Priming pheromones in humans

Ever since McClintock (1971) described synchronized estrus cycles in 135 women who roomed together in a women s college dormitory, the search for possible olfactory cues, as occur in other mammals, has continued. The longer the women in McClintock s study spent time together during the academic year (October through March), the closer the times of onset of their menstrual cycles 

In a second study at a coeducational college, women who lived without roommates in bedrooms of residence halls or apartments developed menstrual synchrony with close friends (Graham and McGrew, 1980). These authors did not find a correlation between cycle length and amount and type of interaction with men. 

A third study of 85 20-year-old women found an effect on menstrual synchrony of living together with one, two, or three other women, and of physical activity (Quadagno etal., 1981). 

These correlation studies stimulated experiments to identify the active chemical cues. Russell etal. (1980) rubbed underarm perspiration from a single woman onto the upper lip of five women aged 19-39 years. After 5 months, the odor-exposed women differed from one another in their onset of the menstrual cycle by 3.4 days, on average, compared with 9.2 days in the control group. Before the experiment, the mean differences had been 9.3 and 8.0 days, respectively. The volunteers were aware of the purpose of the experiment. 

The first systematic, double-blind experiments on the influence of male and female odors on women s menstrual cycles were reported by Cutler eta/., (1986). and Preti etal. (1986), respectively. Neither their subjects nor the administering technician were aware of the true purpose of the study. 

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