Menustruation and the Moon Is There a Connection

Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 1

Menstruation and the Moon—is there a connection?

“Nothing in our society- with the exception of violence and fear- has been more effective in keeping women in their place than the degradation of the menstrual cycle.” -Women’s Bodies, Women’s Wisdom, Dr. Christiane Northrup

Martha McClintock is currently a well-known, respected and prestigious faculty member at the University of Chicago. She started her research career with an undergraduate study based on the whisperings among her dorm-mates in college —their menstrual cycles were starting to all fall on the same day!! Her undergraduate thesis gathered data from a large sample of women in the dorms and found this to be true—women who lived together showed a tendency to have their menstruation start around the same date. That study went on to be published in Nature, one of the most prestigious scientific research magazines (Nature, Vol. 229, pp. 244-245, 22 January 1971). Since then, she has gone on to show how certain pheromones (hormones with a particular odor that are secreted onto the surface of the body) are involved in bringing about this concordance of menstrual cycles. She now has an entire laboratory, federal grant funding and many students of her own working on how pheromones affect our biology and women’s menstruation.

What other factors influence the timing of the menstrual cycle? A link between the moon and menstrual cycles has been a part of human thinking through the millennia—the word “menses” and “moon” share roots in many languages. But what is the evidence? How are the moon and menstrual cycles linked? Is it just coincidence that they have about the same duration? Or do women take in subtle clues from the moon (much like the pheromones of Martha McClintock’s studies) that help regulate their menstrual cycle?

Objectives: 1. Learn the astronomical relationship between the earth, sun and moon and come to understand how that determines the “phases” of the moon that we see from earth.

2. Evaluate evidence for the effect of moon phases on biological and natural systems, including tides, continental movement, plant growth and animal behavior.

3. Carry out small group discussions where we analyze the issue of whether human menstrual cycles are affected by the moon. In each group, one or two people will advocate the view that the moon does affect menstrual cycles and one or two people will advocate the view that it doesn’t. Before the discussion, each person will take some time to read, review and take notes on handouts that support their point of view. Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 2

http://library.thinkquest.org/J0112188/moon_phases.htm

[ Moon Phase Calendar for 2001 ]

Why Does the Moon Appear to Change Shape?

The Moon orbits around the Earth every 29 ½ Earth days. At all times, half of the Moon is lit by the Sun. The other half of the Moon facing away from the Sun is in darkness. As the Moon orbits around the Earth we can see more and more of its lit side. This process slowly changes. These changes are called the phases of the Moon.

Phases of the Moon

New Moon

When the Moon is between the Earth and the Sun, it is called the new moon. The new moon rises and sets about the same time as the Sun does, but we can’t see it because the side that is being lit by the Sun is the side we cannot see from Earth. Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 3

First Quarter

After about one week after the new moon, the moon looks like a half- circle, and it is called the first quarter because the moon has completed one-quarter of its orbit around the Earth. Half of the Moon’s sunlit side is now visible from Earth. The first quarter moon rises at about noon and sets at about midnight.

Full Moon

One week after the first quarter moon, the Moon has moved to a point where the Earth is between the Moon and the Sun. We can now see the entire sunlit side of the Moon. The full moon rises as the Sun sets and sets as the Sun rises.

Last Quarter

One week after the full moon, the Moon again looks like a half-circle, and it is called the last quarter because the Moon has completed all but the last quarter of its orbit around the Earth. Half of the Moon’s sunlit side is again visible from Earth. The last quarter moon rises at about midnight and sets at about noon. Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 4

Effects of the moon on animals

(from http://www.planetfusion.co.uk/~pignut/animal.html) Casual observations and unsubstantiated folklore

The Miskito Indians of Eastern Nicaragua, believe that all animals respond to the tide, that the woodpecker pecks when the tide is changing, and that hunting and fishing is best at the rising tide but not at new moon. They also believe that crops should be planted and harvested at certain phases of the moon.

