What causes the existence of superficial differences among groups of humans?

Question

Quizplus · Accepted Answer

Geographic isolation, or physical separation of populations, can lead to genetic drift and adaptation to different environmental conditions, eventually resulting in the development of superficial differences among human groups, such as skin color or facial features. Temporal isolation, genetic incompatibility, and behavioral isolation are not directly related to the development of superficial differences.

What Causes the Existence of Superficial Differences Among Groups of Humans