tag:theconversation.com,2011:/uk/topics/bonobo-11879/articlesBonobo – The Conversation2023-04-11T16:12:13Ztag:theconversation.com,2011:article/2018002023-04-11T16:12:13Z2023-04-11T16:12:13ZGreat apes like to spin themselves dizzy, a lot like children do, research shows<figure><img src="https://images.theconversation.com/files/519625/original/file-20230405-18-3jddjj.jpg?ixlib=rb-1.1.0&rect=9%2C22%2C3015%2C1990&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/orangutan-portrait-young-monkeys-1975040408">Evgeniyqw/Shutterstock</a></span></figcaption></figure><p>Children love to spin. Whether it is by whirling around on their feet, whipping around on a tyre swing, or tumbling down a grassy hill, they revel in the drunken effects of dizziness that follow. As humans mature, they might outgrow spinning on the playground, but find other ways to alter their senses - dancing, skating, roller coasters, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3202501/">and for some of them, psychoactive drugs</a>. </p>
<p>It turns out humans are not the only primate with a desire to spin ourselves and stimulate our senses. In a <a href="https://link.springer.com/article/10.1007/s10329-023-01056-x">recent study</a>, my co-author Adriano Lameira and I found some other primates like to do this too. The great apes – which include chimpanzees, bonobos, gorillas, and orangutans, in addition to humans – <a href="https://australian.museum/learn/science/human-evolution/humans-are-apes-great-apes/">have a more complex brain than other primates</a> and share a similar neurophysiology. Our findings suggest that they also share our desire to induce altered states of perception. This may even have played a role in the evolution of the human mind.</p>
<p>In <a href="https://www.youtube.com/watch?v=VNKyG4C2VlA">2011</a>, and then again in <a href="https://www.youtube.com/watch?v=XfS5kBGBh00">2016</a>, a captive gorilla named Zola went viral for his flair for “breakdancing” – the spinning, playful displays that he liked to perform while splashing around in water. These videos made me wonder about the spinning behaviour of apes more generally. </p>
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<p>Spinning has been documented as a part of great apes’ repertoire of <a href="https://link.springer.com/article/10.1007/s10071-017-1096-4">communicative gestures</a>, in previous research. But Zola’s behaviour appeared to be as much about fun as it was about communication. </p>
<p>I scoured YouTube for videos of spinning primates and found <a href="https://evolang.org/jcole2022/proceedings/jcole2022_proceedings.pdf#page=606">hundreds of examples</a> of great apes and other primates spinning themselves around in different ways, from pirouettes to backflips. </p>
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<a href="https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Young chimpanzee swinging in tree" src="https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=898&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=898&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=898&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1128&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1128&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519626/original/file-20230405-1625-49lngr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1128&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The apes in the study got dizzy for the fun of it.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-chimpanzee-swinging-tree-264035690">Abeselom Zerit/Shutterstock</a></span>
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<p>In our study, my team focused on 40 videos which showed great apes spinning themselves on ropes and vines. We thought ropes might enable the apes to spin at faster speeds and for more rotations than they could with just their bodies. </p>
<p>Our intuition proved right: they often reached and <a href="https://www.youtube.com/watch?v=J19RDBMAOKU">sometimes exceeded speeds</a> of two to three rotations per second. That’s as fast as human spinning experts we compared, which included ballet dancers, circus performers, <a href="https://www.cambridge.org/core/journals/congress-on-research-in-dance/article/abs/ukrainian-hopak-from-dance-for-entertainment-to-martial-art/11FE9632C947D1663532123655CFEBBA">Ukrainian hopak dancers</a> and <a href="https://www.washingtonpost.com/lifestyle/travel/heres-what-you-should-know-before-attending-a-whirling-dervish-ceremony-in-turkey/2019/04/11/1af4bbac-57af-11e9-9136-f8e636f1f6df_story.html">Sufi whirling dervishes</a>. </p>
<h2>Apes still get dizzy</h2>
<p>These professionals train themselves to be <a href="https://academic.oup.com/cercor/article/25/2/554/305011">immune to the sensory effects</a> of extreme spinning. But – as I can attest, having recently tried this in my office (for science) – spinning around at even one rotation per second will make most people dizzy. </p>
<p>The spinning apes in our study appeared to fare no differently. They would often spin for multiple bouts. Three on average, with each bout lasting for about five-and-a-half rotations. Between bouts, the apes would sometimes let go of the rope and stumble around, often falling clumsily to the ground, before jumping back up to do it again. </p>
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<p>Many of the apes we observed were in captivity, and in these cases, rope spinning may have helped them overcome boredom. But we also found several instances of young mountain gorillas in the wild spinning on jungle vines during playful social interactions, sometimes even taking turns. They too would spin, stumble around, fall, and get back up to do it again. </p>
<p>Given the close evolutionary relationship between great apes and humans, it is likely the motivation to spin stems from a shared tendency to seek and delight in experiences that stimulate and alter our senses. </p>
<h2>Humans turn to drugs</h2>
<p>Of course, humans sometimes go far beyond spinning to achieve this. The deliberate use of psychotropic drugs, from alcohol and tobacco, to marijuana and LSD, is widespread in cultures across the world. </p>
