I’m so over the moon… myth (Part 2)

1 June 2018.

Image: ‘Die Mondfee’ -‘The Moon Fairy’- by Hermann Kaulbach

The last post outlined two common menstrual myths… One about the moon having an influence over the menstrual cycle, another about people influencing each other’s cycles. This post looks at why these myths persist, despite a lack of evidence, and why this may not be brilliant news for gender equality…

Why do these myths persist?

1. They make great stories

Many ancient and contemporary cultures have pretty exciting myths that imply some sort of supernatural relationship between the moon and ‘all women’, especially in regard to the menstrual cycle [1].  Again, this is not surprising, given the similarity between average menstrual cycle length and a lunar month- although it is worth noting that hardly any of these myths actually imply that menstruation/ovulation occurs simultaneously in all menstruating people, at the same time each month. Non-lunar ‘menstrual synchronicity’ is a relatively modern myth, probably originating in the 19th or 20th Century, and likely inspired by research carried out on ‘synchronised fertility’ (i.e. ovulation) thought to occur in some non-human species (later discredited) [2].

Why is this bad for gender equality?

Most (but not all [3]) of the menstrual moon myths associate the moon as a ‘female’ goddess and the sun as a ‘male’ god, to symbolise and explain physical and political differences between male and female humans [1]. So, the sun is typically described as strong, hot, in control of the seasons, and ruler of the daytime (i.e. when humans are awake and conducting most of their activities); the moon is typically portrayed as relatively weak, cold, in control of ‘water’ i.e. the tides, and ruler during the night (i.e. when humans are sleeping and fearful of attack, or supernatural forces- think werewolves, vampires, zombies, ghosts, and the nocturnal setting of virtually every horror film ever made…). Surprise, surprise! Such representations of female versus male humans just so happen to naturalise sexist beliefs and gender inequality.

Illustration for the poem “Witch-Dance.” Internal Illustration from the pulp magazine Weird Tales (September 1941, vol. 36, no. 1). Artist- Hannes Bok

As for non-lunar ‘menstrual synchronicity’, a 2014 study [4] found seemingly positive reasons for the widespread belief in this (admittedly pretty cool) myth, despite the lack of evidence:

… these beliefs serve several functions that enhance gender solidarity: (a) reduction of shame and taboo related to menstruation; (b) a socially acceptable way of constructing modern “sisterhood”; (c) a method for marking women’s relationship to nature; and (d) a pathway to fight back against sexism and sexist assumptions about menstruation and menstruating women.

However, I would argue that ultimately, any non-evidence-based story that positions people who menstruate as possessing some sort of ‘magical’, ‘natural’, or otherwise inexplicable, influence over others, actually supports sexist beliefs about the inherently ‘irrational‘ or ‘abnormal‘ female human body, or mind. It also reminds me of some nasty associations between ‘all women’ and ‘magic’, or gendered animal-like behaviours i.e. witchcraft, ‘bitchiness’, or the implied sexual promiscuity of being like an animal ‘in heat’. So, whilst some individuals might feel empowered by the idea of having a special relationship with the moon, or with other people who menstruate, this is probably only a limited (more personal) form of empowerment, and not really helpful for improving gender relations more widely.

2. People notice ‘synchronicity’

Whenever menstruation happens to fall near a full moon, it is easy to assume some sort of ‘relationship’ between them, especially if primed by cultural myths to expect one. Indeed, since the average menstrual cycle approximates the length of the lunar cycle, the following few periods will likely fall close to a full moon, too- ‘cementing’ the idea of a connection. However, once menstruation begins to diverge from the timing of the full moon, people are less likely to notice the lack of/ waxing/ waning of the moon and so do not realise the change in timing, or assume that their cycle has somehow been ‘thrown off course’ (until it eventually happens to coincide near the full moon, once more!).

This sequence shows the moon each day from an assumed latitude of 45 degrees north- note how less visible the moon is in the lead up to, and after ‘new moon’

Similarly, realising that you are menstruating at the same time as a close friend or relative might seem ‘more than a coincidence’, but that is all it is. It turns out that we’re just not that great at maths! For example, given an average cycle length of 28 days, the maximum number of days by which two people who menstruate can differ in menstrual onset is 14 days, and the average difference is only 7 days [5]. When you add in the fact that most people’s cycles vary up to plus or minus 4 days per cycle, and that a ‘normal’ cycle length ranges from 21-35 days, it is no wonder that people begin to think that their cycle is changing in relation to those around them. When friends menstruate at different times, we are less likely to notice, or to remark upon this fact. It seems we really do want to feel a connection to those we care about, which primes us to prioritise similarities and dismiss differences.

The beauty of maths. Cycles of different lengths will ‘synchronise’ every now and again…

Why is this bad for gender equality?

