Evolutionary sexology: What can our DNA tell us about sex in the Oval O ffice?

"There is not a sexual relationship; that is accurate," said President Clinton, answering a question from Jim Lehrer about his association with Monica Lewinsky. Whatever position you take on the President's sexual appetite - kneeling, missionary or biblically stone-throwing - we can presumably all agree that he was telling the truth at this moment. Even a man as haplessly incontinent as Big Bill must have realised that it would be unwise to try and sneak Monica into the Oval Office stationery cupboard at the very apogee of the scandal. But shouldn't Mr Lehrer, one of America's more experienced television interviewers, have noticed that the President had surreptitiously fiddled with the tense of the question before replying to it? "You had no sexual relationship with this young woman?" Lehrer had asked, a temporally inclusive inquiry which Clinton's oddly precise answer didn't match. Elsewhere in the interview too there were oddities of expression which seemed to hint at long hours spent with advisors, calculating just how he might trace a narrow and mazy path between an indefensible lie and damaging admission.

What about, "I did not urge anyone to say anything untrue"? This statement is not strictly inconsistent with President Clinton having said, "Vernon, tell her that if she keeps her big yap shut she'll be well looked after," but it might, all the same, be felt to fall some way short of complete candour.

What goes through the Presidential mind at such moments of antler-locking confrontation? What, more to the point, goes through the mind of a man who decides to risk prestige, power and respect for the sake of an office affair - of all forms of romantic liaison the one which has the lowest probability of a satisfactory conclusion? I was rather struck by the fact, reported in some papers, that Ms Lewinsky had graduated in psychology from Lewis and Clark College in Oregon - a detail which suggested that she might be in a better position than the average lay-woman (if you'll excuse the term) to reflect on such questions.

There are a couple of problems with this assumption, I can quite see. I don't know, for example, where Lewis and Clark College stands in the academic rankings but you couldn't really say it has an international reputation in the field. It's also true that paper qualifications in this discipline don't offer any guarantee of extra insight. But, assuming her claims are true, you would have thought that the odd fragment of course- work might have come back to her as she negotiated her way towards an association with the most powerful man on the planet. And you would have thought, too, that she might have imagined the concertedly neurological exclamations that would follow any exposure of their secret: "What was he thinking of!", "Is he out of his mind!", "Has he gone completely mad!"

It's possible that I'm hyper-sensitive to the psychological implications of the story, having just read two recent books about the evolution of the human mind - Stephen Pinker's How The Mind Works and Evolutionary Psychiatry, by Anthony Stevens and John Price. Both books consider the ways in which our genetic inheritance may have shaped our emotions and social behaviour and both books argue that 20th-century men and women are a compound of ancient impulses (coded into our very DNA) and learnt behaviour. "If we are to understand the psychiatric disorders from which our contemporaries suffer", write Stevens and Price, "then we have to take into account the ways in which Western society frustrates the needs of palaeolithic man or woman still persisting as living potential within us in our present environmental circumstances".

Pinker, who isn't directly concerned with disease as such, argues that many of the day-to-day impulses we conventionally dismiss as "irrational" make perfect sense in terms of evolutionary struggle - and indeed still have their purposes today.

Now it hardly needs saying that this is tricky territory. It isn't very far from saying that we are born with certain inherited dispositions, to saying that it is futile, or even wrong, to thwart them. Both books are at pains to make it clear that they will have nothing to do with such genetic determinism. Even so their accounts of primal evolutionary strategies can't help but strike the odd contemporary echo - in particular this passage from Pinker, in which he describes the different sexual strategies of men and women: "The reproductive success of males depends on how many females they mate with, but the reproductive success of females does not depend on how many males they mate with. That makes females more discriminating. Males woo females and mate with any female that lets them. Females scrutinise males and mate only with the best ones: the ones with the best genes, the ones most willing and able to feed and protect her offspring, or the ones that the other females tend to prefer." One imagines that possession of the Presidency must be regarded as a fairly solid affidavit of fitness for the environment.

In a crude application of these biological principles the affair would offer no mystery whatever. President Clinton is not just any ordinary Joe, after all, needled by the seed-sowing impulses that afflict all male mammals; he's the silverback Alpha-male of the tribe and so it is hardly surprising that he might succumb to an atavistic impulse to both confirm and display his ascendancy by sexual conquest. By the rather harsh light of evolutionary psychiatry, the conundrum is not why a man of such achievement should seek to add women to a virtual harem, but why other men of achievement don't. Ted Heath needs more explanation than Bill Clinton. And, if it all happened as she said it did, Ms Lewinsky was similarly in thrall to responses that may have been at odds with immediate common sense. Even if the sexual act involved offered no prospect of a genetic harvest, the ancient impulse still operated.

Do we want a caveman in the White House? An evolutionary psychiatrist would argue that, at one level, we don't have much choice in the matter. All of us carry with us the ineradicable presence of our ancestors, a fact conveyed in an unintentionally comical passage from Stevens and Price's book: "What evolutionary psychiatry has recognised", they write in a concluding chapter, "is that the patient also brings the hunter-gatherers, anteaters and reptiles from his ancestral past. By the end of the consultation the room is crammed with this menagerie, each member of which has a right to be listened to, to have their needs fulfilled."

If he's impeached, perhaps President Clinton will plead that he was simply trying to get in touch with his inner iguana. Perhaps, unconsciously, this was what Ms Lewinsky had in mind when she described him as the Big Creep - indicating by that familiar locomotive insult a belated recognition that she had been dealing with the reptile rather than the Rhodes scholar. None of this will do as any kind of excuse, of course, because as well as being mammals we are humans too. The species that invented the zip- fastener can hardly claim that it doesn't know how to keep it shut when circumstances demand.