tag:theconversation.com,2011:/id/topics/gibbons-3879/articlesGibbons – The Conversation2021-09-08T01:31:01Ztag: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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Read more:
<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>
<figcaption>
<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/1651752021-08-01T20:07:27Z2021-08-01T20:07:27ZOrangutans, gibbons and Mr Sooty: what the origins of words in Southeast Asia tell us about our long relationships with animals<figure><img src="https://images.theconversation.com/files/413283/original/file-20210727-23-1td5b4j.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C4489%2C3058&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Forest creatures include some of humanity’s closest biological relatives. Due to human threats, they are also some of the most endangered animals on our planet. </p>
<p>Southeast Asia hosts many unique forest species, and many of our English words for forest creatures have their origins in Southeast Asian languages. What sound to English speakers like exotic loanwords are meaningful in their original languages. </p>
<p>By exploring the Southeast Asian etymologies of these names, we can understand how humans have maintained relationships of respect and affinity with forest creatures over the centuries. And, as these ecosystems are under grave threat, it is important to recognise a different way of relating to our most endangered relatives is possible.</p>
<p>Here, then, are the names of four of my favourite Southeast Asian forest species, and what we know about the origins of their names.</p>
<h2>Orangutan</h2>
<p>Orangutans belong to the great ape family, our closest biological relatives. This familial link is reflected in the word orangutan itself, which Malay speakers today can still recognise as deriving from the phrase <em>orang hutan</em>, which means “forest person”.</p>
<p>My <a href="https://brill.com/view/journals/bki/176/4/article-p532_5.xml">recent research</a> shows this term goes back over a thousand years, contrary to the <a href="https://www.etymonline.com/word/orangutan#etymonline_v_7108">conventional belief</a> it was coined by European visitors to Indonesia in the 17th century. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&rect=48%2C16%2C5446%2C3603&q=45&auto=format&w=1000&fit=clip"><img alt="Two orangutans, on a walk." src="https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&rect=48%2C16%2C5446%2C3603&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413278/original/file-20210727-20-1qr58zv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Orangutans are one of our closest relatives, as reflected in the Malay word <em>orang hutan</em>, or ‘forest person’.</span>
<span class="attribution"><span class="source">Jeremy Zero/Unsplash</span></span>
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<p>Surprisingly, the oldest surviving texts to use the word orangutan do not come from Sumatra or Borneo, where orangutans live today, but from the neighbouring island of Java. One of the oldest texts to mention orangutans is the 9th-century poem <a href="https://en.wikipedia.org/wiki/Kakawin_Ramayana">Rāmāyaṇa</a>. Written in the Old Javanese language, the poem describes “the orangutans, all bearded, climbing up”. </p>
<p>The word orangutan came into Old Javanese from another archaic language related to modern Malay. These early appearances show the word was circulating among the archipelago’s languages well over a thousand years ago. </p>
<p>This origin as the phrase “forest person” shows for many centuries Southeast Asians have viewed orangutans as human-like creatures residing in the forest.</p>
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Read more:
<a href="https://theconversation.com/orangutans-have-been-adapting-to-humans-for-70-000-years-99036">Orangutans have been adapting to humans for 70,000 years</a>
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<h2>Gibbon</h2>
<p>Gibbons are a type of ape ideally suited to swinging through the trees of Southeast Asia’s forests. The word gibbon entered European languages through French in the 18th century.</p>
<p>The French adopted it from the Malay word, <em>kebon</em>. But <a href="https://journals.openedition.org/lexis/4291">recent research</a> shows this Malay word originally came from a group of languages called Northern Aslian, spoken by indigenous communities in peninsular Malaysia. In Northern Aslian, it was probably pronounced <em>kebong</em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two gibbons, just chilling." src="https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413271/original/file-20210727-25-96q13d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Called gibbons in English, many Southeast Asian languages call this creature a <em>wak-wak</em>.</span>
<span class="attribution"><span class="source">Dušan veverkolog/unsplash</span></span>
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<p>Gibbon is a relatively rare term in Southeast Asia itself. It even fell out of use in Malay after the 18th century. More common in the region’s languages is the word <em>wak-wak</em>. Like orangutan, this word appears in the Old Javanese language as early as the 9th century and seems to derive from the crow-like sound gibbons make. </p>
