Oestradiol makes women hot and hard to keep

ResearchBlogging.orgThe estrogen hormone oestradiol is associated with just about every aspect of female beauty. As well as serving as a growth hormone for female reproductive organs, it's associated with having a symmetrical face, large breasts and a low waist-to-hip ratio. Now, the hormone is credited with one more association: it makes women serial monogamists.

Marilyn Monroe

Her relationships explained
by her body cheimstry?

For those who may not have heard of this term, let me explain. A serial monogamist is a person who has sequential relationships, and who tends not to spend much time alone in between partners. While they make what seems to be a lasting commitment to each person, they tend to be superficial, get bored of their significant others easily, and find a new one every so often.

Well, new research has linked oetradiol levels to this kind of relationship behavior.

University of Texas researchers polled women about their personal and sexual behaviors and compared their responses to their saliva oestradiol levels. They also took pictures of the women for an independent analysis of beauty. They found that while the high-oestradiol women were more attractive than their counterparts (by the women's self opinion and independent judges), they also had significantly lower levels of satisfaction with and commitment to their parters and a greater likelihood of infidelity.

Specifically, the women were more likely to have serious affairs, but not more likely to have brief sexual encounters. So they weren't simply more sexually active - they were picky, too. They preferred long-term commitments but were less satisfied by them. So women with high oestradiol levels are classic serial monogomists. This is strong evidence that physiological mechanisms may be a much larger part of mating behaviors and strategies than previously assumed.

This means that your role models may have less to do with how you act in relationships than you might think, at least if you're a woman. But there's one more thing that makes this study very interesting. A synthetic form of oestradiol, called ethinylestradiol, is a major component of hormonal contraceptives, which many women who aren't married but are in relationships take so they can have all the fun of condom-free sex without the risk of getting pregnant. Now, if women are taking this hormone every day, how much is it affecting their behavior? Are the ingested levels enough to make a difference? Are birth control pills changing modern women's mating strategies? Or, more bluntly, is your girlfriend's birth control making her more likely to cheat on you?

Just some food for thought...

Kristina M. Durante, Norman P. Li (2009). Oestradiol level and opportunistic mating in women Biology Letters, -1 (-1), -1--1 DOI: 10.1098/rsbl.2008.0709

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