Suppose a Man and a Woman Like Each Other Very Much

“stinky t-shirt studies” demonstrate that women find attractive the body odors of men whose major histocompatibility complex (MHC) gene variants are most different from their own.  Women’s evolved tendency to be physically attracted to men whose MHC genes are different from theirs increases the probability that their offspring are heterozygous in MHC and are therefore immune to a larger range of bacteria and viruses than offspring who are homozygous in MHC.

WARNING: before a man and woman choose to make a baby together, they ought to spend some time with the woman off the Pill (and probably other hormonal birth control), because under its influence, this natural, protective preference is *reversed*.


(although I don’t know exactly how valuable hetero-MHC is; this may just be a useless all-else-equal result)