Pheromones and their impact on our behavior

Pheromones and their impact on our behavior

The pheromones are chemical signals segregated by an individual and received by another individual of the same species, in which they trigger a specific behavior or development process.

Animals use these chemical signals to communicate messages that range from sexual attraction to aggression or landmarks.


  • 1 Studies on the effects of pheromones on humans
  • 2 The impact of pheromones on the female menstrual cycle
  • 3 Hormones and breastfeeding
  • 4 The detection and transmission of pheromones
  • 5 Psychological stimulation of pheromones
  • 6 The neurological activation of pheromones
  • 7 Pheromones and their mood effects
  • 8 Genetic compatibility and pheromones
  • 9 Conclusion

Studies on the effects of pheromones on humans

Most studies have shown that human sweat increases physiological activation, one way or another.

The idea that something we are not even aware of affects our behavior at such a primary level is, at least, disturbing to some people, but in reality pheromones are controlled by the combination of all our senses.

It is important to realize that any smell It can affect our behavior, but pheromones are produced by our peers (members of the same species) and play a key role in communication. Studies show that pheromones are processed differently than common odors.

The most important behavioral data that support pheromone-based communication in humans have come hand in hand with studies on menstrual synchrony. It has been shown, for example, that female colleagues from the same university begin to menstruate at the same time.

The impact of pheromones on the female menstrual cycle

Synchronization of the menstrual cycle and pheromones

The menstrual cycle of women exposed to the axillary secretions of other women is shortened or lengthened depending on the phase of the other women's cycle. For example, during the late follicular phase, the cycle is shortened by a delay in the release of luteinizing hormone (LH), necessary for ovulation. During the ovulation phase the cycle accelerates in the opposite way. The end result is that some of the female pheromones affect each other so that over time, women who spend a lot of time together have the same menstrual cycle. This synchronization is sometimes known as the McClintock effect.

The impact of male pheromones on the female menstrual cycle

But male pheromones are also able to affect the female menstrual cycle, accelerating and increasing fertility in women. Cutler and Preti, 1986, showed in their research the importance of the presence of male pheromones in the biology of women. They found that Regular sex decreases fertility problems in women, regulates menstrual cycles and correlates with a milder menopause. The cycles of women exposed to male sweat on their upper lip for a month, are shortened or lengthened so that all of them are regulated according to an optimal length of time that lasts around 29.5 days. Exposure to androgens (a pheromone produced by men) accelerates the appearance of the LH peak necessary for ovulation, by affecting the hypothalamus to secrete gonadotropin releasing hormone (GnRH). The researchers also observed an increase in women's overall relaxation.

It may interest you: Sexual behavior and hormones: differences between men and women

Hormones and breastfeeding

A study conducted by Jacob et al in 2004 showed that milk compounds in nursing women have the potential to function as pheromones. Exposure to breastfeeding compounds affects hormonal levels, which in turn affect the menstrual cycle. It is believed that apocrine glands secrete pheromones that are also present in the woman's nipples, a possible means of communication between mother and child.

The detection and transmission of pheromones

Most non-human animal species use a specialized olfactory system to detect pheromones called vomeronasal organ (UFO).

One of the main complications of demonstrating the use of pheromones in humans is that, although the embryo develops a vomeronasal organ, it later degenerates. It is believed that the UFO is vestigial and non-functional in humans. Apparently, the accessory olfactory bulb, where the nerve projections of the UFO are found in most species, is absent in humans. No neuronal connections between human UFO and the brain have been found.

However, humans do detect the compounds or pheromones from other members of our species, what happens is that we do not do it through this organ. Studies have suggested that pheromones are detected by the same sensory organ with which we capture all general odors (volatile molecules), with the main olfactory epithelium.

The psychological stimulation of pheromones

In studies on pheromones it has been found that there is an increase in physiological activation and conductance of the skin in addition to a decrease in skin temperature due to its effect.

Studies on the impact of pheromones on people

In a study by Bensafi et al (2003), the electrocardiogram, pulsations, blood pressure, abdominal and thoracic breathing of a group of subjects of both sexes after smelling androgens and estrogens were analyzed. Most showed significant changes in skin temperature and conductance. The increase in excitation in women and the decrease in men, was shown with variations in the conductance of the skin, as well as the activation of the hypothalamus.

