Major Histocompatibility Complex - MHC in Sexual Mate Selection

MHC in Sexual Mate Selection

Main article: Major Histocompatibility Complex and Sexual Selection See also: Interpersonal compatibility

MHC molecules enable immune system surveillance of the population of protein molecules in a host cell, and greater MHC diversity permits greater diversity of antigen presentation. In 1976 Yamazaki et al demonstrated preference by male mice for females of different MHC. Similar results have been obtained with fish and birds (eg. the black-throated blue warblers). Some data find lower rates of early pregnancy loss in human couples of dissimilar MHC genes.

It has been proposed that MHC is related to mate choice in some human populations, a theory that has found support by studies by Ober and colleagues in 1997, as well as by Chaix and colleagues in 2008. The phenomena might be mediated by olfaction, as MHC phenotype appears strongly involved in the strength and pleasantness of perceived odour of compounds from sweat. Fatty acid esters—such as methyl undecanoate, methyl decanoate, methyl nonanoate, methyl octanoate and methyl hexanoate—show strong connection to MHC.

In 1995 Claus Wedekind found that in a group of female college students who smelled T-shirts worn by male students for two nights (without deodorant, cologne, or scented soaps), by far most women chose shirts worn by men of dissimilar MHCs, a preference reversed if the women were on oral contraceptives. Results of a 2002 experiment likewise suggest HLA-associated odors influence odor preference and may mediate social cues. In 2005 in a group of 58 subjects, women were more indecisive when presented with MHCs alike their own, although without oral contraceptives, the women showed no particular preference.