Whilst gender solidarity can be a really positive thing, both for an individual and wider society, basing it on an embodied experience that is actually a myth, is problematic. For a start, as we know, not ‘all women‘ have menstrual cycles (think pregnancy, breast feeding, menopause, hysterectomy, people on hormonal medications, and transgender or intersex women). So, basing ‘gender solidarity’ on something that necessarily excludes a significant proportion of that gender’s population seems like an unhelpful approach. Secondly, the fact that menstrual synchronicity is not supported by objective evidence, means that it could potentially be used as ‘proof’ of (assumed) female irrationality i.e. that those who believe in the myth are somehow irrational for doing so. Finally, (as I also mention above), I personally find the idea of biological synchronicity a bit creepy, perhaps even slightly ‘witchy’, and yet another example of an unhelpful ‘all women’ gender generalisation.

3. Influential research

Academic researchers have also endorsed these myths. As described in the last post, the work of Martha McClintock in the 1970’s and 80’s, first promoted the idea of menstrual synchronicity [6]. Others built on her work only for it to be discredited later [7], but in the meantime, Tom Buckley resurrected the ‘menstrual moon’ myth after a single conversation with an elderly Yurok native American woman [8].

This woman remembered her aunts and grandmother discussing ‘lunar synchronicity’ and that, if a woman fell out of sync with the moon, she could ‘get back in [sync] by sitting in the moonlight and talking to the moon, asking it to balance [her]‘ [9]. Without knowing much about the menstrual cycle, or the maths behind ‘synchronicity’, or noticing that without cycle variation, there would be no need for any ‘moonlight re-setting’, he took her recollections literally.

In 1995, taking Buckley’s work a step further, Chris Knight speculated that the ‘lunar’ coordination of menstrual cycles in our female human ancestors (ovulating at full moon, and menstruating at new moon) encouraged males to invest in hunting in the light of the moon (and subsequently share meat in exchange for procreative sex with fertile females) [10]. Despite a distinct lack of robust evidence for lunar menstrual synchronicity [11], and ensuing criticism from various other academics, based on the questionable evolutionary benefit of synchronised sexual behaviour in humans [12], these (non-evidence-based) ideas have found a receptive audience in those seeking ‘proof’ of the literal menstrual moon myth.

Why is this bad for gender equality?

Interestingly, the majority, if not all, of these ‘menstrual synchronicity’ researchers are explicitly feminist in their beliefs and theoretical/ analytical approaches. It is not as though they set out in any way to make ‘all women‘ seem any less normal than ‘all men’, and yet, this is precisely what these myths imply. The idea that the female human body is somehow more mysterious, more connected to the natural world, and fundamentally of a different nature to the male human body is not backed by evidence and, unfortunately, only serves to perpetuate gender inequality. Male, intersex, and female human bodies are far more similar than they are different. Yes, the reproductive organs and hormonal constitution of the different ‘sexes’ are somewhat different, but not enough to ever justify social or political inequality, or the perpetuation of unhelpful myths that further stigmatise people who menstruate.

4. Other reasons…

There are lots of other reasons why people may believe in these myths, but in the interest of keeping this post to a reasonable(ish!) length, I will simply list some here and perhaps discuss them in more depth another time! (All of these factors are ultimately bad for gender equality- for the same reasons mentioned in the points above.)

  • Humans are not good at dealing with variability- we like the idea of control, regularity, and ‘similarity’ over ‘difference’
  • People tend not to track their cycles- it’s boring, but this is why nobody realises that their cycles vary from month to month, and only seem to ‘synchronise’
  • Menstrual education is universally poor- why aren’t we taught about menstrual cycle length variation, the lack of evidence for these myths, the impact of the menstrual taboo etc.?
  • Some people simply like the idea of being connected to the natural world (more than we already are)- OK for the individual, not so good for an entire gender.
  • Some people think that making ‘all women‘ seem special, perhaps even ‘better’ than ‘all men’ will help to improve gender equality. (It doesn’t). To rephrase Donna Haraway’s famous quote, “I’d rather be a [human]… than a goddess” [13].

References and notes:

1. Check out this amazing resource all about the various moon myths – https://www.windows2universe.org/mythology/mawu_moon.html

2. See the previous post for more details- or this page – https://en.wikipedia.org/wiki/Menstrual_synchrony#Other_species

3. The Inuit myth of ‘Anningan’ the moon god, is a great example of alternative gender symbolism; ‘Anningan continually chases his sister, Malina, the Sun goddess, across the sky (to rape her- according to some versions of the myth). During the chase, he forgets to eat, and he gets much thinner. This is symbolic of the phases of the moon, particularly the crescent. To satisfy his hunger, he disappears to eat for three days each month (new moon) and then returns to chase his sister all over again. Malina wants to stay far away from her bad brother. That is why they rise and set at different times.’- (I’m glad this moon myth didn’t persist!) Taken from –  https://www.windows2universe.org/mythology/anningan_moon.html

