On May 29, 1832, the French mathematician variste Galois, a young genius and political rebel who spent time in jail for allegedly threatening the king s life, stayed up all night furiously scribbling his ideas onto paper. These scribblings constitute much of what work of Galois survived for posterity. The next day, he was killed in a duel. While the origins of the duel remain obscure to history, the most popular story has it that Galois was involved in an affair and that the woman s fianc e was the one to strike him dead. At the time of his death, Galois was just 20 years old yet his work laid the foundation for a major branch of abstract algebra.

The story may have grown a bit fanciful in its retelling down through the years, yet its essence the combination of youth and lust and genius gets at something essential about what drives humans to heights of creativity and productivity. Valentine s Day, coming up Sunday, may be a multibillion-dollar industry. But the larger driver of economic progress is the sex drive itself.

What drives us to create and produce? What drives us to consume? Why are love and money so intimately intertwined?

Now, creative genius is its own animal, and we ll return to it momentarily. But first, let s look at how sex drives people s spending. There are obvious ways sex gets people to spend more money (flowers, presents, dates not to mention the direct, usually illegal, purchase of sex), but a tremendous amount of economic activity also goes into what s called signaling buying things to communicate one s status, and thus one s desirability as a mate.

Economists such as Ori Heffetz and Robert Frank at Cornell have worked to create a measure of visibility to determine how much of people s consumption is intended to signal status to others. The answer is: quite a bit. The visibility of products like cars, clothing, furniture, jewelry and dinners out can explain at least 12% of the variability in how people spend an extra dollar as their incomes rise that number jumps to 20% for the upper half of earners.

Even more revealing, however, is how men and women respond in an economic experiment when romantically primed that is, when they are shown pictures of attractive people of the opposite sex and then asked to make various consumption decisions. Romantically primed men, in a study published in the Journal of Personality and Social Psychology in 2007, proved much more willing to splurge on things like flashy watches and expensive cars (while they showed no difference in their spending on boring, non-flashy things like tissues and headache medicine). Women, meanwhile, didn t adjust their consumption at all when romantically primed. Instead, romantically primed women indicated that they were more willing to spend time volunteering (such as at a children s hospital or a homeless shelter).

What does all this tell us? It tells us that these consumption decisions are most likely about signaling: for men, of status and access to resources; for women, of altruism. Romantic priming made men no more likely to want to spend time volunteering; and romantically primed women only wanted to volunteer more when their effort would be visible, not when it would be inconspicuous (e.g., picking up trash alone in a park or taking shorter showers to conserve water).

But the drive to find a mate influences much more than what and how much we buy. It also influences how hard we work especially men. Economist Eric Gould, of Hebrew University in Jerusalem, looked at the human capital investments of young men for a 2008 paper in the Journal of Human Capital. Working from a dataset of 12,686 young men and women who were 14-22 years old when they were first surveyed in 1979, Gould reached a stark conclusion: If men s decisions about education and work were unable to earn them returns in the marriage market (that is, a greater likelihood of marriage and/or marriage to a higher-value woman), they would work less, go to school less, and choose the blue-collar sector over the white-collar sector more often.

In a related study, an evolutionary psychologist at the London School of Economics, Satoshi Kanazawa, looked at the biographies of 280 scientists and found that their careers peaked around age 30, with marriage seeming to have a particularly deleterious effect on male genius. What s more, the scientists greatest contributions to their fields followed a similar pattern to the ages when male criminals commit the bulk of their crimes. Kanazawa theorizes that both patterns correspond to the years when men are subject to the greatest competition for mates.

In another study of 6,000 recent jazz, rock and classical albums, evolutionary psychologist Geoffrey Miller, at the University of New Mexico, found that 90% were produced by men and that these men also reached their creative peak around age 30. Similar curves have been found for painters and writers.

Why does a J.D. Salinger write a brilliant novel as a young man and then forever disappear? Why does a James Watson make the greatest discovery in biology in the 20th century at the age of 25 and then produce very little for the rest of his life? Why does a Paul McCartney write brilliant, world-changing songs in his youth and then fade away into doddering irrelevancy?

Why does a doomed young mathematician scribble away furiously at equations in the depths of the night before he is to die for passion?

Certainly, genius and productivity are not the exclusive preserve of the young and lustful. But the fire of progress appears to be fueled by the kindling of human desire. At the very least, the connection is suggestive.

Ryan Sager writes the blog Neuroworld at TrueSlant.com.