<p>Through my research, I suggest the word <em>wak-wak</em> may have inspired the Middle Eastern legend of the <a href="https://en.wikipedia.org/wiki/Al-Wakwak#The_waqwaq_tree">Wakwak Tree</a>: a fantastical tree from a far eastern land whose fruits produced human heads and bodies which cried out “wak wak”. Folk memories of the gibbon’s piercing cry may have been transmitted across the Indian Ocean many centuries before the animal was identified by European science.</p>
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Read more:
<a href="https://theconversation.com/gibbon-song-may-be-music-to-the-ears-of-human-language-students-9528">Gibbon song may be music to the ears of human language students </a>
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<h2>Binturong</h2>
<p>Binturongs, also known in English as bearcats, are long and heavy tree-dwellers with large tails which they use to communicate. The word binturong first appeared in English in the 19th century as a borrowing from Malay. </p>
<p>Binturong also appears in <a href="https://8c6d8b5b-dee4-4f98-a03b-e09ddbea71e0.filesusr.com/ugd/fb0c2e_f84afbbcb72a444680ef1b8d7bef51ea.pdf">a wide variety of languages</a> from Sumatra and Borneo. This shows the word was coined early in the history of the region: probably several millennia ago, before these languages began to diverge. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A binturong having a nap, for a little treat." src="https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413274/original/file-20210727-23-1v5ug60.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The binturong does not leap from tree to tree, instead it makes its way along the ground.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>The earliest form of this word we know about was <em>maturun</em>, which probably meant “the one who descends”. It was inherited by many languages of Borneo and Sumatra, undergoing a series of regular sound changes. This is how the Malay form <em>benturong</em> evolved, which was later adopted by English.</p>
<p>Unlike many other tree creatures, binturongs do not nimbly leap among the branches. Rather, they tend to descend one tree and walk along the ground to another tree. The aptness of the name <em>maturun</em> shows us these early Southeast Asian communities were close observers of animal behaviour.</p>
<h2>Siamang</h2>
<p>The endangered siamangs are the largest type of gibbon. They have distinctive black coats and communicate with a complex system of booming calls. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="This siamang is giving a very big yell." src="https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413277/original/file-20210727-20-1bn142c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Siamangs communicate with complex booming calls.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>The <a href="https://journals.openedition.org/lexis/4291">ultimate origin</a> of the word is probably the word <em>ʔamang</em> (where the <em>ʔ</em> represents a glottal stop), found in several indigenous languages of the Central Aslian group.</p>
<p>When speakers of Malay borrowed the word <em>ʔamang</em>, they added the personal article <em>si</em>. Similar to an honorific like “mister”, <em>si</em> generally applies only to humans, or to animals, spirits or objects that are personified. Malay speakers later interpreted the word <em>amang</em> as “black”, giving rise to a folk etymology of <em>si amang</em> as meaning something like “Mr Sooty”.</p>
<p>The Malay expression was eventually treated as the single word <em>siamang</em>. For the Malays, the charisma exuded by siamangs entitled them to the status of personhood — another recognition of the affinity between humans and our forest ape relatives.</p><img src="https://counter.theconversation.com/content/165175/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Wayan Jarrah Sastrawan receives funding from the European Research Council Project #809994 DHARMA. </span></em></p>By exploring Southeast Asian etymologies, we get a glance into the centuries-old relationships between humans and forest creatures.Wayan Jarrah Sastrawan, Research associate, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/824172017-09-04T13:50:08Z2017-09-04T13:50:08ZHow animal genes go into battle to dominate their offspring<figure><img src="https://images.theconversation.com/files/183840/original/file-20170829-6710-pwups5.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">She'll be more like me than you.</span> </figcaption></figure><p>The burdens of becoming parents are often shared unequally between male and female animals. This is particularly true of species that give birth to live young, where male duties such as defending the breeding territory and building dens or nests rarely compare with the ordeals of pregnancy and labour. </p>
<p>You might have thought that animals just “accept” this imbalance and get on with it. But actually, they compete over how much each parent contributes. This isn’t like the competition to win a mate, with locking horns or displays of plumage. Instead this remarkable battle takes place at the level of the genes. </p>
<p>It now appears it may have evolved very early in animal evolution, perhaps among the first child-bearing animals. What is more, it may even help to explain why animals diversified into different lineages. </p>
