Tag Archives: bonobo

Apes signal ‘hello’ and ‘farewell’ when starting and exiting social interactions

Two bonobos grooming each other at the San Diego Zoo. Credit: Pixabay.

When it’s a simple “hi!”, a head nod, or a bow, humans across cultures signal acknowledgment of the person when engaging in conversation, acts of cooperation, or simply being in the presence of others. Likewise, we also signal disengagement with a gesture or vocalization signifying farewell. This complex social behavior has important implications beyond mere politeness, and apes seem to also purposefully signal the start and end of interactions, according to a new study.

“Investigating how humans and other primates use communication and gaze to coordinate joint action with others is fascinating! It is exciting because it happens on-the-fly – a spontaneous coordination process that bears witness of our sense of joint commitment. Watching two friends having lunch together tells much about how they value each other and their commitment to each other. We thought that, by looking at how apes get into and out of natural interaction of play and grooming, we might find a similar external structure of joint action as in humans; a way by which joint commitment could be studied naturally,” Raphaela Heesen, a postdoctoral researcher at Durham University in the United Kingdom, told ZME Science.

In order to act together to fulfill a common goal, whether it’s building a new house in their community or launching a rover on Mars, two or more people must be jointly committed to acting as a body. This mutual sense of obligation is known as joint commitment, and philosophers and scientists consider it integral to human cooperation, society at large, and the historical success of our species in shaping the world.

But is joint commitment unique to humans? Perhaps not. At least some aspects of it, such as signaling engagement and disengagement, may be shared by apes.

“In humans, joint commitment is not just a product (a mental state) but also a process, or “interactional achievement”. What it means is that, in order for us two to even establish a feeling of mutual obligation (a product of joint commitment) we have to go through an interactional process that requires mutual coordination (in the form of mutual gaze or exchange of communicative signals, in our case language). We first need to establish joint commitment in an entry phase, then maintain it, and later agree to dissolve it in an exit phase. Entry and exit phases of a joint action can thus be used as markers for joint commitment; therefore, entry and exit phases in non-human animal species can be analyzed to investigate joint commitment. In a species that doesn’t communicate before getting into an interaction and while getting out of it, this could mean that there is probably no commitment involved,” Heesen said.

Heesen and colleagues recorded interactions among chimpanzee and bonobo groups in order to investigate whether these closely related species also shared joint commitment features. They got the idea after considering anecdotal evidence that this may be the case. For instance, when two bonobos were interrupted during their grooming, they later used gestures to resume the interaction with each other. Was this a singular event? That’s what the researchers set out to investigate — and it turns out that both chimps and bonobos signal greetings and farewells.

“Our most important finding was that chimpanzees and bonobos do very frequently mutually gaze at each other and communicate when entering and exiting from joint actions.” Heesen said.

To arrive at these conclusions, the researchers analyzed more than 1,200 interactions within five different groups of bonobos and chimpanzees housed in zoos. Bonobos exchanged entry signals and mutual gaze prior to playing 90% of the time and chimps 69% of the time. Exit signals were even more common, with 92% of bonobo and 86% of chimpanzee interactions featuring them.

These greeting and farewell signals included gestures like touching each other, holding hands, butting heads, or gazing at each other.

This video shows two chimpanzees entering a social grooming activity. Madingo (male) approaches Macourie (female) and both mutually gaze at each other (start of the entry phase). Macourie then uses a series of gestures, first attempting to grab Madingo, then touching his shoulder and back (gestures), and finally, grab-pulling him at his hips (gesture). Macourie then starts grooming him on his shoulder once he is sitting in close proximity. The entry stops with the first grooming movements, upon which the main body starts. Credit: Raphaela Heesen and Emilie Genty.

Furthermore, when engaging in entry and exit phases, the apes took into consideration familiarity and power dynamics. Bonobos who were familiar with each other tended to have shorter entry and exit phases, if they existed at all. That’s pretty similar to how humans engage with close friends since they are not afraid to come off as rude or impolite. The shared social history allows them to more rapidly cut to the chase.

“The second most important finding was that, in bonobos, the phases seemed more affected by social dimensions, particularly social bond strength, compared to chimpanzees. Intriguingly, the pattern mirrored what we find in humans and what some people define as “social etiquette” or “politeness”: when interacting with a good friend, you are less likely to put effort into communicating politely. In bonobos, a similar pattern is evident in the structure of the joint action phases. Bonobos produce fewer and shorter entry and exit phases when initiating or terminating a joint action with a closely bonded conspecific as compared to when initiating or terminating a joint action with a weakly bonded one; this pattern was not apparent in chimpanzees by contrast,” Heesen explained, adding that this doesn’t necessarily mean that apes have notions of “politeness” or “social etiquette”, or at least not in the way humans perceive them. “It could also be explained by the fact that apes care about themselves and want to avoid risks with unfamiliar partners,” she added.

Interestingly, the degree of familiarity and strength of social bonds did not seem to have an impact on the social entries and exits among chimps. This may be owed to the strict hierarchical nature of chimp communities, whereas bonobos tend to be more egalitarian.

