And, AND is a chemical called androstadienone, which "is 10 times more abundant in male than female sweat and is suspected of acting as a male pheromone."
In the study, three groups of 12 volunteers, including lesbians, heterosexual women and straight men, were asked to sniff a variety of odours. They included odourless air, four common scents and [the chemical AND] ...
After smelling the odours, the volunteers were given brain scans that revealed which regions of their brains had the greatest increase in blood flow, a measure of how much they had been stimulated. The scans showed that after sniffing AND, a region of the brain called the anterior hypothalamus lit up in heterosexual women and gay men.
The brain scans of lesbian women and straight men showed a marked difference after sniffing the male sweat chemical, however. Brain scans revealed activity increasing in parts of the brain called the piriform cortex and amygdala, which are believed to light up when the brain processes any odour.
The corresponding chemical in women is called EST. All of this and more from this Guardian piece.
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Update: Talking of the Axe effect, check out some of the print ads so lovingly compiled by Myndfcukd.
Update 2: Today's (16 May) NYTimes too has covered this story.