Tag Archives: chimpanzee

Chimpanzee mother tends her son’s wound by applying insects

This photo shows a chimpanzee female, Roxy, applying an insect to a wound on the face of an adult chimpanzee male named Thea. Credit: Tobias Deschner.

In 2019, Alessandra Mascaro, a volunteer with the Ozouga Chimpanzee Project, was filming an adult female chimpanzee named Suzee, who was interacting with her little daughter Sassandra and adolescent son, Sia. Then, at some point, something very peculiar happened. As Suzee was inspecting a wound on Sia’s foot, the chimp mother dashed her fingers under a leaf, caught something which she put in her mouth, pressed it between her lips, then took it out of her mouth and applied it to the wound of her son’s leg.

That something turned out to be insects, part of a wound-tending behavior that turned out to be quite widespread among other members of Suzee’s group. Although Suzee wasn’t hurt herself, her actions indicate that she recognized Sia was in trouble and took action to help her son heal. It’s a remarkable display of prosocial behavior in a non-human species and a sign of empathy.

Self-medication is surprisingly common among animals

It’s not unheard of for animals to self-medicate. Birds, bees, lizards, elephants, and chimps know to ingest certain plants or use them in seemingly unusual ways when they need them. For instance, some lizards respond to a bite by a venomous snake by eating a certain root to counter the venom and baboons in Ethiopia eat the leaves of a plant to combat the flatworms that cause schistosomiasis. Amazingly, sparrows and finches collect nicotine-heavy cigarette butts to reduce mite infections in their nests, showing animals have learned to use pharmacological ingredients even in artificial environments.

But most examples of animal self-medication are documented among great apes. In 1996, American biologist Micahel Huffman first saw a parasite-ridden, constipated chimpanzee in Tanzania chew on the leaves of a noxious plant it would normally avoid. By the next day, the chimp seemed to have completely recovered.

Suzee’s family is an example of another form of self-medication. It’s the first time that researchers have seen chimps apply insects to themselves and others in order to treat wounds.

“We found out that there is a lot of research concerning self-medication, which is the use of secondary plant parts or other non-nutritional substances to medicate themselves. However, so far it was never observed that animals catch and apply insects to treat wounds and also treat the wounds of their conspecifics,” Simone Pika from the Institute of Cognitive Science at the Universität of Osnabrück told ZME Science.

Prosocial behavior among great apes

After studying Mascaro’s amazing video, Pika and colleagues from the Ozouga team decided to monitor the group of chimpanzees in Loango National Park in Western Gabon for other instances of this behavior. It wasn’t easy to find and follow the chimp community, which lives in challenging environments, including forests, savanna, beaches, and swamps. “In addition, there are also forest elephants around, which can be dangerous,” Pika said.

But the researchers rose to the challenge and, over the next 15 months, documented 76 cases of chimps applying insects to wounds on both themselves and others. We don’t know yet what type of insects were applied, nor what their medicinal properties could be but Pika says “there are many studies showing that insects have antibacterial, antiviral, anti-fungal, anti-inflammatory and probably also soothing substances.”

Most likely, the insects serve to provide some pain relief. The Ozouga researchers plan on conducting more research in order to identify the insects being used, as well as document who is applying insects to whom in the chimpanzee group. In the process, they may also learn more about how this behavior first started and how it’s transmitted among the members of the group.

“We know that the majority of our adult males and many females are using the behavior, suggesting that they have learned it. Furthermore, an insect application event always creates a lot of attention in the surrounding chimpanzees, meaning they all approach and want to look at what is going on,” Pika said.

But for the researcher, the most striking thing about this study is the prosocial nature of it all. Helping, sharing, and comforting are complex social behavior that benefits others rather than ourselves, and which we generally ascribe to humans. But if these findings are any indication, we are definitely not alone.

“There are still people doubting prosocial skills in other animals besides humans and I think this example is so clear that it will finally also convince the skeptics,” Pika said.

The findings appeared today in the journal Current Biology.

Gorillas and humans treat their territory the same way, study finds

Gorillas seem to be very territorial, a new study shows, but they seem to understand ‘ownership’ similarly to humans.

Image credits Christine Sponchia.

The study is the first one to demonstrate that gorillas are territorial in nature, unlike previous assumptions. At the same time, the findings suggest that these primates can recognise “ownership” of specific regions in a very human-like manner, and will attempt to avoid contact with other groups while travelling close to the centre of neighbouring ranges in order to avoid conflict.

Which seems like the polite thing to do!

My turf, your turf

“Gorillas don’t impose hard boundaries like chimpanzees. Instead, gorilla groups may have regions of priority or even exclusive use close to the centre of their home range, which could feasibly be defended by physical aggression,” says lead author Dr. Robin Morrison, who carried out the study during her PhD at the University of Cambridge

“Our findings indicate that there is an understanding among gorillas of ‘ownership’ of areas and the location of neighbouring groups restricts their movement.”

Because their home ranges often overlap, and because they’re quite peaceful to other gorilla groups, gorillas have long been assumed to be non-territorial. This would make them markedly different from chimpanzees, who have no qualms about using extreme violence to protect their home turf.

The new study, however, suggests that gorillas are, in fact, territorial animals — but they also display quite nuanced behavior around the issue. The study focused on monitoring the movements of the western lowland gorillas (Gorilla gorilla gorilla) at the Odzala-Kokoua National Park in the Republic of Congo. These animals are notoriously difficult to track, so the team placed video cameras at 36 feeding “hotspots” across a 60-square-km area of the park to help them monitor eight different groups of gorillas.

The team reports that the movements of each group are strongly influenced by the location of their neighbours, being less likely to feed at a site visited by another group earlier that day. They would also try to steer clear of the centre of their neighbours’ home range.

“At the same time groups can overlap and even peacefully co-exist in other regions of their ranges. The flexible system of defending and sharing space implies the presence of a complex social structure in gorillas,” explains Dr Morrison.

“Almost all comparative research into human evolution compares us to chimpanzees, with the extreme territorial violence observed in chimpanzees used as evidence that their behaviour provides an evolutionary basis for warfare among humans,” says co-author Dr Jacob Dunn from the Anglia Ruskin University (ARU).

Dr. Dunn adds that the findings showcases our similarities with the wider primate family, not just with chimpanzees. Observing the way gorillas interact over territory — setting up small, central areas of dominance and wider liminal areas of tolerance of other groups — could help us better understand early human populations. Just like us, he explains, gorillas have the capacity to both violently defend a specific territory and to establish between-group ties that lead to wider social cooperation.

The paper “Western gorilla space use suggests territoriality” has been published in the journal Scientific Reports.

Great apes can tap into other points of view to anticipate actions

One seemingly defining human feature is our ability to second guess other people’s actions based on our own experience. By stepping into someone else’s shoes, we briefly occupy the same mental space. Psychologists call this the ‘theory of mind’ and the scientific community has debated for decades whether non-human animals can access it.

Credit: Pixabay.

Not until long ago, research suggested that infants were incapable of recognizing false beliefs in others which ingrained the impression that other apes, often seen at the same level of intelligence as a toddler, would also be incapable of wrapping their heads around the concept. But then in 2007, a groundbreaking study showed that four-year-old infants can do this — we just had to look closer.

