The chin is unique to present-day humans, our species. It is not present in the anthropoid apes, nor in any other hominin. Even Neanderthals did not have a human-type chin. In medical anatomy, the chin is called the "mental eminence".
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.
- 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.
- 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 ISBN 978-0-226-43965-5
- Hogenboom, Melissa 2016. Mystery ancient hobbit was not human. BBC News Earth.