#primate research

Clear plastic cups and pitchers adorned the wooden table in Des Moines, Iowa. Invisible juice was poured and presented to Kanzi, who enthusiastically chose the fake filled cup, playing along with the man who had come to visit. In many ways, it was the quintessential scene of a children’s imaginary tea party. Only Kanzi, at 44 years old, was a bonobo. The experiment, carried out at the Ape Initiative facility in 2024, was the first to empirically test and document pretend play in a great ape species, with the results published in the journal Science in February. The study adds to an expansive repertoire of research over the past decade that has uncovered robust similarities between ape and human behaviours, upending long-held beliefs about how we distinguish ourselves from our closest kin. “It seems to be a recurring thing in our field where people come up with reasons why humans are special and unique, and then scientists like me test it out, and we find that, actually, maybe we’re not that special after all,” says the study’s lead author, Amalia Bastos, a comparative psychologist at the University of St Andrews in Scotland. “That animals, too, are capable of secondary representations or imagination.” Kanzi, who died last year, participated in several experiments with Bastos and her colleagues to test his ability to make believe. “We start all of these trials by saying, ‘Kanzi, let’s play a game. Let’s find the juice.’ That way we can at least verbally scaffold as much as possible,” Bastos says. In one scenario, two cups were “filled” with juice, and then one was “emptied” into the jug. Kanzi was then asked to indicate which cup contained juice. He chose correctly in 34 out of 50 trials, suggesting he could grasp the concept of a pretend beverage. In another test, he was asked to choose between real orange juice and pretend juice. In 14 out of the 18 trials, he chose the cup containing real juice. Kanzi’s ability to pretend – to envision a reality beyond the one in front of him – would have been unthinkable just a few decades ago. In the 1990s, scientists acknowledged that apes were intelligent, that they could solve puzzles and use tools, that they built strong social relationships and could learn symbols and sign language, and that they could pass the mirror test, recognising their reflections to suggest some level of self-awareness. But primatologists and cognitive researchers were only just beginning to think about some of the more abstract and complex questions of culture, representation and theory of mind in great apes.

continue reading

ITA version here ESP version here

A recent study conducted in Kibale National Park in Uganda has revealed a surprising behavior among female chimpanzees: despite the scarcity of food, mothers continue to play with their young, playing a crucial role in the physical and social development of their offspring.

Kibale National Park is known to be the most densely populated primate forest in the world, with over 1,000 chimpanzees residing there. Researchers, led by Zarin Machanda and Kris Sabbi from Harvard University, began habituating chimpanzees to human presence in 1987, collecting detailed behavioral observations including climbing, feeding, grooming, and play.

Through the examination of 3,891 episodes of adult play recorded within the chimpanzee community of Kanyawara, researchers not only observed that this practice persists in adults unlike most other mammals, but also evaluated how adult play is influenced by diet quality. While play between adults and unrelated immatures decreased during food scarcity, play between mothers and offspring persisted, suggesting that this type of play was less constrained compared to play with other partners.

The observation that mothers continue to play with their young despite food scarcity underscores the crucial importance of play in the animal world and the extraordinary dedication of chimpanzee mothers in ensuring the well-being of their offspring, even in the most challenging times. This suggests that chimpanzee mothers play a crucial role in the physical and social development of their young, even when facing the threat of food scarcity.

That adult chimpanzees play to build relationships or support learning opportunities for younger group members evaluations of the potential functions and evolution of play are incomplete without considering its costs. The fact that chimpanzee mothers bear these costs even when ecology constrains other aspects of their social behavior primarily reveals a hidden cost of motherhood for this species, where, as with humans, mothers are important play partners for their offspring.