There are still many unknowns concerning the origin and evolution of joint commitment, but this study marks a step further in unraveling this behavior that’s so central to human society. Next, the researchers plan to investigate joint commitment in other great apes, such as orangutans and gorillas, as well as more distantly related species like wolves or dolphins.

“I think generally there is much to explore from the way in which primates communicate when coordinating joint action. And one way this can be done is by comparing how different species get into and out of social interactions with peers. There may well be differences in the complexity with which some species do so; perhaps other, more distantly related species do not even communicate when exiting from a social encounter; we advocate more studies to investigate this process,” Heesen concluded.

The findings appeared in the journal iScience.

Scientists identify new species of truffle eaten by apes in Congo

Bonobos, an endangered great ape species only found in the Democratic Republic of the Congo, have inadvertently discovered a new species of truffle, according to a new study. Researchers believe that it could have significant culinary value and is also proof of the vast reserves of undescribed fungal diversity in the region.

Credit Flickr.

While truffles are commonly eaten by humans in high-end restaurants, they are also enjoyed by our closest relatives. Bonobos, which share 98.7% of our genetic makeup, regularly savor the truffle, named by the researchers as Hysterangium bonobo in honor of the monkeys that found it in the first place.

“Truffles aren’t just for gourmet chefs, they’re also for our closest relatives,” Matthew Smith, an associate professor in the University of Florida department of plant pathology and co-author of the paper, said in a statement. “There’s so much to learn about this system, and we’re just scratching the surface.”

Prized for their aromas, truffles are often essential elements of ecosystems, and H. bonobo makes no exception. It plays an important role in enabling trees to absorb nutrients from the soil and supports the diet of animals. Previous studies have reported bonobos eating truffles but this is the first to identify a specific species.

Local communities have long known of the existence of the truffle. They call it “simbokilo,” a Bantu name. The bonobos likely locate it by catching its smell floating through the air or by digging in the soil and sniffing their hands. The truffles are small enough to be eaten whole by the great apes and share features of those with high culinary value.

Alexander Georgiev, co-author of the study and a primatologist at Bangor University, gathered samples of the truffles after he observed a group of bonobos eating them in Congo’s Kokolopori Bonobo Reserve. He hoped a collaborator could identify the species, not knowing it was undescribed. While he had never seen bonobos freed on truffles, his team of field assistants instantly knew what was happening.

“It’s important to realize that even though this paper presents a ‘novel’ interaction and the description of a ‘new’ species for the Western scientific community, in reality, these are interconnected associations that have been known about for untold generations by the locals in the region,” added Todd Elliott, the study’s lead author, in a statement.

The study was published in the journal Mycologia.

Bonobos, our closest relatives alongside chimps, seem have a similar disgust system to humans'. Credit: University of Kyoto.

Bonobos may get disgusted too — which may help trace the origin of this behavior in humans

Bonobos, our closest relatives alongside chimps, seem have a similar disgust system to humans'. Credit: University of Kyoto.

Bonobos, our closest relatives alongside chimps, seem to have a similar disgust system to humans’. Credit: University of Kyoto.

It’s not just humans that get grossed out by putrid stenches and moist textures — bonobos do it too. According to a new study, for these gentle primates, having access to clean food sources is important and they will generally stay away from grub in close proximity to feces, soil, or bad smells. We share 98.7% of our DNA with bonobos, more than we do with any other creature on Earth, which leads to many similarities between bonobos and humans. Perhaps, the origin of disgust might be traced back as a result of findings like these.


Isn’t it funny how we all share the same bodily and emotional reactions? That’s no accident as most can be traced back to some evolutionary adaptation. Scientists think that disgust is an adaptive system that evolved to protect animals from parasites and various pathogens, as a counter-strategy meant to mitigate infections. These threatening organisms often congregate in rotten food or bodily fluids, which we humans find repellent. The same reaction seems to exist in other animals. For instance, grazing ungulates prefer to feed away from areas contaminated by feces, and our primate cousins seem to employ similar strategies as well.

In 2017, researchers at the Primate Research Institute, Kyoto University, reported the first experimental evidence that potential exposure to biological contaminants (feces, blood, semen) can influence feeding decisions in chimpanzees (Pan troglodytes troglodytes). Now, the same team, led by primatologist Cecile Sarabian, has come to similar conclusions regarding bonobos (Pan paniscus).

The researchers carried out a series of experiments in which captive bonobos were presented with various food choices: food contaminated with feces or soil, chains of food items linked to a contaminant, previously contaminated food, or only the odors of feces or rotting food.

The bonobos were happy to eat the clean, uncontaminated food but stayed away from any contaminated food like it was the plague. The closer a foodstuff was to a contaminant, the stronger the repulsion. Conversely, when food was farther away from a contaminant, the primates’ sensitivity waned. “Some individuals just refused to take any food rewards when the latter involved contamination,” according to Sarabian.

