Somebody That They Used to Know
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It has long been known that humans share many features with apes. What has made us stand out in the animal kingdom is our ability to develop social networks. Now, that sense of kinship may also be found among our close cousins.
The animals were ingenuously lured in with fruit juice and a straw to keep their heads from moving, as the researchers showed them a picture of an ape they had lived with in the past, and a picture of a stranger.
The experiment resulted in the bonobos and chimps spending more time looking at the apes they knew, glancing at recognizable features. The difference was only a quarter second on average, leading the researchers to equate this reaction with the way humans would see an old classmate on the street.
One scientist not involved in the study commented that this result failed to prove that apes could recognize their fellows, and rather showed they could feel familiarity.
Nonetheless, it also provided evidence of the long-term memory of apes. One of the bonobos seemed to remember her sister, whom she had not seen in 26 years. This may signal that bonobos, chimps, and humans all inherited long-term memory from a common ancestor, who lived seven million years ago.
In the study, the bonobos and chimps did look longer at old group mates whom they had a positive connection with. However, whether apes can develop the same kinds of relationships as humans, including friendship, remains a controversial point. “It’s sometimes called the f-word in primatology,” one of the researchers said.