Research by a group of scientists from the Rockefeller University, in collaboration with scientists from Duke, revealed that a single human gene determines how one’s sense of smell reacts to the male pheromone androstenone, present in urine and other fluids. In some it will bring out subtle hints of vanilla, while others will be driven towards nausea by the foul manly overtones.
Androstenone, found in higher concentrations in the urine and sweat of men than of women, is used by some mammals to convey social and sexual information, and the ability to perceive androstenone’s scent may have far-reaching behavioral implications for humans.
In the largest study ever conducted of its kind, researchers at Rockefeller University presented nearly 400 participants with 66 odors at two different concentrations and asked them to rate the pleasantness and intensity of each odor. When scientists at Duke University identified OR7D4 as a receptor that androstenone selectively activates, Leslie Vosshall, Chemers Family Associate Professor and head of the Laboratory of Neurogenetics and Behavior at Rockefeller University and Andreas Keller, a postdoc in her lab, formed a collaboration with them, and began collecting blood samples from each participant and isolated their DNA. The Duke team, led by Hiroaki Matsunami, used DNA from each participant to sequence the gene that encodes the OR7D4 receptor.
“With this large dataset, we are able to say that people who express different variants of this receptor perceive this odor differently,” says Vosshall.
Although it has long been suspected that the ability to perceive the odor of androstenone is genetically determined, this study was the first to identify variations in a single gene that account for a large part of why people perceive androstenone’s scent so differently.
With their Duke collaborators, Vosshall and Keller identified two point mutations called single nucleotide polymorphisms along the gene, which gave rise to two variants of the odorant receptor: RT and WM, which differ by two amino acids. As a group, participants with the RT/RT genotype perceive androstenone’s odor as foul and intense. Those with the RT/WM genotype, on the other hand, are more likely to perceive androstenone as less unpleasant. Many cannot smell androstenone at all. Although some participants with the RT/WM genotype can smell androstenone, they experience the smell very differently than those with two copies of the fully functional receptor: To them, androstenone doesn’t smell like urine; it has a vanilla scent.
“There are two independent things that are interesting about this odor,” says first co-author Keller. “One is that it is a potential social signal but the other one is that so many people cannot smell it.”
Two additional point mutations in some of the participants influenced their sensitivity to androstenone, one of which may make humans hypersensitive to this odor. Vosshall and Keller are interested in what it is about these amino acid changes that alter one’s perception of androstenone’s scent, and in whether one’s perception of this potent compound can influence behavior.
Press release: Gene determines whether male body odor smells pleasant …
Nature (where the research is published): Beauty is in the nose of the beholder …