Friday, January 23, 2009

Boyfriends odour can make the difference

Could you identify your boyfriend's sweat?

The more enamoured they are with a lover, the less likely people are to pick out the scent of another suitor• Article• Comments (10)• ZOSIA BIELSKIFrom Thursday's Globe and MailJanuary 22, 2009 at 10:19 AM ESTThe next frontier of sexual attraction lies in the armpit, according to researchers at McGill University who studied how body odour wafts through human relationships."The more in love you are with your boyfriend, the less able you are to identify the body odour of a male friend," said Johan Lundstrom, now an assistant professor of neuropsychology at Philadelphia's Monell Chemical Senses Center.The results, published in the journal Hormones and Behavior last month, support the "deflection theory," which argues that people in love are less aware of potential suitors around them.The research involved getting boyfriends, male friends and female friends of 20 women to sleep for one week in cotton T-shirts with breastfeeding pads sewn into the armpits. The pads soaked up their sweat, while the T-shirts protected the pads from "residual odours that might come from the outside," Dr. Lundstrom said.The 20 women, meanwhile, were asked to fill out a "passionate love scale" questionnaire to find out just how in love they were. The questionnaire asked participants to rate such soul-searching statements about their partners as: "I would feel deep despair if [blank] left me," and "I yearn to know all about [blank]."After the pads were well-soaked in sweat, each woman was asked to pick her lover's T-shirt out from two others worn by strangers. Women in love were able to pick out their boyfriend's body odour 5.2 out of seven tries. In separate tests, they were asked to pick out the male friend's shirt and the female friend's shirt. Those who rated more enamoured on the questionnaire had more trouble distinguishing their male friends' sweat from strangers' sweat.He is now investigating exactly what happens in women's brains as they process the aromas of partners, friends and strangers. This time, he's sending the women through a functional magnetic resonance imager and pumping the aromas from the breastfeeding pads into a tube that goes up their nose.So far, Dr. Lundstrom has found that strangers' odours activate the amygdala and insular cortex, often labelled as the brain's fear networks. When friends' smells floated up the women's noses, they stirred the retrosplenial cortex, which helps humans recall familiar information. And when lovers' scents wafted in, their reward centre was aroused. "It goes to show that hidden within our body odours we have important biological infor-mation," Dr. Lundstrom said.He noted that body odour can also help prevent distant relatives from hooking up, pointing to studies conducted on human leukocyte antigen (HLA) in the mid-1990s. Involved in kin recognition, HLA can be detected by smell."The more similar HLA you have, the more related you are. The studies showed that the more dissimilar HLA you have with someone, the more attractive you think that person is, and the more attractive his or her body odour smells. It's an inbreeding avoidance mechanism. It's been shown that this actually has an impact when you're selecting a partner."Finally, Dr. Lundstrom noted, "you should not stop showering" in hopes of attracting the right mate.

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