Researchers just discovered something weird about chimps and bonobos

Chimpanzees and bonobos are more intelligent than we previously thought according to a new study that suggests the two great ape species have great memories. So, just how good are they? Let’s find out. 

Published in the journal Proceedings of the National Academy, the new study found that chimpanzees and bonobos have the longest social memory of any other animal species on the planet other than humans. 

Both great apes appear to remember the faces of their former companions even if it has been decades since they last saw them. It may not seem like much, but the discovery is key to unlocking our evolution. 

Photo by Sophie Dale on Unsplash

Smithsonian Magazine explained that chimpanzees and bonobos are the closest living relatives that humanity has, and understanding their social memory can help us better understand how we evolved.  

Brian Hare is a cognitive scientist at Duke University who wasn’t involved with the study but told the Washington Post researchers “time-traveled seven million years ago into the mind of our common ancestor we had together, in a way we’d never done before.”

Researchers have long known that great apes have rather great memory abilities but it wasn’t until study co-author Laura Simone Lewis was visiting an ape that she had worked with prompted the new research. 

Photo Credit: Twitter @LauraSimoneLew

Lewis became quite close to a chimpanzee named Kendall while conducting research at the North Carolina Zoo as an undergraduate student. Whenever she visited Kendall, he would investigate her fingernails. 

The researcher ended up spending a summer away from the zoo to conduct research in Africa, and upon her return months later, Kendall greeted her and wanted to inspect her hands as he had done previously. 

Photo Credit: Twitter @LauraSimoneLew

“The feeling I got was that he clearly remembered me after four months away,” Lewis, a comparative psychologist at the University of California Berkeley, told Carl Zimmer of the New York Times. “But I didn’t have the data to prove it.”

Photo by Vlad Kutepov on Unsplash

In order to confirm her hunch, Lewis and her colleagues decided to test for the first time the social memory abilities of two great ape species. 15 chimpanzees and 12 bonobos from the United Kingdom, Belgium, and Japan were chosen. 

Photo by Sean Foster on Unsplash

Each of the test subjects was shown a picture of an animal side-by-side with two other apes, one of which was a stranger while the other was an ape that had been a member of their social group and lived with the ape. according to Smithsonian Magazine. 

Eye tracking technology was used to examine the apes as they were shown the images for a total of three seconds and what was found was that both the chimps and bonobos looked at images of their former acquaintance for 11 to 14% longer. 

“It’s not so different from walking down the streets in a major city, unexpectedly encountering someone you went to school with, and you do that double take,” study co-author and  Johns Hopkins University psychologist Christopher Krupenye told the New Scientist.

According to a statement from Berkeley on the new research, the apes would look even longer at photos the images contained an ape with which the subject had been friendly, some were “seemingly mesmerized by the image.”

Unfortunately, the statement also made clear that while researchers could tell something was happening in the minds of the apes, we still don’t know what that was. Whether the apes experienced rich, episodic narratives or fleeting curiosities will take more research. 

One bonobo named Louise astounded the researchers when it became apparent that she could recognize her nephew after being separated from him for over 26 years, which Smithsonian Magazine noted set a new record for a documented animal memory. 

“It’s a remarkable finding,” Emory University primatologist Frans de Waal explained to Science. “I’m not even sure we humans remember most individuals we haven’t seen for two decades.”