In another experiment, the bonobos were found to be less likely to touch or taste substrates, or even to use tools to achieve such a goal, when confronted with foul smells. These are precisely the reactions that you would expect to see in an animal with a system of disgust set in place.

“These findings build up on the growing literature in primates and other animals, helping us to see convergences and differences in the disgust response across taxa at a behavioral and physiological level, as well as what may have driven such differences through evolutionary times,” Sarabian told ZME Science.

As a side note, it wasn’t quite easy setting up the experiments. Due to new sanctuary policies, the researchers were no longer allowed to perform the experiments on isolated subjects, which led to some unexpected outcomes.

“When I first started by presenting feces replica instead of real conspecific feces, bonobos gathered around and some bold individuals started touching it and sniffing their fingers just after. Then, it became a “thing”, they all wanted to touch and sniff the fake poop — not showing much interest for the piece of brown sponge used as the control. Eventually, after repetitive investigations, bonobos may have realized the trick and ended up stealing the fake poop… playing with it — Fieldwork FAIL!” Sarabian said.

Bonobos stayed away from foods in close proximity to feces. Credit: Kyoto University / Cecile Sarabian.

Bonobos stayed away from foods in close proximity to feces. Credit: Kyoto University / Cecile Sarabian.

Interestingly, infants and juveniles showed much less precaution when handling food close to contaminants, much like human infants behave. Although the infants might get sick as a result of this kind of behavior, the researchers hypothesize that there are some advantages like building their immune system during a critical time in their development.

Previously, Sarabian and colleagues also studied Japanese macaques, which also seem to elicit disgust responses.

“The most intense disgust response I ever witnessed across different field sites and species goes to a Japanese macaque from Koshima island, who accidentally stepped on a poop, and subsequently crossed all the beach jumping on her two hands and remaining foot to find a dead tree trunk where she meticulously rubbed her soiled foot,” Sarabian recounted.

Despite the similarities between human and bonobo disgust responses, there seem to be some key differences. We are pretty reluctant to ingest novel food that looks different from what we’re used to — that’s weird, basically. This kind of behavior — the inclination to stay away from or be cautious around new foods — is called neophobia but Bonobos don’t seem to share it, not at the same intensity at least. During experiments, bonobos stuffed themselves with fruits they had never seen before with no apparent sign of hesitation.

VIDEO: A plum, apple, and papaya were arranged in front of bonobos. Since apples are rare in this environment avoidance of it would indicate food neophobia. In fact the bonobos had not trouble eating each fruit, exhibiting food neophilia. At least for novel fruit. Credit: Kyoto University / Cecile Sarabian. 

As an important caveat, the researchers have not proven that bonobos express disgust, or not in a way that we can recognize, at least.

“Our results look as though the bonobos’ behaviors are driven by disgust, only because we know human behavior in similar situations is driven by disgust, but this is only a functional resemblance, and we cannot know what the bonobos are thinking or feeling at the time they are responding in our experiments,” co-author Andrew MacIntosh, Associate Professor at the University of Kyoto, wrote in an email.

That being said, the researchers plan on continuing to study bonobos and other primates with the intention of investigating the origins of disgust in humans. Sarabian is currently conducting fieldwork in the equatorial forest of the Democratic Republic of Congo, where she is investigating the link between mouthing behaviors and parasite infection in wild bonobos.

“The first step is to test whether the behavioral responses to things that humans find disgusting are similar in other species, like the bonobos tested here. Substances like feces and rotten foods are more or less universal disgust elicitors in humans, so we expect to see similar responses in nonhuman primates. If our responses to these things is seen in other species, it means that they likely have a shared evolutionary history that predates the appearance of humans. Furthermore, humans are pretty visual, so we expect that seeing disgusting things will elicit a ‘disgust response’. But we also know that we exhibit similar responses/feelings when we smell feces or rotten foods, so perception of ‘disgusting things’ is multi-modal,” MacIntosh said.

“Observing similar responses to disgust elicitors in other species, including through different sensory modalities like sight, smell, and touch, can assess whether our own responses are shared with other species,” he added.

The findings appeared in the journal Philosophical Transactions of the Royal Society B.


Unlike humans, bonobos prefer jerks

As the saying goes, you can tell the character of a person by how he treats those who can do nothing to him. If someone’s mean to a waiter, that’s a big turn-off. No one likes a bully — no one except for bonobos, that is.

A new study reports that bonobos, who along with chimps are our closest relatives, don’t really care much for avoiding bullies.

Bonobos are very social. Image credits: Wcalvin / Wikipedia.

Studies have shown that infants as young as six months can distinguish between good and bad guys. Brian Hare, an associate professor of evolutionary anthropology, and doctoral student Christopher Krupenye, both from Duke University, wanted to see if the same carries out for bonobos.

Study after study has shown how human-like bonobos can be, with a study just a few months ago reporting that they sometimes perform random acts of kindness — just like humans. They also tend to be less aggressive than humans, so researchers were expecting bonobos to prefer calmer, more peaceful individuals. However, this wasn’t really the case.

