Body odor or body odour (BO) is present in all animals and its intensity can be influenced by many factors (behavioral patterns, survival strategies). Body odor has a strong genetic basis, but can also be strongly influenced by various factors, such as sex, diet, health, and medication.[1] The body odor of human males plays an important role in human sexual attraction, as a powerful indicator of MHC/HLA heterozygosity.[2][1] Significant evidence suggests that women are attracted to men whose body odor is different from theirs, indicating that they have immune genes that are different from their own, which may produce healthier offspring.[3]
Grammer_2005
was invoked but never defined (see the help page).In one study about smell and romance, straight women preferred the body odor of straight men whose immune systems were different enough that any offspring would have healthy immune systems. For most of human history, infectious disease has been our greatest threat. In modern times we may seek life-partners that satisfy a multitude of needs, but more fundamentally, if you could produce babies with immune systems able to fight a potpourri of pathogens, then your progeny—and your genes—stand a better chance at survival.