The researchers repeated a famous experiment known as the Sally-Ann test which involved two dolls: Sally has a basket in front of her, while Anne has a box. Children first watch Sally put a block inside her basket. Sally then leaves and Ann comes into the picture, who moves the block in the box. As early as four years old, children know which container Sally will start looking for her block when she returns (the basket), even though they recognize it’s the wrong place to look. Later, researchers showed that children as young as two years old could do the same using eye-tracking technology because infants couldn’t voice their thoughts.

Since then, scientists have published compelling evidence that some apes, monkeys, and even parrots are capable of this ability. Now, a recent study adds further weight to this assertion.

Japanese scientists led by Dr. Fumihiro Kano at Kyoto University used 29 chimpanzees, 4 orangutans, and 14 bonobos, whom they split into two groups.

“Nonhuman animals, such as humans’ closest ape relatives, have succeeded in some theory-of-mind tasks; however, it remains disputed whether they do so by reading others’ minds or their behavior. Here, we challenged this behavior-rule account using a version of the goggles test, incorporated into an established anticipatory-looking false-belief task with apes,” the authors wrote in the journal PNAS.

Each group was first acquainted with two different barriers that looked the same from afar. Upon closer inspection, however, one barrier was opaque while the other was see-through.

Next, the apes had to watch a movie while their eye-tracking technology was fixed on them. The movie showed a human watching another human dressed in an ape costume as they placed an object inside a box. The human ‘watcher’ then hid behind a screen (the same as the barrier encountered by each group) while the ape removes the object and transfers it to a second box. The movie ends with the human exiting his hiding spot and reaching is hand midway between the two boxes.

If the apes in the study have a theory of mind anything like us, those who were familiar with the opaque barrier should have expected the human in the movie to look for the object in its original hiding place. The apes who knew the barrier was transparent should have been aware that the human also knew that the object had been transferred. This is exactly what the glances of the apes demonstrated.

The study showed that although both groups of apes experienced the same video, their anticipation of the protagonist’s actions were opposite, in accordance with their past experience with the barrier. This blind-test is extremely difficult and the fact that the apes past it suggest that our evolutionary cousins also have a theory of mind.

“We provide evidence that, in the absence of behavioral cues, apes consulted their own past experience of seeing or not seeing through a novel barrier to determine whether an agent could see through the same barrier,” the authors concluded in the study’s abstract.

Chimps also love to eat crabs, new study shows

While chimps’ diet is mainly vegetarian, they will sometimes supplement it with other types of nutrients. Turns out, crabs are also on the menu.

“Our study is the first evidence showing that non-human apes regularly catch and eat aquatic fauna,” says Kathelijne Koops, one of the study authors.

Chimpanzee fishing for crabs. Image credits: Kathelijne Koops.

Chimps eat a lot of plants, including fruits, leaves, nuts and seeds. They’ll also occasionally eat meat or even honey, which they have advanced methods of accessing. However, they’re still largely vegetarian, with animal products accounting for around 6% of their nutrient intake. A new study, however, found a new entry on the chimps’ menu: crabs.

Koops and colleagues found that chimps in the rainforests of the Nimba Mountains in Guinea searched for streams in the forest. After finding a stream, they scratch its surface, churning the riverbed and looking for crabs to eat.

Chimps ate crabs all ear round, regardless of whether there were ripe fruits available as an alternative. Their preference for crab was also equal in the dry and rainy season, as even during the dry season, there’s still enough water to host some crabs. The one thing that was counterbalanced by crabs was ant consumption: the more insects they ate, the fewer crabs, and vice-versa, suggesting that crabs and ants have similar nutritional value for chimps.

This wasn’t the only surprise, however.

“Female chimpanzees and their offspring fished for crabs more often and for longer than adult males, which we had not expected,” says anthropologist Koops. A possible explanation for this is that the nutrients in the crabs (especially fatty acids) are better for maternal and infant health, but it’s unclear if this is the case. Mothers were also found to teach their children the crab fishing technique.

These findings don’t just shed new light about our closest living relatives, but they could also teach us a thing or two about our own evolution. Anthropological research has shown that for hominins, aquatic fauna has become a more and more important source of nutrition over time, with one theory stating that consuming aquatic fauna helped evolve bigger, more potent brains, as they contain high amounts of unsaturated fatty acids.

“The aquatic fauna our ancestors consumed likely provided essential long-chain polyunsaturated fatty acids, required for optimal brain growth and function,” said first author Dr Kathelijne Koops.

For now, however, this is still a theory. What is clear is that chimps sure love their crab.

Journal Reference: Koops et al. Crab-fishing by chimpanzees in the Nimba Mountains, Guinea. Journal of Human Evolution. Doi: 10.1016/j.jhevol.2019.05.002.


Wild chimpanzees learned how to crack open tortoises — and they’re sharing the knowledge among themselves

Turns out that you can teach an old chimpanzee new tricks — more to the point, they’ll teach themselves.


Image credits Simon Bardet.

A team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig and the University of Osnabrück (both in Germany) report that wild chimpanzees in the Loango National Park, Gabon, have learned how to crack open and eat tortoise. The chimps will smash tortoises against tree trunks in order to get through their tough shells. This is the first time such behavior has been observed and, the team adds, it likely is a cultural one — meaning the chimps share this knowledge inside their groups and through generations.

Breaking their fast

“We have known for decades that chimpanzees feed on meat from a variety of animal species, but until now the consumption of reptiles has not been observed,” says Tobias Deschner, a primatologist at the Max Planck Institute for Evolutionary Anthropology.

“What is particularly interesting is that they use a percussive technique [i.e. smashing] that they normally employ to open hard-shelled fruits to gain access to meat of an animal that is almost inaccessible for any other predator.”

The team observed this behavior in the newly-habituated Rekambo community. Ten chimpanzees engaged in this behavior a total of 38 times over the dry season, the team explains, a period when other food such as fruit is abundant. Tortoise-whacking seems to be a highly social activity for the chimpanzees, the team explains.

“Sometimes, younger animals or females were unable to crack open the tortoise on their own. They then regularly handed the tortoise over to a stronger male who cracked the tortoise’s shell open and shared the meat with all other individuals present,” says Simone Pika, first author of the study and a cognitive scientist at the University of Osnabrück.

The authors also detail an exceptional case in which an adult male, who was sitting on his own up in a tree, cracked a tortoise, ate half, and hid the rest in a tree fork. The male climbed down from the tree, built his nest in another one nearby, then returned the next morning to eat the leftover tortoise. This particular case suggests that chimps can plan for the future, says Pika, which is quite an exciting find.

“The ability to plan for a future need, such as for instance hunger, has so far only been shown in non-human animals in experimental and/or captive settings. Many scholars still believe that future-oriented cognition is a uniquely human ability. Our findings thus suggest that even after decades of research, we have not yet grasped the full complexity of chimpanzees’ intelligence and flexibility.”

“Wild chimpanzee behaviour has been studied now for more than 50 years and at more than ten long-term field sites all across tropical Africa,” Deschner adds. “It is fascinating that we can still discover completely new facets of the behavioural repertoire of this species as soon as we start studying a new population.”

Pika says that chimpanzees offer a unique window into our own history, and that observing them in the wild can teach us a lot about our own evolution.

