Primate

Beyond GPS: ��˾��ֱ�� researchers study monkeys that can plan their routes

ullahnor — Mon, 04 Jun 2018 20:49:30 +0000

Beyond GPS: ��˾��ֱ�� researchers study monkeys that can plan their routes

ullahnor Mon, 06/04/2018 - 16:49

Cutline

A new ��˾��ֱ�� study has found that when foraging for food, vervet monkeys apply simple rules-of-thumb to find short routes (photo by Eve Smeltzer)

Don Campbell

Topic

Breaking Research

Monkeys

Primate

��˾��ֱ�� Scarborough

They might not have mastered GPS technology, but vervet monkeys can find relatively short routes, much the same way that humans do.

A new ��˾��ֱ�� study published in the journal PLOS ONE has found that when foraging for food, vervet monkeys apply simple rules-of-thumb (also known as heuristics) to find relatively short routes without having to think too much about it.

“People are amazed that animals can often find the shortest route when foraging for food, and the big question is how they’re able to figure it out,” says lead author Julie Teichroeb, an assistant professor in the department of anthropology at ��˾��ֱ�� Scarborough.

“Solving these kinds of routes is extremely difficult mathematically but we’ve found that these monkeys, much like us, rely on heuristics.”

Heuristics are basically mental shortcuts meant to ease the cognitive burden of making complex decisions. While these decisions may not be perfect or even the most ideal, they get the job done. After all, getting paralyzed trying to choose from the infinite number of ways to get to several destinations has many costs, especially when trying to locate food.

Monkeys in particular seem to be good at figuring out the shortest route right away without needing much time or practice, says Teichroeb. In the case of vervets, they often end up using a method that humans do called the “nearest neighbour rule,” which is essentially choosing the closest site that hasn’t been visited yet.

Teichroeb and her co-author Eve Smeltzer, a PhD student in ��˾��ֱ��’s department of anthropology, observed the vervets at Lake Nabugabo in Uganda, near Lake Victoria.

PhD student Eve Smeltzer (left) and Assistant Professor Julie Teichroeb (right) are co-authors of the recent vervet monkeys study (photo by Julie Teichroeb)

Using a simple array of platforms containing food, they observed that the monkeys would typically go to the next nearest location. But when the researchers created a condition where using simple heuristics would no longer lead to near-optimal paths, vervets showed an ability to plan their route. A couple of monkeys were even able to routinely figure out the shortest possible path after the condition was introduced, showing individual differences in skill.

“This is only the second animal where planning of foraging routes has been found, the other being noisy miner birds,” says Teichroeb, who is an expert on primate behaviour, specifically evolution of group living and social organization.

Vervet monkeys are found mostly throughout Southern Africa and help serve as a nonhuman primate model for understanding genetic and social behaviours in humans. They’ve been observed to experience hypertension, anxiety, social dependency and even display spiteful behaviour.

While it’s likely other primates can also plan foraging routes, many are hard to observe in the wild since most prefer to live in trees, notes Teichroeb. Vervets on the other hand are perfectly happy on the ground and are relatively comfortable being near humans.

In the future, Teichroeb hopes to vary other characteristics of the food available in her experiments, such as its nutritional quality or ease of access, to see if there’s a change in the routes the vervets take. These variables may also affect behaviour depending on social status with subordinate vervets choosing the closest food site, while those that are more dominant may try to find and defend better food sites.

Teichroeb has observed that the strategy vervets use when they are alone appears to be different from the strategy they use when they’re with others.

“That’s really fascinating and hard to show in natural populations of primates because they’re so social and it’s rare for individuals to leave their group and complete an experiment on their own,” she says.

“I really want to get at what’s most important in the resources that they choose, and how that changes their foraging routes and decision-making.”