<p>It often plays an important role in many <a href="https://doi.org/10.15184/aqy.2021.177">social rituals and spiritual ceremonies</a>. For example, in some indigenous cultures of South America, the use of the <em>ayahuasca</em> (a hallucinogenic brew made from local plants) is used by shamans (and others) to connect with ancestors thought to exist in other realms. </p>
<p>Evidence of similar rituals can be <a href="https://www.pnas.org/doi/full/10.1073/pnas.1902174116#">traced back for millennia</a>. Some scientists have <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2021.729425">argued that psychedelics</a> might have been crucial to the evolution of modern human cognition and culture, enhancing our creativity and helping us to forge deeper social connections.</p>
<p>Mushrooms containing <a href="https://en.wikipedia.org/wiki/Psilocybin">psilocybin</a> might have played an especially important role, as they would have been prevalent in many of the habitats of our hominid ancestors. </p>
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<span class="caption">Hard to deny this young chimpanzee is enjoying twirling around.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-chimpanzee-swinging-jumping-tree-200203994">Abeselom Zerit/Shutterstock</a></span>
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<p>Compared to twirling induced dizziness, chemical substances offer a more intense way to alter your state of consciousness. And it may seem a long way from spinning yourself dizzy to having a spiritual epiphany on a psychedelic trip. </p>
<p>Yet, spiritual practices such as those performed by the Sufi dervishes, <a href="https://www.youtube.com/watch?v=lFIQMM8bZQk">who whirl themselves into a meditative trance</a>, demonstrate the potential for spinning to induce a profoundly altered state of mind. Perhaps even gentle spinning helps us to see the world from a different perspective.</p><img src="https://counter.theconversation.com/content/201800/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcus Perlman 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>Orangutans, gorillas and chimpanzees seem to enjoy the buzz of getting dizzy.Marcus Perlman, Lecturer in English Language and Linguistics, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1281232020-01-16T19:01:11Z2020-01-16T19:01:11ZHomosexuality may have evolved for social, not sexual reasons<figure><img src="https://images.theconversation.com/files/307834/original/file-20191219-11939-s5zoa8.jpg?ixlib=rb-1.1.0&rect=34%2C0%2C4558%2C3050&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">We propose same-sex attraction evolved to allow greater social integration and stronger same-sex social bonds. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-male-couple-holding-hands-standing-287829986">SHUTTERSTOCK</a></span></figcaption></figure><p>How did homosexuality in humans evolve? </p>
<p>Typically, <a href="https://www.ncbi.nlm.nih.gov/pubmed/19539396">this question</a> is posed as <a href="https://www.amazon.com.au/Goodness-Paradox-Evolution-Made-Violent/dp/1781255830">a paradox</a>. </p>
<p>The argument is this: gay sex alone can’t produce children, and for traits to evolve, they have to be passed onto children, who get some form of competitive advantage from them. </p>
<p>From this perspective, some argue homosexuality should not have evolved.</p>
<p><a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2019.02955/full?utm_source=F-NTF&utm_medium=EMLX&utm_campaign=PRD_FEOPS_20170000_ARTICLE">In a paper published yesterday</a> by myself and Duke University professor Brian Hare, we propose human sexuality (including homosexuality) evolved as an outcome of the evolution of increased sociability in humans. </p>
<p>We argue many of the evolutionary forces that shaped human sexuality were social, rather than based on reproductive ability. </p>
<p>This is our “sociosexual hypothesis” for the evolution of gay sex and attraction. </p>
<h2>Sex for bonding</h2>
<p>For humans, and many other animals, sex is not just about reproduction. </p>
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<a href="https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1133&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1133&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310400/original/file-20200116-181608-16veogf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1133&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Bonobos and chimpanzees share about 99.6% of their DNA with humans.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bonobo-green-tropical-jungle-natural-background-1596689767">shutterstock</a></span>
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<p><a href="https://global.oup.com/academic/product/primate-sexuality-9780199544646?cc=au&lang=en&">In our closest primate relative</a>, the bonobo, <a href="https://link.springer.com/article/10.1007%2Fs10329-010-0229-z">straight and gay sex have vital roles</a> in play, social transactions, barter of food, same-sex social bonding and bonding between mating pairs.</p>
<p>We shouldn’t limit our thinking about the evolution of sex to its reproductive functions. We must also consider its social functions.</p>
<p>Based on the social behaviour of primates (and other social mammals), we argue our species’ recent cognitive and behavioural evolution was driven by natural selection favouring traits that allowed better social integration. This is called prosociality.</p>
<p>Early humans that could quickly and easily access the benefits of group living had a strong selective advantage. We believe this led to the evolution of a whole range of traits including reduced aggression, increased communication, understanding, social play and affiliation.</p>
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Read more:
<a href="https://theconversation.com/gay-gene-search-reveals-not-one-but-many-and-no-way-to-predict-sexuality-122459">'Gay gene' search reveals not one but many – and no way to predict sexuality</a>
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<p>Species such as the bonobo, that evolved for high prosociality, evolved to use sexual behaviour in many social contexts. This results in an increase of sex in general, greater diversity in the contexts of sex, and an increase in gay sex.</p>