In a similar way, South sea islanders believe that whale sharks are most easily caught a few days after full moon. [5]

Another belief is that castrating and weaning of animals should be done at certain phases of the moon, or when the moon is in a certain sign of the zodiac. See the links below for more on this. [top] The scientific evidence

Tidal rhythms Numerous scientific papers have been written on tidal rhythms in marine animals. Crabs and other crustaceans seem to feature in these studies quite a lot, probably because they are affected by the tides [2][3][10][11].

In these cases, the animals seem to be following two rhythms: a daily (24 hour) rhythm, and a tidal (24.8 hour) rhythm*. These rhythms persisted in the laboratory under conditions of constant light and temperature.

In many crustaceans, renewal of shells, sexual activity, and regeneration of lost limbs all follow lunar tidal rhythms (Nouvel, H. (1945) Bull. Inst. Oceanogr. Monaco, 42 878; Wheeler, J.F.G.J.Linn.Soc.Zool., 40 325). Activity of crabs has been measured, usually by placing the crabs in a tray, balanced on a knife edge, and connected to a rotating drum to record any movements which the crabs make. Fiddler crabs often became more active at the times when their burrows would have been uncovered by the tide. [10].

Activity of the shore crab Carcinus maemas L. follows a lunar tidal rhythm (Naylor, E., Atkinson, R.J.A. and Williams, B.G. J.Interdiscipl.Cycle Res. 2 2: 173-180), as does the crab Sesarma [3]. Oxygen consumption in the Fiddler crab, Uca pugnax follows a daily rhythm and a tidal rhythm. ([2] ; Webb, H.M. (1971) J.Interdiscipl.Cycle Res. 2 191- 198).

Tidal rhythms of activity have also been observed in fish, such as Blennius pholis [9]; Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 5 amphipods [12]; Mussels (Rao, K.P. (1954) Biological Bulletin 106 357-9); algae [8]

In these examples, the animals may be responding to moonlight, gravity effects and possibly changes in temperature. In some cases the rhythm persists when they are kept in the laboratory under constant light and temperature, in other cases this is not so. Tidal rhythms may be modified daily rhythms, as in some cases the animals switch from a 24.8 hour tidal rhythm, to a 24 hour rhythm in the lab.

A study by Korringa (Vakblad Biol. Sept. 1947 129-137) apparently showed that oysters could respond to changes in the force of gravity associated with the tides. I vaguely remember reading about something like this in Supernature by Lyall Watson. Oysters were moved miles inland to Iowa or somewhere, and they began opening and closing their shells at the time that the tides would rise and fall, if there were tides in Iowa. I also read a sceptical article suggesting that this was simply due to a change to the circadian cycle, that often happens when animals are taken out of their natural environment

Fiddler crabs also change colour daily, becoming lighter at night and darker in the day. On top of this 24 hour rhythm is a 12.4 hour tidal rhythm, which relates to the time at which their burrows are uncovered by the tide. The two rhythms coincide every 14.8 days, producing a noticable semi-monthly colour change. This could be relevant to the next section:

Monthly rhythms

The phase of the moon seems to influence the behaviour of a number of animals. In many cases, the animals are simply responding to the changes in light, which may (for example) make them more visible to each other or to predators, but it is possible that there are monthly circadian rhythms in operation (as in humans), or that the animals are responding to gravitional effects. As in the case of The moon's effects on plants, I am a bit sceptical of the latter hypothesis.

The Palolo worm, Eunice viridis is found on several coral islands in the South Pacific, especially near to Samoa and the Fidji Islands. The palolos reproduce by swarming during the last quarter of the moon in October and November. The terminal parts of their bodies drop off and float over the surface of the water, releasing sperm and eggs. This event is/was so important to the inhabitants of the Banks Islands, that it featured in their Lunar Calendar. A similar species is found in the Atlantic, but here swarming takes place in June or July during the first quarter of the moon. [1]

I have it on good authority that spiny lobsters in the red sea avoid foraging at full moon because of the threat from sharks.

