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Further Evidence of Endocrine Consequences of Human Pheromones

It's been known for some time that women who live together frequently develop synchronized menstrual cycles. This phenomenon is thought to be mediated by pheromones -- compounds that are released by one organism, transmitted by air, and affect the physiology of other members of the same species. This study examined whether humans produce pheromones that regulate neuroendocrine mechanisms in other people.

Researchers recruited 20 women aged 20 to 35 who used barrier contraception and had a history of regular and spontaneous ovulation. They wiped samples of odorless compounds from the armpits of 9 donor women in hormonally distinct phases of the menstrual cycle daily under the noses of the 20 women; half the recipients received samples from the follicular phase for two consecutive menstrual cycles and then were switched to samples taken from the ovulatory phase, and the other 10 recipients received the same compounds in reverse order. The participants were completely unaware of the experiment's hypotheses and the source of the compounds. Each subject provided urine samples every evening that were assayed to detect the onset of the surge of luteinizing hormone that triggers ovulation. All subjects were also studied for one baseline cycle without exposure to compounds.

The results were striking: cycles were shorter than baseline during exposure to follicular compounds and longer during exposure to ovulatory compounds. Compounds from the armpits of women in the late follicular phase of their menstrual cycles accelerated the preovulatory luteinizing hormone surge of recipient women and shortened these women's menstrual cycles. Interestingly, compounds collected from the same donors later in the menstrual cycle, at ovulation, had the opposite effect: they delayed the surge of luteinizing hormone of the recipients and lengthened their menstrual cycles.

Comment: These results likely provide the physiological basis for the well- known phenomenon of synchronous menstrual cycles among women living together. The nature of pheromones remains unclear and will certainly be the subject of intensive investigation. Whether pheromones of a different sort modulate other behaviors remains to be determined.

— C Nemeroff

Published in Journal Watch Psychiatry May 1, 1998

Citation(s):

Stern KS and McClintock MK. Regulation of ovulation by human pheromones. Nature 1998 Mar 12 392 177-179.

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