MICROSMATIC HUMANS REVISITED - THE GENERATION AND PERCEPTION OF CHEMICAL SIGNALS

The responsiveness of humans to conspecific chemical cues as well as their rate of production of diverse potential olfactory signals suggest that it may be inappropriate to characterize members of our own species as “microsmatic.” Skin glands of presumed semiochemical significance are distributed over the entire body surface, with localized dense aggregations occurring in sites such as the axillary, scalp, areolar, and pubogenital areas. Topographical variation in the amount of glandular secretions/excretions is correlated with structural and physiological modifications that potentially enhance their communicative efficacy (e.g., increased vascularization, thick hair growth). Perceptible odors emanating from individuals are the result of a complex interaction between genetically influenced factors (e.g., distribution of skin glands, endocrine and metabolic processes) and environmental variables (diet, chemical action of microorganisms, climate, aerial chemical ecology). Distinctive body odors provide a reliable basis for social discrimination. Thus, within hours of delivery mothers (and other family members) recognize the odor of their neonate. Newborn infants likewise respond preferentially to breast and axillary odors emanating from their own lactating mother. Olfactory cues have also been implicated in recognition of self and unrelated individuals, and in gender discrimination. The primary ontogenetic mechanism involved in the recognition of the odors of individuals (or of other social categories) is familiarization arising from direct exposure. Recognition of kin may also be facilitated by discernible similarity (genetically mediated) in their olfactory signatures. At present, data from studies of the possible role of olfactory cues in human sexual behavior and related endocrine processes are ambiguous and provide no clear evidence of general sex attractants produced by either sex. Odors may nonetheless contribute to sexual arousal through the association of specific scents with previous erotic experiences or particular individuals. © 1991 Academic Press Inc.