How did menstruation become taboo?

A look at the historical roots and theories behind menstrual stigma

Why don’t we call menstruation by its name? Euphemisms serve a purpose. They give us words to talk about things that are considered culturally taboo. The impact of typical menstrual taboos is clear: they can lead to significant challenges in menstrual management, adverse reproductive health outcomes, social ostracization, disease, and even death.

Menstruation stigma is a form of misogyny. Negative taboos condition us to understand menstrual function as something to be hidden, something shameful. And by not naming a thing, we reinforce the idea that the thing should not be named.

But have periods always needed code words? Where did these words come from, and how did they come about? Were periods always considered a negative experience?

Menstrual euphemisms and taboos are old. But not all societies view menstruation negatively.

Menstrual taboos are found in the Quran:

“go apart from women during the monthly course, do not approach them until they are clean” Quran 2:222,

…the Bible:

“…in her menstrual impurity; she is unclean… whoever touches…shall be unclean and shall wash his clothes and bathe in water and be unclean until evening” Leviticus 15

…and in the first Latin encyclopedia (73 AD):

“Contact with [menstrual blood] turns new wine sour, crops touched by it become barren, grafts die, seed in gardens are dried up, the fruit of trees fall off, the edge of steel and the gleam of ivory are dulled, hives of bees die, even bronze and iron are at once seized by rust, and a horrible smell fills the air; to taste it drives dogs mad and infects their bites with an incurable poison.” (1).

Taboos are likely pre-agricultural, pre-modern-brain, and likely even pre-language (2, 3).

Menstruation, after all, far predates language. Our lives as the earliest evolving humans centered around survival, reproduction and biological functions: birth, death, sex, hunting. These elements were central in shaping language, not the other way around. And that’s where anthropologists do their research into menstrual taboo: at the intersections of evolution, behavior, and biology.

But while menstrual negative taboos are nearly universal, there are exceptions, and taboos themselves are variable. Certain societies operate with positive menstrual associations and euphemisms. Some modern-day hunter-gatherer societies, for example, hold an understanding of menstruation as being powerful, healing, protective and sacred (4, 5). These groups are also more likely to have a degree of gender egalitarianism (2, 5).

Some menstrual customs can act as tools that enhance female autonomy, granting social control and relief from work, among other benefits (4, 6, 7). The Mbendjele tribe of Central Africa, for example, still uses sayings like “my biggest husband is the moon” (8). The biggest grass hut of the Mbuti tribe in Zaire is the menstrual hut, where women go when they have their first period, accompanied by other girls and female relatives. There, having a period is considered powerful and blessed by the moon (9).

Even ancient Egyptian medical texts, including the Kahun Gynecological papyrus, ~1800 BCE, and the papyrus Ebers; ~1500 BCE, use the word hsmn for menstruation, which, some argue, also meant “purification” (7). Menstruation, in these texts, is seen positively. Cures for amenorrhea are offered, and menstrual blood is used as an ingredient in ointments, like in one for saggy breasts (hmph)(10, 11).

The creation of menstrual taboos took place independently and repeatedly across different peoples and geographies. But scholars don’t agree on why this happened.

The origin (and function) of negative menstrual taboo is still debated. Freud said it was our fear of blood (12). Allan Court argued the taboo began, in part, because early humans found menstrual blood to be soiling (or, as he put it in 1963, having “a depressive effect on organic materials”) (13). Anthropologist Shirley Lindenbaum theorized in 1972 that taboo was a form of natural population control, limiting sexual contact with “pollution” stigma (14). In 2000, Historian Robert S. McElvaine coined the term non-menstrual syndrome or NMS to describe the reproductive envy that led males to stigmatize menstruation, and to socially dominate women as “psychological compensation for what men cannot do biologically” (15).

All of these theories are tied to the time and place in which they were developed, and many were formed with a presumption of menstrual negativity. Clellan Ford postulated that the menstrual taboo was developed because early societies knew of its “toxic, disease-causing effects” (16). Of course, we now know that menstrual blood is not toxic. But this view persisted in science through the 20th century. In 1920, Dr. Bela Schick coined the term menotoxin after concluding that flowers handled by a menstruating nurse wilted more quickly (5). Harvard researchers Olive and George Smith (pioneers in the fields of gynecology and estrogen treatment) injected animals with bacteria-latent menstrual blood in 1952, killing them (16). According to The Curse: A cultural history of menstruation, the Smiths continued to attribute the deaths to a menotoxin for several years, even after other research found that the animals died from bacterial contamination of the blood, rather than the blood itself (17). Menstrual blood toxicity was disproven in the late 1950s (18).

In 1974, a comparative study of 44 societies found a majority of cultures surveyed viewed menstruation, in part, as what it is: a signal for a reproductive phase. The study also found that the appearance of taboo in a given society may be closely tied to how much or little males participate in that society’s procreative activities, like child rearing and childbirth — that is, higher participation was associated with fewer taboos (though this relationship does not speak to causation)(5).


