Welcome to the inaugural post of The Sex Files. Almost every publication worth its druthers has a sex column these days, full of Carrie Bradshawish musings about life and love, men and women, this and that. Here's our take on the genre. Instead of faux-sociology, we'll give you a broad view of new research and ideas in the sexiest of the hard sciences: reproductive biology, evolutionary anthropology, and genetics. This is sex from the inside out. Keep track of the column at popsci.com/sexfiles, where you can also sign up for an rss feed.
Disassortative mating alert! A group of European scientists led by Oxford biostatistician Raphaelle Chaix has provided some of the most compelling evidence yet that we humans pick our partners based on how different their immune systems—or officially, their Major Histocompatibility Complexes—are from our own.
The MHC is a large and super-important group of related genes that regulate what antibodies we produce. It is unusually polymorphous—that is, it differs quite a bit from person to person, even within genetically similar groups. Theoretically, it makes perfect sense that animals would choose to reproduce with someone with a very different MHC so that the resulting offspring will have immunity to as many disease-causing pathogens as possible. And it has long been known that a number of squirmy little creatures—mice, rats, frogs, and the like—prefer mates who have dissimilar MHCs. But the case for MHC-based mate selection in humans is not so clear-cut.
For the past ten years, it has seemed like every study that "proved" that we choose MHC-dissimilar partners was immediately contradicted by another bit of evidence. When University of Chicago geneticist Carole Ober looked at the Schmiedeleut Hutterites of South Dakota (a group of tremendously fertile Amish-like Anabaptists who isolate themselves on remote "colonies"), she found that an improbably low number of community members—who marry for love but are not allowed to divorce—chose mates with similar MHCs. The effect was so strong that when couples whose immune systems were too similar tried to have children, they had more trouble conceiving, and their fetuses were more likely to spontaneously abort. But later, two ASU biologists surveyed couples across 11 different Amerindian tribes in the Amazon Basin and discovered that similarities between the MHCs of men and women who had chosen to reproduce together were almost completely random. A series of gross-sounding "sweaty t-shirt experiments" performed at the University of Bern conclusively demonstrated that women prefer to smell the sweat of men who are MHC-dissimilar. But if the women were on birth control, their scent preferences were reversed.
The latest study, published on September 12, examined the genomes of fertile Mormon and Yoruba couples to see how exactly their MHCs differed. The results were both fascinating and conflicting. Chaix and her coauthors found that the Mormons were significantly more MHC-dissimilar than randomly chosen pairs of people. Even more interestingly, although the Mormon mates were genetically very close to each other (they're Mormons, after all), the genes in their MHCs were often very different. But (as usual in this area of study, there's a "but") they couldn't find any pattern at all in the MHC-dissimilarity of the Yoruba couples. This might be because Yoruba society is highly patriarchal and stratified, producing a lot of social pressure for genetically similar men and women to mate. Or it might be that in Africa, where modern medical care is less widely available, there is much more selection pressure for antibodies that will protect their carriers against a few especially devastating diseases. More research here is definitely necessary to tease out the precise relationship between histocompatibility and mating choices, and how social and environmental factors might affect this relationship. But if you're a European American woman, sniff hard next time you're at the gym; the best-smelling guy might just be your immunological soulmate.
how new is this?
i swear i heard this on the radio of all placed about three years ago.
I fail to see why a given Mormon couple should be viewed as more genetically similar than any other couple. We're talking about a religious group, not an ethnic group (that is to say, a religious group with millions of members in the United States alone, as opposed to the isolated--and therefore more closely interbred--Anabaptists).
I also object to the casual swipe against Mormons ("they're Mormons, after all"). What other group sends so many of they're young people to live in foreign countries and learn their language? Furthermore, Mormons tend to be disproportionally tech fans, and whenever one of these tech sites think they can safely paint them as backwards hicks they tend to learn quickly learn otherwise. Get a clue.
Yeah uh, thanks guys...(Mormon right here, and proud of it!) lol
I generally take the South Park view of Mormons... but that's neither here nor there. This article is about stinky smelly people being attractive because their stinky smelliness is indicative of their histological compatibility.
So cool your jets guys... they're not saying Mormons are more stinky or smelly than anyone else (and how would they know unless they went around giving random people the sniff test?), they're just saying that the next time you DO happen to smell a Mormon, they have as much chance as anyone else to be your histological soulmate.
I think all they were getting at is that mormons tend to marry mormons (don't you agree?) and since there are not as many mormons as there are, say, muslims or christians the mormon communities TEND to be clustered somewhat. So, for such a community, most of the time people are marrying within it. That said, if this goes on long enough, their genomes become more similar.
Not a hard concept. They could be talking about any group. Not just mormons. Mormon populations were probably convenient for the research.
So, let's not get our panties in a wad. :)
C'mon guys... Think they meant that Morons tend to marry each other, not Mormons.
Let the "The Doc is in Write" instead.
the next time you DO happen to smell a Mormon, you should remember that they have as much chance as anyone else to be your histological soulmate.