Clunio marinus has reproductive cycles synchronised with the phases of the moon (Caspars, H. (1951) Arch.Hydrobiol 416-594) Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 6

The breeding behaviour of the Malayan Black Rice Bug seems to be synchronised with the phases of the moon. More young males rice bugs are caught in light traps at full moon than at any other time. Black rice bugs are serious pests of rice in the far-east [7]. I suppose this may be similar to the behaviour of moths which fly into lights: They navigate by the light of the full moon, so when they encounter other bright lights, they fly around them in circles.

Gerbils in the Negev desert forage more for seeds at new moon than at full, because at full moon they are far more likely to be caught by owls [6].

The moon seems to affect trout fishing. Between 1959 and 1968, the largest catches of trout in lake Neuchatel in Switzerland were just before or just after new moon, and the smallest catches were during full moon (Quartier, A.A.(1970) Influence de la lune sur la peche des truits du lac de Neuchatel. Rapport de la Bibliotheques et des musees de la ville de neuchatel).

Effects of the moon on plants

(from http://www.planetfusion.co.uk/~pignut/Lunar_gardening.html)

Introduction A great many gardeners believe that planting vegetables during specific phases of the moon, and/or on dates made favourable by the motions of the other heavenly bodies, is beneficial. Some almanacs are published especially for this purpose. Gardeners disagree on the exact details, but it is widely believed that planting when the moon is waxing ensures rapid germination and growth . Another idea is that vegetables which grow underground should be planted in the dark of the moon, and those which grow above ground should be planted at full moon [2]. This sounds like sympathetic magic, but that doesn't mean that it won't work. John Reid [9] advises that "Peas that you would have early, sow in the full moon of november, if in a warm place" also that "great, white and red cabbages" should be sown in the full moon in july, and that roses should be pruned before the full moon in October.

In Wiltshire, there is an expression: "Light Christmas, light harvest"[8] meaning that if there is a full moon at Christmas, the harvest will be poor.

The Maoris believed that the moon whom they call Rongo*, protects crops. They always planted sweet potatos on the 11th, 27th and 28th days of the lunar month. Their main agricultural tools are long spades with crescents carved into the handles[13]

The Miskito Indians of Eastern Nicaragua, believe that crops will spoil or the harvest will be light if they are harvested at new moon. They also believe that above ground plants Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 7 should be planted between the first quarter and the full moon, and below ground plants should be planted between the full moon and the last quarter. The Miskito hold similar beliefs about the moon and animals [12]. It is worth remembering these words from Aristotle:

"It is even said that many ebbings and risings of the sea always come round with the moon and upon certain fixed days" [3] Aristotle (who spent his whole life around the mediterranean) found this idea hard to swallow,(and considering some of the other things he believed, this is really saying something!). As a result, Julius Caesar was unaware of the tides** until he invaded Britain.

If you want to know more about this subject, I would strongly recommend Planting by the moon: A gardeners calendar published yearly by prospect books. It can be obtained from the "Planting by the Moon" website (link below)

A scientific explanation

The following is taken from "Agricultural Ecology" by Girolami Azzi,

"According to experienced farmers, lettuce sown when the moon is waning is well developed vegetatively, producing a voluminous and juicy head: If sown with a rising moon, the plants rapidly go to seed without forming a good head. Radishes sown with a rising moon blossom in 50-60 days when temperatures are reasonably high: sown with a waning moon, the interval between sprouting and blooming is much longer, so permitting the plant to develop the meaty root mass utilised by man In these cases, as in many others which are empirically admitted but not yet scientifically proven, it could be affirmed that the period of time between new and full moon is a favourable one for reproduction, while the period between the full and new moons would be favourable to vegetative growth"

The main environmental factor triggering flowering is the length of the night, (a form of photoperiodism). Plant photoperiodic processes are perfectly capable of responding to light levels much lower than those experienced at full moon, so it would be surprising if plants did not respond to the phases of the moon. If the moon can affect the flowering times of plants, then the distinction between "above ground plants" and "below ground plants", makes more sense: in the case of "below ground crops" (onions, carrots, turnips etc.) flowering is usually undesirable; but this is not the case with many "above ground crops" such as sweetcorn and beans (lettuce is one of many exceptions). Azzi tested this with onions ("Effect of the moon on the development of the onion" La Meteorologia Practica An.17, No.6 Perugia 1936) and concluded that

"Sowing with a waning moon, and thus acting in such a way that the interval from Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 8 sowing to germination aproximately coincides with a new moon, the formation of the reproductive organs is considerably retarded or put off, while the bulbs tend to reach a considerable size."