One theory holds that menstrual taboos are at the center of the origins of patriarchy.

Professor Chris Knight, a social anthropologist at London University, has researched the deep historical roots of menstrual taboo. In 1991 he published Blood Relations: Menstruation and the Origins of Culture, and later co-founded EVOLANG, an international conference series on the evolution of language. Knight’s theories are controversial but thought-provoking, and speak to the complexity of discerning the historical roots of menstrual stigma.

Knight believes that the original menstrual taboos were born of female-led and female-advantaging behaviors in early humans — i.e., that females themselves had good reason to establish menstruation as a time when their bodies could not be touched, creating their own taboo. Only later did this taboo transform into something that compromised female autonomy, rather than enhanced it.

For Knight’s theory to hold, early humans would have had to menstruate in sync with the moon, something for which we have no evidence in modern societies. But, as Knight points out, this doesn’t mean our cycle length has no evolutionary significance. The human species evolved under conditions that favored a menstrual cycle of 29.5 days, the same length of the lunar cycle. Our close relatives, chimps and bonobos, have menstrual cycles of ~36- and ~40-day cycles respectively. Other primates have a 19-day and 28-day cycles. Scientists don’t agree on why the human cycle became so close in length to the lunar cycle, or why the original euphemism for cyclical bleeding is moon-related across many cultures. But Knight says we can’t dismiss it as a coincidence before exploring whether there was some adaptive basis for it — how and why it might have benefited females in our evolutionary past.

The theory is best explained in two parts: the possible origins of female-benefiting practices around menstruation, and how they might have changed so dramatically.

Knight’s theory of menstrual taboo begins with the way our human ancestors hunted.

As our Homo habilis ancestors evolved in Africa around two million years ago, they coexisted with big cats — lions, saber-toothed tigers and other large predators with night vision far superior to our own. Hunting in times of little moonlight would have been more dangerous than hunting when the moon was full, illuminating the surroundings.

Early hunting practices provided little meat for females and their young. When chimpanzees hunt, males gang up around their hunted subject and fight over it as they eat it on the spot. This provides no meat for those back at the camp, who find protein to eat in other ways.

Contrastingly, hunter-gatherer societies in Africa today have rules where hunters return to camp with an entire kill, before it’s taken by the women and shared equally.

In Knight’s model, early females played an important role in shaping this new hunting behavior by acting in ways that promoted safety and ensuring that food from the hunt was shared. Females began to gather in isolation from males for a period of time around the new moon (darkness), something that still happens in hunter-gather societies today. During this period, sex would be withheld, and male attention would be focused on the upcoming full-moon hunt. Males would believe females to be menstruating together at this time. After the hunt, if males returned with food, their behaviors of hunt preparation, participation, and food-sharing would be rewarded. The period of sexual isolation would end, and a time of feasting and sexual activity would begin. It’s this cyclical synergy of moonlight, firelight, nutrition, and behavior, rather than gravity, that Knight suggests is creditable for possible menstrual syncing in our ancestors.

By gathering and signaling “no” females may have established blood as being powerful, creating a strong cultural symbol, and the first menstrual “taboo” — different from the way we think of taboos today. Menstruation would become associated with power, with the success of the hunt and with the blood of game animals. This “taboo” on blood may then have also applied to the blood of the hunted kills, leading males to not eat their own kill until the blood was brought back to camp and removed through cooking. The Ju/’hoansi people in the south of the African continent, for example, tell stories of men who are killed by elephants after not observing menstrual taboos, and how hunting when one’s partner is menstruating can lead to being attacked or losing one’s game.

How a practice that benefited females changed

If the original menstrual taboo was one bolstering female power, why did it change? Knight says it shifted as big game become more scarce. As the population grew and big animals became harder and harder to hunt, a monthly hunt wasn’t enough. Populations began having to rely on small game, tubers, and other gathered foods much more continuously, making the traditional work-play rhythm, and all the behaviors and rituals associated with it, less possible.

The desynchronization of the hunt from the moon would have cost the menstrual cycle its own synchronicity. By this point, Knight explains, the timing of nearly everything would have been governed by these practices. As they became irrelevant, any associated rules of sexual isolation or solidarity would have gotten in the way. As the practices collapsed, female cycles started to stagger again, and communal female solidarity was lost.

At that point, something very strange happened, Knight says. “In many places, in order to prevent the whole system from collapsing, the men start ritualizing their own version of menstruation, by cutting their penises (or, in some places ears, noses, or arms) and bleeding together, shedding enormous amounts of blood.”

Menstrual huts — common spaces where females gathered to menstruate together — were then reassigned for the new, better synced, male bleeding ritual. “They became male huts from which women were excluded, renamed as Men’s Houses or Temples.”

