed: here’s how we know, and what it means<figure><img src="https://images.theconversation.com/files/437143/original/file-20211213-13-6feuif.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A thick-tailed greater galago peering out from amid tree branches.</span> <span class="attribution"><span class="source">Michelle Sauther</span></span></figcaption></figure><p>Many South Africans will be familiar with bushbabies – or, at least, with their distinctive call. The small animal, more formally known as the <a href="https://www.ewt.org.za/wp-content/uploads/2019/02/6.-Thick-tailed-Bushbaby-Otolemur-crassicaudatus_LC.pdf">thick-tailed greater galago</a>, takes its common name from that call; it sounds like a crying baby. </p>
<p>Bushbabies are primates. They have large eyes and are nocturnal creatures. They’re usually spotted meandering through tall trees at night in search of fruit to eat. </p>
<p>Very little research has been conducted about bushbabies in South Africa since the 1980s, partly because they are not gregarious or easy to observe. And almost nothing is known about what physiological mechanisms they and other African primates use to cope with environmental and social changes. Climate change and human encroachment on their habitat, for example, may affect their food sources, their reproductive success, and possibly their survival. We set out to help fill in this knowledge gap.</p>
<p><a href="https://academic.oup.com/conphys/article/9/1/coab081/6409752">Our study</a> explored the main factors that contribute to changes in bushbabies’ physiology. These included the influences of diet, weather and their reproductive state. We tested their adrenocortical activity (that is, the hormones they secreted) across a 12-month period at the <a href="http://www.lajuma.com/">Lajuma Research Centre</a> in the Soutpansberg mountains in South Africa’s Limpopo province. </p>
<p>When an animal is exposed to any form of change – for instance predator exposure, temperature changes, or mating – their physiological stress response is activated and the glucocorticoid hormone is secreted. Glucocorticoid hormones play a part in numerous mechanisms in the body. Their primary functions include growth, the maintenance of energy requirements, and the immune and stress responses. An acute secretion of glucocorticoids is healthy. But long-term exposure can have detrimental effects on the body: immunity and reproductive capabilities, for example, may be reduced. So there’s a lot to learn from an animal’s long-term glucocorticoid patterns.</p>
<p>Over the 12 months of our study, we identified the main factors that affect bushbabies’ responses to changes in the environment. We found that female bushbabies were more susceptible than males to elevated glucocorticoid levels brought on by environmental changes. This may have implications for the species’ longer term ability to adapt to dwindling food availability or a shifting climate, for instance. </p>
<h2>Hormonal changes</h2>
<p>When an animal is exposed to some kind of change, glucocorticoids are released into the bloodstream to reach their target organ or tissue. After this they are broken down in the liver to create glucocorticoid metabolites or by-products; these metabolites are then excreted from the body. That means researchers can study animals’ faeces as a proxy to monitor adrenocortical activity. </p>
<p>This method of sampling has become popular in science. It requires little direct interaction with an animal, minimising the risk of stress or injury.</p>
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Read more:
<a href="https://theconversation.com/vulnerable-lizard-species-gets-hot-and-bothered-in-rising-temperatures-171052">Vulnerable lizard species gets hot and bothered in rising temperatures</a>
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<p>The Lajuma Research Centre consists of a variety of habitats including mist-belt forests and savannah grassland. Temperatures range from 37°C in summer to 0°C in winter and rain falls in the summer months. Living in this highly seasonal environment, bushbabies need to withstand fluctuations in food availability. The fruit, insects and gum they eat aren’t as abundant in winter. </p>
<p>They also experience constantly changing social interactions. These are generally solitary animals, but each year they must interact during the mating season or females must look after their offspring during the lactating period.</p>
<p>To survive, the species should be adaptive, or “plastic”: hormonal fluctuations should occur, but there shouldn’t be consistently high concentrations of glucocorticoids.</p>
<p>We started by establishing which assay or “hormone detector” would be most accurate in detecting the metabolites of this species. Then, to explore the effect of seasonal and social factors on metabolite levels, we collected faecal samples from wild individuals over an entire year. Animals were captured using traps – we’ve been trapping these individuals since 2013 for different studies and they kept coming back for the free food. They were identified, weighed, and released, and we collected the faeces that had accumulated in the traps. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437716/original/file-20211215-17-1kkpnzn.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">
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<span class="caption">One of the bushbabies involved in the study.</span>
<span class="attribution"><span class="source">Channen Long</span></span>
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<p>We also determined seasonal food availability by taking tree gum samples and counting the available insects and the seeds in faecal samples. </p>
