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A pheromone is a chemical that an animal produces which changes the behavior of another animal of the same species.

Some describe pheromones as behavior-altering agents. Many people do not know that pheromones trigger other behaviors in the animal of the same species, apart from sexual behavior.

Hormones usually work internally, and they only have a direct effect on the individual that is secreting them.

Pheromones, unlike most other hormones, are ectohormones. They are secreted outside the body, and they influence the behavior of another individual.

This article will take a brief look at pheromones and whether they can be found in humans.

Fasts facts about pheromones

  • Pheromones are similar to hormones but work outside of the body.
  • They induce activity in other individuals, such as sexual arousal.
  • Most insects use pheromones to communicate.
  • Some chemicals have been investigated for pheromone actions in humans but evidence is weak.
  • Many pheromone products can be purchased online, but research suggests that these are ineffective.
  • There are four types of pheromone: releaser, primer, signaler and modulator.

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Do pheromones play a role in human attraction?

Animals secrete pheromones to trigger many types of behaviors, including:

  • raising an alarm
  • signaling a food trail
  • triggering sexual arousal
  • tell other female insects to lay their eggs elsewhere
  • delineating a territory
  • bond between mother and offspring
  • warning another animal to back off

It is believed that the first pheromone, bombykol, was identified in 1959. Bombykol is secreted by female moths and is designed to attract males. The pheromone signal can travel enormous distances, even at low concentrations.

Experts say that the pheromone system of insects is much easier to understand than that of mammals, which do not have simple stereotyped insect behavior.

It is believed that mammals detect pheromones through an organ in the nose called the vomeronasal organ (VNO), or Jacobson's organ. This connects to the hypothalamus in the brain.

The VNO in humans consists of just pits that probably do not do anything. Interestingly the VNO is clearly present in the fetus but atrophies before birth. If humans do respond to hormones, most likely they use their normal olfactory system.

Pheromones are commonly used in insect control. They can be used as bait to attract males into a trap, prevent them from mating, or to disorient them.

According to thousands of websites that promise sexual conquests if you buy their pills, human pheromones exist. However, most proper, well-controlled scientific studies have failed to show any compelling evidence.

Gustav Jäger (1832-1917), a German doctor and hygienist is thought to be the first scientist to put forward the idea of human pheromones, which he called anthropines.

Jäger said that they were lipophilic compounds associated with skin and follicles that mark the individual signature of human odors. Lipophilic compounds are those that tend to combine with, or are capable of dissolving in lipids, or fats.

Researchers at the University of Chicago claimed that they managed to link the synchronization of women's menstrual cycles to unconscious odor cues. The head researcher was called Martha McClintock, and the phenomenon was called "the McClintock effect."

When exposing a group of women to a scent of sweat from other women, their menstrual cycles either accelerated or slowed down, depending on whether the sweat was collected before, during, or after ovulation.

The scientists said that the pheromone collected before ovulation shortened the ovarian cycle, while the pheromone collected during ovulation lengthened it.

However, recent analyses of McClintock's study and methodology have questioned its validity.

There are four main types of pheromones:

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Moths use pheromones to communicate, but what about people?

Releaser pheromones: These elicit an immediate response, and the response is rapid and reliable. They are usually linked to sexual attraction.

Primer pheromones: These take longer to get a response. They can, for example, influence the development or reproduction physiology, including menstrual cycles in females, puberty, and the success or failure of pregnancy. They can alter hormone levels in other beings. In some mammals, scientists found that females who had become pregnant and were exposed to primer pheromones from another male could spontaneously abort the fetus.

Signaler pheromones: These provide information. They may help the mother to recognize her newborn by scent. Fathers cannot usually do this. Signaler pheromones give out our genetic odor print.

Modulator pheromones: They can either alter or synchronize bodily functions. They are usually found in sweat. In animal experiments, scientists found that when placed on the upper lip of females, they became less tense and more relaxed. Modulator hormones may also affect a female's monthly cycle.

A study, published in Respirology in January 2016, showed that a substance called AND (progesterone derivative 4,16-androstadien-3-one) caused swelling in the erectile tissue of female noses. This was taken as evidence that AND might be a functioning pheromone.

Another contender for the role of human pheromone is androstadienone. There is some evidence that androstadienone, a component of male sweat, increases attraction, affects mood and cortisol levels and activates brain areas linked to social cognition. One study found that androstadienone increased cooperative behavior in males.

Androstenone, secreted only by males, has also been tested for its potential role as a pheromone. According to some studies, androstenone increases a woman's libido, especially if she is presented with it close to the time of ovulation.

In March 2017, researchers published findings of an experiment in which they exposed participants to one of three scents. These were a control and a possible pheromone, either AND or estratetraenol (EST). They then asked the participants to do a task that involved assessing for gender perception, attractiveness or unfaithfulness of people whose faces they saw in pictures.

The scientists found no difference in the reaction of the participants, whether or not they were exposed to the scent. They concluded that AND and EST are probably not human pheromones.

Overall, evidence for the existence of pheromones in humans is weak, but it cannot be ruled out entirely. If human pheromones are ever found, their effects are probably very subtle.

If you are interested in trying for yourself, you can buy pheromone perfume online.