The paper “Wild chimpanzees (Pan troglodytes troglodytes) exploit tortoises (Kinixys erosa) via percussive technology” has been published in the journal Science Reports.

Chimpanzees grooming.

Human interference is destroying chimpanzee culture, a new paper reports

Chimpanzees stand out among other non-human species for their diverse behavior and culture. But, that may not keep true for long, as human activity is essentially destroying that culture, a new study reports.

Chimpanzees grooming.

Young chimpanzees grooming one another.
Image credits Tambako The Jaguar / Flickr.

All great apes, chimpanzees (Pan troglodytes) included, are feeling immense pressure as a result of human activity destroying their habitats. Tropical rainforests and savannas (prime habitats for many of these species) are especially-taxed, as they’re being cleared away to make room for croplands, infrastructure, or real estate.

So, it’s not surprising that loss of wildlife is mostly looked at through the lens of biodiversity loss — the decline in the overall number of species or genetic diversity in an ecosystem. However, that’s only part of the picture, a new paper explains. We should also look to what toll our activities take on behavioral diversity in the wild, which is a rarely-looked-at facet of biodiversity.

How chimps are faring

The team, led by Hjalmar Kühl and Ammie Kalan of the Department of Primatology at the Max Planck Institute for Evolutionary Anthropology and the German Centre for Integrative Biodiversity Research (iDiv), worked with a dataset detailing the behavior of 31 chimpanzees from 144 different social groups or communities spread across the ape’s entire geographic range.

Part of this data was available from previous research, and the rest was recorded by the team at 46 locations over the last 9 years, as part of the Pan African Programme (not to be confused with the EU’s Pan-African Programme). The data focused mainly on extraction and consumption of termites, ants, algae, nuts, and honey, tool use, along with the use of stones, pools, and caves for shelter among several other factors. Such activities, the team writes, are passed down socially in chimpanzee communities and vary from group to group, essentially forming a ‘cultural’ background.

The occurence of each type of behavior was analyzed in regards to an overall measure of human impact at each site. This figure aggregates several factors (such as human population density and, road, river, and forest cover) that indicate the level of disturbance and the degree of habitat change caused by human activity.

“The analysis revealed a strong and robust pattern: chimpanzees had reduced behavioral diversity at sites where human impact was high,” explains Kalan.

“This pattern was consistent, independent of the grouping or categorization of behaviors. On average, chimpanzee behavioral diversity was reduced by 88 percent when human impact was highest compared to locations with the least human impact.”

Population size and integrity play a key role in the maintenance of cultural traits in humans, the team writes. It likely functions the same way in chimpanzee groups, they add. Another possible cause for the observed reduction in behavioral diversity may stem from the chimps avoiding conspicuous behaviors that may draw in hunters, such as nut cracking.

Habitat degradation (and its associated resource depletion) may also limit opportunities for social learning in chimpanzee communities — which would prevent them from passing down traditions between generations. The team also cites climate change as a likely cause, as it may influence the growth cycles of the chimps’ food resources, making them unpredictable.

However, it’s overwhelmingly likely that the observed effects are caused by a combination of these factors.

“Our findings suggest that strategies for the conservation of biodiversity should be extended to include the protection of animal behavioral diversity as well,” says Kühl.

“Locations with exceptional sets of behaviors may be protected as ‘Chimpanzee cultural heritage sites’ and this concept can be extended to other species with high degree of cultural variability as well, including orangutans, capuchin monkeys or whales.”

The paper “Human impact erodes chimpanzee behavioral diversity” has been published in the journal Science.


Chimps get grossed out too, pointing to the origins of disgust in humans

Despite sometimes engaging in some pretty gross behavior, chimps don’t like yicky things either, a new paper reveals. The findings offer a glimpse into the roots of our own sense of disgust.


Image via Pixabay.

Chimps aren’t the best-mannered animals out there. In the wild, they have been observed to pick out seeds from feces and eat them. In captivity, some have been spotted engaging in coprophagy — the deliberate ingestion of feces. All of which we’d definitely characterize as being downright disgusting behavior.


But that doesn’t mean they don’t feel disgusted at all. The behaviors we’ve mentioned above usually involve each chimps’ own feces, or at most that of their immediate family members. If presented with bodily fluids or feces from other chimps, however, they will exhibit behaviors very suggestive of disgust. In theory, animals evolved this aversion to protect themselves from parasites and pathogens. In humans, bodily products are a universal elicitor of disgust, and the paper found evidence that exposure to biological contaminants — via vision, smell, or touch — also elicit similar reactions in chimpanzees by influencing feeding choices.

“If chimpanzees and other primates can discern contamination risk via different cues, individuals with higher sensitivities to feces and other bodily fluids may be less infected, which could have important health benefits,” explains Cecile Sarabian, the lead author of the study.

The team worked with 20 chimpanzees (Pan troglodytes troglodytes) at the Centre International de Recherches Médicales de Franceville (CIRMF) in southern Gabon. Throughout a series of experiments, the team was able to show that chimps will generally delay eating potentially contaminated food items.

First, the primates were presented with a choice of three bananas — one on a piece of brown foam (control sample), one placed on a replica pink feces, and one placed on a brown replica. The team reports that the chimps would first select the bananas atop the control foam and the pink feces replica significantly more often than the ones on the brown feces replica. This shows “a preference for food that is not associated with contamination risk” but not an “avoidance of such risk altogether,” as generally, they would still eat all three bananas.

The animals also showed a “weak tendency” of moving away from the smell of potential biological contaminants (conspecific feces, blood, and semen) compared to a control sample of water. Food trials revealed that the smell of blood or semen again had a limited effect on the chimps’ appetite compared to a control odor (they ate the bananas given to them 93%, respectively 92% of times, compared to 93% with control odor). Finally, they also tended to move away from and/or consume food items less often when associated with odors of these potential contaminants, the authors write. These tendencies were overall weak, the scientists add, suggesting that “the threat levels perceived [by the chimps] may not have been great.”

Icky fingers

For the third experiment, the team worked with 42 chimps. The primates were presented with a foraging task designed to put them into surprise tactile contact with two hidden substrates: dough, which has been used in human experiments to replicate the consistency, temperature, and moisture of a potentially contaminated substrate, or a piece of rope used as a control. Both substrates were hidden inside a box so the chimps couldn’t see them. What the chimps did see, however, was that the team placed pieces of banana in each box.

The chimps that received a box with rope substrate ate the banana pieces roughly 91% of the time. In contrast, their dough-boxed counterparts only ate the food 54% of the time. It’s the single most powerful disgust behavior elicited by the chimps in this study. The results are very similar to the behaviors shown by humans when blindly touching soft and moist substrates, which are generally more contaminant-rich than hard and dry substances.

“While anyone watching the reactions of these chimpanzees in the tactile experiments can empathize with them, it’s premature to say that they feel the same as we might in that situation” cautions Andrew MacIntosh, senior author on the study.

“What’s great about these experiments, though, is that the observed responses are functionally similar to what ours would be, providing evidence that the mechanism underlying their behavior could be similar to ours.”

The results help pave the way to understanding the disgust mechanism in humans and the protective function it serves.

