I can tell you that too much money is corrupting American politics. Don't blame the American public. The U.S. Supreme Court has a lot to answer for, because it has made it impossible for Congress to reduce the corrupting influence of money on American political life.

To protest about bullfighting in Spain, the eating of dogs in South Korea, or the slaughter of baby seals in Canada, while continuing to eat eggs from hens who have spent their lives crammed into cages, or veal from calves who have been deprived of their mothers, their proper diet, and the freedom to lie down with their legs extended, is like denouncing apertheid in South Africa while asking your neighbors not to sell their houses to blacks.

Remember that not everyone is as strong as you are. Be mindful of human weakness, and of the fact that it may be more important, in the long run, to get many people taking steps in the right direction than to have fewer achieving the ideal.

So why don't we make ourselves the last generation on earth? If we would all agree to have ourselves sterilized then no sacrifices would be required - we could party our way into extinction!

At present scientists do not look for alternatives simply because they do not care enough about the animals they are using.

Of course, infanticide needs to be strictly legally controlled and rare - but it should not be ruled out, any more than abortion.

There is an obvious evolutionary explanation for the scarcity of altruistic saints: Without a strong predilection for their own interests, our ancestors would have been unlikely to survive, reproduce, and give their own offspring a chance of doing the same. Now conditions have changed and for most of us, surviving and reproducing isn't such a struggle but we still carry the genes of our ancestors and they influence - not determine, but influence - our behavior.