Azzi admits that this is not conclusive, and I am certainly not satisfied with the small sample size (10 plants grown over two years). There does not appear to be sufficient compensation for the weather either: Onion bulbs planted a month apart, in spring, could be subject to completely different weather conditions. If anyone knows of any more recent work on this subject, please E-Mail me.[top]

Another scientific explanation

I recently watched a series on BBC called "Supernatural". One program talked about the influence of the moon on plants and animals, and claimed (among other things) that moon planting could improve potato yields. Their explanation was that plants and animals consist mostly of water, and so are subject to the tides. I had heard this before, as an explanation for all kinds of astrological phenomena, and I always found it rather unconvincing. No sources were quoted on the program, so I e-mailed the producer to ask where I could look for more information. He replied to say that most of the information came from personal communications with the scientists involved (in other words it had probably never been published, or if it had, the program makers had not read the appropriate books or papers). He did point me towards a number of authors, but didn't give clear references. Some I have been able to find, others not. Here is what I have managed to read so far:

The diameters of tree trunks fluctuate with the phase of the moon (the study looked at Spruce - the same tree which Boots climbed to heaven). The authors compared this to the changes in water level in wells, and the ebb and flow of springs, in response to the tides. They concluded that the "moon is influencing the flow of water between different parts of the tree" [9]. The paper also quoted work showing that germination and initial growth of plants is affected by the phase of the moon by E.Zurcher (available at http://iufro.boku.ac.at/iufro/iufronet/d6/wu60603/proc1998/zurcher.htm -Zurcher E. (1992) Journal Forestier Suisse 143 951-966), and a review of similar studies on 600 plant and animal species (Endres, K.P. & Schad, W. Biologie des Mondes Mondperiodik und lebensrhythmen, S.Hirzel Verlag Stuttgart/Leipzig, 1997). Unfortunately I haven't been able to get hold of this last reference, let alone translate it (languages aren't my strong point).

The claim that sap movement in trees is governed by the moon was not new C.F.C.Beeson made similar claims as early as 1946 [14], but denied that this was of any significance in forestry. His article was part of a review of literature on the moon's influence on plants, which was fairly sceptical. Beeson commented that this subject goes in and out of fashion periodically (as do many controversial areas of study), but the majority of studies find no correlation between the moon's phases and plant growth. He did draw attention to a study by Kolisko L. entitled "The moon and the growth of plants" Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 9

(1936), which seemed to provide the best evidence. Kolisko found that wheat growth was greatest at the time of full moon, and in particular, the Easter full moon (I think this may be relevant to the page about Lunar Calendars). H.S.Burr observed changes in the electrical potentials of trees (measured by putting electrodes 1.5m apart in the cambium), in 1945, which were attributed to changes in sap flow. It could simply have been that expansion of the trunks moved the electrodes further apart. (Diurnal potentials in the maple tree Yale J. Biol.Med. 17 727)

Frank A.Brown wrote several papers on the moon and plant growth. I managed to find one that he wrote, claiming that water uptake by bean seeds peaked 4 times every lunar month, around the time of full moon, new moon and the quarters.[15]. Harry S.Truman once said: "if you can't convince 'em, confuse em". I think this sums up Brown's approach to writing papers. The paper I read contained statements like:

"earlier evidence (Brown and Chow, 1973) had suggested that under some circumstances beans in closely apposed vessels mutually induced one another to adopt opposite signs of correlation with subtle geophysical variations, and under other circumstances the same sign" What I think he is saying is that if the beans are too close together, the experiment doesn't work. (O.K. I admit it, these pages are not always very coherent and I have been accused of using too many long words, but I don't do it on purpose, honest!) His experiment also seemed to be unnecessarily complicated, requiring rotating electromagnets suspended over the beans, and beans arranged in rows aligned to points of the compass. It would be quite hard to repeat. Brown also wrote a number of papers on lunar rhythms in animals

