The term “pheromone” has been derived from Greek, Pherein and Horman that refer to “transfer” and “to excite” respectively (Mostafa et al., 2012). Pheromones are found all living beings on the globe that are a primitive form of communication. They exist in the form of chemical molecules having specific behavior to produce hormonal changes. Pheromones in animals and insects have been reported long time back that facilitate to sense food and mating (Mostafa et al., 2012). Pheromones and their role in the human sexual physiology for same or opposite sex were discovered later on in third decade of 20th century. The “aphrodisiacs” are associated with pheromones because they are regarded as sexual stimulants and have a significant role in human reproduction (Semwal et al., 2013). This paper delineates the types of pheromones and its role in human sex and reproduction.
Semwal et al. (2013) reported that pheromones exist in the form of small and volatile organic molecules used for communication in humans and animals. The studies reveal that female moths had the ability to excite and attract the male moths without sighting and hearing. The female can feel odor of male with the help of very sensitive antennae present in pheromones (Semwal et al., 2013; Thornhill and Gangestad, 1999)
Based on function and nature pheromones are classified as primer pheromones, Releaser pheromones, signaler pheromones and modulator pheromone. Primer pheromones produce a long-term change in behavior that activate the menstrual cycle while releaser pheromones generate sexual attraction for a short time. Signaler pheromones generate chemical signals that provide information regarding odor of the sex, genetic odor print and so forth. Modulator pheromone influence different neuropsychological characteristics that affect the mood as well as alter and synchronize the functions of the human body (Mostafa et al., 2012; Semwal et al., 2013).
These types of pheromones also perform different controlling functions including opposite sex attraction and same-sex repellents, and menstrual cycle. They also activate specific regions of the brain that affect social behavior, regulate ovulation, and control physiological characteristics such as the amount/or level of serum present in testosterone, follicle stimulating and luteinizing hormone. A number of human pheromones have been discovered, and their function varies from eliciting the sexual desire to synchronizing menstrual cycles. The main human pheromones include 5α-Androstenone, 3 β-Androstenol, Androstadienone. Androsterone, Copulins, and Estratetraenol (Mostafa et al., 2012; Semwal et al., 2013).
The feeling of smell is imperative for an arousal system, and humans have the ability to store odor retentions and can generate odor preferences or repulsions. Many studies reported that olfactory signals induce emotional responses without perceiving an olfactory stimulus. This may be due to olfactory receptors that send projections to the neocortex for processing as well as to the limbic system for emotional processing. (deCatanzaro, 2015; Mostafa et al., 2012; Thornhill and Gangestad, 1999). Mostafa et al., 2012 mentioned that apocrine glands and body hair develop simultaneously during adolescence that is associated with sexual development. In addition, these non-functional structures hold bonding with the olfactory system. Wyart et al. (2007) also mentioned that the smell of androstadienone of male sweat maintains higher levels of cortisol in females. Hence, it can influence the endocrine balance of the opposite sex.
The pheromones are mainly produced by the glands present in the skin that develop during adolescence. In fact, they are associated with sweat glands and hairs. These glands are located on the body surface including underarms, nipples of both sexes, genital regions, the outer surface of ears, lips and eyelids. The underarms, nipples, genital regions and the outer surface of ears contain varying amounts of hairs. The sufficient area of hairs in this region spread the smell due evaporation process (deCatanzaro, 2015; Mostafa et al., 2012).
In conclusion, the role of pheromones in human reproduction is very important. Its stimulation is especially associated with smell or odor that exhibits in female dominantly. In addition, the sexual desire of females enhance during the time of fertility.
deCatanzaro, D. 2015. Sex steroids as pheromones in mammals: The exceptional role of estradiol. Hormones and Behavior. 68:103-116
Mostafa, T., Khouly, G., Hassan, A. 2012. Pheromones in sex and reproduction: Do they have a role in humans? Journal of Advanced Research.3 (1): 1-9.
Semwal, A., Kumar, R., Teotia, U., Singh, R. 2013. Pheromones and their role as aphrodisiacs: A review. Journal of Acute Disease. 2(4): 253-261.
Thornhill, R., Gangestad, S. 1999. The Scent of Symmetry A Human Sex Pheromone that Signals Fitness? Evolution and Human Behavior. 20(3):175-201.
Wyart, C., Webster, W., Chen, J., Wilson, S., McClary, A., Khan, R.,Sobel, N. 2007. Smelling a Single Component of Male Sweat Alters Levels of Cortisol in Women. Journal of Neuroscience. 27(6):1261-1265.