<h2>Creatures great and small</h2>
<p>One arena in which this battle plays out is over the size of offspring. In principle it’s in both a mother’s and father’s interests to produce bigger newborns, since they are more likely to prevail in the struggle for food and survival. </p>
<p>Yet live-bearing females are more likely to die giving birth to larger offspring or become unable to reproduce again. Their mates needn’t care – unless they are likely to sire more broods together, as with humans and certain gibbons, wolves and mice. Otherwise, the males’ only concern is that their mate invests as much as possible in the offspring they produce together. </p>
<p>This common conflict of interests <a href="https://academic.oup.com/beheco/article/14/3/301/255814/Should-young-ever-be-better-off-with-one-parent">manifests</a> itself in <a href="http://www.jstor.org/stable/3677005?seq=1#page_scan_tab_contents">various ways</a> in nature. Males often desert pregnant females – from <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2535784/">birds</a> to humans, for example – thereby leaving them with the burden of bringing up the young. More rarely, in some normally biparental species females desert males. We see this in some <a href="https://www.nature.com/articles/ncomms9449">beetles</a>, for example.</p>
<p>The genetic battle mentioned previously is another manifestation of this conflict. The males of many species <a href="https://www.ncbi.nlm.nih.gov/pubmed/1997210">can manipulate</a> the genes that they pass on to their offspring so that they induce extra growth at the expense of the mother. As with desertion, this effectively hands the female a greater share of the child-bearing burden than is in her interests. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183842/original/file-20170829-6691-kt09h4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wallaby tonight?</span>
<span class="attribution"><a class="source" href="https://pixnio.com/fauna-animals/rats-mice-and-voles-pictures/deer-mouse-animal-peromyscus-maniculatus">Susan Freeman</a></span>
</figcaption>
</figure>
<p>It works as follows. When an embryo grows inside its mother, it consumes resources from her, signalling its metabolic needs along the way. These signals are influenced by certain hormones which either come from the growth genes of the mother or father. The males manipulate the females to deliver more resources by increasing the extent to which these hormones are produced through a chemical modification of their growth genes during sperm formation. </p>
<p>Females have evolved mechanisms to resist this. They can, for instance, pass on to their offspring what is known as a “silenced copy” of their own growth gene. This can counterbalance the male genes’ influence by making the embryo grow less than it otherwise would. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183843/original/file-20170829-7186-ut0sza.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">Cells dividing.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/human-animal-cells-on-colorful-background-329634500?src=PmIaXm5fWSUa9ID3Y_GSRw-1-51">Kateryna Kon</a></span>
</figcaption>
</figure>
<p>This battle is far less prevalent in truly monogamous species, including humans. This goes back to the fact that it becomes less genetically necessary where the two parents have a common interest in the female producing more offspring in future. </p>
<h2>Mouse control</h2>
<p>British microbiologist David Haig <a href="https://www.ncbi.nlm.nih.gov/pubmed/12728278">first proposed</a> in 2003 that this battle was more likely in organisms where one sex disproportionately contributes to the offspring, such as live-bearing species, particularly polygamous ones. This was used to explain the puzzling size of the offspring of crosses between oldfield mice and deer mice. </p>
<p>Separately, these species produce similar sized offspring. Yet crosses between male deer mice and female oldfield mice produce offspring that are larger, while the offspring from female deer mice and oldfield males are smaller. <a href="http://animaldiversity.org/accounts/Peromyscus_polionotus/">Oldfield mice</a> are monogamous while <a href="http://www.esf.edu/aec/adks/mammals/deer_mouse.htm">deer mice</a> are polyandrous, meaning one female mates with several males. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183841/original/file-20170829-6675-tjluy0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&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 deer mouse.</span>
<span class="attribution"><a class="source" href="https://pixnio.com/fauna-animals/rats-mice-and-voles-pictures/deer-mouse-animal-peromyscus-maniculatus">Pixnio</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Mimicking nature by artificially manipulating a growth gene called igf2, researchers <a href="https://www.ncbi.nlm.nih.gov/pubmed/12728278">showed that</a> these smaller and larger offspring were due to genetics. In further support of the theory, placental mammals and marsupials including kangaroos and opossums have since been <a href="https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-9-205">found to</a> have signs of female resistance to such male manipulation. </p>
