In The Two Types of Men, a fresh, straightforward theory synthesizes how the human species' biological and societal roots gave rise to two categories of men: the weapon user and the weapon maker. Each type with his differing purpose also had differing breeding goals and outcomes. The relatively recent move of humans to an urban (instead of a tribal) lifestyle has caused specific adaptations of these behaviors with far-reaching consequences.

Beginning with the common persistent questions of why women choose violent men as sexual partners and, congruently, why men inflict...