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.

Personality and socialization aren't the same thing.

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

A decent government with an effective, but not gratuitously violent, police force and a fair court system are essential. This deters and incapacitates psychopaths, bullies and hotheads - and if it earns the confidence of the people, they don't have to become violent in self-defence.

When it comes to explaining human thought and behavior, the possibility that heredity plays any role at all still has the power to shock. To acknowledge human nature, many think, is to endorse racism, sexism, war, greed, genocide, nihilism, reactionary politics, and neglect of children and the disadvantaged. Any claim that the mind has an innate organization strikes people not as a hypothesis that might be incorrect but as a thought it is immoral to think.

Parents provide their children with genes as well as an environment, so the fact that talkative parents have kids with good language skills could simply mean that and that the same genes that make parents talkative make children articulate.

Humans are so innately hardwired for language that they can no more suppress their ability to learn and use language than they can suppress the instinct to pull a hand back from a hot surface.