<p>The results revealed that males did not have a significant change in faecal glucocorticoid metabolite levels across seasons or during important social events such as mating. This was unexpected: we had predicted that the mating season, combined with the less favourable winter conditions, would cause a dramatic rise in levels. We suspect the galagos adjust their behaviour to reduce their activities and, thus, their energy use and glucocorticoid secretion during the colder months. </p>
<p>We determined that the lactation period had the greatest impact on female galagos’ glucocorticoid levels. Lactation uses a lot of energy and has <a href="https://www.sciencedirect.com/science/article/abs/pii/S0018506X07002309?via%3Dihub">been shown</a> to cause increases in glucocorticoid concentrations in several other primate species. It could also be an influence of “maternal stress” when the mother must care for her offspring. </p>
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Read more:
<a href="https://theconversation.com/the-bushbaby-family-just-got-a-new-member-heres-how-we-identified-it-73067">The bushbaby family just got a new member. Here's how we identified it</a>
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<p>We found that changes in food availability influenced females’ glucocorticoid concentrations. The lactation period is in summer, when food is amply available. This could create higher levels of competition between individuals. Previous research on lesser galagos has shown females may elevate aggression during times of high food availability and periods when they need to look after their young. Altogether, these factors could have caused the rise in faecal glucocorticoid metabolite concentrations.</p>
<h2>Final conclusions</h2>
<p>Our study shows that faecal glucocorticoid metabolite concentrations are most affected by food availability and reproductive state. Females are more likely to experience higher concentrations because of the physiological costs of reproduction. The results suggest they are more sensitive to environmental change than males. Overall, bushbabies are fairly resilient to change – for now.</p>
<p>This information will help to contextualise future research on the impact of environmental change, human environmental degradation and especially climate change, which may have an impact on the survival of this primate species. </p>
<p><em>Professor Adrian Tordiffe, Professor, Michelle Sauther, Professor Frank Cuozzo, Dr James Millette, Professor Andre Ganswindt and Dr Juan Scheun co-authored the research this article is based on.</em></p><img src="https://counter.theconversation.com/content/173658/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Channen Long received funding from The National Science Foundation, USA (grant number 1638833) and the South African National Biodiversity Institute's National Zoological Gardens. </span></em></p>Little is known about what physiological mechanisms African primates use to cope with environmental and social changes such as climate change and human encroachment on their habitat.Channen Long, PhD candidate and lab manager, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1733852021-12-08T15:52:30Z2021-12-08T15:52:30ZWe’ve proved that wild primates suffer from tooth decay – and chimps are among the worst<figure><img src="https://images.theconversation.com/files/436405/original/file-20211208-21-1ieoopr.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-photo/big-smile-on-young-chimpanzees-face-409846009">Atiger/shutterstock</a></span></figcaption></figure><p>Nearly everyone at some point in their lives is affected by tooth decay. Indeed, half of you reading this article are likely to currently <a href="https://www.who.int/news-room/fact-sheets/detail/oral-health">have it</a>. It’s common knowledge that a sugary diet can cause cavities, but <a href="https://journals.sagepub.com/doi/10.1177/0022034515590377">specific bacteria</a> living in our mouths are part of the process. They consume the sugary foods and release acids into the mouth as a by-product. If this happens frequently, the tissue that makes up a tooth – including enamel and dentine – decrease in mineral concentration. This is called demineralisation, and it ultimately causes cavities. </p>
<p>Apart from humans, some species kept as pets and in captivity (such as in zoos), can <a href="https://link.springer.com/article/10.1007/BF02382058">regularly display</a> tooth cavities. This is mostly due to being fed a diet containing processed sugars that differs from their natural foods.</p>
<p>But we might expect that wild animals wouldn’t suffer from the same dental issues as they are not eating processed foods. In fact, that isn’t the case. It turns out that tooth decay may be relatively common in some species, including in a wide range of mammals such as bats, primates, bears and some other carnivores.</p>
<h2>Cavities in primates</h2>
<p>Primates in particular have been observed to have cavities, including in a diverse range of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0203307">prehistoric species</a>. But dental decay is still generally regarded as rare in wild primates living today, and there has been disagreement between specialists on whether deep cavities found within the front of their teeth are actually tooth decay caused by cavity-forming bacteria, or holes caused by factors other than tooth decay such as <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.1330800210">enamel weakness</a>.</p>
<p>In a <a href="https://doi.org/10.1002/ajp.23349">recent study</a> we wanted to find out for sure whether primates get tooth cavities, and where in the mouth they were found.