<p>We believe something similar happened in recent human evolution. Gay sex and attraction may have evolved because individuals with a degree of same-sex attraction benefited from greater social mobility, integration and stronger same-sex social bonds. </p>
<p>This may sound counterintuitive, given <a href="https://journals.sagepub.com/doi/full/10.1177/1529100616637616?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed">gay people are socially marginalised, ostracised and even criminalised in many societies.</a> </p>
<p>However, our argument addresses the early evolution of human sexuality, not how relatively recent phenomena like religion and religion-based legal structures have responded to sexual minorities.</p>
<h2>Supporting facts</h2>
<p>Many studies since the <a href="https://www.jstor.org/stable/j.ctt173zmgn">pioneering</a> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1447861/">research</a> of Alfred Kinsey and colleagues have emphasised that <a href="https://journals.sagepub.com/doi/full/10.1177/1529100616637616?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed">sexual minorities occur across all cultures</a>, and the levels of gay and bisexual people in populations have been quite stable over time.</p>
<p>Our hypothesis predicts that bisexuality and people who identify as “mostly straight” should be more common than people who identify as exclusively gay, <a href="https://journals.sagepub.com/doi/full/10.1177/1529100616637616?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed">and this is the case</a>. </p>
<p>Recent genetic analyses confirm <a href="https://science.sciencemag.org/content/365/6456/eaat7693">hundreds of genes influence sexuality</a> in complex ways. </p>
<p>We quite randomly inherit half our genes from each parent. Each person’s genetic makeup is unique, so it would be highly unlikely to find two people with exactly the same set of genes influencing their sexuality. </p>
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Read more:
<a href="https://theconversation.com/born-this-way-an-evolutionary-view-of-gay-genes-26051">Born this way? An evolutionary view of 'gay genes'</a>
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<p>Thus, variation is expected, and individuals fall along a spectrum ranging from a majority who are straight, to a minority who identify as gay.</p>
<p>Our hypothesis for the evolution of homosexuality would predict this kind of variation in human sexuality, and can help explain why it is generally stable across cultures. </p>
<p>We believe sexuality is a highly complex trait, interwoven with sociality. Attraction, sexual behaviour, social bonds and desire all contribute to its complexity.</p>
<h2>Asking the right questions</h2>
<p>Height is another feature influenced by hundreds of genes, many of which interact with our external environments in complex ways. </p>
<p>We see a continuous variation in human height – some very tall and very short people exist. </p>
<p>We might draw on nutritional ecology to explore the evolution of human height, but would not feel the need to introduce special evolutionary arguments to explain the existence of tall or short people. </p>
<p>No special explanation is necessary. They are simply exhibiting natural, genetically influenced variations in height.</p>
<p>Similarly, we think asking how gay sex and attraction evolved is the wrong question. </p>
<p>A more useful question to ask is: how did human sexuality evolve in all its forms?</p>
<p>In doing do, we acknowledge homosexuality does not present a paradox needing a special explanation. It is simply a result of our species’ recent sociosexual evolution.</p>
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Read more:
<a href="https://theconversation.com/gay-gene-testing-apps-arent-just-misleading-theyre-dangerous-126522">'Gay gene' testing apps aren't just misleading – they're dangerous</a>
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<p class="fine-print"><em><span>Andrew Barron currently receives funding from Macquarie University, The Australian Research Council and the Templeton World Charity Foundation</span></em></p>Scientists don’t ask how some people evolved to be tall. In the same way, asking how homosexuality evolved is the wrong question. We need to ask how human sexuality evolved in all its forms.Andrew Barron, Professor, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/677602016-10-27T18:07:31Z2016-10-27T18:07:31ZRevealed: the ancient genetic link between chimpanzees and bonobos<p>Between 1.5 and 2 million years ago, chimpanzees (<em>Pan troglodytes</em>) and bonobos (<em>Pan paniscus</em>) evolved from a common ancestor and formed clear <a href="http://www.eva.mpg.de/3chimps/files/apes.htm">physical and behavioural differences</a>. Bonobos are smaller and more slender than chimpanzees. Socially, chimpanzees live in male-dominated groups, while bonobo society is female-dominated.</p>
<p>Until today, no one had considered the idea that these two separate species could exchange genes, largely because of a major physical barrier that separates chimpanzees and bonobos: the Congo River. Chimpanzees live on the northern side of the river, while bonobos live on the southern side.</p>
<p>It has even been suggested that the formation of the Congo River, which also happened between 1.5 million to 2 million years ago, might have been a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2278377/">major driver</a> in causing the two species to differentiate from a common ancestor. </p>
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<span class="caption">The geographic range of bonobos (<em>pan paniscus</em>) and chimpanzees.</span>
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<p>But, as <a href="http://science.sciencemag.org/content/354/6311/477">our study reveals</a>, there is evidence of ancient genetic mixing across species boundaries. We now know that hundreds of thousands of years ago, chimpanzees and bonobos were able to mate and produce offspring, leaving a genetic mark on the animals that live in the wild today. </p>
<p>We have observed from <a href="https://www.researchgate.net/publication/272356540_Hybrids_between_common_chimpanzees_Pan_troglodytes_and_pygmy_chimpanzees_Pan_paniscus_in_captivity">captive populations</a> that it is still possible for the two apes to mate today, even after more than a million years as separate species. But only now has science been able to provide robust evidence of natural occurrences in the wild. </p>
