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Call Your Congressman About the Proposed Tampon Safety and Research Act! Here's How and Why.

New Evidence Shows That Pheromones Influence Menstrual Cycles

The scientist who first published the observation that women living together sometimes menstruate together has now told us why.

Martha McClintock (see also the photo I took of her at the June 1997 conference of The Society for Menstrual Cycle Research), a professor at the University of Chicago, wrote last week in the British journal Nature, which published her initial finding 27 years ago (Menstrual synchrony and suppression. Nature 229: 244-245, 1971; I am asking permission to reprint that paper on this Web site), that odorless chemical signals given off by women - pheromones - can change other women's menstrual cycles. (See an earlier discussion of a similar experiment.)

The authors (McClintock and K. Stern) summarize it in the journal:

They found that odourless compounds from the armpits of women in the late follicular phase of their menstrual cycles accelerated the preovulatory surge of luteinizing hormone of recipient women and shortened their menstrual cycles. Axillary (underarm) compounds from the same donors which were collected later in the menstrual cycle (at ovulation) had the opposite effect: they delayed the luteinizing-hormone surge of the recipients and lengthened their menstrual cycles. By showing in a fully controlled experiment that the timing of ovulation can be manipulated, this study provides definitive evidence of human pheromones.

They regard this as definitive proof that human pheromones exist.

It will be interesting to find out what organ perceives these pheromones.

© 1998 Harry Finley. It is illegal to reproduce or distribute work on this Web site in any manner or medium without written permission of the author. Please report suspected violations to

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