Menstration

Far be it from me to say that I understand women. Further still would be any kind of knowledge of what makes their bodies tick. I’m a guy. My biggest concern today is getting beer for the football game this Sunday.

However, I’ve heard from any number of people supposedly in the know that women have an odd quirk about themselves in that they can often share the same menstruation date.

That is, a group of women that often spend time together will more often than not share the same menstrual day too. O.K., I think I can follow that.

But that seems to bring up the obvious question- If women’s menstruation can center around, or hone in on, one dominant woman, than why would there ever have been a reason for different days of the month? Shouldn’t they all be the same day of the month worldwide?

It seems to me that the animal world pretty much has a season and a set time that all the other females follow around, so why wouldn’t that be the case with humans?

IIRC women have to be in close proximity day after day for their cycles to start synchronizing. You don’t just pick it up from the woman who stands in front of you in the checkout line. Other things can affect cycles, too–age, stress, pregnancy, nursing and so on. For example, it doesn’t matter what the women I work with are up to–I ain’t starting until I get to the little white pills.

As to why human reproduction isn’t seasonal–beats me. I would expect that seasonality has to do with climate conditions, social structure, how much care babies require and any number of other things.

The way the theory runs is that it’s due to pheromones, not just the calendar or even the phases of the moon. Pheromones means you have to be living close enough to the other gals to be able to smell them. This usually means all the women in a family or all the women in an office, not all the women in Illinois.

Seasonal ovulation has to do mainly with food supply. Creatures that are dependent on one or two main food supplies tend to give birth (spawn, hatch out young, etc.) when those food supplies are the most abundant.

Primates, and especially homo sapiens, are opportunists with a varied diet. We can eat anything, and so we don’t have to time our ovulation cycles to the availability of one particular food supply.

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Its artificially induced, but my housemate and I are on the exact same cycle. The third housemate always says he’s glad to have a job to go to that week!

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Before the pill, though, I was more or less in synch with my sister, my best friend, and three of the people I worked with. I definitely think proximity has an effect.

Also, didn’t Cecil cover this? Or was it just another thread I read at some point? Anyways, I think the answer is out there somewhere in the Straight Dope Realm.

The Master on synchronous menstruation