Apes Recognize Old Companions Even After Decades, Study Finds

Research Suggests Long-Term Memory in Apes, Raises Possibility of Emotional Attachment

New research reveals that apes, specifically chimpanzees and bonobos, can recognize the faces of their old companions even after decades of separation.
The study, conducted at three different zoos, used photographs of apes who had either died or left the group, and measured the apes' reactions using a noninvasive eye-tracking device.
Results showed that the apes looked significantly longer at those they knew, regardless of how long it had been since they last saw them, and even longer at those they had been friendly with.
This discovery suggests that long-term memory is a trait possessed by the common ancestor of humans, chimps, and bonobos several million years ago.
The findings also raise the possibility that apes are capable of missing their loved ones, a cognitive mechanism previously thought to be uniquely human.