Edward O Wilson is 78. But his face still lights up like a 12-year-old at the joy of science - “This is science! This is how it is done!” - or at yet another Darwinian controversy: “It’s got Richard Dawkins ballistic!”

He is the supreme scientific grandee, the “new Darwin” as Tom Wolfe called him, the finest prose writer in science and, I would argue, one of the greatest living thinkers. He flew from Boston to London this month to receive yet another award - the Linnean Society’s tercentenary medal. The Linneans were charmed out of their socks. One girl asked him to sign a book. He did so, adding a little drawing of an ant. She swooned.

So let’s start with the ants. There are, give or take, 10,000 trillion ants in the world. One ant weighs about one-millionth of one human. There are, give or take, 6.6 billion humans in the world. The total weight of ants in the world is therefore quite a lot more than the total weight of humans. This is a source of immense satisfaction to Wilson. He is, apart from anything else, the greatest living myrmecologist - ant expert - and it is to ants that he has returned to announce the greatest revolution in Darwinian theory in 50 years.

“We are,” he says, beaming with excitement, “moving to a new paradigm.” It is a paradigm of which Dawkins wants no part.

Ant colonies are “superorganisms” - this is the title of the book Wilson has just finished - and they pose the most important question to Darwinians. Ants live and die for the good of the colony, not themselves: they are hyper-altruistic. But how can this be if evolution is a method of making the individual fit for reproduction?

The first answer, proposed by the great British biologist William Hamilton and popularised by Dawkins in his book The Selfish Gene, is “kin selection”. Genes exist to replicate themselves. This is ideally done by ensuring that the individual reproduces. But it might also be done by ensuring that relatives of the individual reproduce because they share many of the same genes. So altruism starts with family members. Altruism towards strangers, meanwhile, is explained by game theory - computer models show that a cautiously benign approach to strangers is the best evolutionary strategy. Either way, Dawkins’s “selfish gene” is at the heart of the whole process.

Wilson, like everybody else, bought into this idea in the 1960s and 1970s. It was the orthodoxy and the only other contender - group selection - was rigorously suppressed. This was in fact an anti-Darwinian moment, since Darwin himself had thought that selection must happen at the level of the group.

“Kin selection was a very seductive idea,” Wilson explains, “and I promoted it heavily in my books in the 1970s. Unfortunately it has produced a little industry with its own mathematical models. It hasn’t produced much else and, meanwhile, sociobiology has flourished.”

Sociobiology is the study of social behaviour in the light of Darwinian theory. Wilson created the discipline in 1975. He suggested that it could be applied to humans. The left hated this, calling him a racist, a sexist and a fascist. In fact he is a sweet-natured Democrat. But the left wanted to believe in the human mind as a “blank slate”; Wilson had shown this to be profoundly illogical.

There is such a thing as human nature and we are to an important extent preprogrammed. It is sociobiology - particularly the phenomenon of the superorganism - that has led Wilson to reject kin selection. Group selection is the new paradigm that has Dawkins ballistic.

Along with his collaborator David Sloan Wilson (no relation), Wilson wrote a paper outlining his conversion. It was picked up by the New Scientist and in the subsequent article by the two Wilsons they suggested that at some point Dawkins had been forced to acknowledge an error in his interpretation of kin selection. “We were trying to mollify him,” says Wilson with, I think, a slight twinkle.

Incandescent and unmollified, Dawkins wrote to the magazine. He said the statement was “not a semantic confusion; not an exaggeration of a half truth; not a distortion of a quarter truth; but a total, unmitigated, barefaced lie”. He also said it was safe to assume that the “wise and sensible” Ed Wilson was innocent and this was all down to D S Wilson. Both Wilsons responded by producing a quote from a Dawkins book which seemed to show that, however barefaced and unmitigated it was, it wasn’t a lie.

“We are united in our view of group selection,” the Wilsons concluded, “which we converged upon through separate lines of inquiry.” Group selection says that evolution acts on many levels. Take the ants again. “They are constantly at war,” says Wilson. “Give ants nuclear weapons and the world would be destroyed in a week.”

Warring ants will be better off if the entire fitness of the colony can be improved. If it is improved then the methods of that colony will be successful in war and the genes that carried the improvement will be disseminated to a wider ant population. Kin selection may play a part within the colony. But group selection is the far more potent evolutionary force. In his next book Wilson is to study the implications of this new paradigm for humans. Knowing him, it may well turn out to be the first great scientific statement of the 21st century.

“It will be a reexamination of the forces of social evolution - what kind of changes are brought about by higher social organisation in insects and humans. We’ve done the insects now and I’m going into the humans, consulting and studying and building a new picture of the origins of social behaviour in humans.” What has him really excited is that he doesn’t know what he'll find. There are two possibilities - either human social behaviour evolves in much the same way as insects or human culture “has entirely changed the way evolution works”. Either way, the crucial point for Wilson is that group selection may offer us a way out of our deepest problem.

“If inter-group conflict turns out to be a powerful force in human evolution, as Darwin thought it was, then perhaps it would make it easier for the leaders of people on the edge of violence to step back and say, ‘Let’s try the other way, let’s try understanding why we feel this way’. We are bedevilled as a species by hair-trigger aggressive tendencies.”

Something like that, I point out, happened in the Cuban missile crisis when both sides were rational players. “Yes, it wouldn’t work for Hitler or Islamic fundamentalists. There are cases where we have to realise that there’s sickness in the world like cancer, that there has to be drastic action. But we should know what is treatable and what is not.” Wilson is an optimist. He agrees, for example, with the recent finding that human evolution is continuing: “We’re not evolving progressively, getting smarter or acquiring a new organ, what we are doing is homogenising the species.”

In a thousand years, he says, the people in Stockholm may look exactly like the people in Lagos. But - and here his optimism kicks in - we will be a species full of novel possibilities. Interbreeding between previously separated populations will produce new gene combinations so, although we will be more homogenised on average, we will also be more varied.

If, I say, we make it. “Right, if we make it. But we’re getting things figured out. I’m optimistic.” He admits that we’re “in for a rough ride” on global warming but we know how to fix it and eventually we will.

His primary concern is biodiversity and the way human activity is threatening to cause the next big extinction of species, leaving humans in what he has called the “Eremozoic”, the Age of Loneliness. His own contribution to this was a typically fine gesture. He “offered the hand of friendship” to the religious in America. He organised a retreat involving leading scientists and representatives of 30m evangelical Christians. They signed a covenant agreeing that the preservation of biodiversity was a moral and practical good.

Wilson is no atheist; he says we simply do not know enough. And he has a real feeling for religion that makes him impatient with the new wave of militant atheists led by - once again - Dawkins.

“I call them the military wing of secularism. I’m the diplomatic wing. It’s a curious phenomenon, another kind of human polarisation. They feel that religion is an evil, a sickness, and they think all you have to do is keep bombarding the religious and sending men over the top and eventually they’ll fold. I think we have to find common ground.

“These are good, decent people, they’re intelligent. Humans have an innate tendency to form religious belief. It has a lot of beneficial influences. It helps people adjust to their mortality and it binds communities tightly together . . . to have evolved such a powerful tendency and to hold it unto death, that looks like a biological adaptation.”

It’s time to leave him to the Linneans. What can I say? Only this - ladies and gentlemen, Ed Wilson, a credit to our species.

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