This idea soon became gospel in the evolutionary biology world. I had helped promote Hamilton’s work, but as time went on, I developed my doubts about it.

Certainly, in my own research, I’d observed sophisticated societies that evolved through group selection, where individuals would be altruistic for the sake of their group’s survival. The ants are an example. In fact, when you think about it, the creatures that dominate the earth are cooperative — ants, termites, humans.

Meanwhile, Martin Nowak, a Harvard applied mathematician, was entertaining similar questions. He and his colleague Corina Tarnita [now at Princeton University] had been preparing their own paper detailing their misgivings about kin selection. We dovetailed our efforts, eventually producing a paper for the journal Nature where we asserted that Hamilton’s theory was fundamentally flawed. We felt it could not explain how complex societies arose.

Your Nature article, published in 2010, kicked off yet another round of academic warfare. A few months after the paper appeared, more than 130 evolutionary biologists — your colleagues — sent a letter to the editor disputing your thesis. Did you think, “Oh no, here we go again?”

Well, Nature’s editors had a different view. Before publication, they’d sent over an editor from London, and we had a whole seminar going over the issues in our paper. They have pretty high standards, and afterwards, they were satisfied that this was a soundly reasoned article — maybe it was wrong in some places that weren’t obvious, but they decided to print it. In fact, they liked it so much, they made it a cover story.

So why the uproar?

I was canceling, or trying to replace, a body of theory that had gained quite a few followers who’d applied it to their Ph.D.s and their CVs. Their careers depended on it. They had written articles and books and given seminars on it.

So they didn’t like me. They said, “It’s so obvious that it’s true. How can you deny it?” We said, “We have math models. Take a look.”

With the publication of Genesis, you are reopening old wounds. Were you looking to go one more round with your critics?

Yes and no. I did want to settle the questions about group selection for once and for all. I thought it was important to put our theory on a firm mathematical and evidential basis. Either that or dispose of it.

Genesis turns out to be one of the more important books I’ve written. The book shows that group selection is a phenomenon that can be exactly defined. I show that it has occurred at least 17 times.

Group selection is a big part of the great transitions of evolution, where life progressed from bacteriumlike organisms to cells with structures inside, and on to simple organisms that were collections of these cells, to the differentiated organisms forming groups and so on. I presented these transitions against the backdrop of group versus individual selection.

Now, there exists a succession of social behaviors that advanced society is based upon. With humans, our advancement was aided by the fact that we were bipedal, with free arms and grasping fingers, and that we first lived on the savanna, where frequent [natural] fires gave us precooked animals to eat. What’s more, we had a good long-term memory and a capacity for high levels of cooperation, with altruism being a strong motivating factor.

The Hamilton theory implies that a mechanism was going on when relatives got together and that they were more likely to form a group because of their shared genes. However, this explanation is filled with mathematical errors and difficulties. Some of our evolutionary success occurred because groups formed, and they tended to be altruistic. Genetic relationships or not, these groups often cooperated, which is part of why we Homo sapiens were successful.

Might you give us “the elevator pitch,” the summary conclusion of your theory?

It’s the way my colleague David Sloan Wilson puts it. He says that within groups, selfish individuals will defeat altruistic ones. However, in conflict, groups of altruistic individuals will defeat groups of selfish individuals.

You know, we’ve heard everything we can possibly hear about the destructive and negative aspects of human nature. There’s a lot of evidence that we evolved because of qualities we consider unifying and propitious for the future.

Dr. Wilson, in person, you are remarkably genial and polite. Why then are you a lightning rod for so much controversy?

Maybe it’s because I prefer ideas that are original over those that are just pleasing.

Your collaboration with Martin Nowak fascinates. Do you often partner with mathematicians?

I do. I think that mathematical models are a good way of thinking about complex quantitative and sometimes qualitative phenomena.

Mathematical models can predict these things with precision. Biological research tests those models. When I’m trying to build an exact testable theory, as I was in Genesis, I’ll give the applied mathematicians my input, and, with luck, they’ll take hold of a problem.

I find this approach exciting. Partly because of my work with Nowak, I’ve come to believe that a whole new science is emerging that will combine natural history in the field with mathematical modeling and experiments similar to those conducted in a laboratory.

This kind of science will be more interesting to the public and attractive to young people who wish to enter careers in science and technology. It will also give us a firmer base on which to save the natural world.

When you are considering a mathematician to collaborate with, what are the qualities you seek?

The same I would look for in a plumber or a building contractor. I want them to be the best at what they do.

Where else in your career have you entered such partnerships?

When I was working out a theory of pheromone transmission — how odors are transmitted among ants and moths — I collaborated with Bill Bossert, an applied mathematician who later received a named professorship at Harvard.

Earlier, I had gotten together with another brilliant mathematically trained ecologist, the late Robert MacArthur of Princeton University. Together we worked out the theory of island biogeography, which helped explain why there were certain numbers of species of different kinds of organisms on islands of different size.

Some of our data there had been collected years earlier when I’d gone to the South Pacific to study ant species. MacArthur was able to come in with the right model to figure out how my data could apply to the new question.

The theory of island biogeography made your career. But as your 90th birthday approaches, do you think about what you’d like most to be remembered for?

[Laughs.] You know, I’ve never really tried to think about that, honestly.

Well, perhaps I’d like to be remembered for obtaining such a great age and staying productive to the end — I’d like to be remembered for those things I’ve put my efforts into. I’d certainly like to be remembered for having created several new disciplines and bodies of theory that had an impact on science.

I don’t wish to be insensitive, but I am wondering if you ever think about death?

Oh, I’ve learned to live with mortality. My favorite line from Darwin was his last line to his family. He said, “I am not in the least afraid of dying.”

And I’m not either. I look on life as a story. It’s a series of events that have occurred, some of them momentous to you and a few other people. You made it through OK, you did this and that. And it could be written as a story. That’s what a life means.

Too many people think of it as a waiting station for the next life up. Or [they’re focused on whether] maybe they’ll find a way to extend this life by another 10 percent or 20 percent. I don’t think that’s a very smart way to live.

So I’m not afraid. I’m just really anxious to finish this book I’m writing now on ecosystems. And to figure out how I’ll get to Mozambique to do the fieldwork.

This article was reprinted on Wired.com.