Recognizing a fellow human’s face is about more than just identifying a nose or mouth. It’s believed we use something called configural recognition to process the entire facial structure altogether, which is why there’s often a little bit of a lag time when we see a face upside-down (humans have an easier time recognizing other objects, like cars or houses, that have been flipped).

Researchers now believe chimpanzees have something similar to configural recognition. Only they use it to recognize each other’s butts.

Mental Floss