We Have Pubic Hair for a Reason

[Marr]

157. Some physical traits don't have a function, or are secondary results of other changes.

I read a book sometime back on human evolution in which the author argued that the superficial traits we associate with modern humans (smaller jaw, smaller brow ridge, etc.) are only secondary characteristics that come along with domesticity.

When you domesticate foxes, for instance, choosing the more docile specimens generation after generation, you quickly end up with something that looks more like a domesticated dog than a wild fox. Floppy ears, mottled fur, etc., are juvenile characteristics that are somehow tied to domesticity.

Same goes for humans. We essentially bred ourselves to be more domesticated, as it became more and more advantageous for humans to cooperate in larger and larger numbers. Along with that domesticity came a host of physical characteristics, like thinning body hair, a sloping brow ridge, etc.