<p>How early did this mechanism evolve? Researchers have previously <a href="https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-9-205">suggested</a> it arose in live-born mammals, and would therefore be absent in egg-laying mammals – such as the platypus – and other vertibrates. </p>
<p>But that raises questions about all the reptiles, amphibians and fish which produce live young, since the same genetic manipulation would equally be in their males’ interests. To see if it was present, <a href="https://risweb.st-andrews.ac.uk/portal/en/researchoutput/asymmetric-paternal-effect-on-offspring-size-linked-to-parentoforigin-expression-of-an-insulinlike-growth-factor(f577a130-e1eb-49c6-aafe-0f65fe7e8017).html">we looked at</a> a Mexican fish called the amarillo or dark-edged splitfin (see lead image). </p>
<p>Along with co-researchers <a href="https://www.researchgate.net/profile/Yolitzi_Saldivar">Yolitzi Saldívar</a> and <a href="http://www.langebio.cinvestav.mx/?pag=365">Jean Philippe Vielle Calzada</a>, we crossed males and females from two distant populations of these fish, since they would not have evolved mechanisms which cancel one another out in the way that a single population is likely to have. Sure enough, the size of the embryos was influenced by the specific combination of father and mother. We found signs of male manipulation and probable resistance from the females. </p>
<p>Though based on a small sample size, this suggests that these mechanisms evolved much earlier than previously believed: fish split from other vertebrates some 200m years before live-bearing mammals appeared, dating back about 370m years in total. Whether it comes from a single evolution or from several in different lineages, we cannot yet tell. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=605&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=605&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=605&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=760&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=760&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184393/original/file-20170901-27276-5i8lvq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=760&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 magic.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/evolution-biology-scheme-animals-isolated-on-293178890?src=TWxd03vTyW1iwPyOGI7ZqQ-1-39">Ekaterina</a></span>
</figcaption>
</figure>
<p>One consequence of these genetic battles is the effect on reproductive compatibility within a species. The genetic mutations aimed at manipulating offspring that take place among males and females within a certain group of a species are like a sort of arms race. The genes continually adapt and counter-adapt to one another to try and further their reproductive interests. </p>
<p>If they then mate with an animal from a different group of the same species, their genetic mutations can have made them sufficiently unmatched over time that they are unable to reproduce – thus they are now two species. If this started happening much earlier in evolution than was previously thought, it is likely to have influenced how different groups of live-born animals diverged, including lizards, sharks and mammals. From little acorns, these are the kinds of big oak trees that can grow.</p><img src="https://counter.theconversation.com/content/82417/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>Parents’ DNA try to manipulate one another in a bid to shape junior in their mould.Constantino de Jesús Macías García, Director of the Ecology Institute, Universidad Nacional Autónoma de México (UNAM)MIchael Ritchie, Professor of Evolutionary Biology and Speciation, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/714542017-01-18T18:58:43Z2017-01-18T18:58:43ZOnly 25 Hainan gibbons remain – what next for the world’s rarest primate?<figure><img src="https://images.theconversation.com/files/153249/original/image-20170118-3929-h107wy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hello, I'm 4% of the global population.</span> <span class="attribution"><a class="source" href="https://www.zsl.org/users/jessica-bryant">Jess Bryant</a>, <span class="license">Author provided</span></span></figcaption></figure><p>Most of the world’s primate species are threatened with extinction, according to a <a href="http://theconversation.com/60-of-primate-species-now-threatened-with-extinction-says-major-new-study-71441">disturbing new study</a>. But the threat is more urgent and critical for some species than others.</p>
<p>Of all 504 primate species, the rarest and most vulnerable is found only on one tropical island at the southern tip of China. The majestic and enigmatic <a href="http://www.iucnredlist.org/details/41643/0">Hainan gibbon</a> is confined to a single small patch of forest. Only around 25 remain.</p>
<p>Gibbons are small apes found throughout Southeast Asia. They live in forests, and are able to swing from tree to tree at incredible speeds. With all but one of the 19 recognised species officially listed as endangered or critically endangered their future is far from certain.</p>
<p>Not only is the Hainan gibbon (or <em>Nomascus hainanus</em>) the world’s rarest ape and rarest primate, it’s one of the rarest mammals of all. The entire species now consists of a single population of around 25 individuals, which separates into smaller social groups. The animals are restricted to just two square kilometres of remnant rainforest in Bawangling National Nature Reserve on Hainan Island in the South China Sea.</p>