To do this, we used a 3D-imaging technique known as micro-CT scans to look at 8,000 teeth from 11 diverse primate species.</p>
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Read more:
<a href="https://theconversation.com/fossil-tooth-fractures-and-microscopic-detail-of-enamel-offer-new-clues-about-human-diet-and-evolution-163653">Fossil tooth fractures and microscopic detail of enamel offer new clues about human diet and evolution</a>
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<p>Nine out of the 11 species had at least some cavities. And several species had high levels of cavities on their front teeth, including chimpanzees, gorillas, Dent’s mona monkeys, blue monkeys and raffles’ banded langurs.</p>
<p>Crucially, we found that tooth decay causing bacteria had indeed been involved in the cavities we commonly observed on the front teeth, because demineralisation was evident deep below the surface of the tooth. Perhaps in hindsight this is not surprising since soft fruits are a staple of the diet in many primates, so they regularly chew foods with high levels of natural sugars.</p>
<p>And because we studied so many teeth, we were then able to assess variation in patterns of cavities – where they were on the teeth and how that differed in relation to diet and behaviour.</p>
<h2>Why front teeth in primates?</h2>
<p>In humans, including <a href="https://sajs.co.za/article/view/8705">our fossil ancestors</a> and relatives going back millions of years, it is the back teeth that are most commonly affected by tooth decay. The reason why, in living primates, the front teeth seem more susceptible to this disease is probably because of differences in their food, and also in the way they eat. </p>
<p>For example, chimpanzees undertake a <a href="https://link.springer.com/article/10.1007/BF02192634">behaviour called wadging</a>, where they hold chewed fruits in the front of the mouth and then suck out the sugary liquids. These fruits include figs, some of which have high concentrations of sugars. They have even been observed wadging honeycomb. Not surprisingly the front teeth of chimpanzees show extremely high rates of cavities.</p>
<p>Although other monkey and ape species might have different diets and eating behaviours, they all use their front teeth to process fruits and other plant parts that are high in natural sugars. In contrast, some baboons and macaques, which have a much more varied diet, don’t appear to have these tooth cavities.</p>
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Read more:
<a href="https://theconversation.com/monkey-teeth-fossils-hint-several-extinct-species-crossed-the-atlantic-135961">Monkey teeth fossils hint several extinct species crossed the Atlantic</a>
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<p>Interestingly, female chimpanzees had considerably more decayed teeth than males – around 9% compared to only 2% in males. We do not yet know why, but it is likely to be caused by differences in their diet and behaviour, as well as other factors such as pregnancy, acidity of saliva, life history, and bacteria variations between the sexes.</p>
<p>So we humans are not alone in suffering from tooth decay. One other interesting point is that captive primates share our pattern of cavities, with back teeth regularly affected more than the front. This is mostly due to being fed a diet containing processed sugars that differ from their natural foods. </p>
<p>In short, primates’ cavity patterns seem to be a reliable indicator of food-processing behaviours and diet – and therefore, tooth decay has the potential to offer unique ecological insight into both extinct and living primate groups.</p><img src="https://counter.theconversation.com/content/173385/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Towle 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>We studied 8,000 primate teeth and finally confirmed that humans are not the only living primate to suffer from cavities. But there are interesting differences.Ian Towle, Postdoctoral researcher & teaching assistant, London South Bank UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1665532021-09-08T01:31:01Z2021-09-08T01:31:01ZHow gibbon skulls could help us understand the social lives of our ancient ancestors<figure><img src="https://images.theconversation.com/files/419600/original/file-20210906-21-xiged3.jpg?ixlib=rb-1.1.0&rect=0%2C13%2C2995%2C1980&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Peng-Fei Fan</span>, <span class="license">Author provided</span></span></figcaption></figure><p>We have discovered previously unappreciated differences between some male and female gibbons and siamang that could give us new clues about how social behaviour affected primate evolution. </p>
<p>Gibbons and siamang are small apes that live in parts of Southeast Asia, India and China. Most species are socially monogamous and live in pairs. </p>
<p>Like all animals, gibbons and siamang have evolved via natural and sexual selection in response to different environmental and social pressures. Looking at monkey and ape species that live today, including gibbons and siamang, can help us understand the forces that shaped them. This may allow us to discover more about the forces that also shaped their distant relatives, <em>Homo sapiens</em>, and their extinct ancestors.</p>
