(Neige)
Jeanna Bryner
Senior Writer
LiveScience.com




Birth-control pills could screw up a woman's ability to sniff out a compatible mate, a new study finds.


While several factors can send a woman swooning, including big brains and brawn, body odor can be critical in the final decision, the researchers say. That's because beneath a woman's flowery fragrance or a guy's musk the body sends out aromatic molecules that indicate genetic compatibility.


Major histocompatibility complex (MHC) genes are involved in immune response and other functions, and the best mates are those that have different MHC smells than you. The new study reveals, however, that when women are on the pill they prefer guys with matching MHC odors.


MHC genes churn out substances that tell the body whether a cell is a native or an invader. When individuals with different MHC genes mate, their offspring's immune systems can recognize a broader range of foreign cells, making them more fit.


Past studies have suggested couples with dissimilar MHC genes are more satisfied and more likely to be faithful to a mate. And the opposite is also true with matchng-MHC couples showing less satisfaction and more wandering eyes.


"Not only could MHC-similarity in couples lead to fertility problems," said lead researcher Stewart Craig Roberts, an evolutionary psychologist at the University of Newcastle in England, "but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odor perception plays a significant role in maintaining attraction to partners."


Sexy scents


The study involved about 100 women, aged 18 to 35, who chose which of six male body-odor samples they preferred. They were tested at the start of the study when none of the participants were taking contraceptive pills and three months later after 40 of the women had started taking the pill more than two months prior.


For the non-pill users, results didn't show a significant preference for similar or dissimilar MHC odors. When women started taking birth control, their odor preferences changed. These women were much more likely than non-pill users to prefer MHC-similar odors.


"The results showed that the preferences of women who began using the contraceptive pill shifted towards men with genetically similar odors," Roberts said.


Pregnant state


Based on the work by Claus Wedekind, a University of Lausanne researcher who preformed similar studies in the 1990s, Roberts suggests a likely reason for the pill's effect on a woman's odor preferences. The pill puts a woman's body into a hormonally pregnant state (the reason she doesn't ovulate), and during that time there would be no reason to seek out a mate.


"When women are pregnant there's no selection pressure, evolutionarily speaking, for having a preference for genetically dissimilar odors," Roberts said. "And if there is any pressure at all it would be towards relatives, who would be more genetically similar, because the relatives would help those individuals rear the baby."


So the pill puts a woman's body into a post-mating state, even though she might be still in the game.


"The pill is in effect mirroring a natural shift but at an inappropriate time," Roberts told LiveScience.


The results are detailed in the current issue of the journal Proceedings of the Royal Society B: Biological Sciences.

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I find myself wondering who funded this study.

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This is good science.

Proceedings B is the Royal Society's principal research journal for biological sciences. The articles are peer reviewed. Here is the link to the Proceedings B Referee Information.

This research builds on previous work. Here is the link to the article in question.

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Eudaimonia

Not quite the point jseal.

True, while many papers make it past peer review that shouldn't, and therefore, peer review doesn't guarrantee that something which passes is "good" science, just make it much more likely that it is "good" science.

Two real points here: Point 1. OK, there's been this study. How is actual science or the practice of medicine advanced in the first place? IOW, why study this at all? It's pretty much an irrelevant aspect of human interaction.

A couple of possible reasons: 1. Just some researchers spending grant money so they can spend grant money. Scientists have to eat too, you know. 2. A more nefarious possibility is that the scientists were paid to go looking for "evidence" that supported a hidden agenda. And if you for one moment think that isn't a possibility, I have a bridge in Brooklyn to sell you.

More importantly, Point 2. Who is going to use this results of this study, and in what matter? Scientific knowledge is neutral, it just is what it is. However, the knowledge is never disseminated in a vacuum: it is always released into the world of human interaction, meaning that whatever the actual facts may be, there will always be those who will mis-use them for their own political ends.

When one digs down deep enough, one *usually* finds that the people who paid for the study got the results they were looking for; and when they don't, they find a way to twist the fact in their favor anyway.

So, no I wasn't questioning whether or not this was "good", as in, fact-based, empirically-derived science.

__________________
On the kinkometer, my kink measures as a sine wave.

I got on the pill a few months into dating Mr. AZRH, when I was a wee lass of 19. We will celebrate our 18th anniversary of togetherness in October. And I still dig him.

I guess I'm not buying it.

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