Researchers carried out two experiments. First, they showed the bonobos 24 bonobos animated videos of a Pac-Man-like shape struggling to climb a hill. Then, another similar silhouette appears. Sometimes, it would help the protagonist to the top, and other times it would kick him back down.

Credits: Krupenye and Hare.

Next, they watched a live skit in which a human drops a stuffed animal, somewhere out of reach. A second person tries to give the toy back, but a third person steals it. The bonobos were then given the choice of receiving a piece of apple from the helper or from the thief.

In both scenarios, bonobos were able to distinguish the good guys from the jerks, but unlike humans, they tended to pick the jerks.

This was a bit surprising for scientists, who believe that the bonobos interpret rudeness as a sign of domination. Basically, they think that jerks behave this way because they can get away with it as they’re more powerful — and they choose powerful individuals as their allies. Teaming up with bullies could mean they have a lower chance of being bullied themselves.

Perhaps even more interestingly, this could indicate that the innate tendency of humans to shun bullies may be unique to our branch of the primate family tree. It may be exactly this that allowed us to form a society and develop in such large groups — something which other animals might not be capable of.

“In the animal kingdom, there are all kinds of acts of cooperation. But we don’t see things like building skyscrapers or the establishment of institutions,” says comparative psychologist Christopher Krupenye.

“Humans might have this unique preference for helpers that is really at the heart of why we’re so cooperative,” said Krupenye, now a postdoctoral fellow at the University of St Andrews in Scotland.

The study was published in the latest issue of Current Biology.

Credit: Wikimedia Commons.

If you want a glimpse of an ancient human ancestor, the bonobo might be the closest you’ll get

Some eight million years ago, modern humans and the common chimp/bonobo lineages split. Since then, modern humans have evolved to look extremely different from this common ancestor and a new study suggests the bonobos have changed the least. In fact, bonobos have changed very little ever since they split again from chimps some two million years ago, hence scientists say the gentle bonobos serve as a remarkable case of evolutionary stasis.

Credit: Wikimedia Commons.

Credit: Wikimedia Commons.

A living ancestor

You often hear about how chimps share 99% of their genes with humans. That’s certainly true but chimps (Pan troglodytes) aren’t alone. In 2012, Max Planck scientists found bonobos (Pan paniscus) and chimpanzees share 99.6% of their DNA, despite the two species split some two million years ago, perhaps after the Congo River formed and divided an ancestral population into two groups.

But though chimps and bonobos share almost as much DNA with humans, Bernard Wood, professor of human origins at George Washington University, says the bonobos are the closest we are to a ‘living’ ancestor.

Wood and colleagues “carried out systematic dissections of cadavers of most extant primate taxa to gather evidence about how soft tissue – in particular striated muscle – gross morphology differs among living primates, with a focus on the great apes.” They were fortunate enough to have seven Bonobo cadavers donated by the Antwerp Zoo in the Netherlands. This was a very rare opportunity given bonobos’ status as an endangered species.

Armed with data from previous studies, the researchers made an anatomical comparisson between the muscles of the three species.

Differences between head muscles of common chimpanzees, bonobos and modern humans. There are many differences between bonobos and modern humans (right) concerning the presence/absence of muscles in the normal phenotype (shown in colors and/or with labels in the human scheme). Credit: George Washington University.

Differences between head muscles of common chimpanzees, bonobos and modern humans. There are many differences between bonobos and modern humans (right) concerning the presence/absence of muscles in the normal phenotype (shown in colors and/or with labels in the human scheme). Credit: George Washington University.

The study suggests there’s a mosaic evolution of the three species. In other words, some features are shared by humans and bonobos while others by humans and common cimpanzees, and still others by the two ape species. It might be no coincidence that this anatomical mosaical nature may be related to the similar molecular mosaic evolution betwen the three species. Bonobos share about 98.7% of their DNA with humans, roughly just as much as with the chimpanzee, but a small bit of our DNA, about 1.6%, is shared with only the bonobo, but not chimpanzees.

Ongoing debates might also be settled by the new data. Some have suggested bonobos are just highly derived chimpanzees but the present study refutes this idea. It shows bonobos do not display a single muscle or muscle feature that is unique within primate or hominoid evolution. Overall, however, the bonobo has more similar muscles to humans than chimpanzees have. This suggests that the bonobo is more closely linked, anatomically, to human ancestors than common chimpanzees.

Understanding how we’re different from our closest relatives will ultimately help us establish what makes us humans and will also lead to a better understanding of human health.

Scientific reference: Rui Diogo, Julia L. Molnar, Bernard Wood. Bonobo anatomy reveals stasis and mosaicism in chimpanzee evolution, and supports bonobos as the most appropriate extant model for the common ancestor of chimpanzees and humans. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-00548-3.

Just like humans, old bonobos suffer from long-sightedness

A new study has revealed that bonobos, some of humanity’s closest relatives, suffer from similar eye problems in old age. This would seem to indicate that long-sightedness isn’t a problem of modern lifestyle, but something completely different.