<p>In some animals, we see sex differences in physical traits associated with competition between males for mates or resources. In many monkey and ape species, large canine teeth in males are used as a visual signal of aggression. Similarly, the large bony ridge found at the top of some adult male gorilla skulls – known as the sagittal crest – and the fat hump that surrounds it is linked with a male’s ability to win fights and to attract females.</p>
<p>Until now, there was no sign that competition between males played a strong role in shaping male physical traits among gibbons and siamang. My new research, published in the International Journal of Primatology, shows three out of eight species show <a href="https://link.springer.com/article/10.1007/s10764-021-00233-3">sex differences in their skulls and canine teeth</a>. </p>
<h2>Faces, teeth and competition</h2>
<p>These results suggest facial dimensions and canine size in the males of these three species (but not the other five) are important targets for sexual selection. These traits are associated with aggression among males and social signalling. Gibbon and siamang males show weak social bonds with one another, but understanding why enhanced physical traits evolved in the males of some species but not others has not yet been possible by studying their behaviour.</p>
<p>Gorillas and orangutans are subject to selection associated with competition among males, and these results suggest some gibbon and siamang species may face something similar. The males of these species develop size and shape differences in their facial skeletons, and have larger canine teeth compared to females.</p>
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<a href="https://theconversation.com/monkey-minds-what-we-can-learn-from-primate-personality-43063">Monkey minds: what we can learn from primate personality</a>
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<p>Selective pressures on gibbon and siamang males are not thought to come from high-intensity combat among males for access to females, as is the case among some apes. It is more likely that their slightly larger body size and pronounced facial features enhance a male’s ability to ward off intruding males, or to prevent other males from killing their offspring.</p>
<h2>Bony brows</h2>
<p>My results suggest sex differences in the facial skeleton are linked with social communication in Eastern hoolock gibbons. </p>
<p>The bony structure above the eye sockets (known as the browridge) is 24% larger in Eastern hoolock gibbon males than it is in females. The overall size of the skull in males is only 5% larger than it is in females, so the browridge of males is disproportionately large. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417992/original/file-20210826-22-1kicz2g.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&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">Line drawings of a male Eastern hoolock gibbon cranium (left) and a female Eastern hoolock gibbon cranium (right). Males of this species (Hoolock leuconedys) show a more pronounced browridge and larger canine teeth compared to females.</span>
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<p>White fur exclusively highlights the browridge region in Eastern hoolock gibbon males, which is not the case in females. This white fur colour may have evolved to highlight the underlying bony structure. A large browridge in Eastern hoolock gibbon males may act as a visual signal to other males, to communicate social dominance. </p>
<h2>The human connection</h2>
<p>Since three out of eight gibbon and siamang species show sex differences in their skulls and canine teeth, it may be that these differences are linked to subtle differences in social behaviour. To fully understand how and why this is the case, we will need more rigorous research to scrutinise how the sex differences in facial dimensions are associated with specific aspects of male and female social behaviour in a broader range of living primates.</p>
<p>If specific regions of the skull are strongly associated with aspects of social behaviour, for example as a visual signal of aggression or dominance, this could give us insight into the social lives of early human ancestors and relatives, who are known through fossilised skeletal remains.</p>
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Read more:
<a href="https://theconversation.com/the-origin-of-us-what-we-know-so-far-about-where-we-humans-come-from-54385">The origin of 'us': what we know so far about where we humans come from</a>
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<p>Such future research will pave the way to better understand more about how extinct members of the human family tree socialised. This includes the australopithecines (our bipedal ape-like relatives who lived from around 4 million years ago onwards) and members of our own genus <em>Homo</em>, who are known from as early as 2.8 million years ago. </p>