4. Fahs, B., Gonzalez, J., Coursey, R., & Robinson-Cestaro, S. (2014) ‘Cycling Together: Menstrual Synchrony as a Projection of Gendered Solidarity’ Women’s Reproductive Health, 1:2, 90-105, DOI: 10.1080/23293691.2014.966029

5.  Harris, A. L., & Vitzthum, V.J. (2013) ‘Darwin’s Legacy: An Evolutionary View of Women’s Reproductive and Sexual Functioning’, Journal of Sex Research, 50:3-4, 207-246, DOI: 10.1080/00224499.2012.763085 – p 236

6. See the previous post for more details – the original [now discredited] paper is this one- McClintock, M. K. (1971). “Menstrual Synchrony and Suppression”. Nature. 229 (5282): 244–5. doi:10.1038/229244a0

7. Harris, A. L., & Vitzthum, V.J. (2013) ‘Darwin’s Legacy: An Evolutionary View of Women’s Reproductive and Sexual Functioning’, Journal of Sex Research, 50:3-4, 207-246, DOI: 10.1080/00224499.2012.763085 – p 236-238

8. Buckley, T. (1982) “Menstruation and the power of Yurok women: Methods in cultural reconstruction.” American Ethnologist 9(1): 47-60

9. Tim Buckley (above) as quoted in Knight, C. (1995). Blood Relations: Menstruation and the Origins of Culture. New Haven and London: Yale University Press p. 356

10. Knight, C. (1995). Blood Relations: Menstruation and the Origins of Culture. New Haven and London: Yale University Press

11. For instance, Knight (above p 215) states that ‘…repeated statistical studies consistently show that the average human female menstrual cycle length is 29.5 days (Gunn et al. 1937; McClintock 1971; Vollman 1977; Cutler et al. 1980)‘. Yet none of the sources he refers to (referenced in full below) actually found this- they all demonstrate variability, not regularity in cycle lengths;

Gunn et al. were actually the first to demonstrate cycle length variationthe commonest averages lay between 26.0 and 29.0 days” p872. McClintock’s article does not even mention average cycle length- and also describes variable cycle lengths (albeit to argue the case for synchronicity- later disproved).  Vollman does not mention anything about a 29.5 day average cycle length, and also stresses the variability of cycle lengths; let me quote his summarising words (p. 102), “I have tried to describe in detail the data I have collected on women’s reproductive physiology. They demonstrate unmistakably, I think, the individual and singular basis of woman’s reproductive processes.”  Cutler et al. also fail to mention a 29.5 day average cycle length. In fact, their findings also suggest cycle variability, “It is noted that the occurrence of 17 days or more of coital activity among the weekly active women associates with cycle lengths which are mostly within the classic range 26 to 33 days; while that of 17 days or more of coital activity among the sporadic women associates with cycles which are mostly outside the classic range 26 to 33 days.”

So, there is, in fact, no basis for assuming a 29.5 day ‘lunar’ average cycle length.

Gunn, D.L., Jenkin, P.M. and Gunn, A.L. (1937) Menstrual periodicity: statistical observations on a large sample of normal cases. J. Obstet. Gynaecol. Br. Emp., 44, 839–879

McClintock, M.K. (1971) Menstrual synchrony and suppression. Nature, 229; 244–245

Vollman, R. F. (1977) The Menstrual Cycle New York; Knopf

Cutler W. B. Garcia C. R. and Krieger A. M. (1980). Sporadic sexual behavior and menstrual cycle length in women. Horm. Behav.14: 163–172.

12. For example, Foley, R. A., & Fitzgerald, C. M. (1996). Is reproductive synchrony an evolutionarily stable strategy for hunger-gatherers? Current Anthropology, 37, 539–545 or Strassmann, B. (1997). The biology of menstruation in Homo sapiens: Total lifetime menses, fertility, and non-synchrony in a natural fertility population. Current Anthropology, 38, 123–129

13. The original quote is; “I’d rather be a cyborg than a goddess“-  According to Donna Haraway’s “Manifesto” (see reference below), “...there is nothing about being female that naturally binds women together into a unified category. There is not even such a state as ‘being‘ female, itself a highly complex category constructed in contested sexual scientific discourses and other social practices“. A cyborg does not require a stable, essential identity, argues Haraway, and people should consider creating coalitions based on “affinity” instead of identity. She adds that “Cyborg imagery can suggest a way out of the maze of dualisms in which we have explained our bodies and our tools to ourselves.”- e.g. male versus female humans, sun versus moon, normal versus abnormal etc.

Haraway, Donna (1990). “A Cyborg Manifesto: Science, Technology, and Socialist-Feminism in the Late Twentieth Century”. Simians, Cyborgs and Women: The Reinvention of Nature. Routledge. pp. 149–181.


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