<p>Based on 75 complete genomes of chimpanzees and bonobos, we found that central and eastern chimpanzees share significantly more genetic material with bonobos than other chimpanzee subspecies do. This leads us to believe that the gene mixing between bonobos and chimpanzees occurred during two different episodes – the first one, 500,000 years ago and the second one 200,000 years ago.</p>
<p>Our next step will be to explore whether the genetic material received from bonobos has had any selective advantage in the evolution of chimpanzees.</p>
<h2>Gene flow in evolution</h2>
<p>The genetic relationship between chimpanzees and bonobos shows striking parallels to the evolutionary history of modern humans.</p>
<p>Gene flow between diverging species has emerged as an important aspect in the evolution of species. Put simply, if we want to understand how species evolved and diverged from one another, we must understand how genes move between different lineages.</p>
<p>In the past ten years, leading research on the evolutionary past of modern humans, as well as our close, extinct relations – the Neanderthal and Denisovan – have shown the <a href="https://theconversation.com/neanderthals-and-humans-an-interspecies-affair-to-remember-22520">impact of interbreeding</a> in our own evolutionary history. </p>
<p>Studies have also revealed in humans a number of introgressed Neanderthal genes – that is, genetic material from one species is integrated in the genome of another – which could affect our physical appearance, as well as our <a href="https://www.ncbi.nlm.nih.gov/pubmed/26912863">susceptibility to disease</a>. </p>
<h2>What this means for saving chimps</h2>
<p>Sadly, many projections indicate that both chimpanzees and bonobos may go <a href="http://www.janegoodall.ca/chimps-africa-conservation-threats.php">extinct this century</a>. So it is more important than ever to for scientific collaboration to understand and protect these crucial species before they disappear.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=419&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=419&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=419&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=527&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=527&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143449/original/image-20161027-11236-107630f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=527&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We can better protect chimps if we can identify where they’re from.</span>
<span class="attribution"><a class="source" href="https://simple.wikipedia.org/wiki/Chimpanzee#/media/File:Adult_female_and_infant_wild_chimpanzees_feeding_on_Ficus_sur.jpeg">Alain Houle</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Many chimpanzees fall victim to illegal trafficking each year. From our collective experience in chimpanzee and bonobo genetics, we can help guide global chimpanzee conservation efforts to fight this trade. Our newly generated dataset has allowed us to develop a genetic tool we can use to assign the geographical origin of chimpanzees confiscated by conservation authorities, and thus combat the illegal trade of chimpanzees. </p>
<p>But the full potential of these methods are limited by the resolution of the underlying sample of genetic data we have from both species, that is, how well we sampled each geographical area. </p>
<p>Despite our present efforts, there are still large knowledge gaps in unexplored regions of the distributional ranges of bonobos and chimpanzees. Our future efforts will be directed towards filling those gaps and thereby aiding the global conservation of our closest relatives.</p>
<p><em>This article was co-authored by Christina Hvilsom from the Copenhagen Zoo.</em></p><img src="https://counter.theconversation.com/content/67760/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Frandsen does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The two species mated 500,000 years ago, leaving a genetic mark to this day. This knowledge could help save them from extinction.Peter Frandsen, Researcher, University of CopenhagenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/662242016-10-06T18:00:29Z2016-10-06T18:00:29ZCan great apes read your mind?<figure><img src="https://images.theconversation.com/files/140212/original/image-20161004-27269-16hqfws.JPG?ixlib=rb-1.1.0&rect=0%2C144%2C3767%2C2446&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bonobo Jasongo at Leipzig Zoo has a hunch about what you're thinking.</span> <span class="attribution"><span class="source">MPI-EVA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>One of the things that defines humans most is our ability to read others’ minds – that is, to make inferences about what others are thinking. To build or maintain relationships, we offer gifts and services – not arbitrarily, but with the recipient’s desires in mind. When we communicate, we do our best to take into account what our partners already know and to provide information we know will be new and comprehensible. And sometimes we deceive others by making them believe something that is not true, or we help them by correcting such false beliefs.</p>
<p>All these very human behaviors rely on an ability psychologists call <a href="http://dx.doi.org/10.1017/S0140525X00076512">theory of mind</a>: We are able to think about others’ thoughts and emotions. We form ideas about what beliefs and feelings are held in the minds of others – and recognize that they can be different from our own. Theory of mind is at the heart of everything social that makes us human. Without it, we’d have a much harder time interpreting – and probably predicting – others’ behavior.</p>
<p>For a long time, many researchers have believed that a major reason human beings alone exhibit unique forms of communication, cooperation and culture is <a href="http://doi.org/10.1126/science.1146282">that we’re the only animals to have a complete theory of mind</a>. But is this ability really unique to humans?</p>
