It is true that raids and battles killed a tiny percentage of the numbers that die in modern warfare. But in tribal violence, the clashes are more frequent, the percentage of men in the population who fight is greater, and the rates of death per battle are higher.

Of course, genes can't pull the levers of our behavior directly. But they affect the wiring and workings of the brain, and the brain is the seat of our drives, temperaments and patterns of thought.

I don't think aggression works like thirst or sleep. I think aggression is more elicited by particular situations. I think it can be mitigated.

As women are empowered, violence can come down, for a number of reasons. By all measures, men are the more violent gender.

Equality is not the empirical claim that all groups of humans are interchangeable; it is the moral principle that individuals should not be judged or constrained by the average properties of their group.

Space and force pervade language. Many cognitive scientists (including me) have concluded from their research on language that a handful of concepts about places, paths, motions, agency, and causation underlie the literal or figurative meanings of tens of thousands of words and constructions, not only in English but in every other language that has been studied.

Of course the theory of evolution would be vacuous if it offered a glib explanation for every inexplicable act.