Once upon a time (2006), I was having lunch at Biola University in California with an eager young Darwinist who declared that "evolution doesn't care about you when you are old!"
Well, he was young and I was old.
In fact, tax-funded Darwinists, known as "evolutionary psychologists," have begun—contrary to my young dinner companion's effort to dismiss oldsters as irrelevant to Darwinism—to try to explain what we used to think of as "just plain being old" in terms of Darwinism. They do this even though old people can rarely be relevant to natural selection, either as Darwin preached it or as neo-Darwinism preaches it now. We don't procreate.
A Big Explanation
Nevertheless, the researchers plow ahead. According to a recent press release in Science News Daily (July 2, 2010), "the evolutionary mystery of menopause is a step closer to being solved thanks to research on killer whales." A "grandmother" role is posited as the Big Explanation:
A study by the Universities of Exeter and Cambridge has found a link between killer whales, pilot whales and humans—the only three known species where females stop breeding relatively early in their lifespan.
Despite very different social structures between the three species, the research shows that in each case females become increasingly genetically related to those they live with as they get older. Because of this, there is a motivation for older females to do what is best for the survival of those around them.
This creates a "grandmother" role, where the success rate of breeding in the group can be helped by older females sharing parenting knowledge and stopping breeding to allow younger females easier access to resources.
Ah yes. That also explains, of course, the tendency of many human grandmas to retire in Florida, far from their grandchildren, and to see them infrequently as a result. Of course, the pop science world waits breathlessly for the theory about how that, too, helps natural selection. (It also awaits a Darwinian theory about why very old ladies like walkers with seats and baskets.)
A Simple Explanation
The key difficulty with any Darwinian thesis for menopause is that an explanation for menopause (or late-life male infertility) is not even needed. Menopause comes from outliving one's menstrual cycle, in the same way that osteoporosis (softening of the bones, which plagued C. S. Lewis, for example) comes from being, well, old.
However strong our desire to describe or theorize about the pattern of mortality, the simple fact is that bodies just wear out eventually. In times and places where life is hard, people tend to die long before their bodies just wear out from use. As recently as 1900, we are told, the average life expectancy in the United States was 50 years (a common age of menopause). Thus, in that era, many women simply did not live long enough to experience menopause.
In earlier times, the situation was grimmer and even fewer women experienced it. Indeed, living to old age, as in "May you see your children's children" (Psalm 128:6), was traditionally regarded as a special blessing, and certainly not a routine expectation, let alone a reason not to move to Florida.
In easy times, of course, the reverse is true. Currently, the average life expectancy in the United States is said to be 77 years. Hence, today, apart from the marked increase in serious issues about health care in old age, we hear ever more yadda yadda over coffee about the awfulness of menopause.
In general, life expectancy is increasing worldwide, thanks to better disease control, fewer wars, improved health care, and other similar factors. Hence, the number of women experiencing menopause is rising.
The menstrual cycle is not an essential body system. It can and does shut down during a famine (or in women who suffer from anorexia), thus preventing the loss of nutrients via the blood. If it did not shut down, the unfortunate alternative might be stillborn, murdered, or addled children. The American writer Pearl Buck depicted just such circumstances in rural China in her book The Good Earth (for which she won the Nobel Prize for literature in 1938).
Men have similar problems. One oldster I know, after hearing that former Canadian prime minister Pierre Trudeau had a daughter by a mistress when he was 70 years old, said only, "I am filled with admiration for this feat." That gives you some idea how common old-age parenting is, and how likely it is to influence Darwinian natural selection. This goes double for grandmas. •
Note: The author of this article lives in a four-generation clan, where a difficulty can arise when trying to explain relationships to very old seniors, like which children are grandchildren and which are great-grandchildren.
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