It’s a matter of fact that human beings are the only animals with brains. But when it comes to chin, then it is quite confusing if humans are the only animals with chins or not. This claim was made a few years back, but many people counter attacked this claim by saying apart from humans, there are many animals including cats, horses, and elephants that do have chins. But a chin is not just the bottom bit of the face or the front part of the lower jaw. It’s specifically a lump of bone that protrudes forward from the lower jaw. The jaw slopes sharply backwards from the teeth: no chin. Moreover, the cat’s chin is mandible. Therefore, it can not be termed as a chin.
With elephants, things are a bit more complicated. The elephant’s lower jaw has a forward-jutting bit that certainly looks pretty much like a chin. Moreover, their lower jaws are really weird. Elephants have lost the front teeth of their lower jaw for some reason, leaving a vacant space that creates the illusion of a bony promontory. They also have a fleshy lower lip that doesn’t mould to the contours of their front teeth like ours, but instead sticks well forward, tapers to a point, and acts as a mobile appendage to oppose the trunk. So that front bit of the jaw has a clear function: it acts as an anchor and platform for this unusually mobile lip. Thus, for the above stated reasons, it is not wrong to conclude that “Human beings are the only ones to have been born with a chin on their faces.”