Ultimately, the work will aim at discerning how smelling these chemicals might affect human social and sexual behavior. "We will begin working with a collaborator to examine chimpanzee behavior with regard to odor perception," Matsunami said.

However, the sense of smell also can vary from animal to animal and person to person, because of combinations of a number of odor receptors.

"The sex-steroid related odors act as pheromones in pigs," Matsunami said. "Pigs that are ovulating and that are exposed to the pheromones assume a mating posture. It's debatable whether these chemicals act similarly in humans. But there is evidence that smelling these odors can affect the mood and physiological state of both men and women. We have a lot more studying to do, but this finding and others in the future will create a picture of how smell may relate to sexual reproduction."

Matsunami added that there are likely other receptors and receptor variants that may also play roles in how these two chemicals are perceived. Because there are about 400 specific smell receptors and humans can detect more than 10,000 different odors, different combinations of receptor genes and variants must be involved in perceiving each odor, Matsunami said.

Source: Duke University Medical Center