Updated 19.12 | Published 18.49
Chimpanzees seem to remember and recognize friends and family they haven’t seen in years.
The study provides further evidence of how similar they are to humans.
Louise had not seen her nephew for 26 years. Even so, she recognized the face in the picture immediately. It would have been impressive even for a human but Louise is a monkey. She is one of the monkeys included in a study where researchers investigated how well chimpanzees and bonobos – a close relative of the chimpanzee – are at recognizing monkeys they have not seen for a long time.
Looked at photos
The researchers had 26 chimpanzees and bonobos from different zoos look at pictures of other monkeys on a screen. The pictures were shown two by two, and one in each picture pair was an unknown monkey and the other of a monkey that had previously been part of the same group as the test monkeys, but which they had not seen for many years.
To find out if the monkeys recognized the images, the researchers used a camera that read eye movements. If the test chimpanzee lingered with its gaze on an image, the researchers interpreted it as a familiar face.
The monkeys also looked the longest at pictures of monkeys with whom they had had a positive relationship – ones they had played with a lot or cared for them. They did not look as long at monkeys with which they quarreled or had sexual contact.
Not unique
“We humans like to think of ourselves as unique and special creatures that make us very different from other animals. But this study shows how similar we are to chimpanzees and bonobos,” says Laura Simone Lewis at Harvard University, one of the researchers behind the study, in a press release.
The study has been published in the journal Proceedings of the National Academy of Sciences, and the researchers write that it would be interesting to go further and investigate whether the monkeys also miss monkeys they have not seen for a long time.