<p>In a <a href="http://doi.org/10.1126/science.aaf8110">new study published in Science</a>, my colleagues and I tried to answer this question using a novel approach. Previous work has generally suggested that people think about others’ perspectives in very different ways than other animals do. Our new findings suggest, however, that great apes may actually be a bit more similar to us than we previously thought.</p>
<h2>Apes get some parts of what others are thinking</h2>
<p>Decades of research with our closest relatives – chimpanzees, bonobos, gorillas and orangutans – have revealed that great apes do possess many aspects of theory of mind. For one, they can <a href="http://doi.org/10.1177/0956797614536402">identify the goals and intentions behind others’ actions</a>. They’re also able to recognize which <a href="http://dx.doi.org/10.1006/anbe.2000.1518">features of the environment others can see or know about</a>. </p>
<p>Where apes have consistently failed, though, is on tasks designed to assess their understanding of others’ false beliefs. They don’t seem to know when someone has an idea about the world that conflicts with reality.</p>
<p>Picture me rummaging through the couch because I falsely believe the TV remote is in there. “Duuuude,” my (human) roommate says, noticing my false belief, “the remote is on the table!” He’s able to imagine the way I’m misconstruing reality, and then set me straight with the correct information. </p>
<p>To investigate false belief understanding in great apes, comparative psychologist <a href="http://www.fumihirokano.com/p/main-page.html">Fumihiro Kano</a> and I turned to a technique that hadn’t been used before with apes in this context: eye-tracking. Our international team of researchers enrolled over 40 bonobos, chimpanzees and orangutans at Zoo Leipzig in Germany and Kumamoto Sanctuary in Japan in our novel, noninvasive experiment.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140213/original/image-20161004-20235-1ja5x7r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&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 use juice to attract the apes to the spot where they can watch the videos.</span>
<span class="attribution"><span class="source">MPI-EVA</span></span>
</figcaption>
</figure>
<h2>Watching what they watched</h2>
<p>We showed the apes videos of a human actor engaging in social conflicts with a costumed ape-like character (King Kong). Embedded within these interactions was important information about the human actor’s belief. For example, in one scene the human actor was trying to search for a stone that he saw King Kong hide within one of two boxes. However, while the actor was away, King Kong moved the stone to another location and then removed it completely; when the actor returned, he falsely believed the stone was still in its original location.</p>
<p>The big question was: Where would the apes expect the actor to search? Would they anticipate that the actor would search for the stone in the last place where he saw it, even though the apes themselves knew it was no longer there?</p>
<p>While the apes were watching the videos, a special camera faced them, recording their gaze patterns and mapping them onto the video. This eye-tracker let us see exactly where on the videos the apes were looking as they watched the scenarios play out.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kgYNSin3Sfc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Watch a video of what the apes were shown. The red dots show where one ape was looking as she watched the movie. Credit: MPI-EVA and Kumamoto Sanctuary, Kyoto University.</span></figcaption>
</figure>
<p>Apes, like people, do what’s called anticipatory looking: They look to locations where they anticipate something is about to happen. This tendency allowed us to assess what the apes expected the actor to do when he returned to search for the stone. </p>
<p>Strikingly, across several different conditions and contexts, when the actor was reaching toward the two boxes, apes consistently looked to the location where the actor falsely believed the stone to be. Importantly, their gaze predicted the actor’s search even before the actor provided any directional cues about where he was going to search for the stone.</p>
<p>The apes were able to anticipate that the actor would behave in accordance with what we humans recognize as a false belief.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140215/original/image-20161004-20205-oirolj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&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 red dots show the ape looking at the place where he anticipates the person will search – even though he himself knows the stone has been moved.</span>
<span class="attribution"><span class="source">MPI-EVA and Kumamoto Sanctuary, Kyoto University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Even more alike than we thought</h2>
<p>Our findings challenge previous research, and assumptions, about apes’ theory of mind abilities. Although we have more studies planned to determine whether great apes can really understand others’ false beliefs by imagining their perspectives, like humans do, the current results suggest they may have a richer appreciation of others’ minds than we previously thought.</p>
<p>Great apes didn’t just develop these skills this year, of course, but the use of novel eye-tracking techniques allowed us to probe the question in a new way. By using methods that for the first time assessed apes’ spontaneous predictions in a classic false belief scenario – with minimal demands on their other cognitive abilities – we were able to show that apes knew what was going to happen.</p>
