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Meghan, I checked out that T-shirt sniffing study you flagged, and, well, it hardly implies a crisis for pill-users – or a pink slip for novelists.
To recap: The researchers asked women to rate the smells of T-shirts worn by different men. For each woman, they chose three men who were more genetically similar (in terms of a specific set of genes) and three men who were less similar. The genes in question were part of the major histocompatibility complex, or MHC, which plays a crucial role in immune function and is also linked to body odor (possibly because of interactions between the immune system and skin bacteria). The researchers found that when women began taking birth control pills, their smell preferences shifted somewhat toward men with more similar MHC profiles, though the difference was not huge.
Why might this matter? In the past, some research found that women tended to prefer the smell of men whose MHC makeup differed more extensively from their own. That result remains controversial, but from an evolutionary perspective, it makes for a good story. When women mate with less similar men, their kids may have more robust immune systems that can better fend off a wide range of diseases. In theory at least, that advantage may have helped to shape women’s tastes over time. As for the pill, if it were to skew preferences toward MHC similarity, women might smile on less genetically favorable partners, leading to problems in the long run. When women stop taking the pill, for instance, their tastes might shift again, resulting in “the breakdown of relationships," as one researcher speculated. Hence the maelstrom about women choosing the “wrong” men.
Strikingly, however, the current study fails to confirm the premise of that whole story. When women smelled men's T-shirts at the outset, before any of them took the pill, they showed no preference for men with more MHC difference. That is, they did not exhibit the supposed tendency that the pill supposedly disrupts. What’s more, when women taking the pill smelled the T-shirts again, they showed no preference for men with more MHC similarity. Yes, the pill-takers tended to rate the smell of MHC-similar men more favorably than they had before. But to repeat: They still didn’t prefer the similar guys overall. Despite the hype, then, this study’s findings are limited – and pretty messy.
Of course smell can play a role in romance. And the scent of MHC difference could turn out to be one factor – of many – that influences women’s choices. But really, when it comes to searing insight into longing and romantic crisis, T-shirt sniffing has nothing on Flaubert.
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Has anyone been reading about this new U.K. study examining how the birth control pill affects women's choice of sexual partners? As one CBS headline crudely puts it, women on the pill allegedly choose "the wrong partner." That's because, as the authors of the study argue, women NOT on the pill are generally "attracted to men whose genetic makeup differs from their own" which "increases the chances for a healthy pregnancy and a healthy baby," as CBS put it. But women on the pill seem to choose partners who are genetically similar to themselves. I can't quite tell how they've determined this, but it has to do with something called MHC genes, which affect immune responses, and smelling T-shirts. As CBS puts it: "In laboratory studies, women who sniff men's sweaty T-shirts find them more attractive when they come from men whose MHC genes don't match theirs. It's not that certain MHC genes smell better to women -- it's the difference that counts."
On the pill, however, this seems to change, and it has, according to a number of scientists, a lot of implications for relationships going forward, because apparently women who are with men who have similar genetic material get dissatisfed quickly and search for new sex partners. (It's not your hair, honey, or the fact that you don't do the dishes, it's your MHC genes.) But do these kind of studies really tell us very much? Are our sex and romantic lives really so genetically deterministic that we can make predictions based on smelling a man's T-shirt? (God, that would have saved a lot of novelists some trouble.) I'd love to know what some of our more scientifically trained XXFactor bloggers have to say, because the study and the conclusions being drawn raised all sorts of questions for me. It's times like these when you wish more journalists understood biology, because the pieces I've read on this story seem, in general, very crude.