It's not just elephants who have long memories... Great apes never forget a face, study reveals

A study has revealed that they can remember another bonobo or chimpanzee for more than 25 years. Researchers used infra-red eye-tracking cameras to record where the primates gazed when they were shown side-by-side images of other bonobos or chimps. One picture was of a stranger, while the other was of a bonobo or chimp the participant had lived with for a year or more at some point in their life. They found the apes' eyes lingered significantly longer on images of those with whom they had previously lived, suggesting some degree of recognition. They also looked longer at apes with whom they'd had more positive relationships.