If zoos are like arks, then rare animals are like passengers on a voyage of the damned, never to find a port that will let them dock or a land in which they can live in peace. The real solution, of course, is to preserve the wild nature that created these animals and has the power to sustain them. But if it is really true that we are inevitably moving towards a world in which mountain gorillas can survive only in zoos, then we must ask whether it is really better for them to live in artificial environments of our design than not to be born at all.

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.

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

We are not especially 'interested in' animals. Neither of us had ever been inordinately fond of dogs, cats, or horses in the way that many people are. We didn't 'love' animals.

As we realize that more and more things have global impact, I think we're going to get people increasingly wanting to get away from a purely national interest.

Ancient recipients of instant news probably couldn't do very much about it, for instance. Xerxes would still need three months to get his army together, and he might not get home for years.

I'm a Utilitarian, so I don't see the rule against lying as absolute; it's always subject to some overriding utility which may prevent its exercise.