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Subtle signals keep menstrual clocks in sync

点击量:   时间:2018-02-21 01:02:10

By Jonathan Knight THE menstrual cycles of women who live together often become synchronised. Now researchers in Chicago have proved that it’s the pheromones secreted by women which do the trick. Insect attractants are the most common known pheromones. For instance, the compound bombykol secreted by the female silk moth can bring a male fluttering toward her. To look for human pheromones, Kathleen Stern and Martha McClintock of Chicago University placed absorbent pads under the arms of nine women. They stored the pads in alcohol until the phase of each woman’s ovulatory cycle could be precisely determined. They then exposed a second group of women to the compounds by wiping their upper lips with the same pad daily for several days. The pads all smelt alike, since body secretions carry no scent prior to bacterial growth. “All they could smell was the alcohol,” says McClintock. Over several months, the researchers monitored each woman for the surge of luteinising hormone which occurs just before ovulation. They report in this week’s Nature (vol 392, p 177) that pads from women who had not ovulated accelerated the sniffer’s ovulation, shortening the cycle, while secretions from post-ovulatory women lengthened it. Computer simulations showed that these effects would in most cases achieve menstrual synchrony. George Preti, who studies the chemistry of human secretions at the Monell Chemical Senses Center in Philadelphia, says McClintock’s data look solid. “I’m glad she has finally confirmed people’s suspicions with good experimental evidence,