Is it true that aunties are contagious?

　　Female compatriots are all familiar with menstrual synchronization. Among roommates, sisters, mothers and daughters, and even colleagues, many people may have had "personal experience" of menstrual synchronization. Don't trust "personal experience". In the scientific community, the evidence for the existence of "menstrual synchronization" is weak, and there are constant doubts about it. There is no conclusion yet on whether it exists.

　　Intimacy keeps aunt in sync?

　　In 1971, psychologist McClintock published his own research in the famous scientific journal Nature, saying that people living in the same house female There will be a phenomenon of menstrual cycle approaching. She selected 135 residential students at a women's university as the research subjects and divided them into roommate groups, close friend groups, and random groups. After being intimately together for half a year, McClintock conducted group statistics on their menstrual onset days (i.e. the first day of menstruation) and found that the interval between menstruation days in the roommate group and the close friend group changed from 7-10 days to 3-7 days, and the cycles appeared to be similar. As a control, the intervals between menstruation days in the random group were 6-14 days and 5-15 days respectively, which remained basically unchanged. Based on similar phenomena that exist in other mammals, such as the "Whitten effect" in mice (pheromones released by male mice can synchronize the estrus period of female mice), McClintock believes that the cause of this phenomenon is likely to be pheromones.

　　This research result triggered a large-scale discussion, and this phenomenon of menstrual cycle convergence is also known as the "McClintock effect." In the following decades, many scientists have studied this phenomenon, and many of them have obtained results consistent with the "McClintock effect". The research scope covers sisters, colleagues and even gay couples. The methods used in these studies are basically based on what McClintock did back then, that is, counting the differences in women's menstrual days over a period of time.

　　Although there are many research results showing the correctness of the "McClintock effect", there are also some studies showing that there is no obvious menstrual synchronization phenomenon. In addition, the cause of it has not been confirmed for many years, subsequent criticism of the research methods, and the unclear evolutionary significance have put a question mark on the correctness of the "McClintock effect".