<p>At the very least, in several different scenarios, these apes were able to correctly predict that an individual would search for an object where he falsely believed it to be. These findings raise the possibility that the capacity to understand others’ false beliefs may not be unique to humans after all. If apes do in fact possess this aspect of theory of mind, the implication is that most likely it was present in the last evolutionary ancestor that human beings shared with the other apes. By that metric, this core human skill – recognizing others’ false beliefs – would have evolved at least 13 to 18 million years before our own species <em>Homo sapiens</em> hit the scene.</p><img src="https://counter.theconversation.com/content/66224/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Krupenye receives funding from the National Science Foundation. </span></em></p>Realizing that others’ minds hold different thoughts, feelings and knowledge than your own was thought to be something only people could do. But evidence is accumulating that apes, too, have ‘theory of mind.’Christopher Krupenye, Assistant Research Professor, Max Planck Institute for Evolutionary AnthropologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/573212016-04-11T09:50:08Z2016-04-11T09:50:08ZHave humans always gone to war?<figure><img src="https://images.theconversation.com/files/117666/original/image-20160406-28966-1yhjms5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Yuttasak Jannarong / shutterstock</span></span></figcaption></figure><p>The question of whether warfare is encoded in our genes, or appeared as a result of civilisation, has long fascinated anyone trying to get to grips with human society. Might a willingness to fight neighbouring groups have provided our ancestors with an evolutionary advantage? With conflicts raging across the globe, these questions have implications for understanding our past, and perhaps our future as well.</p>
<p>The Enlightenment philosophers Thomas Hobbes and Jean-Jacques Rousseau had different visions of prehistory. Hobbes saw humanity’s earliest days as dominated by <a href="http://www.phrases.org.uk/meanings/254050.html">fear and warfare</a>, whereas Rousseau thought that, without the influence of civilisation, humans would be at peace and in harmony with nature.</p>
<p>The debate continues to this day. Without a time machine, researchers examining warfare in prehistory largely rely on archaeology, primatology and anthropology.</p>
<p>Earlier this year, details of one of the most striking examples of <a href="http://www.nytimes.com/2016/01/21/science/prehistoric-massacre-ancient-humans-lake-turkana-kenya.html?_r=1">prehistoric intergroup violence</a> were published – 27 skeletons, including those of children, had been found at Nataruk near Lake Turkana, Kenya. Blades embedded in bones, fractured skulls and other injuries demonstrated <a href="http://dx.doi.org/10.1038/nature16477">this had been a massacre</a>. The bodies were left, unburied, next to a lagoon on the lake’s former western shore, around 10,000 years ago.</p>
<p>The Nataruk finds are claimed as the <a href="https://theconversation.com/finding-a-hunter-gatherer-massacre-scene-that-may-change-history-of-human-warfare-53397">earliest evidence</a> for prehistoric violence in hunter gatherers. A 12,000-14,000 year-old cemetery at <a href="http://www.archaeology.org/news/2305-140714-egypt-conflict-cemetery">Jebel Sahaba</a> in Sudan was previously thought to be the first, but its date is less certain and <a href="http://www.scientificamerican.com/article/prehistoric-carnage-site-is-evidence-of-earliest-warfare/">some have claimed</a> that since the bodies were buried in a cemetery they were linked to a settlement, and not true hunter gatherers.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117653/original/image-20160406-28935-1rn7e3d.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">Two Jebel Sahaba victims. Pencils point to weapon fragments.</span>
<span class="attribution"><a class="source" href="http://blog.britishmuseum.org/2014/07/14/violence-and-climate-change-in-prehistoric-egypt-and-sudan/">Wendorf Archive, British Museum</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The evidence for warfare becomes clearer in the archaeological record after the beginning of the agricultural revolution around 10,000 years ago, when humanity moved from hunting and gathering to farming settlements. War may have existed before then, but there are few remains from the early days of <em>Homo sapiens</em>, and causes of death can be extremely difficult to ascertain from skeletons. This means that at the moment, the archaeology remains inconclusive.</p>
<h2>Chimps in combat</h2>
<p>Animal behaviour studies provide another means of exploring the debate.</p>
<p>Jane Goodall’s discovery that <a href="http://www.bbc.co.uk/earth/story/20150811-do-animals-fight-wars">chimpanzees make war</a> shocked the world. A group in Tanzania were observed beating members of a rival community to death, one by one, before <a href="https://books.google.co.uk/books/about/The_chimpanzees_of_Gombe.html?id=eloQAQAAMAAJ">taking over the defeated group’s territory</a>. Despite attempts to dispute Goodall’s findings, similar patterns of behaviour were later discovered in other groups, and evidence for warfare in one of our closest relatives became indisputable.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/a7XuXi3mqYM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">When chimps go to war.</span></figcaption>
</figure>
<p>However, bonobos, also known as pygmy chimpanzees, share as much DNA with us as chimps do, but are overall more peaceful, despite some anecdotal reports of aggression between groups. This is partly attributed to differences in the two species’ <a href="https://books.google.co.uk/books?id=fP0c4b3jbMYC&redir_esc=y">social systems</a>. For example, bonobos’ societies are female-dominated, which perhaps keeps male aggression in check, whereas chimpanzees’ social hierarchy is <a href="https://theconversation.com/early-humans-had-to-become-more-feminine-before-they-could-dominate-the-planet-42952">male-dominated</a>.</p>
<p>How did our last common ancestor behave? Were they like bellicose chimpanzees or peaceful bonobos? Although parallels between all three species are fascinating, using them to answer this question is difficult, as ultimately each followed its own evolutionary pathway.</p>
<p>But chimps demonstrate that war without civilisation does exist in a species similar to our own. Not only that, but similarities can be seen between chimpanzee and human hunter-gatherer warfare. For example, in both species, an <a href="http://www.ncbi.nlm.nih.gov/pubmed/22388773">imbalance of power and risk-averse tactics</a> are often a feature of attacks: a group of chimpanzees will assault a lone rival, and hunter-gatherer groups avoid pitched battles in favour of guerrilla warfare and ambushes.</p>
<h2>Two tribes</h2>