<p>Such deeper insights into the social lives of our ancestors may allow a richer evolutionary understanding about the context in which our own species, <em>Homo sapiens</em>, arose.</p><img src="https://counter.theconversation.com/content/166553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katharine Balolia 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>Differences between male and female skulls in some species of gibbon may shed light on how our extinct ancestors lived.Katharine Balolia, Lecturer in Biological Anthropology, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1670632021-09-01T12:43:20Z2021-09-01T12:43:20ZMonkeying about: getting to know ‘ugly’ animals better could be the key to their conservation<figure><img src="https://images.theconversation.com/files/418720/original/file-20210831-23-1vq1wok.jpg?ixlib=rb-1.1.0&rect=8%2C14%2C1908%2C1253&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Proboscis monkeys, although endangered, do not tend to receive large amounts of public conservation support.</span> <span class="attribution"><a class="source" href="https://pixabay.com/photos/proboscis-monkey-proboscis-borneo-212825/">Lekies/Pixabay</a></span></figcaption></figure><p>The current <a href="https://theconversation.com/worried-about-earths-future-well-the-outlook-is-worse-than-even-scientists-can-grasp-153091">threat</a> to the Earth’s biodiversity is no laughing matter, but it may be that raising a smile might help some vulnerable species dogged by unfortunate looks or dark reputations. </p>
<p>Studies of conservation strategies for two endangered primates – the <a href="https://www.nationalgeographic.com/animals/mammals/facts/proboscis-monkey#:%7E:text=Proboscis%20monkeys%20are%20endemic%20to,occasionally%20to%20search%20for%20food.">proboscis monkey</a> from Borneo and the <a href="https://lemur.duke.edu/discover/meet-the-lemurs/aye-aye/">aye aye lemur</a> native to Madagascar – show the surprisingly powerful influence of public attitudes towards less photogenic creatures at risk of extinction.</p>
<p>September 1 marks <a href="https://wildwelfare.org/international-primate-day-2020/">International Primate Day</a>, an opportunity to take a look at how conservationists can best raise the profiles of less-loved primates. </p>
<p>The probsocis monkey, <em>Nasalis larvatus</em>, regularly features in <a href="http://www.bbc.com/earth/gallery/20161021-feast-your-eyes-on-the-ugliest-animals-in-the-world">public votes</a> of the world’s ugliest animals. Both males and females have conspicuous noses, but <a href="https://www2.nau.edu/%7Egaud/bio300b/sexdi.htm#:%7E:text=Sexual%20dimorphism%20is%20the%20systematic,is%20larger%20than%20the%20female.&text=For%20example%2C%20the%20body%20masses,humans%20are%20approximately%20normally%20distributed.">sexual dimorphism</a> (differences in shape, size or colour between the sexes) also results in dominant males with pot bellies, piggy eyes and a vivid red penis contrasting against a black scrotum: none of which induce impressions of beauty, majesty or cuteness – the <a href="https://theconversation.com/even-ugly-animals-can-win-hearts-and-dollars-to-save-them-from-extinction-78507">usual criteria</a> for public affection. </p>
<figure class="align-center ">
<img alt="A closeup of a male proboscis monkey, Nasalis larvatus" src="https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418623/original/file-20210831-15-1rk4utm.jpeg?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">A closeup of a male proboscis monkey, Nasalis larvatus.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Proboscis_monkey_(Nasalis_larvatus)_male_head.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<h2>The power of memes</h2>
<p>A <a href="https://pubmed.ncbi.nlm.nih.gov/32348597/">recent study</a> conducted in Poland aimed to illuminate ways to inspire people’s concern about protecting species, including the proboscis monkey, that aren’t so aesthetically pleasing. Researchers explored the possibility of raising public interest in conserving this curiously ugly monkey through spreading amusing internet memes – images of the monkey with text linking its appearance to Polish jokes and cultural references – within social media and in conservation marketing. The team then monitored the interest in proboscis monkeys versus conservation superstars such as <a href="https://theconversation.com/stopping-koala-extinction-is-agonisingly-simple-but-heres-why-im-not-optimistic-141696">koalas</a> and gorillas by analysing public donations made to related conservation campaigns.</p>
<p>As a result of the campaign, media interest in the proboscis monkey – virtually negligible in Poland prior to 2016 – increased <a href="https://wildlife.org/can-internet-memes-help-conserve-uncharismatic-wildlife/">significantly</a>, equalling coverage for traditional conservation celebrity species. The amusing memes, focusing on the funny side of the monkey’s looks, attracted more positive coverage that inspired several amateur crowdfunding campaigns raising money for the species’ protection in Borneo: which received <a href="https://eprints.qut.edu.au/202815/1/64825062.pdf">donations</a> from 218 donors in total.</p>
<p>Overall, a creature previously all but unknown to the Polish public became a focus of important attention that ultimately contributed to its protection by helping to pay for the conservation of its habitat. These findings suggest that conservationists shouldn’t shy away from using memes to create interest in and raise money for the more overlooked endangered members of the animal kingdom. </p>
<h2>Changing myths</h2>