Several studies have already shown that pheromones (male or female) applied topically increase sexual attractiveness. And in another study it has been observed that men who used pheromones had greater sexual activity with their sentimental partners, although not an increase in autoerotic behaviors.

In another study, Jacob et al. (2001) tested with androgens and estrogens by diluting them with other chemicals to hide their odor. They concluded that androgens can positively influence mood and increase excitement in both sexes. But Jacob suggested that the effects of these compounds are context dependent, since the results vary widely according to different studies.

Wyart et al (2007) in their study on pheromones increased cortisol hormone levels in women. Cortisol is usually released when a person suffers from stress, which suggests that it may be an inducer of increased arousal. Cortisol can also affect the levels of serotonin in the brain, which would have an effect on mood. This study showed an increase in sexual arousal, physiological arousal and a better mood in the women involved.

The neurological activation of pheromones

Studies functional image of the brain It can show exactly how the brain is activated when a person is processing pheromones. In contrast to olfactory stimulation of common odors, pheromones are detected in other receptors, although specific human pheromone receptors have not yet been found, and activate neuronal circuits in both sexes.

The smell of women, for example, activates certain nuclei of the hypothalamus. Men who smell estrogen-like substances activate the paraventricular and dorsomedial nuclei of the hypothalamus. The activation of the hypothalamus is common against ordinary odors, but the difference in activation between men and women is consistent with theories about sexual dimorphism in the brain.

The hypothalamus controls behaviors such as fighting, flight, food and reproduction. The hypothalamus contains various regions with sexual dimorphism, which differ in size between men and women. Studies reveal that these differentiated areas are related to sex and sexual behavior. For example, the preoptic nucleus is twice as large in men as in women, so it is thought that he can participate in sexual behaviors, fundamentally masculine. The ventromedial nucleus intervenes in defensive behavior, and seems to also participate in female sexual behavior. More generally, the anterior hypothalamus has to do with thermoregulation and sweating, what we have seen are the direct effects of pheromones.

Zhou and Chen (2008) conducted a study using axillary sweat to explore differences in brain activation. They exposed women to male sweat collected during sexual arousal and found that the woman's physiological activation was significantly higher when exposed to "sexual sweat" compared to non-sexual sweat. The hypothalamus responded more actively to sexual sweat than neutral sweat.

Pheromones and their mood effects

Apparently Mood can be communicated through chemicals found in axillary sweat. The sweat collected from men and women, whether while watching a funny (happiness) or scary (fear) video can be recognized later. In an experiment conducted by Chen in 2000, sweat was collected from women identified as "happy" and from women identified as "scared." Subsequently, the men who worked on the study were able to distinguish both types of sweats quite effectively.

In a more recent study by Marazziti et al (2010) they found a direct correlation between axillary compounds and the serotonin, which affects mood. Male sweat modulates the affinity of the serotonin transporter, which means serotonin stays longer in the receptor and has a longer effect with an increase in the effectiveness of serotonin. They also observed an increase in impulsivity in women versus men with high levels of serotonin, showing a positive correlation between serotonin values ​​and romantic relationships.

Genetic compatibility and pheromones

As we have seen a person tends to feel more attraction to another person depending on certain odors.

Some time ago a study was published by the University of Bern (1995) in which some of the genetic reasons that made incest difficult. According to the results found, they have to do with the variety of alleles in the genes. According to that study, different alleles attract and similar ones repel, habitually. The idea is that a person feels greater attraction to the smell of someone who has alleles other than their own. According to this theory, this would be a protection that would have been generated through natural selection to provide greater genetic diversity to the couple (and the population).

So, our body generates a more receptive response when the immune systems harmonize and adjust with each other. This factor has recently been exploited by an offline dating agency in the United States. The service acknowledges being based on the conclusions of this investigation in which different women's sweatshirts of several men were given to smell. The result was that each woman was attracted to the smell of who had the most different immune system from her. The explanation, according to the study, was that they would "genetically" complete their immune capacity to give it to their future children. And apparently detecting these genes "is something that the body does unconsciously."


Reproduction is the most important aspect in the survival of a species. For this reason it makes sense that they exist mechanisms beyond our control that urge us not only to procreate, but to find partners that will lead to the most successful offspring. Pheromones are just another way by which we can communicate, both animals and humans.


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