Civilization originates in conquest abroad and repression at home.

It invites a search for ultimate causes: why were Europeans, rather than Africans or Native Americans, the ones to end up with guns, the nastiest germs, and steel?

We scientists have fantasies of being uniquely qualified to make great discoveries. Alas, reality is cruel: most of us are replaceable. For the vast majority of scientific contributions, if scientist X hadn't achieved it that year, scientist Y would have achieved the same result or something very similar soon thereafter.

But this was the only way of life that humans knew for their first 6m years on the planet. In giving it up over the past few thousand years, we have lost our vulnerability to disease and cold and wild animals, but we have also lost good ways to bring up children, look after old people, stave off diabetes and heart disease and understand the real dangers of everyday life.

Biology is the science. Evolution is the concept that makes biology unique.

A blueprint for disaster in any society is when the elite are capable of insulating themselves.

The southward advance of native African farmers with Central African crops halted in Natal, beyond which Central African crops couldn't grow - with enormous consequences for the recent history of South Africa.