Un-natural selection: birth control pills may affect choice of mate

A new paper in the scholarly journal Trends in Ecology and Evolution suggests that oral contraceptives may influence women’s choice of mates, with potentially enormous effects on their quality of life and their ultimate reproductive success.

Commonly used hormonal birth control methods such as Yasmin, Seasonale, Ortho Tri Cyclen, Nuvaring and Loestrin, while extremely effective at preventing unwanted pregnancy, may well have previously unsuspected effects on a woman’s choices of both long-term and short-term partners. This is of interest to the more than 100 million women around the globe who use oral contraceptives, and their sexual partners, too.

The paper, published October 9th, was authored by biologists Dr. Alexandra Alvergne and Dr. Virpi Lummaa at the University of Sheffield in England. It analyzed a large body of research that had gone before. Writes Dr. Alvergne, lead author of the study, “The use of the pill by women, by changing her mate preferences, might induce women to mate with otherwise less-preferred partners, which might have important consequences for mate choice and reproductive outcomes.”

Researchers have long known that women make different sexual choices during their most fertile phase than they do during the rest of the month. This is called cycling mate preferences, and quite simply, it means that most women choose more masculine and symmetrical faces when they are ovulating or close to ovulation. They are also uncharacteristically attracted to dominant males, and most likely to engage in infidelity at this time in their cycle. During the rest of their cycle periods when the women are more likely to be infertile they are more attracted to less masculine faces, and men who are better choices as long-term partners.

Oral contraceptives work by mimicking pregnancy and stifling ovulation, which flattens out the hormonal cycles usually experienced by a fertile woman. Why is this a concern? Says the paper:

New evidence suggests that the pill, by eliminating oestrus, changes the natural cycling preferences in women for markers of both genetic quality and compatibility in mates as well as natural cycling attractiveness to men. As compared with normally cycling women, pill users show no or weaker preferences for facial and vocal masculinity. For instance, the preferred face shape is more masculine during the high conception-probability phase of the menstrual cycle in non-pill users, but pill users do not show similar preference.

The possibility is that a woman could make a choice influenced by birth control that is perhaps not in her best reproductive interests. Even worse, with our cultural customs of lifelong mating and marriage, a woman could change her contraceptive practices and find that she is not attracted to her mate in the same fashion as she was when she was under the influence of prescribed hormones. Either of these outcomes could be devastating to a paired couple.

Oral contraceptives are still regarded as one of most effective forms of birth control available to women (they trail the intra-uterine device by a fraction of a percentage point, but the IUD is appropriate for fewer patients, and is rarely prescribed for women who have not already gone through childbirth). Birth control pills are affordable, simple to obtain, and work extremely well. However, this paper has given us all something to think about: the possibility that altering the hormonal cycles of the human female en masse could have significant reproductive effects for individual women, and the entire species, too.

More research is forthcoming in this arena, and the results are sure to be fascinating.

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Comments (2)

I think this is so interesting. I’ve never been an advocate for birth control. Mainly because of all the changes women experience when first starting them. It just doesn’t seem natural. Now, I am even more convinced that it is not a good practice. One thing your article didn’t mention that I’ve read elsewhere is that birth control also effects the males selection. Biologically speaking, a man’s goal is to impregnate a woman. If she is taking birth control, which makes her seem pregnant (chemically), the man will choose another mate. Interesting!

“As compared with normally cycling women, pill users show no or weaker preferences for facial and vocal masculinity. For instance, the preferred face shape is more masculine during the high conception-probability phase of the menstrual cycle in non-pill users, but pill users do not show similar preference.”
 
Alright, but so what is wrong with dating or having children with men who have more feminine features? Beauty ideals for both genders have been fluctuating for centuries.  Look at Renaissance depictions of male beauty…many of the men are painted having non-masculine features: a boyish figure, lovely long locks of hair, plump lips, and big lovely eyes. What is or is not attractive is determined far more by cultural beauty standards than by minor shifts in hormones. There is no reason to believe traditionally masculine men are more healthy; what if Mr. Manly Man has cancer, an STD, or diabetes, is mentally unstable, is a heavy drinker or smoker. There’s seriously nothing wrong with more feminine-looking men. 
 
The idea that the pill is starting some kind of “unnatural” version of natural selection is completely illogical. Mate selection all throughout human history has been fairly unnatural to begin with. In the past, arranged marriages were the norm, where parents and sometimes the man (practically NEVER the woman) got to choose who to marry off their children to. Most of the time, these were for strategic reasons- making an alliance with another family, ensuring economic security through a dowry. Whether or not the other person was attractive was a bonus, not the reason for the marriage. For most of human history, women had very little choice of whom they were allowed to marry. So I doubt the pill *slightly* altering their perception of sexual attraction is somehow going to lead to some downward spiral of increasingly genetically defective offspring. The alarmist language of this article is downright silly, given an ounce of common sense. 
 
I don’t see what your alternative would be, if the ideal is to promote “natural” selection. Eugenics? Tell people who don’t fit what speculative science tells us is the “right”, genetically superior beauty ideal, to not reproduce? What ounce of difference does it make if women find the feminine-featured Leonardo diCaprio more attractive than the manly Brad Pitt? This article is more or less viewer-baiting pop science. 
 
I’ve been on the pill for years and haven’t noticed ANY change in the types of men I am attracted to. Even if it does have an effect on my levels of attraction, it is probably only marginal. Most people choose their marriage/sex partners based on personality, compatibility, how good they are in bed, sometimes financial security. Attraction is important, too, but so much of attraction is psychological and varies widely from person to person. 
 
PS. The pill is a perfectly legitimate form of birth control. I understand that it is not for everyone, and some people do get negative side effects, and should probably use alternatives. However, I have never experienced anything negative with using the pill. Condoms break all too often, you know. 

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