<p>The aye aye lemur, <em>Daubentonia madagascariensis</em>, provides another example of the power of public attitudes to influence conservation efforts. </p>
<figure class="align-center ">
<img alt="An aye aye clings to a tree at night" src="https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418637/original/file-20210831-21-1qdibcz.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">The world’s largest nocturnal primate, the aye aye is renowned for its unusual appearance.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/oregonstateuniversity/29256433783">Oregon State University/Flickr</a></span>
</figcaption>
</figure>
<p>Where the proboscis monkey is corpulent and flabby, the nocturnal aye aye is spindly, bug-eyed and unkempt. Its two front incisors stick out much like the teeth of <a href="https://www.bfi.org.uk/resources-events-teachers/resources-teachers/gothic-classroom/film-2-nosferatu-1922">Murnau’s Nosferatu</a>, complemented by an unusually elongated, skeletal central finger used to unearth grubs from trees (but also to <a href="https://www.zmescience.com/ecology/animals-ecology/cursed-yet-adorable-aye-aye-has-a-sixth-pseudothumb/#:%7E:text=According%20to%20ancient%20Malagasy%20legends,on%20sight%20by%20superstitious%20locals.">curse</a> unsuspecting humans, according to <a href="https://theconversation.com/malagasy-or-is-it-madagascan-our-research-provides-the-answer-128343">Malagasy</a> legend). Even its name, “aye aye”, is possibly a <a href="https://folklorethursday.com/regional-folklore/madagascar-superstitions-taboos-fighting-the-aye-aye-fady/">linguistic trick</a> to avoid calling the creature directly by instead imitating its cry.</p>
<p>Yet despite these creatures’ damning reputation as harbingers of catastrophe to humans, it is in fact humans who threaten the aye aye’s continued existence. Aye aye numbers have been in <a href="https://ielc.libguides.com/sdzg/factsheets/ayeaye/population">sharp decline</a> since the 1980s, thanks to hunting, deforestation of their habitat for construction and culturally driven persecution due to their “evil” reputation.</p>
<p>Although it was thought that negative perceptions of aye ayes were fairly universal in Madagascar, a <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1002/pan3.10192">recent study</a> by academics from Madagascar and Germany revealed unexpectedly varied attitudes among Magalasy villagers, with certain areas such as the <a href="https://www.researchgate.net/figure/The-Makira-Conservation-Area-of-northeastern-Madagascar_fig1_259104068">Makira region</a> of northeastern Madagascar even being potential strongholds for aye aye conservation due to the local prevalence of positive attitudes towards aye ayes.</p>
<p>In places where negative attitudes dominated, the villagers themselves often could not identify aye ayes in pictures. The animal remained an <a href="https://www.semanticscholar.org/paper/Folklore-and-beliefs-about-the-aye-aye-Daubentonia-Simons-Meyers/96b7a2939c815bd037a41427d72d6348ea256a37">unfamiliar</a>, imaginary threat.</p>
<figure class="align-center ">
<img alt="An aye aye clings to a tree at night" src="https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=609&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=609&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=609&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=765&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=765&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418638/original/file-20210831-13-64kw0t.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=765&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Aye ayes are feared in many local areas for their mythical ability to lay curses on humans.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Aye-aye_(Daubentonia_madagascariensis)_5.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>In fact, interviewees’ regard for the aye aye seemed to vary with direct knowledge of aye aye behaviour. Although negative views were more frequent than positive, the latter were associated with understanding about the aye aye’s usefulness for controlling pests on <a href="https://www.thenaturegatherer.com/ghostly-lemur-helps-farmers-madagascar/">vital crops</a>. </p>
<p>Firsthand knowledge and experience of aye ayes was associated with positive views, pointing to the importance of sharing knowledge within conservation strategy as well as the possibility of shifting seemingly entrenched beliefs.</p>
<p>In time and with patience, farmers aware of the aye aye’s pest control powers might help generate vital local action in support of conservation by helping to craft new narratives centring the creature’s role in our ecosystems. Understanding how and why people perceive certain animals as less appealing than others could be the key to expanding public conservation efforts successfully.