While it is believed that biological and societal factors influence choice of partners, a new study has suggested that immunity traits may be more involved in selecting a mate.
The study by scientists in China, France, and the United Kingdom have shown that the Major Histocompatibility Complex (MHC), a large genomic region involved in immune response, influences mating selections and that this may be mediated by preferences based on body odor.
It was shown in some previous studies that humans have a tendency to prefer MHC-dissimilar mates, encouraging heterozygosity at MHC loci in offspring and resulting in improved immune response.
However, other studies, both directly in couples and also indirectly in "sweaty T-shirts" experiments, have reported conflicting results.
And the recent study adds on to the debate, in which researchers employed genome-wide genotype data and HLA types in a sample of African and a sample of European American couples, that led them to distinguish MHC-specific effects from genome-wide effects.
The group examined whether husband-wife couples were more MHC-similar or MHC-dissimilar in comparison to random pairs of individuals.
It was found that African couples were not more MHC-similar or MHC-dissimilar, although genome-wide they were more similar than random couples, probably as a consequence of social factors.
However, European American pairs were predominantly MHC-dissimilar, and drastically so in comparison to the genome, supporting the hypothesis that the MHC influences mate choice in this population.
Future studies may add to this debate of whether biological traits play a significant role beside social traits in the process of mating.
The study was published recently in the open-access journal PLoS Genetics.