August 13, 2008

The Pill May Lead Women To Mr. Wrong

A recent British study showed that women who take a contraceptive pill may also be changing their taste in men and leading them to those who are genetically less compatible.

The study, reported by a team of researchers at the University of Liverpool, suggests that taking the pill can change the type of male scent they are attracted to. Researchers said the hormones in the pill may influence the way that women assess male sexual attractiveness.

The pill is thought to disrupt an instinctive mechanism that brings together people with complementary genes and immune systems.

Couples with different genes are less likely to experience fertility problems or miscarriages. Experts believe that women are naturally attracted to men with immune system genes different to their own because of their smell.

The pill's impact on a woman's ability to judge genetic compatibility through smell could not only impact fertility and miscarriage risk, researchers said, but it could contribute to the end of relationships as women who stop or start taking the pill no longer find their boyfriend or husband so attractive.

Previous research has suggested that women prefer the smell of men who are different from them in a cluster of genes called the major histocompatibility complex (MHC), which governs the immune system.

The most recent study, published in the journal Proceedings of the Royal Society, tested a group of 97 women, some of whom started taking the pill during the course of the research. All had their MHC genes tested and were asked to sniff T-shirts worn in bed by men with different patterns of MHC genes.

When the women started taking the pill their preferences shifted towards the scent of men with more similar genes to their own, researchers said.

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

"Not only could MHC-similarity in couples lead to fertility problems, but it could ultimately lead to the breakdown of relationships when women stop using the pill, as odor perception plays a significant role in maintaining attraction to partners," Roberts said.

The research also found differences between women in relationships, who tended to prefer odors of men with different MHC genes, and single women, who tended to prefer the smell of MHC-similar men.

This could potentially indicate that if women are tempted to have an affair, they are more likely to choose a man with very different genes, to maximize the diversity of any offspring that they might have.


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