<p>Anthropologists, whose knowledge of “traditional” societies could provide clues as to how our ancestors behaved, also took sides in the Hobbes-Rousseau debate. Margaret Mead’s research on Samoan islanders led her to conclude that “<a href="http://users.metu.edu.tr/utuba/Mead.pdf">warfare is only an invention</a>”, which had not existed before civilisation, while <a href="http://www.nytimes.com/2013/02/17/magazine/napoleon-chagnon-americas-most-controversial-anthropologist.html?_r=0">Napoleon Chagnon</a> reported that among the Venezuelan Yanomamö, fighting and raids on enemy villages were commonplace. Both were criticised: Mead for overlooking widespread evidence of <a href="https://books.google.co.uk/books?vid=9780674548305&redir_esc=y">violence in Samoa</a>, and Chagnon for inappropriately using a society of small-scale farmers as a <a href="https://books.google.co.uk/books/about/Beyond_War_The_Human_Potential_for_Peace.html?id=kPsTTYEl86kC">proxy for prehistoric hunter-gatherers</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=303&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=303&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=303&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=381&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=381&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117678/original/image-20160406-29006-1iz7jfr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=381&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chagnon’s claim that the Yanomamö live ‘in a state of chronic warfare’ is hotly disputed.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/132084522@N05/16748243030/">Sam valadi</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Of course, any traditional society that anthropologists choose to study has still been exposed to outside influences. And they differ vastly from one another, not least in their participation in warfare. But early accounts suggest that lethal aggression did exist between some hunter-gatherer groups before their contact with other societies. </p>
<p>Waldemar Jochelson, who studied the Siberian <a href="http://www.biodiversitylibrary.org/bibliography/88108#/summary">Yukaghir</a> in the 1890s, described them as having persecuted their enemies like “wild beasts”. Similarly, the <a href="https://archive.org/details/TheAndamanIslandersAStudyInSocialAnthropology">Andamanese</a>, from isolated islands in the Bay of Bengal, had longstanding feuds between themselves and participated in dawn raids on enemy camps.</p>
<p>It’s difficult to conclude that prehistory was free from intergroup aggression. Military historian <a href="https://books.google.co.uk/books/about/War_in_Human_Civilization.html?id=3u1mPgAACAAJ">Azar Gat</a> and evolutionary psychologist <a href="https://books.google.co.uk/books/about/The_Better_Angels_of_Our_Nature.html?id=J7ATQb6LZX0C">Stephen Pinker</a>, among others, argue that warfare existed before the agricultural revolution. Pinker also claims that violence has overall decreased over the centuries. This may seem difficult to believe given the gloomy headline news in 2016, but such a zoomed-out view of history at least suggests hope for the future.</p>
<hr>
<p><em>A version of this article first appeared on the <a href="http://london-nerc-dtp.org/2016/03/04/conflict-over-conflict-have-humans-always-made-war/">NERC DTP blog</a>.</em></p><img src="https://counter.theconversation.com/content/57321/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Peacey receives funding from the London NERC Doctoral Training Partnership. </span></em></p>Archaeological remains, traditional tribes and conflict among chimpanzees can tell us much about the history of human warfare.Sarah Peacey, PhD in Ecological Systems of Cooperation, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/374912015-02-12T10:39:55Z2015-02-12T10:39:55ZApes make irrational economic decisions – that includes you<figure><img src="https://images.theconversation.com/files/71773/original/image-20150211-25679-rdtqd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A male bonobo who likely holds some irrational biases when it comes to economic decision-making.</span> <span class="attribution"><span class="source">Christopher Krupenye</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Just the other day I found myself in the waiting room of an automotive dealership. While my car was being serviced, I flipped through a product brochure. One ad for an oil change boasted that it would clean out at least 90% of used oil. Another for new brakes guaranteed maximum performance for twelve months. No one was advertising oil changes that leave behind 10% sludge, or brakes that begin to fail after only a year.</p>
<p>That’s because advertisers know that people are sensitive to how options are framed. We appraise goods more highly when their positive attributes are emphasized over their negative attributes, even if the details describe essentially the same situation (e.g., 90% clean versus 10% dirty).</p>
<p>This is called attribute framing, and it’s just one example of many irrational biases that humans exhibit when making economic decisions. Other examples include loss aversion (the preference for avoiding losses over acquiring gains), the endowment effect (people ascribe more value to something once they own it), and the reflection effect (people shift their risk preferences when dealing with gains versus losses).</p>
<p>These irrational biases are common, they’re really hard to overcome, and they have pervasive impacts on human market behavior. For example, people are more likely to spend a sum of money when it is <a href="http://dx.doi.org/10.1002/bdm.519">framed as a bonus</a> than when it is framed as compensation for a previous loss, like a rebate, which has implications for population trends in spending versus saving. Framing also influences people’s medical decisions, such as their tendency to undertake <a href="http://dx.doi.org/10.1007/s12160-011-9308-7">preventative measures in personal health care</a>. And it’s often leveraged by marketing agencies to improve sales. </p>
