Menstrual synchronization is not new to lesbians. The actual fact is that you can find a lot of people who have had a lot of experience with menstrual synchronization in their roommates, sisters, mothers and daughters, and even colleagues. The company’s main goal is to provide the best possible service to its customers.
The phenomenon of “menstrual synchronization” is not new to any of our female peers. The first time I saw this, I was able to get to know it. The first thing you need to do is to take a look at the “menstrual synchronization” phenomenon and question whether it exists.
Does intimacy synchronize periods?
In 1971, psychologist McClintock published his study in the prestigious scientific journal Nature that women who live in the same house experience a convergence of menstrual cycles. She selected 135 residents at a women’s college as subjects for her study and divided them into roommate, close friend, and casual groups. After six months of close contact, McClintock grouped them on the first day of menstruation and found that the interval between the roommate and close friend groups changed from 7-10 days to 3-7 days, resulting in a convergence of cycles. In contrast, the interval between menarche days in the random group as a control group was 6-14 days and 5-15 days, respectively, which remained basically unchanged. Based on similar phenomena in other mammals, such as the “Whitten effect” in rats (pheromones released by males synchronize estrus in females), McClintock suggests that this phenomenon is likely to be caused by pheromones.
The results of this study led to a massive discussion of the convergence of menstrual cycles, also known as the “McClintock effect”. In subsequent decades, many scientists have studied this phenomenon, many of whom have obtained results consistent with the “McClintock effect,” covering sisters, colleagues, and even gay couples. These studies also used methods that were largely based on McClintock’s practice of counting the difference between women’s menarche days over time.
While there are a number of studies that demonstrate the validity of the McClintock effect, there are also studies that show that there is no clear synchronization of menstruation, and the years of uncertainty about its cause, subsequent criticism of the methodology, and uncertainty about its evolutionary significance have all contributed to the lack of a “McClintock effect. The “McClintock effect” is questionable.
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Question 1: What am I supposed to “smell” about the magical and mysterious pheromones?
In the various menstrual synchronization studies, we can easily capture the key word – pheromones, which are thought to be the main cause of the “McClintock effect”.
Pheromones are actually phonetic translations of pheromone, also known as pheromones, a term coined by German biochemist Peter Karlson and Swiss entomologist Martin Luscher in 1959 and defined as “pheromones that are secreted by an individual outside the body, received by other individuals of the same species, and affect their physiology or behavior. The term was coined by Peter Karlson and Swiss insect scientist Martin Luscher, who defined it as “a substance that is secreted by one individual into the body, received by other individuals of the same species, and affects their physiology or behavior.
There are many different kinds of pheromones, the best known of which are sex pheromones. Many insects release sex pheromones to attract the opposite sex, and some orchids mimic the sex pheromones of female wasps to attract male wasps to pollinate them. Many studies now suggest that sex pheromone recognition is primarily associated with the vomeronasalorgan (VNO) rather than through the olfactory epithelium. Many mammals have plunger nasal organs, such as elephants and rats, and their behavior has been shown to be influenced by pheromones – but humans do not have plunger nasal organs.
So the magical pheromones are shrouded in mystery in humans. Although it is generally accepted that human sweat glands (especially in the armpits) can secrete sexual pheromones, such as androstenedione and androstenediol, it has long been a controversial topic as to whether we can receive such signals or not. The complexity of human behavioral and physiological systems has made research difficult, and until now no pheromone has been definitively proven to have an effect on the human body. This controversy adds to the uncertainty surrounding the phenomenon of menstrual synchronization, which has long been speculated to be a pheromone at work.
In an attempt to demonstrate that the physiological cycle is related to pheromones, McClintock published a study in 1998. She collected sweat extracts from the armpits of 9 women during the follicular phase (before ovulation) and the luteal phase (after ovulation), and then applied them to the upper lip of 20 women (presumably the 20 girls received a lot of grant money to come to ……). The participants were asked not to wash their faces for 6 hours, and everything else in their lives went on as usual. The result was that sweating during the follicular phase caused the participants to come early, while sweating during the luteal phase caused them to come later. Combined with the fact that hormones in the follicular phase promote ovulation while hormones in the luteal phase inhibit ovulation, McClintock believes that this result proves that the pheromones released during different periods can influence the physiological condition of others. But this conclusion is slightly weak, and the number of days of early and delayed onset (about 2 days) is somewhat small, even about the same as the fluctuations in period length – something McClintock himself had to admit.