This photo shows Fuku (female: 17 years old) grooming Hoshi (female: 32 years old). She needs only 5 to 10 centimeters between her fingers to eyes to get pin-focus for grooming. Credit: Heungjin Ryu (CC BY-NC 4.0)

Long-sightedness affects the ability to see nearby objects. You may see very well distantly, but closer objects can be out of focus — especially when reading or using a computer. While it can affect people of all ages, people over 40 years old are especially vulnerable to it. The modern lifestyle is often blamed for this condition.

We spend too much time focusing our eyes on things which are close-by, we tire them working on computers and we don’t spend enough time in open spaces where our eyes can relax. But new studies have cast that theory into doubt by studying our closest relatives: chimps and bonobos. Previous studies have indicated that chimps also get long-sightedness in old age, and now, a new study has found the same thing in bonobos.

“One day, I was with another researcher and observed the oldest male bonobo Ten (TN) grooming Jeudi (JD),” Ryu recalls. “TN had to stretch his arm to groom JD, and only when he found something on JD’s body would he come close to remove it using his mouth. It was funny to see how he groomed.”

But while it may have been funny to them, it really is a struggle for bonobos and might have serious consequences for their survival. So scientists started studying exactly how their eyesight fares by using digital photographs to measure the grooming distance of 14 wild bonobos of various ages, ranging from 11 to 45 years old. The measurements showed that the distance increased exponentially with age — in other words, older bonobos groomed from further away, just like a human would hold the book a bit further away.

“The results we found were very surprising even for us,” Ryu says. “When I started to collect data, I did not expect that age could be such a strong predictor of long-sightedness.”

This also indicates that modern lifestyle isn’t to blame for the decline in our eyesight, or at least not entirely. There’s something else causing a decline in eyesight, a process deeply rooted in our evolutionary history.

Journal Reference: Heungjin Ryu, Kirsty E. Graham, Tetsuya Sakamaki, Takeshi Furuichi. Long-sightedness in old wild bonobos during grooming. Current Biology, November 2016 DOI: 10.1016/j.cub.2016.09.019 |

Chimps interbred with bonobos, surprising study reveals

Just like early humans interbred with Neanderthals, it seems that our closest relatives also had some fun times with each other. According to a new genetic analysis, one percent of the chimpanzee genome comes from bonobos.

Chimps and bonobos are the only two species in the genus Pan and they represent our closest genetic relatives. Both species inhabit the Congo jungle in sub-Saharan Africa, and in some areas their habitats are really close to each other – though separated by the Congo river. Despite being intelligent and exhibiting several human traits, they are endangered and often hunted or kept as captives. This is the main reason why the study was carried out – not to identify connections between the two species, but to help preserve the chimpanzees.

“This is the largest analysis of chimpanzee genomes to date and shows that genetics can be used to locate quite precisely where in the wild a chimpanzee comes from,” said Dr Chris Tyler Smith, from the Wellcome Trust Sanger Institute.

“This can aid the release of illegally captured chimpanzees back into the right place in the wild and provide key evidence for action against the captors.”

Still, the research did yield some interesting biological info. Researchers found that the two species diverged from a common ancestor between 1.5 and 2 million years ago. But some chimp populations had a surprise: bonobo DNA embedded in their own genes.

“We found that central and eastern chimpanzees share significantly more genetic material with bonobos than the other chimpanzee subspecies. These chimpanzees have at least 1% of their genomes derived from bonobos. This shows that there wasn’t a clean separation, but that the initial divergence was followed by occasional episodes of mixing between the species.

Many biologists didn’t even consider interbreeding between the two species so this came as quite a surprise, but the results are pretty clear. There is a clear resemblance between what study on our own species have found — early humans and Neanderthals diverged from the same ancestor, but they also interbred for a long time. Non-African humans carry within them a significant part of Neanderthal DNA. Dr Tomàs Marquès-Bonet, leader of the study from the Institute of Biological Evolution (University Pompeu Fabra and CSIC), Barcelona, said:

“This is the first study to reveal that ancient gene flow events happened amongst the living species closest to humans — the bonobos and chimpanzees. It implies that successful breeding between close species might have been actually widespread in the ancestors of humans and living apes.”

Journal Reference: Chimpanzee genomic diversity reveals ancient admixture with bonobos. Science, 2016; 354 (6311): 477-481 DOI: 10.1126/science.aag2602

Bonobos use flexible “baby communication”

Researchers have found that just like babies, bonobos exhibit a type of communication in which they use the same sound with different intonations to say different things. They use these high pitch “peeps” to express their emotions.

Bonobo (Pan paniscus) mother and infant at Lola ya Bonobo

Bonobo (Pan paniscus) mother and infant at Lola ya Bonobo

Formerly called pigmy chimps, bonobos are endangered great apes found only south of the Congo River and north of the Kasai River, in the humid forests of Congo. Like all great apes, they exhibit some similarities to humans; they can pass the mirror recognition test, they can communicate through vocalizations and they can also communicate using lexigrams (geometric symbols). Now, a new study has found that they use the same call to mean different things in different situations, and the other bonobos have to take the context into account when determining the meaning – something only observed in humans, especially babies.

