Ernst Mayr at 93

Natural History, May, 1997 by Natalie Angier

At least that amount. It has something to do with the poor quality of education in America. Many students here don't even know where Mexico is located.

You talk at length in your book about proximate versus ultimate causes, and the importance of addressing both in trying to understand how life works.

Yes, this is part of the philosophy of biology, that there are two causations in biology, proximate and ultimate. The proximate causation is the one that answers the "how" questions. Physiology, molecular biology, and developmental biology all study proximate causations of how something works. But then we have the ultimate causations, which ask the "why" questions. Evolutionary biology, much of ecology, and behavioral biology are all concerned with the why questions. Why do birds migrate to warm climates in the winter? They've been selected to do so because otherwise they would die in the winter.

Do you think the proximate fields like molecular biology are in ascendance these days? You've quoted biochemist George Wald, who said, "All biology is molecular. "

George Wald's claim was based on strict reductionism, and reductionism is dead. It's now so clear that every time you have a more complex system, new qualities appear that you could not have predicted from the components. That's the principle of emergence. I once gave a lecture in Copenhagen, and I said something I now realize to be wrong. I said, emergence is characteristic only of biology. That was in 1953, when emergence was very suspect, nobody believed it. The famous physicist Niels Bohr got up to object, and I thought he'd say emergence was metaphysical and supernatural and all sorts of things. Instead he said, "We have emergence all over the inanimate world," and he gave the famous example of water. If you know all the characteristics of hydrogen and all the characteristics of oxygen, you still couldn't predict that the product would be liquid. So that's the end of reductionism.

As for molecular biology, there's no branch of biology that doesn't use molecular techniques now, because they're so extraordinarily powerful. But since we have the problem of emergence, it's clear that molecular biology alone isn't the whole answer.

The concept of group selection was once taboo, but now it's undergoing a kind of resurrection. What do you think of it?

In my book, I focus on two kinds of group selection, which I call soft and hard group selection. If a group is superior because all of its individuals are superior, and it's still individual selection, then I call it soft group selection. However, if the social group as an entity has more success in the struggle for existence because there's internal cooperation--they jointly search for food, they have sentinels warning of enemies--then we have hard group selection, which goes beyond the average fitness value of the components.

In other words, the whole is greater than the sum of its parts.

Exactly. Hard group selection is very important for human evolution, because our ancestors consisted exactly of these cooperating social groups. And as anthropologists have known forever and ever, some of these groups were more successful than others at driving away competitors from a water hole, or just wiping them out. Genocide is a part of our history. On the other hand, I think it was exactly the selection of social groups that furthered the development of the ethical system, including altruism. Here I disagree with those sociobiologists who don't believe in group selection.