Despite media reports to the contrary, the University of New Mexico did not pay for Geoffrey Miller and Brent Jordan to get 5,300 lap dances in two months. In fact, Miller has never even been in a strip club. And frankly, they’re getting tired of everyone’s asking.

Miller, an evolutionary psychologist at the University of New Mexico, and Jordan, his recent undergraduate research assistant, did conduct a study examining the impact ovulation has on lap dancers’ tip earnings. But they gathered data via a Web site, where strippers logged in anonymously to provide information about their earnings, productivity and menstrual cycles during 296 work shifts (about 5,300 lap dances). The results: While ovulating  and therefore the most fertile  strippers made an average of $30 per hour more than menstruating women and $15 per hour more than women elsewhere in their cycles. Women on the pill  who typically don’t ovulate  made significantly less than naturally cycling women overall and had no “estrus earning peak.”

Jordan first became aware of this phenomenon while working his way through college managing a strip club, where his duties included “physical protection,” collecting nightly reports on women’s tips and providing dancers with tampons when necessary. Jordan noticed that the women getting tampons reported lower tips than those who didn’t. So he started collecting “preliminary data” to analyze for his evolutionary biology coursework.

“Studies like this,” Miller says, “can tell us about the nature of human sexuality and attraction and answer important questions scientists have been debating for decades.” For example: Conventional scientific wisdom says that almost all mammals except humans go into estrus (a k a “heat”). Cats yowl and raise their hind ends in the air; female primates get visibly engorged in relevant areas. But humans, scientists have long believed, do no such things. Miller and Jordan’s research indicates otherwise. “It’s highly controversial because it’s science blurring the line between humans and other primates,” Miller says, “but our results give clear economic evidence that human estrus actually does exist.”