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The Vomeronasal System

The forked tongue of a snake is a delivery system for odor detection. A pair of chemosensors, one in each branch of the fork, provides direct inputs to a part of the snake's brain called the vomeronasal or Jacobson's organs. Why is the snake's tongue forked? This provides directional information to the snake, because the two receptors are stimulated to different degrees by odors coming from different directions. The ability to know direction of an odor is important to snakes, many of which are nearly blind and rely on odor to detect prey.

Why do snakes have forked tongues? What has been discovered about the VNO in humans?

Humans also have a vomeronasal organ. For years researchers considered it vestigial (obsolete and unused). However, in the late 1980s and early 1990s, a number of research teams suggested otherwise. They discovered that the human vomeronasal system responded to chemicals entering tiny pits on both sides of the nose. Researchers suggested the vomeronasal system might be involved in sexual attraction, acting as a detector of human pheromones (hormones often used for communication, including sexual attraction). However, the activity of the vomeronasal organ appears to be unconscious.

Why is there not more public information about potential human sexual pheromones?

You can imagine the commercial impact of a substance that unconsciously triggered sexual attraction. It could produce huge profits for pharmaceutical or cosmetic industries as well as aiding therapy for sexual disorders. If made available to the public, it might be as profitable as Viagra. These implications have not escaped researchers. Secrecy surrounds research into the vomeronasal system in humans, and if there is a way to exploit this system to enhance sexual attraction, publicity will not occur until the discovery is patented. In the meantime, all sorts of unvalidated "sexual pheromones" are for sale over the internet. In all likelihood they have no effect other than a placebo effect.


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