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What is the menstrual cycle?



Replies:
Storks bring 'em. My 2nd child will be born in a few weeks, and you wouldn't believe the trouble we've had --- storks absolutely refuse to fly into Chicago's O'Hare airport, and I can't say I blame them.... So anyway let's talk about this more generally. Why babies? Why did evolution produce life forms that are all the time making copies of themselves and then dying, instead of life forms that just live indefinitely until accident kills them off? Probably because the environment changes all the time, glaciers, meteor strikes, Republican leadership of Congress, etc., and you need a mechanism by which species can adapt quickly. At the same time you need insurance, a fall-back mechanism whereby you can cut your losses and get out of an experimental adaptation that isn't working. So it works this way: life is essentially genetic material, DNA molecules. These molecules build themselves a body out of their environment, and the body carries around the molecules and with greater or lesser ingenuity protects them from harm, including with greater or lesser adaptability that from minor environmental changes (we learn to come in out of the rain). But once the body is built, it's hard for it to learn really new tricks to deal with major environmental changes, as alas we all learn as we get older. So every few decades the molecules design and build a new body and move into it. Every time they do this some of them randomly change a few of the characteristics of the body. Normally the New Improved Body isn't as good, so the molecules cut their losses and the new model bites the dust. But when radical environmental change comes along and the standard model falters, the New Improved Body (some versions of it) will work and the molecules survive.

Christopher Grayce



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