Humans are the only species on Earth with a chin protrusion. Even our closest relatives, chimpanzees and gorillas, have lower jaw bones that are inclined backward and do not have a forward protruding tip like ours. Scientists at the University of Iowa have investigated why this anatomical feature exists.
According to Milli.Az, for a long time, two main theories dominated in the scientific world regarding the presence of the chin:
Chewing mechanism: It was thought that the chin developed to reduce the physical stress generated during chewing.
Speech ability: It was claimed that this protrusion was created to withstand the mechanical pressure caused by the movement of the tongue and mouth muscles during speech.
Through biomechanical analyses, scientists have proven that the chin actually plays no significant role in reducing the stress generated during chewing or speaking. On the contrary, in some cases, this protrusion can even increase the stress.
So then why did the chin develop? According to the research, the chin is a byproduct of evolution.
As humans evolved, the facial structure became smaller and receded backward.
While the facial bones shrank, the front part of the lower jawbone changed more slowly compared to other parts. As a result, while the face receded, the tip of the lower jaw remained somewhat "excess" in the center and formed the chin protrusion seen today.