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Facts on Pheromones

Perhaps best known as a way to attract the opposite sex in humans, pheromones -- chemicals released by an organism -- also act as natural external cues about the environment in many species. This applies not only for many species of animals but to humans as well. Although once thought of as folklore, pheromones provide a potential link to different forms of signaling, such as mate selection in humans. In some animals, pheromones serve as the central communication device.

Menstrual Alignment
- An interesting phenomenon attributed to pheromones was brought to light in a 1971 study by Martha McClintock. According to ScienceNews.org, the study monitored women in college dormitories and ultimately showed that women aligned their menstrual periods. Not a mystery for long -- the alignment was attributed to secreted pheromones, which ultimately altered and aligned menstrual cycles.
Caste Selection
- Many animal species live and die off pheromones. Termite species take pheromone communication to the extreme. They not only communicate and dictate termite behavior but determine a termite's physical form and role within society. Termite "castes" are signaled via pheromones; if the termite group is short on workers, then more termites will be signaled to become workers. Alternatively, if the termites are signaled to become soldiers, they'll defend the colony.
Alarms and Tracking
- Pheromones have extensive range, much like the range in a human voice. They signal the identity of individuals, and each colony has different pheromones that represent different things, such as alarm signaling. These signals will put everyone on high guard, letting them know danger is around.
  
  Alternatively, if you've ever wondered how ants keep track of the direction they're going when hauling food, it's due to pheromones that have been left in the tracks by other ants.
Sexual Selection
- Although not understood completely, humans do have an affinity for the natural odors of the opposite sex. These odors are secreted via glands within the armpits and are strongest when sweating. Tons of artificial pheromones are available; however, no scientific evidence backs up their effectiveness.
Pheromones in Mammals
- Although pheromones might not play as key a role as in insects, pheromones still play critical roles in mammals. This includes giving off scents related to mating behavior, as well as marking territories--a common behavior in dogs and cats.

Animals & Science