Do monkeys know how much fruit your sunglasses are worth? In episode 96 of Parsing Science, we talk with Jean-Baptiste “JB” Leca from the University of Lethbridge’s Department of Psychology about his field research observing interactions among macaques at a Hindu temple in Bali. There, the monkeys have learned to rob tourists of everything from smartphones to flip flops, and then barter their return to temple staff in exchange for food. His open-access article, “Acquisition of object-robbing and object/food-bartering behaviours: a culturally maintained token economy in free-ranging long-tailed macaques,” was coauthored with Noëlle Gunst, Matthew Gardiner and I. Nengah Wandia, and published on January 11, 2021 in Philosophical Transactions of the the Royal Society B: Biological Sciences.



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Hosts / Producers

Ryan Watkins &  Doug Leigh

How to Cite

Watkins, R., Leigh, D., & Leca, J.B. (2021). Parsing Science – Monkey Business. doi: 10.6084/m9.figshare.14307824


What’s The Angle? by Shane Ivers


JB Leca: They steal objects from tourists, and then they engage in something that looks like a bartering interaction.

Ryan Watkins: This is Parsing Science, the unpublished stories behind the world’s most compelling science and stored by the researchers themselves. I’m Ryan Watkins.

Doug Leigh: And I’m Doug Leigh. Today, in Episode 96 of Parsing Science, we’ll talk with Jean-Baptiste “JB” Leca from the University of Lethbridge, about his field research observing interactions among macaques at a Hindu temple in Bali, where the monkeys have learned to rob tourists to everything from eyeglasses to flip flops, and then barter they’re returned to temple staff in exchange for food. Here’s JB Leca.

Leca: Hi, I’m JB Leca. I’m an associate professor in the Department of Psychology at the University of Lethbridge. I’m a cultural primatologist. I’m interested in culture in non-human primates. I was born and raised in France. I did my grad school in France, master and PhD program at the Primate Research Institute in Strasbourg. And in 2002, after my PhD, I decided that I wanted to do research on social learning in non-human primates, and cultural behaviors in monkeys. So, I applied for postdoc funding to do research at the Primate Research Institute in Oyama, Japan. I got in touch with a great professor there, Mike Huffman, who’s now a colleague, and has been a friend for many years. And so we met in Japan in 2003. And that’s when I started to do research on cultural behaviors in non-human primates. [I] started to work on a number of behavioral innovations that are socially learned and culturally transmitted across generations of monkeys. At that time, I was working on Japanese macaques. And at some point, we started to work on a project regarding culture in monkeys that Mike Huffman has been conducting for many, many years. It’s about stone play behavior that is socially learned within a population of monkeys … and then groups-specific [or] population-specific, and then it’s a behavior that is transmitted across generations.

Watkins: Even though long-tailed macaques are also called crab-eating macaques, they’re actually known to be very opportunistic omnivores. But just because they’ll eat almost anything, doesn’t mean that they don’t know what they like. And at the Uluwatu Temple in Bali, a troupe of these monkeys gets what they want, by robbing people of things like their sunglasses, flip flops and smartphones. Not so that they can take selfies for Insta on the beach, but instead to hold them for ransom to barter pack for food that they deem to be of equivalent value. So we started out our conversation with JB by asking how he first learned about this unusual human-primate economy.

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