M.G.Maw[17] looked at stem elongation rates in Galanthus nivalis (snowdrop), Corydalis cava (climbing corydalis), Anemone nemorosa (Wood anemone), Symphytum tuberosum (tuberous comfrey), Allium ursinum (Ramsons wild garlic), Aegopodium podagraria (ground elder) and Campanula rapunculoides (a sort of bellflower). Snowdrop grew fastest 5 days before the full moon, climbing corydalis at the second quarter, Wood anemone had a 7.3 day growth rhythm in phase with the moons quarters, comfrey's growth peaked at the second quarter, ramsons peaked at new moon, ground elder at full moon, and bellflower at the second quarter. The statistics and method seemed a little bit dubious to me: Abrami sampled 3 or 4 plants of each species, but only presents results from the plant which "most closely approximated mean population growth and phenological stages". Consequently the statistics were too complicated for me to understand. I was also recommended to read work by T.M.Lai (1976) and "Goldsworthy's ideas on electromagnetic detection in plants" (wasn't he the cop who plugged his pot plant into a lie detector?) I haven't managed to find anything by these people yet. All this has made me rather more sceptical about some of the things I watch on TV. [top]

Yet another scientific explanation

Lunar cycles can influence the activity, behaviour and breeding of animals (click here for Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 10 more on this). Plants are vulnerable in the first few days after germination, planting at a phase of the moon when pests are active could reduce the yield. The Malayan black rice bug is a serious pest, and seems to be caught more in light traps at full moon [10]. Gerbils in the Negev desert forage for food most at new moon, when they are less at risk from owls [11]. It seems likely to me that mice and rats (which can eat a lot of newly planted seed) might do the same. [top]

* Rongo is a male name, but the Maoris also call the moon by the female name Hina or Sina. The ancient Babylonians also believed the moon to control the growth of crops. Their androgenous moon deity was called Sin[13] [back]

**Recently, Randall Cerveny of Arizona State University has discovered that the temperature in the Arctic and Antarctic is 0.55 degrees C greater at full moon than at new moon. The moon also affects temperature in temperate latitudes, but not in the tropics. This may be due to transfer of heat by tidal effects on wind patterns, distortions of the earth's magnetic field by the moon, lunar effects on meteoric dust or simply the reflection of sunlight off the moon onto the earth. Others have commented that the earth is slightly closer to the sun at full moon, and that this may also play a part. The moon's cycle has also been implicated in other climatic effects. [4][5][6] . [back] Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 11

Lunar and Menstrual Phase Locking Figure 1: One menses onset of each lunar period cycler. The calendar shows autumn 1977 dates in relation to the lunar phase. The 68 lunar period cyclers )those who show a mean cycle lenght of 29.5+ 1 day) are described here. Each dot shows the first cycle onset of one subject. Only one menses date per subject is entered to avoid weighing the data in the direction of the trend.

(from http://www.athenainstitute.com/sciencelinks/lunarandmenst.html, Cutler, W.B., Lunar Menstrual Phase Locking) Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 12

Who created mathematics? Where did it begin? To answer these questions, we need to think about what mathematics is. In their work on ethnomathematics, Borba (1990) and D’Ambrosio (1990) define the compnonents of ethnomathematics as the follows: ethnos—within a cultural environment mathema—explaining and understanding in order to transcend, managing and coping with reality in order to survive and thrive. tics—techniques such as counting, ordering, sorting, measuring, weighing, ciphering, classifying, ordering, inferring and modeling.

Thus they define mathematics as the quantitative techniques that humans develop in response to the problems, struggles, and endeavors of human survival. So what was the first use of quantitative techniques in human development? It is important to realize that this development development of quantitative thinking always takes place within a cultural context. It is influenced by and influences that culture. Indeed, quantitative thinking is a vital component of culture.

So what was the first use of quantitative techniques or tics in human development? And who were the first people to do this mathematics? The evidence points to women as the first people to do mathematics and to menstruation as the motivation for this activity.

