June 20, 2020
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Myth, Evolution And Science Love Under The ­Crimson Moon Clock

Period pollution is a myth. What it does in biology is cleansing, a monthly exorcism of pathogens. And by all means, make love.

Myth, Evolution And Science Love Under The ­Crimson Moon Clock
The Venus of Laussel, seen to symbolise the menstrual cycles
Photograph by Getty Images
Myth, Evolution And Science Love Under The ­Crimson Moon Clock

Consider the period. Lukewarm uterine jus. Bloody snot that smells of womb silt, lumpy with ­gobbets of dead endo­metrium that has been the weft of life for about a lunar month. For all the hymning and ­humming and hawing, it ­indicates the failure of conception.

Repugnance is a sort of aesthetic judgement. That menstrual blood has been the object of revulsion, not mere sensory dislike, not ‘animal-reminder’ disgust, is perhaps on account of the idea that it issues forth from a sphincterless, incontinent ostium, located between the plumbing for faeces and urine. And that the said blood carries in it the curdled pickings of tissue deb­ris and some imagined putrefaction and contamination. It is a visceral disgust that predates the germ theory of disease, and is based on a knowing that precedes rational thought. It never needed a manifesto or a plebiscite or a sub-­committee to manifest itself. It’s from the time of the early carriers of faith, when they lived in a state of fear and benightedness, whose nat­ure, according to the med­ieval Jewish philosopher Maimonides, was the nature of mute animals; when they believed that in the savannah and the desert and the forest and the night sky were hidden benevolent and evil spirits; before they knew what a gamete was, or a blastocyst, or the end­ometrial lining.

All religions have incubated myths about this stuff, of miasma and pollution: leading to the menstruating woman as an obscenity, a physical and spiritual threat for men and other women, and the sacred. The lore, without any pleading, has seeped into the demotic and the disgust of every language and culture, every species of religious belief.

There was visceral disgust. There also was the Venus, with 13 notches on her crescent-like horn, signalling a magical connection to the spheres.

As creeds and their clergy tend to subsist on the surrender of the private lives of their followers, the most important regulation of the marital relationship by religion has always been about sex ‘during her emission / monthly sickness’. For Hindus it comes from a convoluted story of Indra killing Vrita and suffering some variant of Brahmahatya dosha. Menstruating women are forbidden from having sex, touching a cow, tulsi or food, especially pickles. For Orthodox Jews, it is the practice of Niddah—a separation—a proscription of sexual ­intercourse during what is termed as the wife’s unclean period. Interestingly, the ban on male-female contact is enforced prior to the ­beginning of the menstrual flow itself. The proscription on coitus is related not only to menstrual bleeding, but to any type of vaginal ­bleeding. In Islam, the ­injunction is from the Quran (2:222): “They question thee (O Muhammad), concerning menstruation. Say it is an illness, so let women alone at such times and go not into them till they are cleansed. And when they have purified themselves, then go in unto them as Allah hath enjoined upon you.”

During the 19th century, it was the opinion of some western physicians that menstruation had no purpose whatsoever, that it was a pathological condition, which did not exist in pre-biblical times. “It has become a fixed habit of the female sex in consequence of the vitiating influence of civilisation.” In 1878, the British Medical Journal carried a series of letters that claimed a menstruating woman could cause bacon to putrefy. In 1920, Dr Bella Schick, who’d earlier bec­ome famous for developing a test for susceptibility to diphtheria, claimed to have isolated a ‘menotoxin’ in the perspiration, saliva and blood of menstruating women. This was seconded by David Macht of the Johns Hopkins School of Medicine, who after his own set of experiments, concluded that these menotoxins “contaminate by contact to such an extent that they retard development and even kill plants”. Funnily, the experimental designs of Schick and Macht did not use a control fluid (non-menstrual blood). The last mention of menotoxin was in an obscure letter to the editors in the Lancet in 1977 by Brian, Heathcoat and Pickles from the dep­artments of botany and physiology, University College, Cardiff. “We conclude that a component of menstrual extracts caused an acceleration of ageing and browning in excised Kalanchoe flowers (incubated in humidity chambers).” The authors spe­culated that the toxin could be a prostaglandin. This was patently moronic. Prostaglandins are found in blood and clots, and possibly every kind of human tissue. Curiously, the controls used by the authors were unused tampons and towels. In any case, menotoxins weren’t described as miasmatic or vaporous. They didn’t fly out and cause harm. Also, there have been no studies reported on the effects of ‘menstrual ext­racts’ on the human penis.

A Fante girl in Ghana at the celebration on the onset of her puberty

Photograph by Getty Images

The ‘ketchup on the steak’ discourse comes possibly from perennial folk wisdom, but is also a theological hop and jump from a very basic and inveterate castration anxiety. A small but a significant number of couples find sex during periods acceptable and pleasurable.

