Not the cologne, not the perfume, not the deodorant. When it comes to choosing a partner, what our noses usually take into account is the composition of certain volatile molecules of the immune system, those of the so-called Major Histocompatibility Complex (MHC).
The French scientist Raphaëlle Chaix has reached that conclusion in a study published today in the journal Plos Genetics . Chaix's team conducted an investigation with two population groups: Yoruba from southwestern Nigeria and Mormons from Utah (United States). And although in the first group they did not obtain satisfactory results, in the second they found that the husband-wife pairs studied were genetically more diverse in terms of MHC than the pairs of individuals associated at random. However, Chaix cautions that it will be necessary to study a greater number of populations to better understand the diversity and the real importance of these genetic factors.
This is not the first time that MHC molecules have been shown to condition humans when it comes to mating. A decade ago, Claus Wedekind and his colleagues at the University of Bern asked a group of female students to smell unwashed t-shirts of unknown men and to rate them according to how pleasant the smells were. The results showed that women found the smell of men with MHCs different from theirs more pleasant .
