The pattern of human evolution

The systematic morphological variation between human geographic groups is widely and quite correctly attributed to climatic and cultural adaptations. Certainly, the main distinguishing characters of race as socially defined have clear adaptive significance. These features include skin color, hair color and form, and stature and body proportions. However, the forensic bases for racial identifications involve skeletal features whose variation is often without obvious adaptive significance. The adaptive advantage prognathism vs. orthognathic faces, shoveled vs. flattened incisors, rounded vs. squared orbits, and others remain unknown.

Multiregional evolution provides an explanation for the distribution of these non-adaptive variants. This paper discusses the Multiregional explanation, focusing on the center and edge hypothesis to account for the initial distribution of regional features such as these, and tracing the evolutionary history of regional continuities in several different areas. The point we wish to establish is that history as well as adaptation is an important cause of modern human variation.