However, a majority abst­ains during this time, deter­red by individual perceptions of messiness, hygiene, infection transmission and menstrual blood-induced genital soreness. Coitus can be messy but not always so, dep­ending upon whether the flow is des­cribed as a “trickle” or a “flood”. The current consensus (in medical literature) on the subject goes something like this: the idea that menstrual discharge is unc­lean is an unsound one since it contains only bits of uterine tissue and blood exuding from an otherwise sterile env­ironment. This discharge is known to be high in fib­rinolytic enzymes that keep the menstrual blood from clotting. These substances are not known to induce any skin inflammation or penile soreness. In fact, the blood could act as a lubricant during coital activity. However, if any one partner has been diagnosed with a sexually transmitted infection or HIV, then intercourse during periods could increase one’s chances of acquiring it (over and above the risk associated with intercourse at other times). Intercourse during menses is known to increase bleeding and reduce period-associated pain by virtue of causing rhythmic uterine contractions during the org­asm. The other advantage of menstrual coitus is a much higher degree of freedom from the fear of pregnancy; 5-7% of couples in a study of fertility awareness-based methods practised menstrual coitus as a means of avoiding pregnancy.

A tremendous comrade of the movement to search for the menstrual pheromone was the psychologist Martha McClintock. While pursuing her bachelor’s degree from Wellesley College, Massachusetts, she noticed that women cohabiting in dormitories tended to synchronise their cycles more often than not. This phenomenon, which she labelled “menstrual synchrony”, was the subject of her first publication in Nature in 1971. She proposed this to be a result of two opposing pheromones, one that shortens cycles and the other lengthening them. The evolutionary purpose of this phenomenon, however, was unknown. She went on to subsequently hypothesise that menstrual synchrony was but a small part of the phenomenon of social interactions influencing biological events such as pregnancies, inter-pregnancy intervals and reproductive senescence (menopause), through biochemical pathways.

Taboo Sans Frontiers

The Umayyad Mosque in Damascus, Syria; “so let women alone at such times...until they are cleansed,” says the Quran

Photograph by AP

There was also a sugg­e­stion by Leonard and Aron Weller of Bar Ilan Univers­ity, Israel, that coh­abitation as a causation worked only when there was prolonged but not very intimate contact. In their observations of 30 pairs of cohabiting lesbians, no menstrual synchrony occurred. However, 30-50% of cohabiting sisters, het­ero­sexual female friends and co-workers who spent long hours at work ­together were seen synchronising their cycles.

All faiths have incubated myths, of miasma and pollution. Compare the Hindu dosha, the Jewish Niddah and the Quran’s 2:222 proscription.

For as long as a decade, the menstrual synchrony theory remained unchallenged, till studies modelled on McClintock’s design began emerging, which failed to demonstrate its occurrence through cohabitation. The first proper critique came from the anthropologist H. Clyde Wilson, who, after looking at studies done thus far, pointed out errors that were inherent in McClint­ock’s and subsequent studies. First, he noticed that none of these studies inclu­ded women with cycle frequ­ency outside a specified range. So, for instance, women cycling at less than 10 times or more than 13 times a year were ­excluded. Second, these studies presumed the next onset of menses based on self-­reported cycle lengths. None considered the normal cycle variability within women.

Menstruation isn’t clockwork, even in women who bel­ieve it to be so. The chance that a random pair of women would menstruate around the same time was high after three or more cycles based on the phenomenon of varying cycle interval rather than cycle lengthening or shortening caused by cross-acting pheromones. Third, he pointed out that McClintock failed to define what constituted the onset of menses. If a woman began menstruating on the first of January and continued to do so till the 5th, then her cohabiting partner’s period was considered synchronous if her periods started anywhere between the 1st to the 5th.

The chance that two such cycles would be deemed ­synchronous because of nine possible days in which ­periods could overlap rose to 30% only as a result of this faulty definition. All these ­errors ­increased the probability of finding menstrual synchrony in a sample. No significant levels of menstrual ­syn­chrony however, occurred when these errors were ­corrected, as was dem­onstrated in later studies.

There are several other reasons why the menstrual synchrony hypothesis needs to be laid to rest. In several exp­eriments on mammals (bab­oons, chimpanzees, golden hamsters), the phenomenon has not been definitely demo­nstrated, and, wherever it has, the studies have suffered from the same methodological errors detailed earlier. The inciting pheromones have not been identified, and, whenever they have, there has been a failure to induce synchrony using these in exp­erimental situations. The theory of menstrual synch­rony also runs aground bec­ause it is counterintuitive to evolutionary theory wherein synchrony should be a biological state best avoided, as it would induce intense mate competition among simultaneously ovulating females.

