Human body scents: conscious perceptions and biological effects.

Compounds collected from the torso and axillary area of sleeping men can be distinguished based on the number of MHC alleles matching between the man and the woman choosing the scent she prefers. Compounds from breastfeeding women and their infants increase the sexual motivation of other women and change the timing of ovulation. Here we show that these human compounds, collected on cotton, frozen and thawed, were perceived as mild scents and rarely identified as coming from another human (9% of male compounds, 12% of female compounds). It was their pleasantness, rather than their familiarity, that was associated with MHC allele matches between the donor and the smeller. In contrast, neither liking nor disliking the mild scent of breastfeeding compounds, nor their detection or reported strength was associated with modulation of sexual motivation or ovulation.