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From: mikes@tekecs.UUCP (Michael Sellers)
Newsgroups: net.sci
Subject: Re: Biorhythms
Message-ID: <7242@tekecs.UUCP>
Date: Fri, 2-May-86 14:06:54 EDT
Article-I.D.: tekecs.7242
Posted: Fri May  2 14:06:54 1986
Date-Received: Sun, 4-May-86 23:26:21 EDT
References: <935@cylixd.UUCP> <719@bentley.UUCP> <3435@hplabsb.UUCP> <335@brl-smoke.ARPA>
Organization: Tektronix, Wilsonville OR
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> In article <3435@hplabsb.UUCP> bl@hplabsb.UUCP (Bruce T. Lowerre) writes:
> >Is it just coincidence that the average human menstrual cycle equals the
> >lunar cycle?
> 
> I don't know, but I can tell you how to find out:  Examine analogous
> cycles in other species.  If virtually all of them track the lunar
> cycle, then I would say there is an (unknown) causal connection;
> otherwise it would appear to be coincidental.

Humans, chimps, and possibly a few of the other higher primates (maybe
orangs and gorillas? I can't remember) have a genuine menstrual cycle that
averages at about 28 days.  I think chimps actually have something like a
26 or 27 day average, according to my rememberance of the Larousse book.
Most other mammals have an estrous cycle where the uterine lining is absorbed
rather than sloughed off and where the time of fertility is longer (seasonal).

I don't know if the 28-day cycle is coincidence or not; I suppose it could go
either way.  Given the variability between women, though, I would vote for
coincidence (though my wife is extremely consistent -- and each of our children
has been born right around the time of the full moon... ).

		Mike
-- 

		Mike Sellers

	UUCP: {...your spinal column here...}!tektronix!tekecs!michaels

"You have to do stupid things once in a while if you're going to be a hero."
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