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Menstrual Synchrony or Menstrual Overlap: What Difference Does It Make? |
This past summer, my
sister-in-law obtained for me a copy of Professor Beverly I. Strassmann's
"Menstrual synchrony pheromones: cause for doubt?" (Human
Reproduction, vol 14. no. 3, pp. 579-580, 1999).
I had originally requested
my sister-in-law's aid in obtaining several of Strassmann's papers, as Elsimar
Coutinho, author of the book "Is Menstruation Obsolete?" had drawn
upon Strassmann's anthropological work in shaping his own arguments for
menstrual suppression, arguments I wished to rebut.
It turns out that
Strassmann and other researchers have been unable to reproduce the findings of
Martha McClintock's 1971 study, "Menstrual Synchrony and Suppression"
(Nature, vol. 392, pp. 177-179, 1971).
McClintock had found:
"There was a significant increase in synchronization (that is, a decrease
in the difference between [menstrual] onset dates) among room mates, among
closest friends, and among room mates and closest friends combined."
Strassmann, however, found that
among Dogon women in Mali, West Africa: "...the [menstrual] onsets for
different women were independent of each other...regardless of whether the
women...were co-wives, friends, or members of the same family, lineage or
village (Strassmann 1990, 1997)."
Strassmann also observed:
"...Wilson (1991, 1992) noted three statistical errors in the evidence for
menstrual synchrony: (i) failure to control adequately for the convergence of
onsets by chance; (ii) inflation of the initial difference in onsets resulting
in the spurious conclusion of synchronization over time; and (iii) sampling
biases. Studies that correct for these statistical errors have found no
evidence for synchronization, even as a weak effect (Jarret, 1984; Wilson et
al., 1991; Trevathan et al., 1993)."
What does this all mean? For me,
it meant going back and rethinking my May 1999 query letter to Rolling Stone magazine. In this
letter, I'd suggested a scenario in which the all-male Beatles were actually an
all-female band, consisting of "Jane, Paula, Georgia and Ringa."
Based on Stern and McClintock's "Regulation of ovulation by human
pheremones" (Nature, vol. 392, pp. 177-179, 12 March 1998), I further
suggested that if these female Beatles had been menstrually synchronized, the
album known today as Sergeant Pepper's Lonely Hearts Club Band might instead be
known as Aunt Ruby's Bleeding Hearts Club Band.
And this, in turn, might have led
to a very different gender balance in the music industry today.
But apparently, there is the
possibility menstrual synchrony is mere "statistical artifact." Does
this negate the point I'd tried to make with my female Beatles scenario?
After some consideration I decided
that, regardless of menstrual synchrony's statistical significance, menstrual
overlap most certainly is significant, as Strassmann herself alludes to:
"Given a cycle length of 28 days (not a rule--but an example), the maximum
that two women can be out of phase is 14 days. On average, the onsets will be 7
days apart. Fully half the time they should be even closer (Wilson 1992; Strassmann
1997). Given that menstruation often lasts 5 days, it is not surprising that
friends commonly experience overlapping menses..."
Behind my query letter to Rolling
Stone magazine lay the desire to explore the creative potential of
menstruation, not only for female bandmates, but also for female producers,
arrangers, composers and lyricists; and by extension, all female artists:
writers, filmmakers, painters, dancers, and so on. (Which is not to say
menstruation can't also be a fruitful subject matter for the male artist as
well!)
Coming at it from a slightly
different angle, I would hazard a guess that in Dogon society, which practices
female circumcision on girls between the ages of 3-5, enforces the use of
menstrual huts, and in which "co-wives" is a meaningful social
category, "female bandmates" as social category is simply
inconceivable.
Unfortunately, "female
bandmates" as social category seems to be just about as inconceivable in
"modern Western" society as in Dogon, given the relative infrequency
with which young women form bands, compared to young men.
What's your opinion? Email us and let us know! We'd especially like to hear from
those of you with a scientific background, qualified to evaluate the contradictory
studies.
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But
perhaps the past, whether ancient or just 30 years ago, is not the place to be
looking for menstrual synchrony. Click here to read an email from a student at
Drexel University who suggests exogenous hormones may play a role in menstrual
synchrony in modern populations.
X Blood, Bread...Oranges and Apples?