Down in San Antone, a busty long-haired marketing professor has made a career of pissing off feminists — sex-positive or otherwise — by studying how a woman’s ovulatory cycle influences her choices in romantic partners, clothing, food, and presidential politics. Now, Kristina Durante of the University of Texas at San Antonio is saying women are vastly more prone to catfights during that time of the month, as sexual competition heats up.

With her wingman, Vladas Griskevicius, the evolutionary psychologist conducted three experiments to test the psychological motivations of women who were ovulating. In the experiments, the researchers gave an unspecified number of study participants a fixed amount of money she might choose to share with another person, playing the so-called “dictator game.”

The results were clear. Women who were ovulating were willing to share only a quarter of the money, half as generous as women who were not ovulation. And when offered a choice between maximizing their individual winnings versus gains relative to other women, study participants who were ovulating preferred greater social standing, choosing to outpace the proverbial Joneses.

"We found that ovulating women were much less willing to share when the other person was another woman," Durante said in a statement. "They became meaner to other women."

Griskevicius had trouble wrapping his mind around it, saying the results were surprising. “What’s interesting about this finding is that ovulating women are so concerned about their relative position that they are willing to take less for themselves just so that they could outdo other women,” he said.

Evidence for the findings was bolstered by the third experiment. In sharing money, ovulating women were found to be much more generous to men than women, revealing a prime sexual motive. Although both researchers professed surprise at the study outcome, they appear to have reverse-engineered previous work finding women hysterically chained to their biology, as men are to theirs. Now, the controversial science of evolutionary psychology is leveraged to advance the principles of modern business marketing.

In the experiments, women who were not ovulating shared approximately 45 percent of the money with a man. However, those were ovulating gave the player a good 60 percent, providing further evidence for dramatically altered motivational perceptions during that time of the month. Still, Durante said the finding was unexpected.

“These findings are unlike anything we have ever seen in the dictator game,” she said. “You just don’t see people giving away more than half of their money. One possibility is that we’re seeing ovulating women share more money as a way to flirt with the men.”

Below is a speech about "ovulatory psychology" Durante gave at a TED conference last year in San Antonio.

Source: Durante, Kristina, Griskevicius, Vladas. Money, Status, and the Ovulatory Cycle. Journal of Marketing Research. 2014.