With taxes, if they aren't working right, we can change them with a stroke of the pen. It's basically a market-type mechanism. People make their own choices. You run the taxes, and you get the results.

After The Bomb we developed a fairly good system for moving food around and have avoided the kind of massive famines that attract the media. Although of course we've had a fair number of them, particularly in Africa, since The Bomb was written. But we have had a steady level of attrition of malnutrition and malnutrition-related disease. Probably something on the order of 5 to 10 million people starve to death each year, but they're spread out; they're not dramatic news events.

People have to decide, first of all, how they'd like to live, and how secure they want to be from disaster. After that, scientists can help determine what would be necessary to achieve that.

Stanford may be the best university in the world, but you can get all the way through here without knowing where your food came from, without being able to say where we came from, without being able to give a coherent description of why the climate is changing and why we should be concerned about it. So I started teaching a course in human evolution and the environment that's open to all Stanford students, no prerequisites.

Recycling helps make people feel involved, and in some cases can be useful. Although you've got to do careful life history studies of what you're recycling. If all you're doing is recycling - if you've got three automobiles, and 10 children, and a 7,000-square-foot dot-com palace and second home up in the mountains that has to be heated - the recycling isn't making much difference.

We ought to take good care of everybody we have on the planet, but we ought to regulate the rate at which people join us. The old saying is, "It's the top of the ninth inning, and humanity has been hitting nature hard, but you've always got to remember that nature bats last."

The National Academy of Sciences would be unable to give a unanimous decision if asked whether the sun would rise tomorrow.