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Question 2: The research methods are problematic
In 1992 a scientist named H. Wilson published an article that systematically dissected in detail the problems in the research methods of menstrual synchronization studies over the years, suggesting to us that these problems give
In 1992, a scientist named H. Wilson published a systematic and detailed analysis of the problems with the methodologies of menstrual synchronization studies over the years.
First, he points out that previous menstrual synchronization studies have been based on the vague and seemingly reasonable assumption that “when two women are randomly compared on their menstrual day intervals, the difference is randomly distributed. But Wilson showed computationally that even if you do nothing and find pairs of unrelated women who compare their menstrual intervals with each other, about half of them will tend to be synchronized because each has a different cycle length, and the convergence is especially pronounced when the number of experiments is small and the statistics are short. In contrast, most studies of menstrual synchronization have been characterized by small sample sizes and short durations.
Second, how the dates are chosen when comparing menstrual day intervals can also make a big difference in the results. Suppose the length of woman A’s menstrual cycle is 28 days, and she comes on days 1, 29, and 57; whereas the length of woman B’s menstrual cycle is 30 days, and she comes on days 15, 45, and 75. How can we determine whether their menstrual cycles tend to be synchronized or separated? If we compare female A’s first and second menstrual times with female B, we find that: the first time they differ by 14 days and the second time by 16 days, tending to be separated; if we compare female A’s second and third menstrual times with female B, it becomes: the first time they differ by 14 days and the second time by 12 days, tending to be synchronized. The same data leads to opposite conclusions, and one accidentally falls into a mathematical trap.
Furthermore, Wilson found that many experiments had artificial exclusions of participants or data that did not fit the experimental design. In some experiments, participants who had irregular periods (about 25% according to the count) had different numbers of periods than others, and the researchers removed these data from the count, which undoubtedly compromised the objectivity of the study.
Based on his own analysis of study error, Wilson analyzed and calculated the results of several representative studies that concluded that menstrual synchrony was essentially “no significant menstrual synchrony” after accounting for error.
Wilson also suggested some options for optimizing the experiment, such as extending the duration of the experiment and increasing the sample size.
After Wilson’s article, the number of studies that concluded that menstrual synchrony was a significant decrease, which is one indication that his analysis did identify the problem and provided a more careful and rigorous approach for later studies. After him, a number of other possible problems with menstrual synchronization studies were raised, such as the potential bias in the way participants recalled the date of menarche at intervals when collecting data, and McClintock’s 1998 study not being single or double blinded when applying sweat extracts.
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Question 3: What are the evolutionary implications?
The “Whitten effect” in rats was mentioned earlier, and the pheromones released by males synchronize the estrus of females, which has positive implications for reproduction: females are all ready, so males can “spread the seeds” at once, reducing reproductive costs. “This reduces the cost of reproduction. So it is thought that the evolutionary significance of menstrual synchronization is similar, providing an explanation for the phenomenon that in ancient polygamous lifestyles, synchronization of female periods helped improve reproductive efficiency and prevented men from “finding the wrong person” and wasting their energy.
But there are also different views, with some researchers arguing that if menstrual synchronization exists, it is bad for reproduction because it causes competition among women, wasting some of their fertility and reducing reproductive efficiency, while the variability of women’s ovulation can make them less controllable by men, giving them more choice in choosing men and making them more likely to have better offspring.
And McClintock himself, who proposed the “McClintock effect,” argued that menstrual synchronization had no role, but was an occasional evolutionary “byproduct” and a coincidence. The discussion at the level of evolutionary significance can promote multiple perspectives, but it never provides direct evidence for the phenomenon of menstrual synchrony.
Research on menstrual synchrony has been controversial all the way through and is still inconclusive. Neither pro nor con scientists have definitive proof of the existence of menstrual synchrony and whether it is related to pheromones. However, they all agree that the study of pheromones is of great significance to mankind, and that this magic may open up new senses that mankind has never been aware of, and open up new areas that we have never explored before. Bold speculation followed by rigorous and careful verification, in a constant cycle of hypothesis building and rebuilding, is the way to go.