This evidence begins with the Ishango bone, a small scratched bone found on the shores of Lake Edward in Zaire, Africa. A microscopic analysis of the incisions on this bone shows that it is a six month lunar calendar (Marshack, 1972, p. 27-32). This bone has been dated between 25,000 and 20,000 B.C.E. Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 13

The Ishango Bone

Notched bone from the Congo, Africa. 25,000 to 20,000 BCE. The markings on the Ishango Bone represent a six-month lunar calendar.

While the Ishango Bone is the most well known lunar calendar, other such lunar calendars have been found in Europe dating from throughout the Paleolithic period (30,000-10,000 B.C.E.) (Zaslavsky, 1992, p. 1; Sjöö & Mor, 1991, p. 144-149) such as the Isturitz baton and the Blanchard bone plaque.

The Isturitz Baton

Engraved baton made of antler, from Isturitz, France, 25,000 to 20,000 BCE. The markings represent a five-month and a four- month lunar calendar.

The Blanchard Bone Plaque

Found in Abri Blanchard in the region of Dordogne, France, 25,000 to 32,000 BCE. Meandering markings possibly represent a two-month lunar calendar.

These lunar calendars are the oldest known use of number by humans. This quantitative thinking demanded a time-factored way of thinking, an awareness of the passing of time and the cycling of the natural world. This recognition of the cycles of the moon and the recording of time is the earliest evidence of human activity based on quantitative techniques. Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 14

And who made these lunar calendars? What was the human condition, the mathema to which this quantitative technique was a response? Was it the inherent cyclical nature paralleling that of the moon possessed by women? Was it women who first did this mathematics?

And in what cultural context or ethnos did these lunar calendars arise? The Paleolithic period was characterized by the development of Goddess worship on the European continent where much of the evidence of lunar calendars has been found. This Goddess worship was marked by images of the sacred female as life giver with an emphasis on the vulva, breast, and buttocks and the use of red ochre paint representing menstrual blood (Marshack, p. 281-340; Eisler, 1987, p. 1-7; Gadon, 1989, p. 3-21) such as the Venuses of Willendorf and Laussel.

The Venus of The

Willendorf Venus of Laussel

Small stone image painted with red ochre. Bas relief image from Laussel, France. 25,000 From Willendorf Austria, 30,000 to 25,000 to 20,000 BCE. The horn has thirteen marks, BCE. the number of moons in a year.

Gadon suggests, "The earliest rituals may have honored the menstrual cycle, the womb blood that nurtured new life" (1989, p. 11). Evidence of this can be seen in the stylized artifacts form the Paleolithic Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 15

Abstract Female Form

From Dolni Vestonice in the Czech Republic. 25,000 to 20,000 BCE.

Mammoth ivory Disc with Vulva Line pendant in the shape of a highly abstracted female from with From Brno in the Czech Republic, 25,000 widespread legs and a to 20,000 BCE. vulva line Circular disc representing an abstract vulva

It was in this culture that the lunar calendars arose. This was a time when women, their bodies, their sexuality, and their life giving ability were honored and at the center of the spiritual life of human communities.

The question of which gender made which specific Paleolithic markings or drawings is largely unanswerable and probably irrelevant, since both genders have had to practice these arts in order to learn time’s dimensions... But the menstruant, having the most direct connection with the lunar cycle, would have been the first to know; she had motive, method, and opportunity to be the originator of lunar notation. (Grahn, 1993, p. 156)

Thus, the lunar calendars would not have been merely methods of keeping time but also reflective of the resonance between the phases of the moon and the sacred menstrual cycles of women.

This evidence points to the conclusion that women’s menstruation gave rise to the earliest mathematics. It also suggests that women were the first mathematicians.