Lead author Zanna Clay was studying these endangered apes in their native Congo when she started noticing their peeps – she and her colleagues quickly understood that the same sounds were being used in different circumstances. Dr. Clay, a biologist at the Université de Neuchâtel, was also surprised by the frequency of these calls.

“Bonobos peep in just about every context you can imagine,” Clay says in an interview. “They peep when they’re traveling, feeding, grooming, resting, nest building, playing, aggression, alarm – you name it. This is striking because bonobos also produce many other calls which are much more fixed in their apparent use and function.”

Along with colleagues from the University of Birmingham, they started to look at these calls in more detail. Their complexity quickly became apparent.

“It became apparent that because we couldn’t always differentiate between peeps, we needed to understand the context to get to the root of their communication,” she said.

Other animals used fixed calls – individual vocalizations specific to a certain situation. But using function-flexible calls can make for more complex communication.

“In humans, protophones are the building blocks of speech, in that they vary in function across different emotional states and contexts,” Clay says. “This contrasts with fixed calls in human babies, such as laughter and crying, which resemble typical primate calls. The peep seems to be a rather exceptional call in the bonobo repertoire in its degree of flexible usage.”

This represents an important evolutionary moment of transition – bonobos are shifting to flexible calls and more advanced speech. Given enough time, their speech might develop into something similar to human communication.

“Although humans are unique in terms of our amazing speech and language capacities,” Clay says, “the foundations underlying these abilities appear to be already present in the last common ancestor we share with great apes. The findings suggest the existence of an intermediate stage between fixed vocal signalling seen in most primate calls and fully fledged flexible signalling in humans.”

According to previous research, humans developed this ability some 6-10 million years ago. It appears that features like this one are deeply enrooted in the primate lineage.


Claudine Andre, the founder of Lola ya bonobo, and the “friends of the bonobos of the Congo’, an NGO which works in DRC with Timbo, one of her best bonobo friends. Photo courtesy of Christian Ziegler.

Bonobo anatomy offers clues on how our body evolved

A pair of anthropologists compared the anatomical features o bonobos to those of homo sapiens and other apes to infer any clues that might help us understand how we evolved to look the way we do.

Claudine Andre, the founder of Lola ya bonobo, and the “friends of the bonobos of the Congo’, an NGO which works in DRC with Timbo, one of her best bonobo friends. Photo courtesy of Christian Ziegler.

Claudine Andre, the founder of Lola ya bonobo, and the “friends of the bonobos of the Congo’, an NGO which works in DRC with Timbo, one of her best bonobo friends. Photo courtesy of Christian Ziegler.

You might have seen those Neanderthal or Homo Erectus casts in a museum a bunch of times, only to wonder: “oh, so that’s how they look like.” Well, not entirely so. Remember, there’s no preserved tissue of any of our ancestors, some of whom lived as long ago as 2.8 million years ago (H. habilis). All the muscle, tissue or hair you see reconstructed in museums or documentaries are made by professional artists under the guidelines of biologists and anthropologists. Based on bone shape, wear and other features, we can roughly infer how other hominids might have look like, but that’s about it. There’s only so much you can tell from looking at fossils. There’s no tantalizing evidence pointing to how much body fat or muscles a typical Homo Erectus used to have, or what the organs looked like for that matter.

Adrienne L. Zihlmana of University of California, Santa Cruz and Debra R. Bolter of Modesto College, California sought to understand how we evolved anatomically as a species by looking at our closest relative: the bonobo (Pan paniscus). But as much as we’re strikingly similar, the bonobos differ from us in one important aspect: violence. While humans and the common chimpanzee wage war and kill each other, bonobos do not. “There has never been a recorded case in captivity or in the wild of a bonobo killing another bonobo,” notes anthropologist Brian Hare.

“We go to this sanctuary and we play these fun problem-solving games with them to just try and get inside their heads and figure out exactly how they think,” says Vanessa Woods, Hare’s colleague. “They’re wonderful animals to be related to. It’s a shame so few people have heard of them.”

To learn more about the bonobos, the two anthropologists dissected the bodies of 13 bonobos who died of natural causes over a period of thirty years. The researchers carefully took notes pertaining to their anatomical features, like fat and muscle percentage. Some key findings include: a lot less body fat than humans, even in those cases where the bonobos lived in captivity and were sedentary; more muscle mass in the upper body and less in the lower body, i.e. the legs; finally, bonobos have a lot more skin than humans.

