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Posted by sengd001 on August 13, 2008, 9:57 pm || Total Votes: 1
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MSNBC
The Pill makes women pick bad mates
Ability to sniff out a compatible partner affected by taking contraceptives
By Jeanna Bryner
updated 10:17 a.m. PT, Wed., Aug. 13, 2008
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 matching-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.
© 2008 LiveScience.com. All rights reserved.
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Already voted! | Topic: Medication
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Comments:
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Comment by Linda_gx on August 18, 2008, 3:19 am
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It's an interesting read, and does have thought provoking points.
I read not long ago, that pregnant women are more likely to be attracted to different people than uaual, from the point of protecting the unborn baby, they are attracted to healthier people, male or female.
Taking this into consideration, it seems that people who weren't ovulating would pick 'healthier' mates....??
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Comment by iotangel on August 14, 2008, 4:18 am
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Lol...seems a bit of a stretch to assume that just because the woman is more drawn to MHC-similar smells in the lab- that her choice of mate is "bad". Hell, the mate could be bad either way. Haha.
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Comment by sengd001 on August 13, 2008, 10:01 pm
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Makes sense doesn't it?? Smell does stimulate the pheromones in humans leading up to sexual attraction, however I seriously doubt this is one of those make or break deals with chemistry or sexual compatibility, any thoughts??
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