Works Cited

 Borba, M. (1990). Ethnomathematics and education. For the Learning of Mathematics, 10(1), 39- 43.  D'Ambrosio, U. (1990). The history of mathematics and ethnomathematics. How a native culture intervenes in the process of learning science. Impact of Science on Society, 40(4) 369-78.  Eisler, R. (1987). The Chalice and the Blade. San Francisco: Harper & Row.  Gadon, E. (1989) The Once and Future Goddess. San Francisco: Harper.  Grahn, J. (1993). Blood, Bread, and Roses: How Menstruation Created the World. Boston: Beacon Press.  Marshack, A. (1972). The Roots of Civilization. New York: McGraw-Hill.  Sjöö, M. & Mor, B. The Great Cosmic Mother. San Francisco: Harper.  Zaslavsky, C. (1992) Women as the first mathematicians. International Study Group on Ethnomathematics Newsletter, 7(1), 1.

* With appreciation to Judy Grahn for her subtitle to Blood, Bread and Roses. Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 16

A Straight Dope Classic from Cecil's storehouse of human knowledge

What's the link between the moon and menstruation?

24-Sep-1999

Dear Cecil:

What's the connection between the human menstrual cycle and the moon? Do our cycles last exactly one lunar month for a reason, or is it just a coincidence? I wonder how our cycles--not to mention our calendars--would work if we didn't have a moon. --Barbara Berr, via the Internet

Dear Barbara:

The smart money says it's coincidence. In Science and the Paranormal (1983), astronomer George O. Abell writes, "The moon's cycle of phases is 29.53 days, while the human female menstrual cycle averages 28 days (although it varies among women and from time to time with individual women); this is hardly even a good coincidence! The corresponding estrus cycles of some other mammals are 28 days for opossums, 11 days for guinea pigs, 16 to 17 days for sheep, 20 to 22 days for sows, 21 days for cows and mares, 24 to 26 days for macaque monkeys, 37 days for chimpanzees, and only 5 days for rats and mice. One could argue, I suppose, that the human female, being more intelligent and perhaps aware of her environment, adapted to a cycle close to that of the moon, while lower animals did not. But then the 28-day period for the opossum must be a coincidence, and if it is a coincidence for opossums, why not for humans?"

Then again, who knows? People have figured there was a connection between the lunar month and menstruation for as long as women have been getting the monthlies. Moon, month, and menstruation are all related etymologically. No less an authority than Charles Darwin believed that menstruation was linked to the moon's influence on tidal rhythms, a legacy of our origin in the sea. The coincidence between the lunar and menstrual cycles is closer than George Abell would have us believe--studies have found the average Moon and Menstruation Info Lab Larry Frolich Anatomy and Physiology II Page 18 menstrual period is 29 days and change. At least some critters' biologies are linked to the lunar cycle; in the lemur, for example, estrus and sex tend to occur around the time of the full moon.

Efforts to turn up similar patterns in humans have had unimpressive results, however. Several researchers over the years have claimed to detect lunar rhythms in menstrual onset and such; others see nothing. Biologist Winnifred Cutler, in a 1980 paper, found that 40 percent of women in a random sample showed "a preponderance of menses onsets in the light half-cycle of the month" (the two weeks centered on the full moon). To me this suggests 60 percent of the women didn't show any coincidence. If there really is a moon-menstruation link, you couldn't prove it by me.

--CECIL ADAMS

Lunar cycles and violent behaviour Cathy Owen, Concetta Tarantello, Michael Jones & Christopher Tennant Objective: It is commonly believed that the full moon exerts an influence on violence and aggression in psychiatric settings. The literature to date is contentious. This study used a robust methodology to examine the hypothesis that there was an increased frequency of violent and aggressive behaviour among hospitalised psychiatric clients at the time of the full moon.

Method: Prospective data were collected in five inpatient psychiatric settings across the Northern Sydney Area Health Service. Morrison's hierarchy of violence and aggression was used to rate behaviour. Lunar phases were clearly defined and Poisson regression used to examine relationships between lunar phase and violence. Extraneous temporal variation was considered.

Results: No significant relationship was found between total violence and aggression or level of violence and aggression and any phase of the moon.

Conclusion: Future research could profitably examine the implications of a belief in the lunar effect among health workers in the face of evidence that no relationship exists between violence, aggression and the lunar cycle. Australian and New Zealand Journal of Psychiatry 1998; 32:496 499