Percentage of muscle distribution to upper and lower limbs in Pongo pygmaeus, Gorilla gorilla, P. paniscus, and H. sapiens. Credit: (c) Adrienne L. Zihlman

Percentage of muscle distribution to upper and lower limbs in Pongo pygmaeus, Gorilla gorilla, P. paniscus, and H. sapiens. Credit: (c) Adrienne L. Zihlman

Now, since the bonobo is more of a cousin than an ancestor, what ca we learn from these anatomical features? Well, it’s safe to say that at some point the genus Homo and the genus Pan split from a common ancestor. With this in mind (and there’s quite a deal of speculations), the researchers suggest that the primary differences between humans and bonobos can be accounted to the crucial period when early humans began walking upright. This naturally called for more fat, more leg muscles, and less upperbody muscles. They also believe that we humans have less skin because as we moved around and moved faster on two legs—our skin developed an ability to sweat as a means to keep cool and that led to thinner skin, they report in Proceedings of the National Academy of Sciences.  This “comparison of soft tissues between Pan and Homo provides new insights into the function and evolution of body composition,” the researchers write in the study abstract. 

This classy looking chap is a bonobo - a great ape species which is widely overlooked and often forgotten. A new research suggests bonobos are losing vital habitat due to both forest fragmentation and poaching. (c) Crispin Mahamba/Wildlife Conservation Society-DRC Program

New study adds new dimension to the threats posed to the Bonobo – the ‘forgotten ape’

This classy looking chap is a bonobo - a great ape species which is widely overlooked and often forgotten. A new research suggests bonobos are losing vital habitat due to both forest fragmentation and poaching. (c) Crispin Mahamba/Wildlife Conservation Society-DRC Program

This classy looking chap is a bonobo – a great ape species which is widely overlooked and often forgotten. A new research suggests bonobos are losing vital habitat due to both forest fragmentation and poaching. (c) Crispin Mahamba/Wildlife Conservation Society-DRC Program

The Bonobo, or Pygmy Chimpanzee as it was once called, is one of our closest relatives, yet one of the most poorly studied. This fascinating ape displays unique social order and other highly interesting traits, and unfortunately like all great apes it is also endangered. Very little is known, however, about how many specimens are there in the wild or how exactly threatened the bonobos currently are. In the most extensive study of its kind to date, a team of international scientists modeled bonobo habitat based on scarce and ready-available data in order to find what the true scale of these threats is. The results reveal that the bonobos are quickly running out of space and their habitat is far narrower and spaced apart than previously believed.

“This assessment is a major step towards addressing the substantial information gap regarding the conservation status of bonobos across their entire range,” said lead author Dr. Jena R. Hickey of Cornell University and the University of Georgia. “The results of the study demonstrate that human activities reduce the amount of effective bonobo habitat and will help us identify where to propose future protected areas for this great ape.”

“For bonobos to survive over the next 100 years or longer, it is extremely important that we understand the extent of their range, their distribution, and drivers of that distribution so that conservation actions can be targeted in the most effective way and achieve the desired results,” said Ashley Vosper of the Wildlife Conservation Society. “Bonobos are probably the least understood great ape in Africa, so this paper is pivotal in increasing our knowledge and understanding of this beautiful and charismatic animal.”

A great ape society based on love

One of mankind’s closest living relatives, the bonobos share more than 98% of our DNA or nearly as much as chimpanzees. Actually, they closely resemble chimpanzees with the key physiological distinction that they’re smaller hence the pygmy nickname. The similarities more or less end here though; while chimpanzees are loud, competitive and aggressive, the bonobo apes live in a peaceful, matriarchal and egalitarian society. In times of seldom conflict and tension or when promoting bonding or sharing alike, the bonobos choose to address all of these through sexual behavior. Like in human society, for Bonobos sex transcends reproduction and is seen as a means of expression and passionate caring. With this in mind, bonobos serve as a powerful symbol of peace and cooperation. Unfortunately, these great apes are listed as highly endangered, according to the  IUCN Red List.

Bonobos, like their chimpanzee cousins, live in “fission-fusion” societies and therefore tend to vary in party size. Communities of up to 100 bonobos will usually split into small groups when searching for food during the day and come back together to sleep at night. Also, bonobos are considered the most vocal of great apes as they frequently use complex vocal communication accompanied by hand gestures. Animal behaviorists believe these vocal fixtures play a pivotal role in bonobo society, helping them communicate with one another where favorite food sources are located, as well as the quality and preference of these foods function of vocal sequences.  The voice itself, or better said howl since it’s not articulated,  is quite pleasant to the human ear being melodic and high pitched, in contrast to the deeper and more guttural vocalizations of a chimpanzee.

This undated handout photo provided by Friends of Bonobos shows mother and a baby bonobo in the Congo. (c) Vanessa Woods/Duke University/AP

This undated handout photo provided by Friends of Bonobos shows mother and a baby bonobo in the Congo. (c) Vanessa Woods/Duke University/AP

Bonobos live only within the lowland forests of the Democratic Republic of Congo; a country beset by war, filled with corruption and where sadly poachers have their way. Previously, it was thought they inhabit approximately 500,000 square kilometers (193,000 square miles) of tropical forest south of the Congo River and north of the Kasai River, where the average rainfall is between 63 and 80 inches per year. This latest assessment shows, however, that bonobo range has dwindled greatly.