“Moreover, such results may have implications for animal welfare and management. We can better inform staff and keepers about the adaptive value of such sensitivity and its flexibility, as well as identify which individuals may be more at risk of infection and therefore require more attention,” concludes Cecile Sarabian.

The team is now working on “expanding our ‘disgusting’ work” to other primate and non-primate species to get a more bird’s eye view of how the emotion forms and functions.

The paper “Avoidance of biological contaminants through sight, smell and touch in chimpanzees” has been published in the journal Royal Science Open Society.

A chimpanzee photographed by Alexander Weiss during his 2010 visit to the Gombe National Park in Tanzania. Credit: Alexander Weiss.

Wild chimpanzees have remarkably stable personality traits

Scientists revisited wild chimpanzees in Tanzania after more than 40 years and found evidence of personality stability.

A chimpanzee photographed by Alexander Weiss during his 2010 visit to the Gombe National Park in Tanzania. Credit: Alexander Weiss.

A chimpanzee photographed by Alexander Weiss during his 2010 visit to the Gombe National Park in Tanzania. Credit: Alexander Weiss.

Humans and chimps diverged from a common ancestor only six to eight million years ago. Along with bonobos (Pan paniscus), they’re our closest relatives in the animal kingdom. Bearing this in mind, it’s not all that surprising to learn that chimps share many aspects of human conduct and evolution such as tool use, complex social hierarchies, cultural traits, but also inter-group violence.

Worn friends and old habits

In 1973, Buirski et al. described the personalities of 24 wild eastern chimpanzees (Pan troglodytes schweinfurthii) living in Gombe National Park, Tanzania. The chimps were rated on a personality questionnaire called the Emotions Profile Index (EPI), which assigns scores based on eight major predispositions: Trustful, Distrustful, Controlled, Dyscontrolled, Aggressive, Timid, Depressed and Gregarious.

Most of the EPI ratings were consistent across different researchers which suggests there was an underlying personality to each chimp’s behavior. The researchers were familiar with chimps for several months to several years.

The ratings showed that chimps could significantly differ in their behavioral patterns, with important implications for group hierarchy and organization. The researchers found differences in disposition between sexes, in some respects quite similar to the kind we see in humans. For instance, female chimpanzees were more Trustful than males while males were more Gregarious than females. Alpha male chimps were found to be more Aggressive and less Timid while the lower ranking males were more Dyscontrolled and more Timid. What’s more, some of the rated personalities could be off the charts, much to the surprise of scientists at the forefront of this pioneering 1970s work. One prime example was the case of a female named Passion who showed deviant personality traits. Researchers rated her as more Aggressive, Depressed, and Distrustful, and less Trustful, Timid, Controlled, and Gregarious. In later years, she, along with her daughter Pom, killed and ate four infants belonging to other females in the group.

A chimpanzee photographed by Alexander Weiss during his 2010 visit to the Gombe National Park in Tanzania. Credit: Alexander Weiss

A chimpanzee photographed by Alexander Weiss during his 2010 visit to the Gombe National Park in Tanzania. Credit: Alexander Weiss.

More than 40 years later, Alexander Weiss, a psychologist at the University of Edinburgh, returned to Gombe for the second systematic quantification of wild chimp personality traits. This new study went the extra mile and gauged the personality traits of 128 individuals using 24 different measures (such as excitable, sensitive, helpful, curious). The individuals in the study also included the 24 chimpanzees from the earlier study, Weiss told me.

“These ratings are continuous variables that indicate, for each chimpanzee, where they stand in comparison to other chimpanzees on a trait. We obtained ratings on 128 chimpanzees including individuals that were observed in detail while alive but who have since died. The present data therefore resemble ratings of the personalities of living and deceased historical figures by people who knew the individuals well, or by historians,” the authors wrote in the journal Scientific Data.

The population studied by the researchers exhibited a wide range of personality traits and behaviors, as Weiss recounted.

Dr Alexander Weiss. Credit: The University of Edinburgh.

Dr Alexander Weiss. Credit: The University of Edinburgh.

“My work for this paper chiefly involved meeting the field assistants and asking them to fill out the questionnaires, and sometimes answering questions via my interpreter. This, to me, was quite exciting because these field assistants were responsible for collecting amazing data on some of the most famous chimpanzees in the world, and they featured in Jane Goodall’s books. I also spent some time at Gombe, though, and just seeing chimpanzees in the wild was awe-inspiring. I witnessed some aggressive interactions between males in which the whole group got agitated, but also saw some juveniles playing, females with their infants, and behaviors that I had only read about or seen videos of, such as the branch clasp grooming display,” Weiss told ZME Science.

When Weiss and colleagues compared their results to those reported by Buirski et al. in 1973, the two lined up ‘surprisingly well’. This was despite the four decades-apart studies employed different questionnaires performed by different researchers.

“Our study collected data using a different questionnaire, one which has been used to study chimpanzees in zoos, research centers, and sanctuaries, and ratings were made by 18 Tanzanian field assistants,” Weiss told ZME science.

“We found evidence that ratings of similar traits in the earlier study were correlated with the ratings that we obtained. More importantly, however, the goal of this paper was to provide a resource that future researchers could use to learn more about the evolution of personality in chimpanzees and humans, too,” he added.

A unique window into the lives of our closest relatives

The personality ratings were made on a modified form of the Hominoid Personality Questionnaire (HPQ), which involved six personality dimensions rather than the eight dimensions employed in EPI. The HPQ dimensions are Dominance, Extraversion, Agreeableness, Neuroticism, Openness, and Conscientiousness. Human personality is typically characterized by five dimensions or the ‘Big Five’ which involve all the aforementioned HPQ dimensions except Dominance.

The EPI and HPQ ratings had at least nine statistically significant correlations. For instance, EPI Aggressive and HPQ Neuroticism positively correlated, which is consistent with the fact that, in humans, the experience of anger and hostile emotions is a facet of Neuroticism. Likewise, the “positive association between EPI Gregarious and HPQ Extraversion is consistent with the fact that gregariousness defined high Extraversion” in previous studies. Gregariousness is a facet of human Extraversion.

There were also, however, some differences in correspondence between a few pairs of personality scales, though the results fit expectations for chimpanzees. For instance, there was a negative association between EPI Timid and HPQ Openness and a positive association between EPI Gregarious and HPQ Openness.

Despite some caveats, the correlations between the two ratings indicate the existence of stable personality traits in the population of Gombe chimpanzees. The dataset could prove insightful for other scientists seeking to understand the evolutionary cues that gave rise to personality traits in both humans and chimpanzees. Rare work such as the present study also provides a unique window into the lives of our species’ closest living relatives. Many chimp populations across Africa are threatened by habitat loss, poaching, and human diseases. By understanding how chimps ‘tick’ and that they’re not all that different in behavior from humans in many respects might thus help conservation efforts a great deal.

“I don’t think this is an original idea, namely as Jane Goodall has brought this up, but I think that one psychological obstacle to improving conservation efforts is that humans tend to think of different species of animals just as that, a species. Individual differences in behavior, emotional reactivity, and other tendencies, that is, the personalities of individuals, are lost in the process. The fact is, however, that chimpanzees very likely differ as much from one another as do we humans, and so losing chimpanzees would mean losing these wonderful individuals and individuals yet to come,” Weiss said.