It’s this, Knight believes, that’s at the crux of all the world’s patriarchal religions. “Wherever you find these temples and churches, in Judaism, Christianity, they are men’s huts writ-large, male controlled and dominated.” Even after agriculture began, these male bleeding rituals continued.

This all may have set the stage for the treatment and view of menstruation in extremely patriarchal cultures of the Romans, Greeks, and later religions, which have led us into our modern west.

(For some context for time, this story began about two million years ago in the time of homo habilis, the ~600 thousand year stretch of history between “ape-like humans” and homo erectus. Fire use began around 1.5 million years ago, and cooking began less than one million years ago. Big-game scarcity, and the outcomes of it, is in the much more recent period since the last Ice Age).

At the base of all the world’s religions, we find one fundamental idea. Some things are sacred. And if the body isn’t sacred, nothing is,” says Knight. “Blood was a mark of the sacredness of the body. So the paradox is, that the very thing that benefited women throughout evolution is now made to be, and experienced as, the most disempowering.”

We may never know how, exactly, menstrual taboos were established.

Of course, there are deep controversies around these histories, leaving many elements up to interpretation. Both menstrual synchronicity and asynchronicity may have their adaptive evolutionary advantage — some research suggests synchrony decreases female–to-female competition for mates and favors genetic diversity, for example (19). But the quality of evidence of estrous synchronicity in human and non-human populations is questioned and hotly debated, and has been written about by Clue’s Oxford collaborator Alexandra Alvergne, as well as Knight, among others.

For an in-depth explanation of Knight’s theory, you can read more here, or in his book. Knight’s theory has been referenced by peers as the “most important ever written on the evolution of human social organization”. His is arguably the only theoretical framework for this deepset history of menstrual taboo to date, which may be reflective of the taboos themselves in academia.

It’s clear that the way we talk about menstruation is slow to change because of how deeply menstrual taboos are ingrained in our cultures, beliefs, and histories. The societies which give us our understanding of our bodies were formed around these taboos. Changing taboos requires the systems to change.

In part two of this series, we’ll discuss how the words and euphemisms we use to describe menstruation reflect current norms.

Download Clue today to track your period.


  1. Murphy TM. Pliny the Elder’s Natural history: the Empire in the encyclopedia. Courier Corporation; 2004.
  2. Knight C. Blood relations: Menstruation and the origins of culture. Yale University Press; 1995 May 24.
  3. Wilson HC. On the origin of menstrual taboos. American Anthropologist. 1964 Jun 1;66(3):622–5.
  4. Agyekum K. Menstruation as a verbal taboo among the Akan of Ghana. Journal of Anthropological Research. 2002 Oct 1;58(3):367–87.
  5. Montgomery RE. A Cross‐Cultural Study of Menstruation, Menstrual Taboos, and Related Social Variables. Ethos. 1974 Jun 1;2(2):137–70.
  6. Buckley T, Gottlieb A, editors. Blood magic: The anthropology of menstruation. Univ of California Press; 1988.
  7. Frandsen PJ. The menstrual “taboo” in Ancient Egypt. Journal of Near Eastern Studies. 2007 Apr;66(2):81–106.
  8. Knight C, Lewis J. Towards a Theory of Everything. Human Origins: Contributions from Social Anthropology. 2016 Dec 30;30:84.
  9. Lewis J. Ekila: blood, bodies, and egalitarian societies. Journal of the Royal Anthropological Institute. 2008 Jun 1;14(2):297–315.
  10. Stevens JM. Gynaecology from ancient Egypt: The papyrus Kahun: A translation of the oldest treatise on gynaecology that has survived from the ancient world. The Medical Journal of Australia. 1975;2(25–26):949–52.
  11. Joachim H. Papyrus Ebers: The First Complete Translation From the Egyptian. Reimer: Berlin. 1890.
  12. Erwin E, editor. The Freud encyclopedia: Theory, therapy, and culture. Taylor & Francis; 2002.
  13. Coult, Allan D. 1963a Unconscious inference and cultural origins. American Anthropologist 65:32–35.
  14. Lindenbaum S. Sorcerers, ghosts, and polluting women: An analysis of religious belief and population control. Ethnology. 1972 Jul 1;11(3):241–53.
  15. McElvaine RS. Eve’s seed: Biology, the sexes, and the course of history. Schaum’s Outline Series; 2001.
  16. Ford CS. A comparative study of human reproduction. Department of Anthropology, Yale University; 1945.
  17. Delaney J, Lupton MJ, Toth E. The Curse: A cultural history of menstruation. University of Illinois Press; 1988.
  18. Backe J. Befleckte Weiblichkeit–Spuren tradierter Menstruationsmythen in der Werbung für Produkte der weiblichen Intimhygiene. Gynäkologisch-geburtshilfliche Rundschau. 1997;37(1):30–8.
  19. Ims RA. The ecology and evolution of reproductive synchrony. Trends in ecology & evolution. 1990 May 1;5(5):135–40.