Pheromones :: Biology Essays Research Papers

Pheromones Have you ever wondered how different species know when to mate and who to mate with? How can they tell the difference between someone of the same sex, much less whether another organism is of the same species? This can be answered by chemical signals kn own as pheromones. Pheromones are unique and highly specific chemical signals produced by an organism that signals its presence to other members of the same species. Each organism have different pheromones they release during mating that helps them to id entify each other and start the process of mating. Pheromones come not only in forms of sex attractants, but also as alarm pheromones, aggregation pheromones, and dispersion pheromones(1). How do we know that such a chemical exists in organisms? In 1956, German scientists were able to identify the first ever pheromone in silkworm moths. After 20 years of research and over half a million female moths later, they were able to extract a pecu liar compound from certain glands located on the tip of the abdomen. When even a small amount of this substance was exposed to male moths, they would begin to beat their wings madly in a iflutter dancei. This indicated that they had detected the powerfu l sex attractant from the females that caused this type of behavior. After extracting extraneous matter and purifying the substance, scientists ended up with the first ever chemically pure pheromone. Since then, various other organisms have been studied and more is understood about the effects of pheromone, but not much is known about how pheromones work in more complex vertebrates such as humans. The next logical question to ask is how are these chemical signals recognized? Studies have shown that pheromone is first recognized by the chemical receptors in the vomeronasal organ (VNO) and olfactory bulbs located in the nose; signals are then sent t o the hypothalamus of the brain. In an experiment conducted on virgin male mice where their VNO was removed, the mice were found to generally not mate with receptive females, even if the maleis olfactory nerves were not damaged. This showed that the VNO s are needed in order start certain chains of reactions already programmed in the brain. Further studies show that when male mice have begun to associate sexual activity with other cues from females, including smells they become less dependent on the VNO s.