I don't shout people down. I argue people down, perhaps.

If you have a faith, it is statistically overwhelmingly likely that it is the same faith as your parents and grandparents had. No doubt soaring cathedrals, stirring music, moving stories and parables, help a bit. But by far the most important variable determining your religion is the accident of birth. The convictions that you so passionately believe would have been a completely different, and largely contradictory, set of convictions, if only you had happened to be born in a different place.

Or why it is acceptable to train fast runners and high jumpers but not to breed them. I can think of some answers, and they are good ones, which would probably end up persuading me. But hasn't the time come when we should stop being frightened even to put the question?

The true scientific understanding of the nature of existence is so utterly fascinating; how could you not want people to share it? Carl Sagan, I think, said 'when you're in love, you want to tell the world.' And who, on understanding a scientific view of reality, would not, as it were, fall in love and want to tell the world.

Granted, we may try to help our own family members because they share our DNA. Or help someone else in expectation that they will help us later. But when you look at what we admire as the most generous manifestations of altruism, they are not based on kin selection or reciprocity. An extreme example might be Oskar Schindler risking his life to save more than a thousand Jews from the gas chambers. That's the opposite of saving his genes.

If a healing technique is demonstrated to have curative properties in properly controlled double-blind trials, it ceases to be alternative. It simply, as Diamond explains, becomes medicine.

We admit that we are like apes, but we seldom realise that we are apes. Our common ancestor with the chimpanzees and gorillas is much more recent than their common ancestor with the Asian apes - the gibbons and orangutans. There is no natural category that includes chimpanzees, gorillas and orangutans but excludes humans.