Scientists still aren’t sure why humans have chins

What sets Homo sapiens apart from other animals? Among other things, our chins, NPR reports. That piece of bone jutting out from your jaw is somewhat of a mystery—one that’s inspired a diversity of wild theories to explain its purpose, according to a paper published this month in Evolutionary Anthropology. The author of the paper dismisses a number of these explanations, such as the possibility that the chin serves as a sexual signal (such traits usually only appear in one sex—like the mane of a male lion). Another proposal is that the chin acts to protect your throat—an idea the paper’s author also shoots down, because for this to be a substantial advantage, humans would have to be constantly punching each other in the face.