Women of childbearing age can learn to detect progressively fainter odors with astonishing sensitivity, according to new research. The discovery adds to a growing body of evidence showing that smells may be far more important to women than to men.
Previous research has suggested that women may follow their noses during much of their reproductive years. Women find most attractive the smells of men whose immune system genes differ slightly from their own--the sign of a promising genetic match. They prefer wearing perfumes that amplify their own immune system smells (ScienceNOW, 8 March 2001). And within 2 days of giving birth, mothers already prefer the smells of their own babies to those of other infants.
In the current study, Pamela Dalton and colleagues at the Monell Chemical Senses Center in Philadelphia set out to determine whether humans can hone the ability to smell food-related odors. At the outset of the experiment, the five men and five women were equally good at detecting benzaldehyde, which smells like almonds, and citralva, from citrus fruit. But in 30 sessions conducted over 2 months, women became an astounding 5 orders of magnitude more sensitive to the odors, whereas men didn't improve at all. Further trials with children ages 4 to 10 and postmenopausal women show that only women of reproductive age appear to have this ability.
The work, which appears this week in the early online issue of Nature Neuroscience, suggests that women can enhance their sense of smell--even for odors with no inherent biological significance. This ability, says Dalton, could help a woman select healthy foods for herself during pregnancy, bond with her newborn, and avoid poisons while feeding her children. But in the modern age, having a sensitive sniffer could also be a curse. It may explain why women are more vulnerable to environmental illnesses such as sick building syndrome, Dalton suggests.
"We know very little about how hormones affect olfaction," says Martha McClintock, professor of psychology and olfaction researcher at the University of Chicago. "This is a real breakthrough in linking the two."