Traditional biological ­summations, till the 1990s, considered menstruation a fun­­ctionless consequence of cyclical flux. There hadn’t been a proper effort to locate menstruation within the ­coo­rdinates of evolutionary ­theory. In the early 1990s, the molecular biologist Margie Profet, with a breathtaking lack of subtlety, wrote an ­ast­onishingly seductive 50-page treatise in the Quarterly Review of Biology about the whys and wherefores of ­menstruation that tilted the moral-­political landscape on the question “Why doth she bleed?”

It wasn’t a thesis on the physiology of menstruation, but its evolutionary purpose. All evolutionary theory is ­ess­entially economics. It’s a cost-benefit scrutiny. The fact is that the monthly moulting and replenishing of the endometrium is nutritionally expensive. If menstruation were costly and pointless, natural selection would have eliminated it long ago. Women, on an average, lose 50 ml of blood every month and an equal amount of tissue. Some women lose enough blood to significantly deplete their iron stores. It’s also reproductively costly: it lengthens the female reproductive cycle: the business of sloughing off and regeneration of endometrial tissue is time-consuming and narrows the window of fertility. So, there’s a bit of question-­begging here. Why does the body not simply maintain its uterine lining or at least res­orb and not discard the uterine nutrients? There must be a higher purpose to this.

The monthly crimson isn’t a ­sickness. It’s arts and crafts week in the uterus about 450 times in a woman’s lifetime.

Profet proposed that menstruation serves to protect the uterus and the tubes from colonisation by pathogens. Countless bacteria, viruses and parasites tend to piggyback on the sperm to invade the uterus. Menstrual blood exerts direct, hydraulic pressure on uterine tissue, forcing it to shed, and drop-ships large cohorts of immune cells in the uterine cavity, to dir­ectly inhibit those pathogens. Spiral arteries that open into the lining of the uterus trigger menstruation by abruptly constricting, dep­riving the local tissues of blood, causing their death, and then, equally abruptly, the arteries open up again, which causes the blood to prise and uproot the dead ­tissue and flush it out along with any microbial Trojan horses that might have found their way in. It’s the great menstrual bloodjob.

Mens­trual blood is meant to flow out easily (unlike blood at most wound sites), beca­use it lacks the normal level of clotting factors. According to Profet, among menstruating species, the deg­ree of bleeding “is pos­itiv­ely cor­related with the average body size and sexually transmitted pathogen load of that species. Profuse bleeding would be especially adaptive in species with promiscuous breeding systems or continuous ­sexual receptivity.”

Profet’s paper was immediately picked up and celebrated by the popular press. The myth of menstrual pollution, by that time, had bec­ome stale with overuse and diminishing returns. Profet, in her framing of the evolutionary question, inverted the myth. Menstruation, she said, was the body’s way of ridding itself of the pollution. It was the monthly exorcism of pathogens. “Pollution, in the form of pathogens, is an unavoidable concomitant of insemination.”

Hers was the regnant theory on evolution and menstruation for a while, till it was brought down by the ant­hropologist Beverly Strass­man. What followed in the pages of the Quarterly Rev­iew of Biology was perhaps the liveliest debate on evolutionary theory, conducted anywhere, in print. But that’s a story for another day.

So, can we forgive the ­sordid religiosity of the ­adherents of Sabarimala? It wouldn’t exist without the muck heap of power control that demands and obtains obedience from its subjects. The monthly crimson isn’t a sickness. It’s arts and crafts week in the uterus about 450 times in a woman’s lifetime. As Jesus Christ is believed to have said in Latin at the Last Supper: Hoc est corpus. This is my body. Better still, as its much improved corruption goes: Hocus Pocus.


Myths. Period.


  • Veggies will go bad upon touching, won’t pickle.


  • A slap on the face on your first period will give you “beautiful” red cheeks.


  • Sex can kill your partner.


  • Flowers will die on touch.


  • Throwing unwashed pads will attract ghosts.


  • You can’t make whipped cream, it will curdle.


  • Wash your face with first period blood for clear skin.


  • Dough won’t rise, all you cook will be a disaster.
  • You can’t touch plants.


  • Mayonnaise will curdle. Wine will turn into vinegar.


  • You can’t make sushi.


  • Nuns say it’s a “curse”; evil spirits possess you.


  • Drinking milk from cows will contaminate the herd.


  • No meat, rice, vegetables, sour food, cold water; no baths, sitting on wet earth.


  • Teeth fall off if you walk behind a menstruating girl.

Dominican Republic

  • Don’t drink lemonade.

South Africa

  • Lions can smell you.

Papua New Guinea

  • Touching menstrual blood will “dull a man’s wits”

Ancient Romans

  • Children conceived during periods would be monsters.

Medieval Europeans

  • They burnt toads to ease flow, and wore the ashes.

(Ruma Satwik is a ­gynaecologist and Ambarish Satwik is a ­vascular surgeon and writer. Both are based in Delhi.).

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