Scientific Validation of Pheromones: Research Highlights

The vomeronasal organ (VNO) is an organ in the nasal cavity which some scientist believe is one of the body's main receptors of pheromones. The VNO was first discovered in the year 1703 by a Dutch military doctor on a soldier with a facial wound. 

The VNO is assumed to be an evolutionary relic -- an organ no longer used by human beings.  Many anatomy textbooks, and some recent research publications, claim that the VNO exists only in an embryo developing in a mother's womb. Accordingly, recent studies contradict the argument that the VNO is the human body's main receptor of pheromones and instead suggest that human pheromones are processed through our main olfactory system and that this is how they affect the secretion of hormones by the hypothalamus, which in turn affects behavior.

Whether or not there is a functional human VNO is no longer a concern because there is evidence that humans are affected by pheromones. The majority of scientist agree that human behavior does change when exposure to pheromones occurs. To help you further understand the evolution of pheromones, we have outlined research highlights below for your review.



In 1959, the name pheromone (derived from the Greek pherein "to transfer" and hormon "to excite") was coined by P. Karlson and M. Luscher to identify the host of chemical signals that had been detected through the study of other insects and mammals.  Karlson and Luscher defined a pheromone as "a substance secreted by an animal to the outside of the individual, which is then received by another individual, classically of the same species, which then elicits some behavior or developmental response in the latter.

Human pheromone discoveries began as early as 1960. David Berliner, a young professor of anatomy at the University Hospital of Salt Lake City, bent on identifying chemicals that are in the skin, scratched skin cells from the discarded plaster casts of skiers who had broken their bones on the ski slopes.  He put the cells in solvents and allowed the extracts to stand in open bottles in the laboratory.  That's when he observed that researchers who were in close proximity to the skin extracts experienced a remarkable change in mood (from discordant to harmonious).

Naturally, no conclusions were drawn because not only were pheromones unheard of at the time, but the very notion of skin extracts having anything to do with human behavior seemed preposterous.

Berliner then froze the skin extracts and forgot about them until 1990 when he remembered the skin cell extracts that had been frozen for 30 years.  He had been following the publications about the vomeronasal organ (VNO) and pheromones, and was curious to know whether his skin cell extracts would have an effect on the VNO. 

Further exploration revealed that the heartbeat and breathing of the test subjects slowed down and their muscles relaxed. This "relaxation response" that the pheromones brought about may just be the clue to their aphrodisiac effect since the likelihood of sexual encounters are significantly increased when a person is relaxed.



There have been recent studies that suggest that human pheromones are processed not by the VNO but instead by cells in our olfactory system, please review the websites listed below for additional information on these findings. 

http://www.ncbi.nlm.nih.gov/pubmed/17917120

http://www.ncbi.nlm.nih.gov/pubmed/19235878

George Preti, a chemist of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, led a study wherein female volunteers were exposed for six hours to male pheromones concentrated from men's armpits (masked by fragrance).  The female participants' levels of luteinizing hormone (LH), a key player in the menstrual cycle, were monitored.

Preti's team found that a surge in blood levels of luteinizing hormone occurred after the women's exposure to the male pheromones.  LH levels, produced in pulses by the pituitary gland, typically surge right before ovulation but also occur in many smaller peaks throughout the menstrual cycle. The application of male underarm secretions hastened the onset of these smaller pulses.  This LH surge has been linked to a woman's predisposition towards reproductive activity.  Preti's study underscores the fact that these behavior-altering chemicals (pheromones) can affect the brain, hormone levels and hence our bodies and our mood, without our even realizing it.



Astrid Juette, a Vienna University biologist, was the first scientist to show the connection between female pheromones (copulins) and male testosterone levels.  Juette synthesized the ovulatory vaginal secretions in women, based on work in  Rhesus monkeys -- and her discoveries were startling.

Copulin secretions vary dramatically during various phases of a woman's menstrual cycle. Juette's objective was to test if males are able to smell maximum fertility (that phase of the female cycle that coincides with the "in heat" phenomenon in the animal kingdom) -- and observe if males changed their behavior and physiological state as a result of perceiving the scent.  She found that the testosterone levels (measured by saliva) of males in the ovulatory-smell group increased to nearly 150% of starting levels.

Another important message that comes from Juette's subsequent studies was the discovery that  the processing of scents in the human brain is more direct than other sensory stimuli (such as visual or auditory, for example) -- and scents elicit non-conscious behavioral (and psychological) reactions via biological pathways.