</p><img src="https://counter.theconversation.com/content/167063/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Jeffries 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>Less attractive endangered species don’t tend to receive the same public attention as their more beautiful counterparts: new studies show how we might help change that.Mike Jeffries, Associate Professor, Ecology, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1619442021-06-23T11:46:04Z2021-06-23T11:46:04ZWhy we dispute ‘Dunbar’s number’ – the claim humans can only maintain 150 friendships<figure><img src="https://images.theconversation.com/files/406126/original/file-20210614-66119-1trea54.jpeg?ixlib=rb-1.1.0&rect=33%2C0%2C4459%2C2531&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/man-differs-crowd-3d-illustration-422003848">Photobank gallery/Shutterstock</a></span></figcaption></figure><p>Many of us are aware of the claim that humans can maintain no more than <a href="https://www.bbc.com/future/article/20191001-dunbars-number-why-we-can-only-maintain-150-relationships">150 friendships</a>. That figure is called “Dunbar’s number” after the evolutionary psychologist Robin Dunbar, who first introduced the idea <a href="https://www.sciencedirect.com/science/article/abs/pii/004724849290081J">three decades ago</a>. Dunbar claimed that the number of neurons in the neurocortex would limit an organism’s capacity to process social information. This would in turn limit the number of relationships that an individual can maintain.</p>
<p>But while the number has achieved widespread fame, and is often referenced in the plans of <a href="https://qz.com/846530/something-weird-happens-to-companies-when-they-hit-150-people/">business managers</a> and <a href="https://www.projecthorseshoe.com/2018/10/15/using-dunbars-number-to-design-online-worlds/">software developers</a>, it hasn’t achieved widespread acceptance in scientific circles.</p>
<p>In collaboration with our colleague Andreas Wartel, a researcher in evolutionary biology, <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2021.0158">we investigated</a> the empirical underpinnings of Dunbar’s number, and found that it doesn’t stand up to scrutiny when larger datasets and more modern statistical methods are used.</p>
<p>Dunbar has since <a href="https://theconversation.com/dunbars-number-why-my-theory-that-humans-can-only-maintain-150-friendships-has-withstood-30-years-of-scrutiny-160676">challenged our findings</a>, questioning our methodology. We therefore want to clarify our approach and comment on his critique.</p>
<h2>Social brains</h2>
<p>The idea that there may exist a correlation between social complexity and intelligence was <a href="http://cogprints.org/1737/2/SocialFunction.pdf">first proposed</a> in 1976 by Cambridge neuropsychologist Nicholas Humphrey. Unfortunately, no accepted “intelligence test” for animals exists, so researchers turned instead to measures of brain size as a hypothetical proxy for intelligence. Robin Dunbar hypothesised that the <a href="https://www.britannica.com/science/neocortex">neocortex</a> – the top layer of the cerebral hemispheres – is the intelligent part of the brain that handles social information.</p>
<figure class="align-center ">
<img alt="A group of monkeys" src="https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/406163/original/file-20210614-118145-th1x17.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many primate species groups express high levels of sociality. This also holds true for other mammals and birds.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mother-baby-macaque-sit-calmly-while-56902156">BasPhoto/Shutterstock</a></span>
</figcaption>
</figure>
<p>Dunbar proceeded to <a href="http://etherplan.com/neocortex-size-as-a-constraint-on-group-size-in-primates.pdf">identify a correlation</a> between relative neocortex size and social group size in primates: the bigger the neocortex, the bigger the social group. Using this relationship and the average size of the human brain, he extrapolated to get an estimate of human group size. It is this estimate that has since been termed “<a href="https://www.sciencedirect.com/science/article/abs/pii/004724849290081J">Dunbar’s number</a>”.</p>
<p>The correlation has been confirmed in other studies, though almost all of them have used <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218655">the same dataset</a>. However, the correlation <a href="https://par.nsf.gov/servlets/purl/10223072">can disappear</a> when adding more data to statistical models, such as information about other aspects of primate life. Researchers have found that primate neocortex and brain sizes may be <a href="https://www.researchgate.net/profile/Alex_Decasien/publication/315870122_Primate_brain_size_is_predicted_by_diet_but_not_sociality/links/5a8afee8a6fdcc6b1a43c236/Primate-brain-size-is-predicted-by-diet-but-not-sociality.pdf">better predicted by diet</a> than by sociality.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dunbars-number-why-my-theory-that-humans-can-only-maintain-150-friendships-has-withstood-30-years-of-scrutiny-160676">Dunbar’s number: why my theory that humans can only maintain 150 friendships has withstood 30 years of scrutiny</a>
</strong>
</em>
</p>
<hr>
<p>In another study, we found that one can summon <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218655">almost any correlation</a> between brain data and different aspects in primate lives by selecting what data is included in an analysis. There’s a perfectly good reason for this inconsistency of results. Many variables that have been hypothesised to influence primate brain evolution are exceptionally noisy and correlated with each other. This illustrates a core problem with Dunbar’s number: the correlation it is based on is shaky and disputed.</p>