The study found that the vervet monkeys would typically go to the next nearest location, but when researchers created a condition where using simple heuristics would no longer lead to near-optimal paths, vervets could plan their route (photo by Eve Smeltzer)

Humming lemurs? UTM researcher decodes the secret language of ring-tailed lemurs

ullahnor — Fri, 07 Jul 2017 19:35:09 +0000

Humming lemurs? UTM researcher decodes the secret language of ring-tailed lemurs

ullahnor Fri, 07/07/2017 - 15:35

Cutline

Ring-tailed lemurs have the largest vocal repertoire of all lemurs and are known to make 22 different vocal sounds

Blake Eligh

Author legacy

Blake Eligh

Topic

Global Lens

��˾��ֱ�� Mississauga

Primate

Why do lemurs go “hmm?”

It's to protect them from predators and bolster social cohesion within the troop – not because they don’t know the words.

In research published in Ethology, ��˾��ֱ�� Mississauga primatologist Laura Bolt looked at the behavioural usage of “hmm” calls by Madagascar’s ring-tailed lemurs. She focused on two specific vocalizations – “moans” and “hmms” produced by male lemurs, which are the lowest ranking members in the female-dominant troop structure. Her research may provide clues about how ancient human ancestors may have socialized with each other.

Bolt spent five months at the Beza Mahafaly Special Reserve, a remote protected park in southwest Madagascar, studying vocal communication in male members of five different lemur troops. Ring-tailed lemurs have the largest vocal repertoire of all lemurs and are known to make 22 different vocal sounds, some of which Bolt tested for their role in social cohesion.

“Social lemurs – those who live in social groups – are the living primates most like our early ancestors,” Bolt says. “Patterns of individual and sex-specific call usage are still poorly understood. Gaining a better knowledge of how group-living lemur species use contact calls helps to inform our understanding of the evolution of primate cognition.”

Ring-tailed lemurs spend their days moving through the tree canopy or along the forest floor in search of food, leaving the troop vulnerable to predators like the mongoose-like fossa, harrier hawks, and feral cat and dog populations. Contact calls are thought to help the lemurs keep track of other members of the troop, providing a measure of safety.

Lemur moans are short, high-pitched vocalizations that are used most frequently when lemurs are apart from each other in the trees or on the ground. In contrast, the “hmm” vocalization is quieter and is used most frequently when lemurs are moving, feeding and keeping watch for predators.

“We found that male ring-tailed lemurs used both moan and hmm calls to maintain proximity to their nearest neighbour,” Bolt says. “They performed both moan and hmm vocalizations at higher rates during behaviours that could lead to separation from group members, such as during travel or vigilance.” For the moan vocalization, the highest call rates occurred when the nearest neighbor was further away.

Bolt (below) found that “hmm” vocalizations were used most often by low-ranking males, especially when preferred companions were nearby. Since low-ranking individuals are often targets of aggression in this species, and Bolt concludes that low-ranking males make “hmm” sounds as a way to stay close to specific members of the group who will show them more tolerance.

“These results further our understanding of how ring-tailed lemur vocalizations may function to keep social groups together,” she says.

The study was supported by funding from the Natural Sciences and Engineering Research Council of Canada (CGS-D award), the Ontario Graduate Scholarships program, the American Museum of Natural History, the Edward J. Noble Foundation, the St. Catherines Island Foundation and the University of Toronto.

Monkeys play the odds, say ��˾��ֱ�� researchers

ullahnor — Tue, 10 Jan 2017 20:06:02 +0000

Monkeys play the odds, say ��˾��ֱ�� researchers

ullahnor Tue, 01/10/2017 - 15:06

Cutline

Assistant Professor of Psychology Daphna Buchsbaum: “It might be that they are not that very different from us at all” (photos by Emma Tecwyn)

Peter Boisseau

Author legacy

Peter Boisseau

Topic

Subheadline

A study on statistical reasoning among capuchin monkeys finds the first evidence that a monkey species is capable of making decisions on the basis of probabilities

It wasn’t exactly a Planet of the Apes moment, but when two University of Toronto researchers recently proved monkeys can reason about proportions and ratios, it opened a world of possibilities to tickle the fancy of even a Hollywood scriptwriter.

