There is a human genetic fluke that is surprisingly common, due to a change in a key pair of chromosomes. In the normal condition the two look the same, but in this disorder one is malformed and shrunken beyond recognition. The result is a shortened life span, higher mortality at all ages, an inability to reproduce, premature hair loss, and brain defects variously resulting in attention deficit, hyperactivity, conduct disorder, hypersexuality, and an enormous excess of both outward and self-directed aggression.

It is called maleness.

Melvin Konner traces the arc of evolution to...