It’s impossible for the researchers to check every bonobo nest in the country, but what they attempted to do is the next best thing: create a model. Based on data of bonobo nest locations collected by numerous organizations between the years 2003-2010, the researchers identified 2364 “nest blocks,” with a block defined as a 1-hectare area occupied by at least one bonobo nest. Where nests weren’t identified in a region before, these interpolated based on previous data. The group then tested a number of factors that addressed both ecological conditions (describing forests, soils, climate, and hydrology) and human impacts (distance from roads, agriculture, forest loss, and density of “forest edge”) and produced a spatial model that identified and mapped the most important environmental factors contributing to bonobo occurrence.

Just a quarter of bonobo range is suitable

Results showed that the most obvious marker that skewed bonobo presence was human intervention through agriculture. The major takeaway that the study offers however is that only 28 percent of the bonobo range is classified as suitable for the great ape, and of these suitable area only 27.5 percent of it is located in existing protected areas. So technically, only a quarter of the bonobo range is actually suitable for them.

“Bonobos that live in closer proximity to human activity and to points of human access are more vulnerable to poaching, one of their main threats,” said Dr. Janet Nackoney, a Research Assistant Professor at University of Maryland and second author of the study. “Our results point to the need for more places where bonobos can be safe from hunters, which is an enormous challenge in the DRC.”

Dr. Nate Nibbelink, Associate Professor at the University of Georgia, added: “The bonobo habitat suitability map resulting from this work allows us to identify areas that are likely to support bonobos but have not yet been surveyed, thereby optimizing future efforts.”

“By examining all available data provided by a team of leading researchers, we can create the kind of broad-scale perspective needed to formulate effective conservation plans and activities for the next decade,” said Dr. Hjalmar S. Kühl of the Max Planck Institute for Evolutionary Anthropology.

“The fact that only a quarter of the bonobo range that is currently suitable for bonobos is located within protected areas is a finding that decision-makers can use to improve management of existing protected areas, and expand the country’s parks and reserves in order to save vital habitat for this great ape,” said Innocent Liengola, WCS’s Project Director for the Bonobo Conservation Project and co-author on the study.

Hopefully, with this new found knowledge at hand, conservation efforts spearheaded by NGOs and the local government might help save the bonobos and offer them the minimum decency and respect any living being deserves by not invading their homes.

“The future of the bonobo will depend on the close collaboration of many partners working towards the conservation of this iconic ape,” said Dr. Liz Williamson of the IUCN/SSC Primate Specialist Group and coordinator of the action planning process which instigated the bonobo data compilation for this study.

The results were reported in a paper published in the journal Biodiversity and Conservation. The team was comprised of researchers from the University of Georgia, University of Maryland, the Wildlife Conservation Society, ICCN (Congolese Wildlife Authority), African Wildlife Foundation, Zoological Society of Milwaukee, World Wildlife Fund, Max Planck Institute, Lukuru Foundation, University of Stirling, Kyoto University, and other groups.

Apes comfort each other ‘like humans’

Not as unique as we thought

An “emotionally competent” young ape rushes to hug another juvenile that has just been attacked.

I think the idea of animals doing something “like humans” is pretty outdated as it is – so many things that we thought were unique to us have been proven to be if not common than at least… not unique. Here’s just a short list of those things (you can easily find more):

Again, this is just a short list, but I hope I’ve made my point. Now, researchers working at an African sanctuary have found that young bonobos cuddle and calm their friends when they went through a trauma.

Socially competent bonobos

'Emotionally competent' bonobos were more likely to console other apes

‘Emotionally competent’ bonobos were more likely to console other apes

Researchers capture footage showing “emotionally competent” young apes rushing to hug other juveniles that were screaming after being attacked. Bonobos who were more empathic were more likely to jump and help relief other members.

“It’s almost as if one first needs to have one’s own emotional house in order before one is ready to visit the emotional house of another.”, said Prof Frans de Waal from Yerkes National Primate Research Center at Emory University in Atlanta. “This is true for children, and apparently also for bonobos.”

To make this even more interesting, Dr Clay also oberved another interesting aspect. The Olola ya Bonoboo sanctuary is home to many bonobo victims of bushmeat hunting – apes which were taken from their families at a very young age. These youngsters are cared for by humans, and after what usually takes a few years of rehabilitation, they are transfered to an enclosure with another group of bonobos. Dr. Clay reported that just like human orphans, orphan bonobos have a much harder time managing their emotions.

After a fight, Dr Clay explained, these orphan apes “would be very upset, screaming for minutes”.

“Mother-reared juveniles would recover and snap out of it in seconds,” she added.

Over 370 post-distress interactions were observed; some 318 cause by fighting and 55 that were caused by throwing tantrums. Researchers found that typically, the better a bonobo was at controlling his own emotions, the more likely he was to console his friends – a trend which is also observed in humans.


Apparently, this news caused quite a stir, and many people were surprised that apes behave in such a “human like” fashion.

“But they are our closest relatives, so personally I would argue that the best guess of their emotions is that they’d be the same as our own in a similar situation.”, explained Richard Byrne, a professor of evolutionary psychology at the University of St Andrews.