Chimpanzees can master circular relationships, rock-paper-scissors about as fast as a 4-year-old

If you keep losing at rock paper scissors, here’s a depressing tidbit: chimps, regardless of age and sex, have shown that they can learn and play the game.


Image via Pixabay.

It’s not the most complicated game out there, I’ll agree, but it’s still pretty impressive! The team, led by Jie Gao of Kyoto University in Japan and Peking University in China, report that although it might take them a bit longer than it would a human, chimps are perfectly capable of mastering the game up to a young child’s level.

Rock paper scissor chimp

Gao’s team set out to find whether chimpanzees (Pan troglodytes) have the ability to notice and understand extended patterns. Rock-paper-scissors is a really good way to see if they can: the rules are pretty simple and constant but become non-linear during play, meaning the chimps have to understand the rules and how pairings of two signs function in order to play.

Circular (non-linear) relationships are a bit more difficult to grapple with than your regular, run of the mill linear relationships. In the latter, the state of an initial object A will dictate the outcome of object B. But in a circular relationship, the state of A dictates the outcome of B, which in turn changes A. They’re harder to work with because a brain would need to keep constant tabs on the objects involved in the relationship to be able to predict an outcome.

Successfully doing so with rock-paper-scissors would suggest that chimps’ brains can process and understand the relationship network formed between the signs, update what they already know, and solve problems. Which would mean that they’re pretty smart as far as animals go. Smarter than believed up to now, despite proving themselves to be pretty smart in the past.

For the trials, the team worked with seven chimpanzees from the Primate Research Institute at Kyoto University, of both sexes and different ages. Through a computer touchscreen, they were trained to pick the strongest of two options they were presented with. First, the team thought them the rock-paper pairing, then rock-scissors, and finally scissors-paper. After the chimps showed that they understand how the pairs fit together, all pairings were randomly displayed on the screen for them to pick. Five of the seven chimps completed the training, each with about 307 sessions under his or her belt.

Chimp RPS.

One of the chimps playing R-P-S during the trial.
Image via Springer.

The results showed that the chimps were able to learn the circular pattern that the game is based on. However, it took them significantly longer to learn the third (scissor-paper) pair than the others — suggesting that they had trouble re-learning what they were thought about the two signs previously, i.e. that they had some difficulty actually closing the loop on the game’s circular relationship.

As a control, the team then thought the game to 38 preschool children (aged three to six) in order to compare how fast the two groups learned. The kids had a breeze grasping the game, and needed an average of only five sessions to do so. Performance varied quite a lot by age, however. The team notes that children under 50 months (about four years) tended to play the game more with luck rather than skill. The older the child, however, the more accurate his or her response when randomly presented with all three pairs.

“This suggests that children acquire the ability to learn a circular relationship and to solve a transverse patterning problem around the age of four years,” says Gao.

“The chimpanzees’ performance during the mixed-pair sessions was similar to that of four-year-old children.”

Gao hopes the findings will inspire future studies into how age and sex influence the ability of members of various species to learn circular relationships.

The paper “Learning the rules of the rock–paper–scissors game: chimpanzees versus children” has been published in the journal Primates.

What does gestural communication of great apes tell us about human language?

Our language is one of the features that define us as human beings and distance us from all other animals. Though no other species has developed language like us, animals communicate with each other through a vast set of signals.

A chimpanzee asking for a snack from a keeper at Wellington Zoo, New Zealand. Image credits: Gabriel Pollard.

In the case of great apes, they communicate by vocalizations, facial expressions, body displays or gestures. Due to the phylogenetic proximity between humans and great apes, the study of gestural communication is particularly attractive since it allows to hypothesize how language evolved in our species. And the evolution of human language is one of the hardest scientific topics to do research. The reason is simple: language does not fossilize. That is why we are forced to look for other clues to enlight us about how our language evolved and great ape gestures can lead us much further in the search for answers than we previously thought.

First of all, great apes employ gestures in an intentional, flexible and goal-oriented ways and display them in various contexts like grooming, playing or feeding. For example, to request food, great apes usually use begging gestures in which they stretch their arms and open their hands towards other conspecific with food.

But why gestures can be considered as a precursor of human language? Well, neuroscience brought some interesting and strong findings but is not my intention discuss that kind of gestural theories based on brain data. Instead, I’m going to take a quick look at robust data collected during long-term field studies conducted in different study sites. Yeah, we already know that in our ontogenetic path, before we speak, we communicate to the world using gestures. In our species, gestures emerge first. Speech appears later. But this is not the proof that tickles my guts!

There is no doubt that great ape gestures are flexible. All scientific papers about primate gestural communication support this evidence. Same gesture for different purposes and different gestures for the same purpose. Pretty much similar to what we do with our spoken language. Different words for the same meaning and vice versa. So, we can highlight that apes communicate different things in very different situations.

One particular paper, written by Amy Pollick and Frans de Waal, reports an outstanding discovery: the gestural repertoire varies from group to group of the same species, in some kind of gestural dialect. Some gestures were only observed in particular circumstances and at one study site. Once again, pretty much similar to our language. Moreover, and in a broader view, Graham et al. (2017) made a diagram about gestural repertoires of chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) and these two great ape species share a very significant amount of gestures while some of them are unique to each species. Such striking overlap of gestures and, at the same time, the still more mind-blowing exclusivity of some gestures between chimpanzees and bonobos reveals us a scenario in which, most likely, the different languages of today evolved from an ancestral language. We are biologically programmed to speak but our language evolved itself in a cultural way, as apparently occurs with great ape gestures.

Furthermore, Hobaiter & Byrne (2014), focused on an attempt to translate the meaning of chimpanzee gestures. At the first glance, it may seem and exaggerated anthropocentric approach, trying to humanize all animal behavior. But for those who have spent many hours observing great apes gestural communication (like me), the similarities between human and great ape gestures pop out at you. So, in the paper cited above, the authors identified some gestures that sound us like “move away”, “please, groom me”, “stop that” or “follow me”.

Will be the great ape’s gestural communication the holy grail to understand the roots of human language? I guess so. The growing body of evidence that comes to us from primatological studies are quite exciting and it makes me very optimistic to solve the riddle of the evolution of our language. We need to keep collect data and test some hypothesis.

This is a guest post from Miguel Oliveira.


Pollick, A. S.; de Waal, F. B. M. (2007). Ape gestures and language evolution. PNAS, 104(19), 8184-8189;

Hobaiter, C.; Byrne, R. W. (2014). The meanings of chimpanzee gestures. Current Biology, 24(14), 1596-1600;

Graham, K. E.; Furuichi, T.; Byrne, R. W. (2017). The gestural repertoire of the wild bonobo (Pan paniscus): a mutually understood communication system. Animal Cognition, 20(2), 171-177;


Edible Ebola vaccine for wild apes could revolutionize how we fight the disease

Like humans, chimpanzees and gorillas can get infected with Ebola. Just like humans, they too can suffer from epidemics. To protect them from the disease as well as prevent it from spilling onto human populations, researchers have been working on an oral vaccine to combat Ebola in the wild. Results have been very encouraging, but researchers run into legal, political, and ethical obstacles that make it difficult to push the research further.

Fighting Ebola

Image: USAID Africa Bureau.

