McClintock, Martha

As an undergraduate at Wellesley College, Martha McClintock noted that her female dormmates tended to synchronize their menstrual cycles over time. When she pointed this out to a group of scientists at a pheromone conference, she was challenged to study the phenomenon scientifically if she wanted to be believed. She took up the challenge, recruited 135 women from her dorm, and collected the data on dates of onset of menstrual cycles. The data strongly supported her informal observations and she wrote up the results of her study as her senior thesis. 

Kathleen Stern and Martha K. McClintock at the University of Chicago could show that a woman s follicular or ovulatory phase of her menstrual cycle may he extended or shortened if the woman had odourless axillary (underarm) sweat from other women applied to her upper lip over several cycles, until eventually the ovulations were synchronised. [10, 11] This phenomenon had been known earlier in women living in closed communities, e.g. barracks, brothels, convents or prisons. Behavioural scientists recognised it as a relic of ancient times, when the simultaneous birth of many young creatures produced a sru-plus, which offered a better chance of sruviving predators. 

The likelihood of the existence of human pheromones became the subject not only of more frequent speculation, but also of more systematic observation after Martha McClintock (1971) reported on the synchronisation of menstrual cycles among women living in close proximity to one another. Subsequently, specifically designed studies substantially strengthened the supposition that olfactory signals perceived subconsciously are responsible for this (Russell et al., 1980). 

This effect has been described as the McClintock effect, named after the primary investigator, Martha McClintock, at the University of Chicago (see references McClintock and Stern, 1971 and 1998). The McClintock effect, however, is still not... 

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