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New York Monthly Herald. June 2006 Issue P.20

WOMEN AND MATES

Women sniff out ideal mates


Researchers have come up with hard evidence that what women really want from a mate is somebody who reminds them of their father. They have discovered that women sniff out men whose body odor is similar to that of their fathers. The theory is that a man who smells similar to a woman's father is likely to have a compatible immune system. The nature odors that all humans produce are called pheromones. They are influenced to a degree by a cluster of genes related to the immune system called the Major Histocompatibility Complex (MHC).

Diversity: Previous research found that women prefer the smell of men who have different immune system genes from their own. This was thought to ensure that their offspring have as wide a range of immune response genes - and therefore greater protection against infection - as possible. However, the new results show that the odor selection of women is even more finely tuned than was previously thought. A total of 49 unmarried women were tested by asking them to smell T-shirts worn by men for two consecutive nights. The US researchers, led by Dr Martha McClintock from the University of Chicago, found that women preferred men with a genetic smell somewhat the same - but not identical - to their own. Dr McClintock said: "We had men wear the t-shirts at night while they were sleeping. "So the scents that we collected were really quite mild. They would be like what you would smell on someone's pillow or sheet." Analysis showed a significant correlation with odor components produced by immune system genes inherited from the women's fathers. The scientists suggest that being attracted to some of father's gene smells may be a safe gamble for a woman to ensure her offspring gets a tried and tested immune system.

Strong immunity: On the other hand, she would also want enough different genes to give her baby a wide range of immune responses. Being attracted to men who smell slightly, but not too much, like her father represented a good compromise. Dr McClintock said the whole process seemed to work on an unconscious level. "These scents were not detectable as human scents. The women knew they were scents, but had no idea that they were human scents." It seems that humans are no different to other animals. Research in mice has shown that females prefer males that are just slightly unfamiliar over those that are either very familiar or very unfamiliar.

 

Secrets of human attraction

Chemical signals bypass the thought process


A gene that could explain how humans pick up powerful chemical signals called pheromones may have been pinpointed for the first time. The discovery promises to give scientists a new understanding of our basic instincts. Pheromones are known to trigger physical responses including sexual arousal and defensive behavior in many species of insects, fish and animals. There has long been speculation that humans may also use these chemicals to communicate instinctive urges. Women living together often synchronize their menstrual cycles because they secrete an odorless chemical in underarm sweat. But until now scientists have not been able to explain how and where in the body the chemicals are picked up and their messages passed to the brain.

Special organ: Many animals, including mice, rabbits and pigs, have a special organ called the vomeronasal organ (VNO). This relays chemical signals directly to the most primitive centers of the brain, stimulating instinctive reactions. In human embryos these organs exist but they appear to perform no function after birth. Now, scientists at Rockefeller University in New York and Yale University in Connecticut believe they have found a gene which may create pheromone receptors. A receptor is an area on a cell that binds to specific molecules. Called V1RL1, the gene resembles no other type of mammalian gene and bears a strong similarity to those thought to create pheromone receptors in rats and mice. "People have taken an anatomical approach to the issue in the past. This is the first attempt to look at the molecular biology," said Dr Peter Mombaerts from Rockefeller University in the journal Nature Genetics.

Ancient clues: Dr, Mombaerts and his colleagues also found seven related snippets of DNA which should produce a protein but appear to have been turned off at some stage in their evolution. Why these "pseudogenes" exist is a mystery. One possible explanation could be that in their distant evolutionary past humans made more use of pheromones than they do now. Much work still needs to be done to prove V1RL1 is a gene and does create pheromone receptors. A biotechnology company called Senomyx in California is looking at how the gene may work and which aspects of human behaviour are controlled by pheromones. Some ethicists are worried research could lead to pheromone abuse. Carefully targeted artificial pheromones could be misused to modify human behavior in advertising, politics and even warfare.