Women Can Smell Genetic Differences

Jan. 22 -- If you have ever been attracted by a person's scent, it may be their genes you smell. Researchers believe that women can identify men based on differences as small as a single gene.

In the most recent issue of Nature Genetics scientists look at the link between women's preference for the odors men give off and a group of genes called the Major Histocompatibility Complex (MHC) — which are an important part of the body's immune response.

A group of 49 women were asked to smell 10 boxes which contained pieces of T-shirts that had either been worn by men or contained a familiar household odor such as bleach or clove.

The men who had worn the T-shirts were selected based on their MHC genes, and were told to sleep in the shirt for two consecutive nights while avoiding other scents entirely, such as colognes and even contact with other people.

The women were then asked to rate each scent based on their familiarity, intensity, pleasantness, and spiciness, as well as choose the one odor which they would choose if they had to smell it all the time.

"A clear pattern emerged," said Dr. Carole Ober, co-author of the study and a geneticist at the University of Chicago. "The women did not choose scents of men with genes totally similar to their own, or totally dissimilar to their own. They chose men with an intermediate level of difference."

"The real surprising thing is that there was something special about paternally [from one's father] inherited [genes]," said Wayne Potts, an expert in the area of MHC research at the University of Utah.

Moreover, the women showed no preference for odors from men with the same gene types as their mothers, but did show a preference for odors from men who shared genes they inherited from their fathers.

"Given that you often can't tell who you're father is, it would be important to evolve a way that you can," said Martha McClintock, co-author of the study and a professor of psychology at the University of Chicago.