Why are humans the only species with a chin?

Live Science reports on a research study by Noreen von Cramon-Taubadel on the development of the human chin, which does not have an evolutionary advantage. "Instead, it appears that structurally, we have to have a chin, but not because the chin evolved to have a particular function," von Cramon-Taubadel said. "More and more studies are showing that things that we used to think were terribly important in terms of differences between humans and other apes actually could evolve just by random drift and gene flow."