<p>Also, other researchers question the value of extrapolating cognitive trends from other primates to humans. While the human brain is anatomically <a href="https://www.gwern.net/docs/algernon/2001-finlay.pdf">remarkably similar</a> to that of other primates, it functions differently in terms of memory and information processing.</p>
<p>One crucial difference between humans and other animals is that non-human species only have a <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.161011">limited capacity</a> to recognise ordered sequences of information, for example a string of words. This key cognitive element, which sets humans apart from other animals, may explain why only humans learn languages and flexibly plan for the future.</p>
<h2>Deconstructing Dunbar’s number</h2>
<p>With all this in mind, <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2021.0158">we replicated</a> Dunbar’s original analysis with a larger dataset and more advanced statistical methods. To ensure robust results, we used three different but overlapping datasets, two different statistical approaches, and carried out analyses both including all primates, and a more limited sample including only monkeys and apes.</p>
<p>Our results were clear. Estimates of Dunbar’s number were highly inconsistent, and the 95% confidence intervals – a measure of the certainty of the estimates – were consistently far too large to specify any one estimate as a cognitive limit on human group size. Our analyses and results <a href="https://royalsociety.altmetric.com/details/105313768/twitter">were awaited by many</a> in the scientific community.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1390240835296505862"}"></div></p>
<p>Many aspects of Dunbar’s number are misleading. Dunbar’s method arrives at an estimate of <em>average</em> human group size. But then it is used to indicate <a href="https://psycnet.apa.org/doiLanding?doi=10.1037%2F1089-2699.12.1.7"><em>maximum</em> human group size</a> – two different things. Sometimes Dunbar’s number comes from data on relative <em>neocortex</em> size; other times from data on relative <em>brain</em> size. Sometimes <em>all primates</em> are used in the analyses, but at other times <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2007.0693"><em>only monkeys and apes</em></a>. </p>
<p>Responding to our study, Dunbar even proposed that a proper analysis should <a href="https://academictimes.com/human-social-networks-might-not-be-limited-by-dunbars-number-but-dunbar-disagrees/"><em>only include apes</em></a>. And recently, he used a clustering method to identify <em>four evolutionary “grades”</em>, classifying primate species together with <a href="https://onlinelibrary.wiley.com/doi/pdf/10.1111/brv.12730">total disregard</a> for their evolutionary relationships.</p>
<p>This creates a situation where every new suggestion also produces a new, different “Dunbar’s number”. Effectively, this means that the original estimate is revised over and over again, without these revisions being stated and acknowledged.</p>
<h2>Dunbar’s criticism – a technical comment</h2>
<p>In his <a href="https://theconversation.com/dunbars-number-why-my-theory-that-humans-can-only-maintain-150-friendships-has-withstood-30-years-of-scrutiny-160676">comment on our paper</a>, Dunbar suggests that we committed a statistical error by using a statistical method known as ordinary <a href="https://www.ck12.org/statistics/Least-Squares-Regression/lesson/Least-Squares-Regression-ADV-PST/">least squares regression</a> instead of a different method, called reduced major axis regression, not acknowledging that we also reached the same conclusion with other methods.</p>
<p>His suggestion of using the <a href="https://towardsdatascience.com/diving-deeper-into-linear-regression-81adaa7b79e5">reduced major axis method</a> is a poor one, as it severely over-corrects the slope bias in the results, delivering misleading results. Nevertheless, if employing Dunbar’s newly suggested approach the estimate for the average (or maximum) human group size was not 150. The new estimate was 289.8, but again with very large 95% confidence intervals between 226.0 and 371.6 (in other words, the estimate is highly uncertain). If the analysis is carried out only on monkeys and apes, rather than all primates, the estimate is instead 404.1, with 95% confidence intervals between 300.6 and 543.3.</p>
<p>These are, however, not new suggestions for the cognitive limit on human group size, but simply more illustrations of how poorly this approach works. Overall, “Dunbar’s number” is a concept with limited theoretical foundation lacking empirical support.</p>
<p><em>This article was co-written by Andreas Wartel.</em></p><img src="https://counter.theconversation.com/content/161944/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Johan Lind received funding from Knut and Alice Wallenberg Foundation, KAW 2015.005. </span></em></p><p class="fine-print"><em><span>Patrik Lindenfors does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research calls into question the validity of ‘Dunbar’s number’.Johan Lind, Associate Professor in Ethology, Stockholm UniversityPatrik Lindenfors, Researcher, Zoological Ecology, Stockholm UniversityLicensed as Creative Commons – attribution, no derivatives.