The birth control pill may have done more than just help liberate women, it may also have changed “the laws of attraction” between the sexes, according to a new study.
Suspecting that the Pill, which contains synthetic versions of the female hormones estrogen and progesterone, might have a far-reaching impact on what modern women want, two British anthropologists went hunting for information on how big an effect a little tweak to our hormones might make. Their findings were published Wednesday in Trends in Ecology and Evolution.
Women who have their hormone levels smoothed out by the Pill tend to seek men who look like good long-term prospects, says the new report’s lead author, Alexandra Alvergne, an evolutionary anthropologist at the University of Sheffield. On the contrary, a woman on a normal menstrual cycle will have a burst of hormones around the time of ovulation that will drive her to lust after the hottest, sexiest guy in the room.
The data for Alvergne’s new research was buried in earlier studies that were designed to tease out the relationship between a woman’s cycle and her choice of a mate. Previous researchers had just thrown out data from women who were taking the Pill because that information skewed their results.
Once information from women on the Pill were excluded, the earlier studies clearly showed that both women’s and men’s preferences changed depending on how close a woman was to ovulation, Alvergne says. If a woman was at the peak of her fertility, she’d be drawn to pictures of men whose faces had been made to look more masculine. She was also more likely to be attracted to men with an immune system that was genetically different from hers — which some scientists suspect could make for healthier offspring.
Even the men wer e impacted by a woman's cycle. Studies show that women who don't take the Pill actually look different and peak in their sex appeal in the days leading up to ovulation. Their voices become deeper, their faces take on a more symmetrical appearance and they dress more provocatively. Thus, they are more attractive to men when they are their most fertile.
One rather titillating study looked the impact of menstrual cycle on the income lap dancers bring in. Sure enough, women made the most money when they were most fertile.
That's unfortunate news for women on the Pill — they lose their natural ovulation-induced sexiness.
Choosing ‘dad’ or the ‘cad’
But when women aren’t ovulating, they tend to gravitate toward photos of men with a more feminine look, Alvergne says. The theory is that when hormones aren’t raging, women want to be with a less testosteronized man, one who is likely to stick around for the long haul.
With the Pill to smooth out peaks in hormones, researchers found that women weren’t ever drawn to the macho man, says Alvergne. And the fallout from that little hormonal tweak could be very significant, she says. What if the man a woman chooses when she’s on the Pill isn’t the one she’d like to be with when she goes off of it — to make babies, for example?
Scientists have playfully named the two female mating strategies as a choice between the “cad” or the “dad,” says Helen Fisher, a biological anthropologist at Rutgers University and author of “Why Him? Why Her?”
Until more research is done, we won’t know what Pill’s long term impact on the species might be, Fisher says. “This is a perfect example of why researchers need to look beyond the physical impact of a drug and consider the psychological and behavioral side effects,” she adds.
Ultimately, the changes in behavior wrought by the Pill might be good for women, Fisher suggests. When we lived in a hunter-gatherer society, there was a village to help raise the children, so picking the most macho man might have been fine. In modern society, it makes much more sense to pick the dad rather than the cad, Fisher says. “Then the woman has at least one person to help raise the baby,” she explains.
Linda Carroll is a health and science writer living in New Jersey. Her work has appeared in The New York Times, Newsday, Health magazine and SmartMoney.