Love Darts! The Truth About Human Pheromones

Love…it can happen to anyone, at anyplace, on any day...

It is a sturdy emotion that makes us lose grip over our own control, and drive us into action dimed insane by the “clear-headed” among us.

Love has always been present, and love stories have been documented throughout history: Form “Romeo and Juliet” till “Bonnie and Clyde”. The classical passionately believed that love is transmitted by arrows or darts shot by the mythological Eros, or Cupid.

Once the arrows reach the lover, they travel through his eyes into his heart, pierce it and overwhelm him with longing and desire.

But, for love to happen there should be attraction in the first place. What triggers attraction? Is it a muscular body, a good haircut or a warm smile? Or could it be induced by the human love darts : pheromones?


A General Definition

Pheromones are molecular messengers that transmit information from one member of a species to another member of the same species, and influencing its behavior. In the animal kingdom, pheromones have been scientifically proven to exist and they’re function is well established. However, in humans, pheromones are still under investigation.


Types

There are several types of pheromone:

Alarm pheromones, as the name suggests send SOS signals to other members of the same species. Such compounds are released when a specific organism is being attacked by a predator, leading to trigger of either a fight or an escape response (1)

Aggregation pheromones function in defense against predators, and overcoming host resistance by mass attack. (1)

Territorial pheromones help in defining the territory of a particular organism. For example, dogs deposit the so-called pheromones, present in their urine on specific landmarks to mark the perimeter of the claimed territory (1).

Perhaps the most studied of the pheromones are sex pheromones. They are indispensable for survival and replication. These sex pheromones send signals about the availability of a partner for mating. Furthermore, they are well-known for their “male effect”: after a separation of at least one month, the rams are introduced into a flock of sheep in ovarian inactivity; there was a resumption of sexual cycles in a large proportion of females. Pheromones secreted by the sebaceous glands, seems to cause this phenomenon.

Of special interest are the human pheromones, which are claimed to enhance the libido (sex drive) of an individual. Several companies even market human pheromones claiming that they possess aphrodisiac properties. Nonetheless, the number of studies available on human pheromones is very limited. For instance, androstenone, a steroid present in the sweat of the armpits, is being advertised by several companies. This product (smelling like urine) is presented as a sexual attractant, but its effectiveness has never been demonstrated in humans. However, its effectiveness has been proved in pigs.


The Proof

To prove their effectiveness, scientists have turned to the pheromones receptor: the vomeronasal organs (VNOs).
The VNOs are located inside the nose, just as are the organs that pick up olfactory signals (smells). This diagram shows the location of the vomeronasal organ in adult humans.


Until recently the VNOs were thought to be vestigial or functionless organs that we humans no longer use: the human VNOs lack the characteristic capsule and large blood vessel of other mammal’s VNOs. Even more, the sensory epithelium is not fully developed. However, convincing behavioral and anatomical evidence has since brought the notion of a human VNO into the realm of scientific fact. (2)

This system has its own separate organs, nerves, and connecting structures in the brain. Some anatomists (Professor Antoine Corban) refer to the VNO as the 13th cranial nerve. Pheromone information from the VNO is carried straight to the hypothalamus, the older part of the human brain, bypassing the cerebral cortex making us unaware of its present. We cannot “smell” pheromones in the same way as we might smell roses.(3)

Scientists disagree about whether humans still use pheromones as a method of inter-personal communication: current research seems to indicate that we do, although the effects occur below our conscious awareness. Any effects that do exist are considerably less obvious in human beings than in other animals.

The best known case involves the reported synchronization of menstrual cycles among women: The McClintock effect. This study exposed a group of women to a whiff of perspiration from other women. It was found that it caused their menstrual cycles to speed up or slow down depending on the time in the month the sweat was collected; before, during, or after ovulation. Therefore, this study proposed that there are two types of pheromone involved: "One, produced prior to ovulation, shortens the ovarian cycle; and the second, produced just at ovulation, and lengthens the cycle. (3)

A similar study attempted to find out whether or not males can sense ovulation by smelling copulins, fatty acids in vaginal secretions. Males smelled copulin samples from women who were in three different phases of the menstrual cycle. The results showed that males generally could not distinguish between pre-menstrual, menstrual, and ovulatory scents. However, the males also rated the physical attractiveness of the females, and results showed that females were rated more attractive when the males were smelling their copulins, and that the testosterone levels in males increased when they were smelling the copulins. (3)

In addition, women are more attracted by the odor of men who are the most different of them by their MHC genes, starting from puberty (Wedelind, 1995)

Another study shows that babies prefer clothing worn by their own mothers. In this study, ten mothers were asked to wear a cotton pad in their bras for three hours. The pads were then given to their babies to see whether or not they could distinguish between the pads worn by their mothers and those worn by strangers. At the age of six weeks, eight babies had responded by sucking to their mother's pad, one responded to a stranger's pad, and one did not react to its mothers pad, but reacted with a cry to a stranger's pad. Researchers believe this could suggest that men and women choose their mates by sniffing out those that have "compatible immune systems."(3)


Conclusion

Attraction isn’t a choice! Sometimes you can look at the person and feel obliged to talk to them or to follow them and observe them carefully without even being attracted to their looks…attraction is an evolutionary process that takes control over our own mind and body, long enough to make sure that our selfish genes reproduce. It is an intricate topic that even today’s modern science does not dare to explore it in the profundity it truly deserves.

Author:Mario Zanetti



References:

1) http://en.wikipedia.org/wiki/Pheromone
2) http://serendip.brynmawr.edu/bb/neuro/neuro99/web3/Bernstein.htmlDo human pheromone exists?
3) http://serendip.brynmawr.edu/exchange/node/2052