Humans are the only animals on earth with chins. The chin could be a "spandrel" or evolutionary by-product. It may be the result of the human face shrinking over time as our posture straightened and our faces shortened, or a remnant from a period of longer jaws.
The chin isn’t just the lower part of your face: It’s a specific term for that little piece of bone extending from the jaw. While it may seem odd, humans are in fact the only animals that have one. Even chimpanzees and gorillas, our closest genetic cousins, lack chins. Instead of poking forward, their lower jaws slope down and back from their front teeth. Even other ancient hominids, like the Neanderthals, didn’t have chins —their faces simply ended in a flat plane.
Picture Credit : Google