Apes Possess The Longest Lasting Social Memory Outside Of Humans: Study Finds

Saturday - December 23 2023, 01:58 UTC - 11 months ago

A recent study found that apes have the longest-lasting social memory ever documented outside of humans. The research team worked with chimpanzees and bonobos in zoos in Scotland, Belgium, and Japan to to test the ape's recognition of individuals they haven't seen in over 25 years. The study, which was published in the Proceedings of the National Academy of Sciences, demonstrated that apes pay more attention to individuals with whom they had more positive relationships, suggesting that their lasting memory is more than just familiarity.

Study finds the longest lasting non-human social memories ever documented.

Apes recognize photos of groupmates they haven’t seen for more than 25 years and respond even more enthusiastically to pictures of their friends, a new study finds.

The work, which demonstrates the longest-lasting social memory ever documented outside of humans, and underscores how human culture evolved from the common ancestors we share with apes, our closest relatives, was published today in the journal Proceedings of the National Academy of Sciences.

“Chimpanzees and bonobos recognize individuals even though they haven’t seen them for multiple decades,” said senior author Christopher Krupenye, an assistant professor at Johns Hopkins University who studies animal cognition. “And then there’s this small but significant pattern of greater attention toward individuals with whom they had more positive relationships. It suggests that this is more than just familiarity, that they’re keeping track of aspects of the quality of these social relationships.” .

Apes recognize photos of groupmates they haven’t seen for more than 25 years and respond even more enthusiastically to pictures of their friends, a new study finds. Credit: Johns Hopkins University .

Adds lead author Laura Lewis, a biological anthropologist and comparative psychologist at University of California, Berkeley: “We tend to think about great apes as quite different from ourselves but we have really seen these animals as possessing cognitive mechanisms that are very similar to our own, including memory. And I think that is what’s so exciting about this study.” .

The research team was inspired to pursue the question of how long apes remember their peers because of their own experiences working with apes—the sense that the animals recognized them when they’d visit, even if they’d been away for a long while.

“You have the impression that they’re responding like they recognize you and that to them you’re really different from the average zoo guest,” Krupenye said. “They’re excited to see you again. So our goal with this study was to ask, empirically, if that’s the case: Do they really have a robust lasting memory for familiar social partners?” .

The team worked with chimpanzees and bonobos at Edinburgh Zoo in Scotland, Planckendael Zoo in Belgium, and Kumamoto Sanctuary in Japan. The researchers collected photographs of apes that had either left the zoos or died, individuals that participants hadn’t seen for at least nine months and in some cases for as long as 26 years. The researchers also collected information about the relationships each participant had with former groupmates—if there had been positive or negative interactions between them, etc.

The team invited apes to participate in the experiment by offering them juice, and while they sipped it, the apes where shown two side-by-side photographs—apes they’d once known and total strangers. Using a non-invasive eye-tracking device, the team measured where the apres’ eyes moved and for how long.