Chin up: A novel functional explanation for the evolution of the chin

Abstract The human chin, also frequently referred to as the mental prominence, is a part of the human anatomy whose evolutionary origin and function have divided scientific opinion to this day. There were suggestions it could have been used in defence, assisted in the mastication process, aided in the formation of words (i.e. speaking), or that it played a role in mate choice. None of these explanations were satisfactory. This paper, backed up by observations on people from different parts of the world and cultures, using their chin to hold or clamp down objects resting on a person's arms in front of the body or to free the person's hands for other tasks, offers an explanation that has support from results on the evolution of bipedalism from apes to bipedal australopithecines, including Homo sapiens , and the importance of the hands in hominids as well as the heritability of the trait.