Smell with inspiration: the evolutionary significance of olfaction.

The olfactory receptor gene family is the largest in the mammalian genome (and larger than any other gene family in any other species), comprising 1% of genes. Beginning with a genetic radiation in reptiles roughly 200 million years ago, terrestrial vertebrates can detect millions of odorants. Each species has an olfactory repertoire unique to the genetic makeup of that species. The human olfactory repertoire is quite diverse. Contrary to erroneously reported estimates, humans can detect millions of airborne odorants (volatiles) in quite small concentrations. We exhibit tremendous variation in our genes that control the receptors in our olfactory epithelium, and this may relate to variation in cross-cultural perception of and preference for odors. With age, humans experience differential olfactory dysfunction, with some odors remaining strong and others becoming increasingly faint. Olfactory dysfunction has been pathologically linked to depression and quality of life issues, neurodegenerative disorders, adult and childhood obesity, and decreased nutrition in elderly females. Human pheromones, a controversial subject, seem to be a natural phenomenon, with a small number identified in clinical studies. The consumer product industry (perfumes, food and beverage, and pesticides) devotes billions of dollars each year supporting olfactory research in an effort to enhance product design and marketing. With so many intersecting areas of research, anthropology has a tremendous contribution to make to this growing body of work that crosses traditional disciplinary lines and has a clear applied component. Also, anthropology could benefit from considering the power of the olfactory system in memory, behavioral and social cues, evolutionary history, mate choice, food decisions, and overall health.