Individual versus group selection results in a mix of altruism and selfishness, of virtue and sin, among the members of a society.

All three of the Abrahamic religions were born and nurtured in arid, disturbed environments.

But once the ants and termites jumped the high barrier that prevents the vast variety of evolving animal groups from becoming fully social, they dominated the world.

The most dangerous of devotions, in my opinion, is the one endemic to Christianity: I was not born to be of this world. With a second life waiting, suffering can be endured - especially in other people. The natural environment can be used up. Enemies of the faith can be savaged and suicidal martyrdom praised.

All my life I have placed great store in civility and good manners, practices I find scarce among the often hard-edged, badly socialized scientists with whom I associate. Tone of voice means a great deal to me in the course of debate. I despise the arrogance and doting self-regard so frequently found among the very bright.

The great challenge of the twenty-first century is to raise people everywhere to a decent standard of living while preserving as much of the rest of life as possible.

The worst thing that will probably happen-in fact is already well underway-is not energy depletion, economic collapse, conventional war, or the expansion of totalitarian governments. As terrible as these catastrophes would be for us, they can be repaired in a few generations. The one process now going on that will take millions of years to correct is loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us.