<p>Sadly, numbers have plummeted over the past 50 years. As with so many other species, this precipitous decline is the result of decades of deforestation and an expanding human population which hunts the gibbons for food or poaches them for traditional medicines and the illegal pet trade. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=610&fit=crop&dpr=1 600w, https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=610&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=610&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=767&fit=crop&dpr=1 754w, https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=767&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/153258/original/image-20170118-26536-1dvbvy8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=767&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 gibbons are ‘sexually dichromatic’ … males are black and females are yellowy-brown.</span>
<span class="attribution"><a class="source" href="https://www.zsl.org/users/jessica-bryant">Jessica Bryant</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Southeast Asian animals are particularly vulnerable to these so-called anthropogenic pressures. The deforestation rate is the highest among the world’s tropical regions and alarmingly it is predicted that up to 85% of the biodiversity is likely to <a href="http://www.savethefrogs.com/threats/palm/images/2010-Sodhi-SE-Asia-biodiversity-conservation.pdf">disappear by 2100</a>.</p>
<h2>How to save the Hainan gibbon</h2>
<p>To protect a very rare species on the brink of extinction, you first have to understand its genetic health. Has the inbreeding that inevitably occurs in a very small population caused any unwanted traits, such as weakness to a disease, to become more common?</p>
<p>My former student Jessica Bryant recently led an <a href="http://onlinelibrary.wiley.com/doi/10.1111/mec.13716/abstract">assessment</a> of the genetic health of the Hainan gibbon. She gathered genetic samples of the current population from faeces and compared them to historical samples found in museums. Her work showed the Hainan gibbon has seen a major drop in genetic health, which can in turn lead to ill-health or fertility problems.</p>
<p>The study shows that genetic diversity has declined since the 19th century and even further within the last 30 years, representing declines of around 30% diversity from historical levels. </p>
<p>There is also evidence for a recent population bottleneck and an earlier bottleneck in the late 19th century when numbers were already pretty low. Such bottlenecks can occur when there is a dramatic reduction in the size of a population which leads to a reduction in the variation in the gene pool of that population, which in turn can affect the offspring of that population. </p>
<p>Those 25 gibbons are now closely related. Individuals will find even other social groups are filled with their half or full siblings, and inbreeding is likely to increase in the future – there simply aren’t enough of these gibbons for them to mate with anyone but a close relative.</p>
<p>This <a href="http://onlinelibrary.wiley.com/doi/10.1111/mec.13716/abstract">genetic study</a> and other <a href="http://onlinelibrary.wiley.com/doi/10.1002/ajp.22617/abstract">recent research</a> by an international team from UCL, the Zoological Society of London, Bawangling National Nature Reserve and Kadoorie Conservation China, suggest that the long-term recovery of the Hainan gibbon will require <a href="http://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-015-0430-1">intensive management</a> and new strategies may have to be developed to ensure their survival. </p>
<p>One option is to relocate some individuals to new areas of Hainan Island. But this is risky: without buy-in from local people and the authorities, a new gibbon population would be threatened by hunting or deforestation – the same forces that caused their demise in the first place.</p>
<p>These fascinating apes are clearly capable of grabbing the public’s imagination. When an entirely new species, the <a href="http://onlinelibrary.wiley.com/doi/10.1002/ajp.22631/full">Skywalker gibbon</a>, was discovered recently, the announcement enjoyed international attention.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"819662991721263104"}"></div></p>
<p>While the Hainan gibbon’s future may seem bleak, scientists across the world are working together to better understand the needs of extremely rare species. In the case of the Hainan gibbon, we just have to hope that this is enough to save them from being the first ape to go extinct.</p><img src="https://counter.theconversation.com/content/71454/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen Chatterjee receives funding from RCUK. </span></em></p>It risks becoming the first ape to go extinct.Helen Chatterjee, Professor of Gibbonology, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/95282012-09-23T20:33:59Z2012-09-23T20:33:59ZGibbon song may be music to the ears of human language students<figure><img src="https://images.theconversation.com/files/15449/original/8bnd5pqy-1347586610.jpg?ixlib=rb-1.1.0&rect=6%2C147%2C1017%2C571&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">It's easy for uninhibited humans to elicit vocal responses from gibbons by imitating their song.</span> <span class="attribution"><span class="source">Jerome Ludmann</span></span></figcaption></figure><p>Gibbons and humans have more in common than might immediately seem apparent. Among many behavioural traits shared by our two species is singing. Not just that – the songs of gibbons have the potential to teach us about the origin of our own human capacities. </p>
