We usually think of natural selection as acting to get rid of genetic variation, but for human faces, variation is actually favorable. Behavioral ecologist Michael Sheehan of the University of California, Berkeley explains that distinction in our faces is part of an evolutionary trend to make us recognizable in social environments.

"I think when we think about evolution and selection we usually think about things like some mutation that makes you a faster runner or something and so that’s really great and so therefore selection fixes it. But in this case we’re actually looking for a selection that maintains genetic variation. So we want -- it’s not good to have a big nose or a small nose in and of itself. But it’s good to have a nose that’s different from everyone else in the population is sort of the basic idea."

Sheehan says that while we may take recognition for granted, it’s still an issue today.

"If you go on Google and you type in "mistaken identity arrest" or "mistaken identity jail" you can find lots of cases of people that have gone to jail because of mistaken identity."