Editing Simian (section)

==Biological key-features==
In a section of their 2010 assessment of the evolution of anthropoids (simians) entitled "What is an Anthropoid", Williams, Kay, and Kirk set out [http://www.pnas.org/content/107/11/4797.full a list of biological features common to all or most anthropoids], including genetic similarities, similarities in eye location and the muscles close to the eyes, internal similarities between ears, dental similarities, and similarities on foot bone structure.<ref name="Williams"/> The earliest anthropoids were small primates with varied diets, forward-facing eyes, acute color vision for daytime lifestyles, and brains devoted more to vision and less to smell.<ref name="Williams"/> Living simians in both the New World and the Old World have larger brains than other primates, but they evolved these larger brains independently.<ref name="Williams"/>

Simians characteristically have relatively large brains, fused mandibles, binocular and color vision, and the females have a single fused uterus.<ref>Henry R. Hermann Ph.D., in Dominance and Aggression in Humans and Other Animals, 2017</ref> They also have fewer teeth and are more sexually dimorphic in terms of body size and anatomy.

The traits that separate New World simians from Old World simians are the nostrils and their dentation. New World simians have broad noses with forward facing nostrils and three premolars in each quadrant of the mouth, while Old World simians have narrower noses with downward facing nostrils and a narrow septum and only have two premolars.{{Citation needed|date=December 2024}}