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.

Evolutionary psychology is one of four sciences that are bringing human nature back into the picture.

Knowledge is a continuous fabric, in which ideas are connected to other ideas. Reason-free zones, in which people can assert arbitrary beliefs safe from ordinary standards of evaluation, can only corrupt this fabric, just as a contradiction can corrupt a system of logic, allowing falsehoods to proliferate through it.

I have never been a fan of science fiction. For me, fiction has to explore the combinatorial possibilities of people interacting under the constraints imposed by our biology and history. When an author is free to suspend the constraints, it's tennis without a net.

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.

We really are creatures of a violent world, biologically speaking - watching violence and learning about it is one of our cognitive drives.

Since violence is largely a male pastime, cultures that empower women tend to move away from the glorification of violence and are less likely to breed dangerous subcultures of rootless young men.