<p>Decision-making research can help economic institutions – built on the erroneous assumption that people will behave rationally – to account for predictable irrationality. It can also help us to design choice environments that lead people to make decisions that are better for them. For these reasons, Daniel Kahneman was awarded the <a href="http://www.nobelprize.org/mediaplayer/?id=531">Nobel Prize in Economics</a> in 2002, for his contributions (with the late Amos Tversky) to the understanding of irrational decision-making.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/71774/original/image-20150211-25718-1mm8q8t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most people have lots of experience in the marketplace, but our biases go much deeper than just what we’ve learned there.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Man_Shopping_at_the_Market_of_Antigua,_Guatemala.jpg">Christopher Crouzet</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Irrational… but why?</h2>
<p>Recent research attempts to understand where these biases come from. In most societies, humans interact with monetary markets from a young age; it seems intuitive that such exposure would be the principle source of decision-making strategies and biases. Culture and socialization must be involved, right? </p>
<p>But while human culture and market experience may play a role, it now seems clear that choice biases are much more deeply rooted in our biology. Previous investigations had shown that some other species – including <a href="http://dx.doi.org/10.1073/pnas.042491999">European starlings</a> and <a href="http://dx.doi.org/10.1086/503550">capuchin monkeys</a> – may also exhibit irrational biases such as framing effects. However, because these species are fairly distant relatives of humans, it is difficult to know if framing effects are shared as a result of common ancestry, or if they evolved independently in each species. To address this question, my colleagues, <a href="https://sites.google.com/site/alexrosati/">Alexandra Rosati</a> and <a href="http://evolutionaryanthropology.duke.edu/people?Gurl=&Uil=10341&subpage=profile">Brian Hare</a>, and I <a href="http://dx.doi.org/10.1098/rsbl.2014.0527">investigated attribute framing</a> in human beings’ closest living relatives, bonobos and chimpanzees.</p>
<p>We tested 23 chimpanzees at <a href="http://www.janegoodall.org/programs/tchimpounga-chimpanzee-rehabilitation-center">Tchimpounga Chimpanzee Sanctuary</a> in the Republic of Congo and 17 bonobos at <a href="http://www.friendsofbonobos.org/">Lola ya Bonobo sanctuary</a> in the Democratic Republic of Congo. In the study, we presented the apes with choices between several peanuts and some fruit. In the positive “gain” condition, we framed the fruit option positively. We initially presented it as a single piece of fruit, but, half the time that the apes chose it, we provided them with a second piece as well. The negative “loss” condition was identical, except that in this condition we framed the fruit option negatively. Here we presented the fruit option as two pieces of fruit, but, half the time the apes chose it, we took a piece back and only provided the ape with one.</p>
<p>Even though in both conditions apes who chose the fruit option received identical payoffs — a 50-50 chance of getting one or two pieces of fruit — they chose the fruit option significantly more when it was framed positively than when it was framed negatively: apes, too, make irrational economic decisions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/71775/original/image-20150211-25709-1ak7so6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This chimp’s irrational biases are likely similar to yours.</span>
<span class="attribution"><span class="source">Alexandra Rosati</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Irrational apes</h2>
<p>Because bonobos, chimpanzees, and humans all exhibit framing effects, it is unlikely that this trait evolved independently in each lineage. Instead, it appears that choice biases are evolutionarily ancient. They were probably present in the last common ancestor of bonobos, chimpanzees, and humans, which lived about six million years ago, and may even be much older. That framing effects are shared with several non-human species also suggests that these biases are deeply rooted in our biology, and can arise in the absence of experience with uniquely human monetary markets. Choice biases may have evolved in response to certain challenges in foraging ecology, or they may represent a by-product for selection on other traits, such as emotions. </p>
<p>Interestingly, we found that male apes were much more susceptible to framing than female apes were. In humans, gender differences in decision-making may result from a number of different factors, including gender-specific socialization, motivational differences, or experience with markets. Our results underscore the importance of studying large populations of non-human animals: since animals lack many uniquely human characteristics such as gender norms, animal studies can address more basic hypotheses about the origins of individual differences in human decision-making.</p>
<p>Our findings contribute to a large body of research on human decision-making that tells a pretty consistent story: choice biases are deeply ingrained, and they’re often really hard to overcome. Even the well-informed psychologist may find him- or herself getting duped by marketing sway on a daily basis – at the mall, the grocery store, the local coffee shop. While decision research can facilitate more effective marketing strategies, it can also be used by health professionals, banks, architects, and urban planners to build better environments, environments that make people happier and help them to make better decisions.</p><img src="https://counter.theconversation.com/content/37491/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Krupenye receives funding from the National Science Foundation, the National Academy of Sciences, and the United States Agency for International Development.</span></em></p>Just the other day I found myself in the waiting room of an automotive dealership. While my car was being serviced, I flipped through a product brochure. One ad for an oil change boasted that it would…Christopher Krupenye, PhD candidate in Evolutionary Anthropology, Duke UniversityLicensed as Creative Commons – attribution, no derivatives.