Pheromones are biologically active substances secreted from the body of animals that elicits physiological and behavioral changes in another individual of the same species. Pheromones are ectohormones released from the body to exert influence on another animal of the same species. The word Pheromone is derived from two Greek words Pheran which means to transfer and Horman to excite. Humans, like other animals also release pheromones from the body, but its quantity is less significant since it has no relevance in communication. Human pheromones do not have to be consciously perceived to affect the recipient, but have been shown to affect our behavior when used at subconscious levels.
In the course of evolution, humans have lost the ability to detect and respond to pheromone consciously. But researchers say that perception to pheromones is still in our brain but on the subconscious level. At an instinctive level, the pheromones dictate our interaction with other humans.
Role of Androstenes
In males, the pheromone producing Apocrine glands are located in the skin especially in the Arm pit. The arm pit has high concentration of Apocrine glands and hence forms the Axillary organ for human odour. These Axillary organs become functional at the onset of puberty. After sexual maturity, these Axillary organs start to secrete steroid secretions containing sixteen Androstenes. The concentration of the Androstenes (Androstenone and Androstenes) is very high in males compared to females. Researchers say that these Androstenes function as the major male pheromone that subs serves the social and sexual behavior of human males.
Classes of Human male pheromones
The male pheromone is a group of four pheromones. These are
1. Androstenone – This is the most prominent male human pheromone causing a dominant, intimidating and aggressive character. It is also present in females in lower quantity.
2. Androstenol – This pheromone signals the sociability of males. It causes conversation, and functions as a good ice breaker.
3. Androstenone A – This male pheromone signals masculinity. This creates a feeling of protection and reliability normally found in a peaceful alpha male.
4. Androstadienone – It is called as love pheromone since it creates good feelings and reactions.
Role of Copulins
Copulins are exclusive female pheromones released from the reproductive tract at the time of ovulation. These are fatty acid substances that have no effect on females but it can increase the level of androgens in males during interaction. These chemicals become air borne and influence the near by males. Copulins are considered as Pseudo psychological chemicals that can affect or control the hypothalamus of males. Some studies revealed that the Copulins can affect the male’s dominance. It is interesting that, if the Copulins affects a male strongly, he becomes pleasant and tries to please the female. This is not a sexually driven act but an unconscious reflex. But each female’s Copulins affect each male’s behavior differently at different levels.
From Nose to Brain
In many mammals, there is a Vomeronasal organ inside the nasal tract to detect pheromones. This pheromone detector has nerve innervations and the Vomeronasal terminalis nerve takes the information to the limbic system of the brain. It has been reported that humans also have this vomeronasal organ that can detect human pheromones in a sex specific manner and produces specific physiological changes in the body. Researchers identified pheromone receptor gene in the olfactory mucosa of human beings. This study confirms the presence of vomeronasal organ in human beings also. Scientists have confirmed that the occurrence of small patches of clear cells similar to nerve cells located on both the sides of the nasal septum just inside the nasal openings. These are considered as the poorly developed vomeronasal organs concerned with the detection of human pheromones. The chemical signals are transmitted to the hypothalamus to elicit behavioral responses.
Existence of pheromone sensing centers in the brain indicates the possible role of human pheromones in the biological basis of sexual orientation. Studies conducted using f-MRI (functional Magnetic Resonance Imaging) revealed that brain centers like Orbitofrontal cortex, Right Fusiform cortex and Right hypothalamus are the brain areas that responds to airborne human pheromones. This reveals that the existence of human pheromones links the sensory aspect of social behavior with the neuronal and hormonal aspects of behavior.
Olfactory sexual dimorphism
Like the male –female sexual dimorphism, olfactory sexual dimorphism also exists in males and females to detect human pheromones. For example, a female can detect even a lower level of male pheromone Androstenes than the males. This seems to be the cause of behavioral dimorphism.
Some interesting studies and reports
There are studies and research reports coming in to explain the influence of human pheromones in socio-psychological behavior. Some of these studies are based on mere observation and some are based on group studies.
1. It has been observed that the Andropenes from males can correct the irregular menstrual cycle in females.
2. Smell of Andropenes can maintain high Cortsol level, a steroid hormone in females.
3. The Andropenes act as a Pheromonal chemo signal to influence the hormone balance in females.
4. Female pheromones can synchronize Menstrual cycles in closely associated females.
5. Copulins can alter the approach of females to males. Depending on the strength of Copulins at different periods, attracting and hating behavior can develop.
6. Synthetic Andropenes are used to make perfumes, deodorants, body lotions etc for the use of males. Manufacturers claim that, these aromas can increase the masculine features and lovable characters of males.
These studies and reports are interesting, but there are controversies regarding the methodology, sample group selection etc to study the influence of human pheromones. So the actual role of the pheromones in human beings has to be found out. Since human pheromones have little role in human social and behavioral aspects, it is better to consider it as a part of evolutionary change. We human beings are highly hygienic, so that our pheromones become the victims of the daily bath. Use of perfumes, deodorants, body sprays etc also kill our pheromones so they cannot do anything in our daily life.
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