What are pheromones?
Pheromones (their name has been derived from Greek words meaning “excitement transmitters”) are chemical compounds selected by evolution. They occur in certain concentrations, depending on genetics, species and individual secretion outside the body. They may be unknowingly picked up by another representative of the same species who will begin, modify, strengthen or change certain physiological and behavioural responses.
Pheromones are not perceived consciously as perfumes or fragrances. They affect the human nervous system subconsciously. We still don’t know how many different pheromones our body produces, and thus far only some of them have been tested.
Pheromones act like messengers
Humans express many non-verbal behaviours that carry different messages. Pheromones can carry information about sexual and social status, such as gender, level of maturity, readiness to reproduce, individual identity, relationship, health, domination, partnership and ability to compete, which can have a significant impact on adaptation and development. Chemical signals are the main factors affecting our socio-sexual relations. Pheromone communication is based on the processing of information from the cortical and subcortical structures of the brain (involved in regulating emotional behaviour), but without any cognitive or conscious assessment.
Pheromones are ex.pressions of genetic sexual selection, which could have been important for human evolution. Pheromone signals trigger neuronal, hormonal, physiological and behavioural changes. This is very important for complex pheromone communication in human sexual selection.
Where do pheromones come from?
Pheromones occur in various anatomical structures or tissues of the secretory system. In mammals, they are mainly produced in:
- preputial glands,
- perianal glands,
- sebaceous glands, apocrine glands,
- axillary glands,
- submaxillary glands,
- Harderian glands,
- tear glands
Body fluids in which pheromones are found include:
- vaginal and prostatic secretions,
One of the most important sources of pheromones in humans is probably the axillary glands under the arms, due to the fact that the surface on which they spread is warm, which accelerates the release of compounds into the air. It is also important that they are located at the nose level of other people, which is reflected in the relaxed reactions of children or mothers when sleeping with their heads near the armpit, and caring behaviour when a man puts his hand on the woman's shoulder, thus exposing her to the action of his pheromones.
Pheromones and sexual behaviour
It should be noted that in humans, pheromones activate the hypothalamus that controls the autonomic nervous system (AUN) which plays a key role in releasing sex hormones, sexual arousal and reproductive behaviour.
Chemosignals, thus far poorly researched, have a special impact on the sexual behaviours caused by pheromones. Various experiments have been carried out using fragrances and perfumes. Most of the available information concerns the effects of research on women, less is known about the sexual reactions of men. For example, perfumes work in the first phase of sexual behaviour and are involved in the hedonistic perception of a partner. These signals can make human faces seem more attractive, they can increase sexual interest and attraction, as well as affection and irritability, but they have no influence on familiarity or trust. Men, on the other hand, assess the woman's body odour associated with the ovulation phase as more pleasant, sexy, rather than the scent associated with the barren phase. What's more, a woman’s face and breasts demonstrate changes in morphology during the ovulation phase. This changes the perception of men - women seem more attractive then.
Pheromones and emotions
The influence of pheromones on human emotions is associated with their subconscious action (on the hypothalamic-pituitary-gonadal axis). In experiments using a randomly chosen scent, which was previously associated with the scent of a woman, it was found that it causes the secretion of the luteinizing hormone, which in men is responsible for the functioning of the interstitial cells of the testicles. The hormone can be secreted even in the absence of this scent, which means that olfactory stimuli can activate the pituitary-gonadal axis of the male by imitating activation caused by the presence of a woman. The luteinizing hormone is most likely very important to the relationship between the sexual behaviour and the sense of smell of humans. It has been shown that when women smelled the pheromone known as 4.16-androstadien-3-one, the cortisol concentration (a steroid hormone) in their saliva increases. It was also found that a mixture of aqueous solutions of five fatty acids of the ovulatory phase causes an increase in testosterone in the men's saliva and increases, in comparison to the control group, the accuracy of the presented women’s photographs and voices.
Pheromones have no scent
It turns out that pheromones do not have such a strong influence on cognitive processes and consciousness as they do on the neuroendocrine system and behaviour. The effect of androstadienone, a male, odourless steroid detected in sweat, blood and semen, on cortical processes, hypothalamus and amygdala, even when it is not consciously recognised - was confirmed by the results of several studies, thanks to the use of brain imaging techniques. This fact explains that human pheromones modulate the psychological and physiological state without being consciously detected as scents.
The role of pheromones and their impact on our choices and behaviour are downplayed. Scent is a very important identifying factor - every person has a unique scent, conditioned by a complex pattern of chemical secretions. The secretion of sebaceous and sweat glands is regulated by sex hormones. The scent that arises, enhanced by the type of pheromones, can be attractive to one person, but irritating to another. Thus, pheromones not only affect the choice of partner, but are also important in establishing various social and emotional relationships.
Impact of pheromones on humans
In addition, pheromones play a role in maintaining continuity of the species. This is evidenced by the fact that they are released at different intensities, e.g. during the woman's menstrual cycle. When a woman is ovulating, she seems more attractive, which provides information about her reproductive ability.
The secretion of pheromones is also conditioned by the person’s age, e.g. the hormonal balance changes during the menopausal and postmenopausal periods. Research is being conducted on the use of replacement therapy, which could help women stay more attractive during menopause.
We will certainly be hearing more about pheromones in the future. The ongoing research will reveal more areas influenced by these mysterious messengers.
Interesting facts about pheromones
You can find many analogies between pheromones of very different organisms. The chemical structure of the elephant's sex pheromone is identical to the structure of this pheromone in the moth. The human sex pheromone, on the other hand, is the same as the one found in wild boar.
Women's preferences as to the appearance of the man's face, his tone of voice, coquettish, flirtatious behaviour, as well as the neuromodulation of the reward system depend on the phase of the ovulation cycle.
It has also been shown that the hormones produced by the ovaries can control the sexual arousal of women, which is most intense during the peri-ovulatory period.