SOURCE

Angering animal welfare activists, Mauritius invites primate research labs to set up shop

The persistent fight by animal welfare activists to end nonhuman primate research has found its way to Mauritius, an island in the Indian Ocean two-thirds the size of Rhode Island. In the 1700s, Dutch and Portuguese seafarers introduced the long-tailed macaque to the island, where the animals thrived and, in recent decades, formed the basis of an export industry supplying biomedical labs in the developed world. Now, Mauritius has decided to get into the business of nonhuman primate experimentation itself even as such work is becoming increasingly constrained in North America and Europe. Last month the move touched off a heated debate in Mauritius's National Assembly about whether the government could adequately protect the macaques used in research and whether the new industry might endanger a far bigger lifeline for the island—tourism.

The ability to imagine has long been thought of as uniquely human - but scientists have discovered that apes can also extend their mental lives “beyond the here and now”. In a series of tea party-like experiments, researchers at Johns Hopkins University in the US demonstrated for the first time that apes can use their imagination and “play pretend”. One bonobo engaged with cups of imaginary juice and bowls of pretend grapes, in a similar way you’d expect a toddler to. The study, published in the journal Science, says its findings have challenged long-held assumptions about the abilities of animals, suggesting that the capacity to understand pretend objects is within the cognitive potential of an enculturated ape. This ability likely dates back up to nine million years ago. A ‘game-changing’ discovery into Apes’ minds “It really is game-changing that their mental lives go beyond the here and now,” says co-author Christopher Krupenye. “Imagination has long been seen as a critical element of what it is to be human but the idea that it may not be exclusive to our species is really transformative. “Jane Goodall discovered that chimps make tools and that led to a change in the definition of what it means to be human and this, too, really invites us to reconsider what makes us special and what mental life is out there among other creatures.” How do scientists know apes can use their imagination? Up until now, there had been no controlled studies of pretense in nonhuman animals, despite anecdotes of animals seemingly engaging in “pretending behaviour”. For example, young chimpanzees in the wild have been observed carrying and playing with sticks, holding them in a similar way to how a mother would hold her infant. Krupenye and co-author Amalia Bastos, who is a lecturer at Scotland’s University of St Andrews, wondered if they could test this capacity to pretend in a controlled environment.

Researchers have successfully adapted a standardized system for analyzing facial expressions to include bonobos, our closest living relatives, alongside chimpanzees. The study, led by an international team of scientists from multiple institutions including Leipzig University and the Max Planck Institute for Evolutionary Anthropology, extends the Chimpanzee Facial Action Coding System (ChimpFACS) to another species closely related to humans and chimpanzees, bonobos. The research has been published in PeerJ. The research confirms that bonobos possess a repertoire of 28 distinct facial movements, including 22 specific muscle actions, demonstrating facial expression capabilities comparable to their chimpanzee cousins. This finding provides new tools for understanding how these endangered great apes communicate and express themselves. "This adaptation of ChimpFACS for bonobos fills an important gap in our ability to study facial expressions across different primate species," explains lead researcher Dr. Catia Correia-Caeiro. "We can now systematically compare facial movements between humans, chimpanzees, and bonobos, offering insights into the evolution of facial communication."

Here’s a seemingly counterintuitive fact: power dynamics between males and females in nature are not clear-cut at all. For a long time, it was believed that males generally dominated females socially among primates, because they are bigger, stronger, and more necessary for the group’s survival. But this view is increasingly being challenged by the scientific community — and with good reason. A new study has shown that in most populations and species, neither sex clearly dominates the other. So falls the long-standing myth of male dominance. The results of the study were published Monday in the journal Proceedings of the National Academy of Sciences. Researchers from the Max Planck Institute for Evolutionary Anthropology (Germany) and the University of Montpellier (France) compiled data from 253 studies covering 121 primate species. They focused on agonistic interactions — fights, threats, submissions — between adult males and females, which make up half of all social conflicts in primate groups. Their findings challenge the long-held notion that males are naturally the dominant sex, suggesting instead that male dominance is more the exception than the rule. “Power relationships between males and females are much more flexible than is often assumed,” explains Dieter Lukas, one of the study’s authors. The study found that only 17% of primate populations showed strict male dominance, 13% strict female dominance, and in 70% of cases, dominance was shared or ambiguous — meaning it was not clearly held by one sex.