It must be almost equally discouraging for scientists to see the graph that plots the age at which eminent male scientists make their big discoveries. It peaks at age 30 and then plummets, giving precious little time after one's hard-earned Ph.D. to get that invitation from the Nobel prize committee. The productivity of jazz musicians and painters is also highest in their mid-30's. And it's not just creativity that attains its zenith early in the male career. Crime, too, follows just the same parabolic curve.

Dr. Satoshi Kanazawa, an evolutionary psychologist at the London School of Economics who has studied these patterns of male achievement, believes he has the explanation. Young men in any profession are driven to seek wealth and prestige because these attributes are attractive to women. Once men's urges to start a family have been satisfied, the wellsprings of productivity, whether in science, art or crime, run dry, Dr. Kanazawa suggests.

In support of his thesis, published in the current Journal of Research in Personality, he notes that marriage seems to have a quenching effect on both creativity and crime. Scientists who remain unmarried, he says, reached their peak of productivity at age 40, much later than the wedded sort. Criminals, too, retain their productivity much longer if unwed but tend to hang up their crowbars after marriage. "Both crime and genius are manifestations of young men's competitive desires to gain access to women's reproductive resources," he concludes.

Dr. David M. Buss, an evolutionary psychologist at the University of Texas at Austin, said he agreed with the general idea that scientific productivity, writing and crime are all activities driven by men's pursuit of wealth and status. But Dr. Kanazawa's thesis, in attributing everything to a switching on and off of some male competitive drive, was a "wild oversimplification." For one thing, men need to command resources after marriage as well as before, or they will find themselves divorced. Indeed, income in the United States peaks around age 55 for men, Dr. Buss said.

Evolutionary psychology is the attempt to relate human behaviors to the purposes for which they evolved. Since evolution's criterion for success is getting as many genes as possible into the next generation, it is reasonable to seek to understand human behavior in terms of reproductive advantage.

Dr. Buss has shown that women in many different cultures are attracted to men with money and prestige. "Scientific and artistic endeavors are male attempts to compete for status and resources, although I don't think men conceptualize it that way," he said. Evolution has built in a drive for male competitiveness and status-seeking because it is attractive to women; there's no need for the drive to be conscious.

In his recent book, "The Mating Mind," Dr. Geoffrey Miller argues that intelligence and creativity are the product not of natural selection, the struggle for survival, but of sexual selection, the struggle for reproductive advantage. The peacock's tail, a flamboyant example of sexual selection, is a costly encumbrance of no help at all to physical survival, but of great value in seducing peahens.

Sexual selection tends to work much faster than natural selection and has a tendency toward weird excess because of a runaway reinforcing process — the peahens, who favor long tails, and the peacocks, who have them, both have more progeny, so in the next generation even longer tails are de rigeur.

Dr. Miller, an evolutionary psychologist, , sees human intelligence as the weirdest excess of all. We're far smarter than was necessary for just surviving in the savannah, he says, and our close cousins the great apes never needed to develop our kind of intelligence. Therefore intelligence and creativity must be the product of sexual selection: women preferred smarter men, the better singers and dancers and spell-binders, and vice versa.

If Caesar had only known that his desire to emulate Alexander — his spectacular conquest of Gaul, his renowned oratory, his elegant military histories, his provident reform of the calendar — stemmed from an unconscious drive to bed more women, would he not have wept all the more?