Ebola has devastated wild apes populations. In the past three decades alone, the disease wiped out a third of wild populations. Chimps have also suffered from the disease, and Ebola has repeatedly shown that it can jump from them to us and back to them. Furthermore, the virus can jump to fruit bats (perhaps the most prolific spreader of the disease), monkeys, forest antelopes, and porcupines. Needless to say, the fewer infected animals we have in the wild, the better.

Considering all of this, researchers have been working on an edible vaccine for several years already — something which has been described as a glimmer of hope.

“In 2014 the world was gripped by fears of an Ebola virus pandemic. Yet few people realise that Ebola has already inflicted pandemic scale mortality on our closest relatives,” says lead researcher Dr Peter Walsh from the University of Cambridge. African apes are also threatened by naturally occurring pathogens like anthrax, and the increasing overspill of human pathogens such as measles. A glimmer of hope lies in the fact that many of the disease threats are now vaccine preventable.”

The new vaccine has proven not only effective but also shows minimum side effects. All that is needed to make sure that the vaccine will have a positive effect in the wild is to test it more… and this is where the problems start.

A terrible irony

After decades of using chimpanzees to test drugs for humans, the US — the last developed country still using chimps for such tests — closed the research facilities and banned subsequent testing. At the time, this was viewed as a great victory for animal rights but ironically, it may end up costing populations in the wild.

The carcass of a chimpanzee killed by Ebola in the Republic of Congo. (Image: Peter D. Walsh et al., 2017).

Any vaccination for wild animals must be tested in captivity first to ensure its safety. There have been some tests, but not really enough to get the ball rolling — it may be that the law that protects chimps may end up hurting wild populations.

“We have developed a very promising tool for inoculating ape species against the myriad deadly diseases they face in the wild, but continued progress relies on access to a small number of captive animals. This may be the final vaccine trial on captive chimpanzees: a serious setback for efforts to protect our closest relatives from the pathogens that push them ever closer to extinction in the wild.”

So now we have a vaccine which seems to work but needs more testing. The vaccine is set to help wild chimp and ape populations. But testing is no longer legal because we tested human drugs on chimps. It really is ironic, and while it is legal to experiment on chimps when it benefits their species, such funding is extremely limited. Sadly, no one seems to be willing to provide the necessary funds, even though this is about more than just protecting our closest relatives (which by the way, should be enough) — it’s about protecting ourselves as well. If we limit the expanse of Ebola through the wildlife, we reduce the chance of another pandemic.

Researchers argue that many zoos and sanctuaries have much worse conditions than research facilities — especially considering that the vaccine is safe and has almost no side effects.

“Some pressure groups argue that all research on captive chimpanzees is tantamount to torture, not just because of procedures but also due to confinement,” says Walsh.

“Enclosures and animal care are now of a very high standard, with chimpanzees housed in large social spaces. The modest traces of stress we detected during our trial were akin to the values observed in college students anticipating exams.”

At the end, we are faced with a difficult ethical dilemma:

“In an ideal world, there would be no need for captive chimpanzees,” says Walsh. “But this is not an ideal world. It is a world where diseases such as Ebola, along with rampant commercial poaching and habitat loss, are major contributors to rapidly declining wild ape populations.

“Oral vaccines offer a real opportunity to slow this decline. The major ethical debt we owe is not to a few captive animals, but to the survival of an entire species we are destroying in the wild: our closest relatives.”

Chimp took down drone with careful planning

Calm and calculated – a chimp at a Dutch zoo took down a drone, squashing it with a tree branch. That’s pretty interesting (and a bit sad, if you’re the drone owner), but according to a paper published in the journal Primates, it may have more significance than it seems. According to the publishers, the chimp carefully planned the attack, just like a human would.

This year, on April 10, a Dutch film crew was using a drone to document a chimp enclosure at the Royal Burgers Zoo in Arnhem. However, the chimps didn’t like it, so some of them picked up branches from a nearby willow tree and two females, Tushi and Raime, climbed up on scaffolding to get closer to the drone and strike it, as you can see below.

“When the drone came a bit closer to the chimpanzees, a female individual made two sweeps with a branch that she held in one hand. The second one was successful and downed the drone. The use of the stick in this context was a unique action. It seemed deliberate given the decision to collect it and carry it to a place where the drone might be attacked. This episode adds to the indications that chimpanzees engage in forward planning of tool-use acts,” researchers write in the study.

They sent the drone smashing to the ground, and then looked at it for a while with inquisitive faces, before ultimately abandoning it. The footage went viral across the globe, but people missed a few important details. For example, when the female actually strikes the drone, you can see a grimace: her teeth were clenched and she was obviously tense, but she showed no signs of fear. This suggests that she acted on the drone not out of fear – but as a calculated move. In other words, she planned to attack it.

Prof Jan van Hooff, from Utrecht University, said: “The use of the stick as a weapon in this context was a unique action. It seemed deliberate, given the decision to collect it and carry it to a place where the drone might be attacked. This episode adds to the indications that chimpanzees engage in forward planning of tool-use acts,” Lukkenaar says, explaining the broader significance of the filmed event. This incident also shows the apes cautiously inspecting the contraption and even throwing it around before they lose interest in it.

To make things even more remarkable, chimps at the zoo were never really taught how to use weapons and tools, they just picked it up themselves. Previous studies showed that the chimps at this Dutch zoo spontaneously and innovatively use up to 13 types of tools in a variety of ways, especially with sticks (for example picking up fruits that are too high in the tree).

Journal Reference: Jan A. R. A. M. van Hooff , Bas Lukkenaar – Captive chimpanzee takes down a drone: tool use toward a flying object. (link)

all chimps classed endangered

All chimps – wild or captive alike – now classed as ‘endangered’ in the US

The  U.S. Fish and Wildlife Service reports it has classed all chimpanzees, whether captive or wild, under the  Endangered Species Act. Previously, chimpanzees kept captive in labs for biomedical research, entertainment or as pets were classed as “threatened”.The USFWS director  Dan Ashe agrees that this has transmitted an erroneous mixed message to the public. Whether captive (and hopefully cared for) or living in the wild, all chimps belong the same species, and this species is definitely endangered and in dire need of help.

all chimps classed endangered


In 2010, the Service received a petition from a coalition of organizations, including the Jane Goodall Institute,  The Humane Society of the United States and other groups, to class all chimps under the same act.The new decision from the USFWS indiscriminately protects all chimps in the US by the same laws, and is heralded by chimp sanctuaries and NGOs as an important step towards consolidating chimpanzee conservation efforts.

“Extending captive chimpanzees the protections afforded their endangered cousins in the wild will ensure humane treatment and restrict commercial activities under the Endangered Species Act,” Ashe said. “The decision responds to growing threats to the species and aligns the chimpanzee’s status with existing legal requirements. Meanwhile, we will continue to work with range states to ensure the continued survival and recovery of chimpanzees in the wild.”

In the early 1990s, chimps numbered about a million, but the population spread out across 22 equatorial nations has plummeted since. According to the Jane Goodall foundation, between 172,000 and 300,000 chimps are alive today, marking a steep decline following massive habitat loss, poaching, pet trade and, not least, disease outbreaks.

