Jon Noble jon_p_noble at
Mon Feb 10 06:35:02 EST 2003

--- Gili Bar-Hillel <abhillel at> wrote:
> Jon wrote:
> >Yes but that extra day (day and a half is nearer)
> >would quickly make a difference, you'd be half a
> month
> >out after a year.
> You're also assuming that most women have 28 day
> periods like clockwork, and 
> that is definitely not true. I think for most women,
> it is only roughly 
> regular, and only roughly 28 days - some women are
> completely irregular, or 
> have perfectly regular 6 week cycles, or any number
> of variations on that.

I'm well aware of the iregular nature of cycles
(although all three women here are very regular), and
you are right, I quite explicitly assumed 28 days, but
on the other hand this is the oft quoted figure, not
29 days. Indeed i suspect that the iregular nature of
these things is an evolutionary mechanism to ensure
that women who can count still pass on their genes.
I'd be interested to learn if there is any research to
suggest that a different figure has ever been accepted
historically or by other cultures.


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