Love at First Smell

Everyone has experienced the power of odors[1] to evoke emotional responses or to call up deep memories. And scientists have abundantly documented how many different kinds of animals send signals (including sexual cues[2]) to one another using airborne chemicals, or pheromones[3]. Many people have jumped to the natural conclusion that human pheremones must exist; some companies even claim to sell them. But researchers have found no concrete evidence of a human pheremone--until now.

Kathleen Stern and Martha McClintock, both at the University of Chicago, collected compounds from the armpits of women in the follicular phase of their menstrual cycles. These compounds, when presented to other women, sped up the cycles of the recipients and hastened the onset of ovulation. Nearly three decades ago, McClintock showed that women who spend lots of time together tend to develop synchronized menstral cycles. The new work, published in the March 12 issue of Nature, helps explain why this process occurs. It also provides the first proof that people really do send sexual signals through pheremones.