Chin

The chin is the bottom part of the face. It is under the mouth and is the forward part of the jaw.

The chin is unique to present-day humans, our species. It is not present in the anthropoid apes, nor in any other hominin.Ichim, Ionut; Kieser, Jules & Swain, Michael 2007. Tongue contractions during speech may have led to the development of the bony geometry of the chin following the evolution of human language: a mechanobiological hypothesis for the development of the human chin. Medical Hypotheses 69 (1): 20–24. Neanderthals did not have a human-type chin.Klein R.G. The human career: human biological and cultural origins. University of Chicago Press. 2nd ed sources are p285 (comparison of H. erectus with H. sapiens), and p303 (Neanderthal jaws). 3rd ed 2009 is  In medical anatomy, the chin is called the "mental eminence".

Its absence in Homo floresiensis is grounds for thinking that small hominin was not of our species.Hogenboom, Melissa 2016. Mystery ancient hobbit was not human. BBC News Earth. 

It is thought that our chin may have become shaped like this to improve the muscle attachments of the lips and tongue. Chins can be larger or smaller, depending on the person. Even though chin sizes vary a lot, it is usually further forward than the rest of the face in normal humans.

 References 

Category:Basic English 850 words
Category:Face