The point of the chin
The chin is what makes humans unique and aides to the proof of our evolution from our ancestors. The most common explanation as to why humans have chins is that it provides a buffer against the mechanical stresses of the jaw. It is also often argued that the chin developed during natural selection of mates - the chin made the male human more attractive and so this trait evolved to become a constant feature. More recently it has been suggested that the chin developed in response to the progress of our distinctive form of speech, due to the movements of the lips and manipulation of the tongue in order to produce the sounds we know as words, the chin developed in order to support this new use of the mouth and tongue.
And some people simply like to go with the theory that we have a chin so that we may fold towels with ease.
Elephants, chins, and what it means
The fact that some scientists have determined that elephants are the only other species to have a chin has opened up a lot of debate surrounding this issue. There has even been discussion that humans and elephants appear to have evolved from similar ancestors due to the similar characteristics and anatomical likenesses we share.