大象传媒

It is important for social animals to be able to recognise one another quickly. Humans are able to recognise each other immediately from their faces. This method is also important for chimpanzees, but a recent study shows that the animals' buttocks also play a role. Neuropsychologist Mariska Kret from Leiden University in the Netherlands is one of the scientists involved in the research.

(Photo: chimps in Belgium, 2011. Credit: Georges Gobet/AFP/Getty Images)