Wild chimpanzees were listed as an endangered species under the U.S. Endangered Species Act in 1990. Now captive chimps have been classed under the same ruling, helping  the 1,724 chimps currently living in captivity in the US, 730 of which reside in labs, gain protection. Previously, captive chimps were classed differently to encourage breeding and conservation efforts. However, what  “we actually did was expand a culture and an attitude of treating these animals as commodities for research or sale… and for entertainment,” Ashe says.

So, what’s the added benefit for captive chimps now? Well, for one, research labs that use chimps for experiments are now legally bound to obtain a permit. A permit will also be required to sell chimpanzee blood or tissue across state borders. In order to obtain the permit, research labs now have to “demonstrate that their research would be directly and substantially supporting the conservation of chimpanzees in the wild,” Mr. Ashe said. One way to do so is to support chimp sanctuaries and conservation projects with monetary aid. Writing a check won’t be enough though, according to Ashe, and other efforts will be required for labs to obtain a permit.

“This rule change will help put an end to the exploitation of chimpanzees and we are happy about that,” said Erika Fleury of the North American Primate Sanctuary Alliance, a group of eight primate sanctuaries in the United States and Canada that cares for close to 600 chimpanzees and monkeys.

In 2013, the US National Institutes of Health (NIH) was advised to retire its decade-old colony numbering 360 chimpanzees to a national sanctuary. Only a handful should have remained under NIH custody, kept only for research whose benefits are considered highly important to mankind. But, as of February, only six have left the government-research facilities, while 24 chimpanzees died waiting, National Geographic reports. The problem is that there simply isn’t enough room for these many chimps. There are only two chimpanzee sanctuaries in the US : Save the Chimps in Fort Pierce, Florida, and Chimp Haven in Shreveport, Louisiana. Both are operating at full capacity. So, laws and policies that protect chimps against abuse, harm or inhumane treatment are basically useless if not joined by funding to support sanctuaries. But it’s a first step. The money might follow.


Ebola has killed off a third of the world’s gorillas and chimpanzees

The great apes are suffering greatly from Ebola too – gorillas and chimps are facing the greatest threat ever, after Ebola has wiped out a third of the populations since the 1990s.

Ebola and great apes

Chimps and gorillas are also threatened by Ebola. Image via National Geographic Expeditions.

It’s easy to forget just how similar we are to apes and chimps. We share 94% of our DNA with chimps, and these two species are the closest living evolutionary relatives to humans, sharing a common ancestor with humans about four to six million years ago. Considering how similar we are, it should be no surprise that Ebola affects them.

In fact, the disease is much more dangerous for them than it is for us, with mortality rates of 95% for gorillas and 77% for chimpanzees, compared to about 50% in humans. The Ebola outbreaks are infrequent, but when they do strike, the effects are devastating. A study from 1994 found that a single Ebola outbreak wiped 25% of the chimps in a small population. But things got a lot worse in 1995, when 90% of gorillas in a national park in Gabon were killed. The problems continued throughout the 2000s, and in 2002-2003 another outbreak killed 5,000 gorillas in the Democratic Republic of Congo.

When you consider that there are under 100,000 gorillas in the wild, that’s a pretty big deal; and Ebola shows no signs of stopping. When you also consider that great ape populations are threatened by poaching and habitat destruction, the picture becomes much bleaker. The lack of habitat means that more individuals will come into contact with each other and are therefore much more likely of transmitting the disease.

Back in 2003 an article on the decline of great apes, written by a team led by primatologist Peter Walsh, predicted that:

Without aggressive investments in law enforcement, protected area management and Ebola prevention, the next decade will see our closest relatives pushed to the brink of extinction.

So far, he seemed to have been right.

An Ebola vaccine exists for great apes but…

Image via Babies Wild Animals.

Here’s where things get even more complicated. A vaccine for Ebola already exists for chimps and gorillas… but we can’t implement it, because testing on chimps is illegal. Across the European Union, where the vaccine was developed, it’s illegal to test drugs on chimps, even if the end result would greatly help them… so one can only wonder whether an exception should be made in this case. Talk about irony.

The US is the only developed country where testing on chimps is still allowed, which is ironic in its own way, but that’s a different story. But even the US is starting to shut down its chimp labs,

In the long term, conservation efforts aimed at restoring forest habitat could also help curb the spread of the virus, but a vaccine could work wonders here. Hopefully, a satisfying solution will be found, helping and protecting great ape populations from the threat of Ebola.


Chimps like African and Indian music – not Western music

Chimps prefer silence to all types of Western music(even classical music), but that doesn’t mean they don’t like music at all. A new study published in the American Psychological Association found that chimpanzees like traditional African and Indian music.

“Our objective was not to find a preference for different cultures’ music. We used cultural music from Africa, India and Japan to pinpoint specific acoustic properties,” said study coauthor Frans de Waal, PhD, of Emory University. “Past research has focused only on Western music and has not addressed the very different acoustic features of non-Western music. While nonhuman primates have previously indicated a preference among music choices, they have consistently chosen silence over the types of music previously tested.”

Previous findings had already indicated that primates generally prefer slower tempos, but this study indicates that they in fact favor certain tempos.

“Although Western music, such as pop, blues and classical, sound different to the casual listener, they all follow the same musical and acoustic patterns. Therefore, by testing only different Western music, previous research has essentially replicated itself,” the authors wrote.

So in order to try something fundamentally different, researchers used other kinds of music: Japanese, African and Indian music. The results were observable immediately.

“Chimpanzees may perceive the strong, predictable rhythmic patterns as threatening, as chimpanzee dominance displays commonly incorporate repeated rhythmic sounds such as stomping, clapping and banging objects,” said de Waal.

Basically, they liked the African and Indian music, because generally they tended to have extreme ratios of strong to weak beats. In that regard, Japanese music has average ratios, being somewhat similar to Western music – which is probably why the chimps didn’t like it.

This research shows that there is likely an evolutionary tendency towards music in primates.

“Chimpanzees displaying a preference for music over silence is compelling evidence that our shared evolutionary histories may include favoring sounds outside of both humans’ and chimpanzees’ immediate survival cues,” said lead author Morgan Mingle, BA, of Emory and Southwestern University in Austin. “Our study highlights the importance of sampling across the gamut of human music to potentially identify features that could have a shared evolutionary root.”

Laboratory Chimpanzees Released Into Sanctuary After 30 Years Of Cages – Their reactions are heart melting

30 years. They spent the vast majority of their lives in a lab, and after 30 years, they are released in a sanctuary. Their reactions say it all – this an exuberant, heart warming reaction, their joy and bewilderement can’t be captured in words. Watch the hug they have at 1:25… that just says it all!

I don’t really want to discuss animal testing here… the only thing I want to say is that if we declare that humans have a right to freedom and pursue happiness, then we should seriously think about granting the same rights to some animals – because their reactions are nothing less than human.

Chimps are rational, not conformist – study shows

The fact that chimpanzees are extremely intelligent should no longer surprise anyone. Most people also know that they have their own social cues and are very sensitive to them, but even so, they usually refuse to conform to what the majority of group members are doing, preferring to stick with their personal preferences. However, now, a new study has shown that they do change their strategy when they can obtain greater rewards.