<p><a href="http://onlinelibrary.wiley.com/doi/10.1002/ajpa.22124/full">A recent study</a> in this field, published by Japanese researcher Takeshi Nishimura and colleagues in the American Journal of Physical Anthropology (AJPA), enjoyed the mixed blessing of widespread publicity. </p>
<p>Sadly, the methods and implications of the paper itself were badly misrepresented, with publications focusing on the joke or sensation value of singing gibbons.</p>
<p>I’m more interested in viewing the Japanese research in the wider context of <a href="http://en.wikipedia.org/wiki/Communication_Theory_as_a_Field">communication theory</a> and <a href="http://www.phys.unsw.edu.au/jw/speech.html">voice acoustics</a>. </p>
<h2>Background</h2>
<p>The Japanese research emerges from a framework in evolutionary studies (with papers such as <a href="http://www.nature.com/nature/journal/v438/n7066/full/438288a.html">this one</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/10859570">this one</a> and <a href="http://www.gibbons.de/main/papers/pdf_files/2000musicevol.pdf">this one</a> and <a href="http://books.google.com.au/books/about/On_the_origins_of_language.html?id=IehrAAAAIAAJ&redir_esc=y">here</a>) in which cross-species comparison permits speculation on the origin of human capacities.</p>
<p>Among the features of gibbon behaviour that correspond to humans are:</p>
<ul>
<li>monogamy, and the “nuclear family”</li>
<li>voice development in adolescence, especially in the male</li>
<li>the capacity for upright posture</li>
<li>vocal duetting in which male and female have acoustically complementary ranges, the adult male’s voice being lower than the female’s.</li>
</ul>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/azNzz_OyieQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>Walking instruments</h2>
<p>As <a href="http://www.sciencedirect.com/science/article/pii/S0378595598002238">Martin Braun</a> reminds us, all mammals are walking wind instruments. Research in acoustic communication addresses several key questions, among them:</p>
<ul>
<li>how sound is produced anatomically</li>
<li>whether it is <a href="onlinelibrary.wiley.com/doi/10.1196/annals.1360.003/full">learned</a> or stereotypical (the aspect of <a href="http://www.gibbons.de/main/papers/pdf_files/2000musicevol.pdf">acquisition</a>)</li>
<li>what social or <a href="http://www.biolinguagem.com/biolinguagem_antropologia/merker_2009_synchronouschorusing_humanorigins.pdf">intra-specific</a> purpose it serves</li>
<li>the nature of the <a href="http://www.ncbi.nlm.nih.gov/pubmed/11458831">neural networks</a> responsible for its perception and production</li>
</ul>
<h2>Back to the study</h2>
<p>The authors of the AJPA study are interested in all of these interrelated factors. But their paper focuses in particular on the way the distinct acoustic signal (or sound) of female gibbons is produced and what this tells us about the feedback loop between sound-production and self-perception in the subject.</p>
<p>At the core of the AJPA study is a series of experiments – first modelled on a computer and then carried out in the laboratory – designed to test a rather complex theory: that female gibbons have the ability to modify the configuration of their vocal tracts in order to amplify signals in a specific range. </p>
<p>In this range, their voices are capable of extraordinarily effective exploitation of limited anatomical means.</p>
<p>In other words, humans and gibbons have both evolved neural control over their respiratory tracts. It is therefore what the brain achieves that allows this level of performance: the vocal tracts themselves are not especially well-suited to their task!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=545&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=545&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15450/original/7vv2xdx9-1347586773.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=545&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">bergeycm</span></span>
</figcaption>
</figure>
<p>Where musical instruments such as flutes and trumpets have relatively fixed properties of <a href="http://en.wikipedia.org/wiki/Bore_(wind_instruments)">bore</a>, length and shape, the respiratory tracts of mammals are capable of modification in a variety of ways, including:</p>
<ul>
<li>lowering of the larynx </li>
<li>adaptation of the posture of the larynx</li>
<li>lifting of the soft palate</li>
<li>nasalisation</li>
<li>adaptation of the shape of the mouth</li>
<li>position and posture of the tongue, and</li>
<li>adaptation of the <a href="http://books.google.com.au/books/about/Singing_and_the_Actor.html?id=muLhDoBGydkC&redir_esc=y">opening of the lips</a>.</li>
</ul>
<p>Significantly, all of these are more-or-less involved in the production of the variety of sounds on which language tends to depend. </p>
