For the female half of the population, it may bring a satisfied smile. Scientists have found that evolution is driving women to become ever more beautiful, while men remain as aesthetically unappealing as their caveman ancestors.

Researchers have found beautiful women have more children than their plainer counterparts and that a higher proportion of those children are female. Those daughters, once adult, also tend to be attractive and so repeat the pattern.

Over generations, the scientists argue, this has led to women becoming steadily more aesthetically pleasing, a “beauty race” that is still on. The findings have emerged from a series of studies of physical attractiveness and its links to reproductive success in humans.

In a study released last week, Markus Jokela, a researcher at the University of Helsinki, found beautiful women had up to 16 percent more children than their plainer counterparts. He used data gathered in America, in which 1,244 women and 997 men were followed through four decades of life. Their attractiveness was assessed from photographs taken during the study, which also collected data on the number of children they had.

This builds on previous work by Satoshi Kanazawa, an evolutionary psychologist at the London School of Economics, who found that good-looking parents were far more likely to conceive daughters. He suggested this was an evolutionary strategy subtly programmed into human DNA.

He cited two findings from the Longitudinal Study of Adolescent Health, a U.S. government-backed study that is monitoring more than 15,000 Americans. The measurements include objective assessments of physical attractiveness.

One finding was that women were generally regarded by both sexes as more aesthetically appealing than men. The other was that the most attractive parents were 26 percent less likely to have sons.

“Physical attractiveness is a highly heritable trait, which disproportionately increases the reproductive success of daughters much more than that of sons,” Kanazawa said. “If more attractive parents have more daughters and if physical attractiveness is heritable, it logically follows that women over many generations gradually become more physically attractive on average than men.”

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