The study on statistical reasoning among capuchin monkeys by Daphna Buchsbaum, an assistant professor of psychology, and Emma Tecwyn, a postdoctoral researcher, is the first evidence a monkey species is capable of making decisions on the basis of probabilities.

The Faculty of Arts & Science researchers' study, published online in Animal Cognition, tested the monkeys using jars of desirable peanuts and undesirable pellets in different ratios to prove they can reason about relative amounts, as opposed to just making straightforward comparisons about quantities. The 19 monkeys who participated in the study are from the ‘Living Links to Human Evolution’ Research Centre at the Royal Zoological Society of Scotland, Edinburgh Zoo, UK.

The study also demonstrated that the monkeys – like great apes – share a capability once thought to be uniquely human.

“It might be that they are not that very different from us at all,” says Buchsbaum, adding that in a sense, the results also further our understanding of ourselves as humans.

While it still leaves capuchin monkeys a long way from the talking hero apes of the popular movie series, the type of intuitive ability they demonstrated in the lab tests is a building block for complex thinking, such as understanding cause and effect, and language.

The researchers say infants use the same ability to understand other people’s goals and preferences.

“I think the fact that monkeys do share this ability would make us potentially more optimistic that they might also be capable of more sophisticated social inferences,” says Buchsbaum. “While monkeys are unlikely to be capable of learning language, the ability to track probabilities is absolutely related to language learning.”

The statistical reasoning abilities shared by human infants and monkeys are part of a broader range of cognitive skills that encompass everything from predicting the behaviour of others to being able to reason about someone’s desires and mental state.

Buchsbaum notes there are more immediate applications for this ability in monkeys such as how to forage and compete for food successfully.

For now, the scientists are satisfied to add to their growing knowledge about the evolutionary traits of humans and other animals, particularly primates.

Until recently, the ability to make inferences using probabilities was thought to develop relatively late in childhood. But recent work revealed this ability in infants as young as 10 months old to a one year old.

Other research suggests that great apes such as chimpanzees, gorillas and orangutans also share this intuitive statistical ability with human infants.

What’s intriguing about the monkey study is it suggests that this ability developed earlier on the ancestral tree before apes and humans branched off, Tecwyn says.

Humans shared a common ancestor with chimps about six million years ago. But we last shared a common ancestor with capuchin monkeys about 30 million years ago.

“So we could make the inference that this ability is at least that ancient,” Tecwyn says.

It is possible but unlikely, that statistical reasoning is a trait capuchins evolved independently, and it is not shared by other monkey species, adds Buchsbaum.

“Given that humans, apes and capuchins all share the trait, it is more likely that it evolved once earlier rather than independently in these different groups.”

Researchers have long been on a quest to establish what makes humans unique from other animals and conversely, what cognitive abilities are shared. Like the ape studies before it, the capuchin research further lays to rest the idea that probabilistic reasoning is one of the traits that makes humans unique.

Buchsbaum says an exciting avenue for future research would be investigating whether animals other than primates also share this ability to make intuitive statistical inferences, and whether non-human animals are capable of more sophisticated social reasoning often thought to be unique to humans.

“But regardless, within the broader animal kingdom, I don’t think we can doubt monkeys are pretty sensitive and intelligent animals,” Buchsbaum says.

Other collaborators on the research – conducted at the Living Links research centre at the Edinburgh Zoo – are Stephanie Denison of the University of Waterloo and Emily Messer of Heriot Watt University, Edinburgh.

Primate

Beyond GPS: ��˾��ֱ�� researchers study monkeys that can plan their routes

Humming lemurs? UTM researcher decodes the secret language of ring-tailed lemurs

Read more about lemurs

Monkeys play the odds, say ��˾��ֱ�� researchers