Asked by Lisa McMillan of East London, United Kingdom

This question never seems to go away. Most scientists would say that there is little evidence that humans rely very much upon pheromones as a sexual attractant. Pheromones are special chemicals produced by animals that serve to direct behavior, including sexual behavior. In mating, other animals rely upon the sense of smell much more than we humans do.

It is argued that we humans have virtually lost our ability to be attracted by pheromones and hence pheromones are important in human sexuality only minimally or not at all. Nevertheless, some scientists contend that a tiny sense organ in our nasal cavity, the Vomeronasal Organ (VNO) which is sometimes called Jacobson’s Organ, is capable of detecting chemical sexual attractants passed on unconsciously between people. The VNO is located in the vomer bone between the nose and the mouth. How it functions in humans is disputed. In animals, it is much clearer:

• Mice use the VNO to detect pheromones - vital in making mousy mating.
• Cats use the VNO to detect nepetalactone. This give them the “high” from catnip.
• Snakes use the VNO to sense prey by sticking out their forked-tongue and withdrawing it - touching the VNO in the process.
• Elephants stimulate themselves by transferring sensory stimulating chemicals to their VNO via the tip of their trunks.

In humans, the VNO first appears during fetal development. Strangely, it then shrinks to almost nothing by the time of birth. We don’t know why. In adults, a small pit can be found in the nasal septum of some people, but not in all. Again, we don’t know why. Some scientists think that this tiny remnant means that the VNO still can work - at least in some humans. But what the VNO can do is anyone’s guess. Anyone care for a pheromone perfume for Saturday night?

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au