<p>But the aim of the Japanese research was to explore whether gibbons “tune” the shaping of their throats, mouths and lips to the frequencies generated by their vocal folds.</p>
<h2>It’s a gas</h2>
<p>The researchers used helium in their experiments. The use of helium as the medium in which the gibbon vocalised is thus a means of ascertaining how the subject responded to the effect – which in humans tends to shift the resonant frequencies of the voice towards “squeaky” higher “<a href="http://www.phys.unsw.edu.au/jw/formant.html">formants</a>” (the acoustic response within an instrument – or voice – that defines the quality of sound, or timbre).</p>
<p>As in humans, gibbon vocalisation in the helium condition resulted in a shift of resonance to higher formants. Significantly, this was more pronounced in the higher range of the gibbon calls. This higher range marks their characteristic achievement of high-intensity vocal production able to carry over distance.</p>
<p>If this suggests parallels with human singing, it’s worth spelling out that <em>all</em> female gibbons achieve this remarkable capacity for self-amplification instinctively. Gibbon song is not learned – the ability is hard-wired. </p>
<p>By contrast, the opera singers to which the study’s title refers achieve a parallel ability only after careful training, and relatively few humans attempt this lest they resemble the dread example of <a href="http://en.wikipedia.org/wiki/Florence_Foster_Jenkins">Florence Foster Jenkins</a>, as per the video below. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/aIerl7VNkVo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>To hear the more effortlessly competent performance of a variety of gibbon species, a visit to Thomas Geissmann’s impressive <a href="http://www.gibbons.de/">gibbon research website</a> is warmly recommended.</p>
<h2>What comes next?</h2>
<p>The research done by Nishimura and team opens up some fascinating avenues for follow-up studies, including:</p>
<ul>
<li>replication with human subjects, both expert singers and non-singers</li>
<li>replication with other primate species (this is, apparently, underway)</li>
<li>play-back of the helium-condition calls to <a href="http://www.amentsoc.org/insects/glossary/terms/conspecific">conspecifics</a> (as well as being great vocalisers, gibbons are sophisticated listeners. The purpose of studying this area further would be to see whether other gibbons recognised in any way the humanly distorted recordings as gibbon-song)</li>
</ul>
<p>One of the most interesting things about gibbon/human voice comparison is how easy it is for suitably uninhibited humans to elicit vocal responses from gibbons by imitating their song. </p>
<p>This doesn’t work for many species – try it out on most dogs, cats, horses, chimpanzees and you will encounter failure … or worse.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iAmx_XdQky8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>But gibbons safely contained behind barriers are remarkably tolerant of human attempts at their song. I have personal experience of this at Twycross Zoo in the UK and Perth Zoo in Australia. My youngest son, when a boy treble, was able to imitate female gibbon calls with considerable accuracy.</p>
<p>This seems consistent with his ability to perform the high-lying solos in works such as <a href="http://www.youtube.com/watch?v=eh31j6L95Ok">Allegri’s Miserere</a> that require precisely the acoustic control explored in this study, and whose range conforms to that in which the gibbons sing most effectively. </p>
<p>So <a href="http://www.ncbi.nlm.nih.gov/pubmed/10085516">some investigation</a> of similarities with the voices of pre-adolescents in both species might also be of interest, especially with a view to tracing the means by which the ability is acquired in gibbons.</p>
<p>While the gibbon call is clearly acquired as a means of high-intensity transmission that permits communication across distance in dense rainforest vegetation, I have heard gibbons “rehearsing” precisely the same songs quietly: a solitary female in an isolated pen at Twycross Zoo in the UK; and two juveniles in quarantine under the supervision of their curator at Perth Zoo in Australia. </p>
<p>This adds additional dimensions of the roles of energy and pragmatics to the findings of this study: it illustrates that, while gibbons are capable, much like human sopranos, of ear-splitting volume, they can also achieve the same calls quietly. </p>
<p>In “engineering” terms this means they can control breath-flow alongside the “tuning” effects already described.</p>
<p>Investigation of these features would be of interest in order to tease out implications of this study for the <a href="http://www.amazon.com/Music-Language-Evolution-Nicholas-Bannan/dp/0199227349">evolution of human language</a>.</p><img src="https://counter.theconversation.com/content/9528/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Bannan 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>Gibbons and humans have more in common than might immediately seem apparent. Among many behavioural traits shared by our two species is singing. Not just that – the songs of gibbons have the potential…Nicholas Bannan, Professor in Music Education, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.