Study reveals that chimpanzees can remember the faces of friends and family decades after they last saw them
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Some years ago, this writer was lucky enough to be in the West African nation of Guinea working on a story about chimpanzees. I spent several days at a sanctuary for chimpanzees rescued from the exotic pet trade. One memorable morning was spent photographing a group of youngsters, one of which came and sat next to me and showed some interest in my camera. I showed the young chimp some of the pictures displayed on the screen on the back of my camera and he glanced quickly at each and every picture. But then, when I scrolled through to a close-up photo of him, he immediately lent forward and started gently touching the screen. I couldn’t help but wonder if he recognised himself.
Perhaps he did. A study conducted by a team from the John Hopkins University in the United States and published this month in the journal Proceedings of the National Academy of Sciences, reveals that our closest cousins, chimpanzees and bonobos (bonobos, which at first glance appear to be very similar to chimpanzees, were only identified as a separate species in 1929) have a very similar length of memory to humans and, further cementing how similar chimpanzees and humans are to one and other, that our closest cousins remember faces, family connections and friends even if decades have passed since they last saw one and other.
The researchers, who worked with chimpanzees and bonobos at zoos in Scotland, Belgium and Japan, invited the apes to participate in the experiment by offering them juice. Then, as our hairy cousins sipped their treat, they were shown two side-by-side photographs of apes they’d once known and ones they’d never met. Using a non-invasive eye-tracking device, the team measured where the apes looked and for how long, speculating that they’d look for longer at images of apes they recognised.
The results were striking, with the researchers discovering that the ape’s attention was biased toward former group mates over chimpanzees they’d never seen before and that this memory might be retained more than 26 years after separation. Even more intriguingly, the study showed that the apes seem to retain a stronger memory of individuals they had a positive relationship with. The study authors report that the most notable instance was of one bonobo showing a strong bias towards images of her sister and nephew, whom she’d last seen 26 years earlier.
Lead author Laura Lewis, said: ‘The idea that they do remember others and therefore they may miss these individuals is really a powerful cognitive mechanism and something that’s been thought of as uniquely human. Our study doesn’t determine they are doing this, but it raises questions about the possibility that they may have the ability to do this.’
And if chimpanzees can remember other chimpanzees long after they last saw them, then it also raises the question as to why this writer can’t even remember what he had for breakfast this morning…
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