© Max Planck Institute for Psycholinguistics

Chimps are curious by nature, showing a rich palette of interests, both intellectually and socially. But they are also rather hesitant to abandon their personal preferences, even when it becomes ineffective; many researchers suggested that they are slaves to routine, doing the same things over and over again almost mindlessly, regardless of the results. But Edwin van Leeuwen from the Max Planck Institutes for Psycholinguistics and Evolutionary Anthropology conducted a series of experiments in Germany and Zambia to see under what circumstances the chimps are willing to change their behaviors.

The researchers studied 16 captive chimpanzees at the Wolfgang Kohler Primate Research Center in Germany (Leipzig) and 12 semi-wild chimpanzees at the Chimfunshi Wildlife Orphanage Trust, a sanctuary that houses more than a hundred chimpanzees under nearly natural conditions in the north-western part of Zambia. The chimps were trained to operate two different vending machines. A minority of the group was made familiar with one machine and the majority of group members with the other machine. Basically, wooden balls were thrown into their living space. The chimps could insert the ball in the vending machines and they got a nut in exchange.

Then, the team wanted to see if the chimpanzees in the minority group would change their behaviour toward using the vending machine that the majority used. The benefits the two machines provided were identical, so they wanted to see if the minority would cave to the social majority pressure; they didn’t.

Peanuts over popularity

But in the second experiment, they changed the way the vending machines worked – so the one that the minority used now gave 5 nuts instead of one. Over time, most of the chimps switched to using the minority one, showing that they recognized the advantage and showed rationality, not conformism.

“Where chimpanzees do not readily change their behaviour under majority influences, they do change their behaviour when they can maximise their payoffs,” Van Leeuwen says. “We conclude that chimpanzees may prefer persevering in successful and familiar strategies over adopting the equally effective strategy of the majority, but that chimpanzees find sufficient incentive in changing their behaviour when they can obtain higher rewards somewhere else.” “So, it’s peanuts over popularity” he jokingly adds.

Via Max Planck Institutes for Psycholinguistics and Evolutionary Anthropology.

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.


Gorilla mother uses makeshift ladder to help her young climb an obstacle [PHOTO]

While chimpanzees, which are our closest relatives sharing 98% of our genetic blueprint, are notorious for their widespread tool use, the same can’t be said about gorillas. The great apes have only been caught twice by researchers engaged in tool use. One used a stick to explore the depth of a muddy river and another turned a tree trunk to use it as a bridge. Finally we’ve got a third documented instance of gorilla tool use, and it’s most touching one too.


(c) Science Mag

Deep in the Volcanoes National Park (Rwanda), an adult female was observed using a bamboo culm as a ladder for her offspring who couldn’t pass an obstacle otherwise. At first glace, the behavior might seem unintentional, however the researchers surprised the whole moment and saw that the mother reacted and came to aid with the makeshift ladder only after the offspring cried for help.  When the infant gorilla grabbed the lowered pole, the mother then grasped it more firmly, which allowed the infant to scurry up to join her. Beautiful!

The findings were reported in the journal Behavioural Processes

[NOW READ] Gorillas: more similar to humans than previously thought

Brent is 37 years old and has lived at Chimp Haven in Keithville, La., since 2006. Brent paints with his tongue.(Photo: Humane Society of the United States)

Abstract art painted by chimps to be auctioned. Raises awareness on lab cruelty

The Humane Society of the United States (HSUS), recently initiated a bold and creative project in which they enlisted six member organizations of the North American Primate Sanctuary Alliance. HSUS asked the organizations if they would each submit a piece of art made by chimps belonging to their respective sanctuaries. In the end, some pretty creative and expressive pieces of art were submitted. The winning piece was authored by the most eccentric of the chimp artists, being painted through a technique using the tongue only.

Brent's award-winning painting.(Photo: Humane Society of the United States)

Brent’s award-winning painting.(Photo: Humane Society of the United States)

The winning entries were chosen only last week, after more than 27,000 people voted their favorites online, and topping the list was the art made by Brent, a 36-year-old chimp who paints only with his tongue. His sanctuary, Chimp Haven of Louisiana, won a grant of $10,000 from The HSUS. Jane Goodall, famed primatologist and U.N. Messenger of Peace, was also part of the judging panel.

“All of the art was beautiful and unique, just like chimpanzees!” Goodall said. “It was difficult to choose. It’s so important that the public support all of these sanctuaries in their mission to provide exceptional care to chimpanzees, and other primates, who have suffered through so much.”

Cheetah, of Save the Chimps in Florida,  came in at second with his meticulous work. His entry was also Goodall’s favorite out the bunch. The chimp’s sanctuary was awarded $10,000.Ripley of the Center for Great Apes in Florida won third prize, for a $2,500 grant, followed by paintings by Jamie of Chimpanzee Sanctuary Northwest, Jenny of Primate Rescue Center, and Patti of Chimps, Inc., convey the unique style of each chimpanzee.

Second prize entry made by Cheetah, who lived alone in a lab for 13 years and endured more than 400 biopsies before being rescued by Save the Chimps. (c) Save the Chimps

Second prize entry made by Cheetah, who lived alone in a lab for 13 years and endured more than 400 biopsies before being rescued by Save the Chimps. (c) Save the Chimps

There’s more to the project than just showcasing cute and amazing chimpanzee art or rewarding the sanctuaries that care for them. The project seeks to raise awareness on the dire conditions these chimps were forced to  during their past ‘careers’ as research chimps or in the entertainment industry.  Brent, Cheetah, Jenny and Jamie were all used in biomedical research. Cheetah had it the worst of all – 19 years of medical research and in that time had more 400 liver biopsies, according to his sanctuary, Save the Chimps in Fort Pierce, Fla., which is home to 261 chimpanzees.

Third prize entry by Ripley. Like many chimpanzees used as actors, Ripley was eventually dumped in a roadside zoo. There, he witnessed the shooting death of his brother and two other chimp companions after human error resulted in the chimpanzees’ escape. Ripley found sanctuary at Center for Great Apes and impresses his caretakers with his resilience and forgiveness.

Third prize entry by Ripley. Like many chimpanzees used as actors, Ripley was eventually dumped in a roadside zoo. There, he witnessed the shooting death of his brother and two other chimp companions after human error resulted in the chimpanzees’ escape. Ripley found sanctuary at Center for Great Apes and impresses his caretakers with his resilience and forgiveness.

Recent advances in medicine, like in-lab culturing of organs from adult stem cells and computer models have significantly reduced the number of research on chimps – ideal animal models since they share 98.5% of their DNA with humans. Still, there are many yet employed in research. In all good faith, most scientists appreciate, while admitting research made on them is cruel, that the chimps are still indispensable to research of treatments that could save thousands if not in some cases millions of lives.

The National Institutes of Health is set to retire more than 300 chimpanzees soon, while the U.S. Fish & Wildlife Service has recently proposed the listing of chimps as endangered under the Endangered Species Act. If the proposal passes, then chimps would be out of the labs for the good.

As for the artworks, these will be auctioned off and the proceeds will benefit the North American Primate Sanctuary Alliance .

 “We cannot thank these sanctuaries enough for providing their chimpanzee residents with such peaceful and enriching lives. They deserve the public’s support for the amazing work they are doing and will continue to do as hundreds more chimpanzees make their way to retirement after decades in laboratories,” said Kathleen Conlee, vice president of animal research issues at the HSUS.

You can view all of the entries here.