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Dr D Narayana Reddy
Dr D Narayana Reddy


Smell right

Are humans guided in their relationships by pheromones?

Doctor, my husband does not allow me to use deodorants. He says that my body smell arouses him. But others may think that I am a stinker and do not take care of my personal hygiene; can you advice him?” complained a lady.

While we aren’t very forgiving of body odour, we do love the natural scent emitted by our romantic partners or potential mates. Driving this reaction are pheromones, chemical substances responsible for attracting members of a species to one another.

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

Pheromones can be secreted to trigger many types of behaviours: alarm; following a food trail; sexual arousal; telling other female insects to lay their eggs elsewhere; respecting territory; bonding (mother-baby) and backing off.

49Smellright Illustration: Bhaskaran

There are four principal kinds of pheromones:
* Releaser pheromones: They elicit an immediate response, 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.
* Signaler pheromones: These provide information. They may help the mother to recognise her newborn by scent (fathers cannot usually do this).
* Modulator pheromones: They can either alter or synchronise bodily functions. 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. Researchers at the University of Chicago claimed to link the synchronisation of women's menstrual cycles to unconscious odour cues. This is called "the McClintock effect". Modulator hormones may also affect a female's monthly cycle.

Research on pheromones in humans indicates that the main odour-producing organ is the skin. These odours are largely produced by the skin's apocrine sebaceous glands, which develop during puberty and are usually associated with sweat glands and tufts of hair. These glands are located everywhere on the body surface, but tend to concentrate in six areas: the axillae (underarms); the nipples of both sexes; the pubic, genital, and circumanal regions; the circumoral region and lips; the eyelids and the outer ear.

There are variations in odour perception between human adult males and females. This is most evident in the case of women's acute ability to smell musk, which are steroids. These compounds are similar to the male sex hormone testosterone.

Moreover, women's sensitivity to these substances varies as a function of where they are in their menstrual cycle: during menstruation, women are no more sensitive to musk than men, but about ten days after menstruation (ovulation), women reach their maximum sensitivity. In addition, women on the pill, women who have had ovariectomies, pregnant women and post-menopausal women are relatively insensitive to these substances. Men secrete musky odorants in abundance. The fact that men's bodies secrete these substances and that women are most sensitive to them when they are most fertile indicates that these substances may have an olfactory-sexual role in human sexuality.

We have to look at pheromones, specifically in humans, from a different perspective. With our highly developed intellect and rich complement of emotions, ambitions, motivations and desires, it may not be profitable to look at human pheromones the same way we look at animal pheromones. Instead of looking for odorants that cause a definite physiological response, it may behove us to look at how possible pheromones affect our attitudes. We are not machines that blindly fall into some stereotyped behaviour in response to an odour, but we may be machines that are nudged towards a type of behaviour by pheromones in concert with our higher intellect.

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Topics : #Sex

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