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T A B L E_T A L K
This week, Peter Matthiessen joins us in Table Talk. Share thoughts and
ask questions about "The Jungle Book" and its influence on the author in
the Books area.
R E C E N T L Y "Jungle Book" fever A life without play dates The nurture assumption Is that all there is? Blarney for bairns - - - - - - - - - - BROWSE THE MOTHERS WHO THINK FEATURE ARCHIVES - - - - - - - - - - Mamafesto
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BREED OLD, DIE LATE AND LEAVE A BEAUTIFUL BRAIN | PAGE 1, 2
It turns out that the experience of my mother and the British noblewomen confirm the findings of studies of Drosophila fruit flies, those pesky nuisances of college biology labs. Studies have found that flies selectively bred for longevity have fewer young, and flies selected for late fertility live longer and are more resistant to stress and disease. These studies point to a genetic link between bearing offspring early and dying young. Older mothers should not get too smug, however: Both male and female flies prevented from mating at all live the longest. And, like the flies, childless women on average do live longer, despite a higher rate of breast and endometrial cancer. Nearly half of the British aristocrats who lived into their 80s and 90s had no children, while less than a third of women who lived only into their 50s and 60s were childless. Since they were all married, we can happily assume that, unlike the female flies, it was not celibacy that accounted for their longevity. To any mother who has struggled through sleepless nights or battled a steady onslaught of baby-born viruses or nursed a sick child, the link between number of children and parental life span seems intuitively obvious. We only have so much energy and each child obviously requires a substantial investment of this scarce commodity. That life span should be correlated to age at first birth seems less intuitive, however. Researchers are careful to point out that older mothers do not necessarily live longer just because they have fewer kids. Indeed, the precise reasons for the importance of age are unclear. It could be that if a woman is able to have children in the 11th hour, she is clearly one of the genetic elect. As the authors of the Boston study put it, the ability to have kids after a certain age, say 40, may simply be a marker for longevity: Late pregnancy implies late menopause, which in turn implies the later onset of age-related disease such as Alzheimer's, heart disease and stroke. According to yet another study, led by Jonathan L. Tully of Massachusetts General Hospital and published last month in Nature Genetics, when the ovaries of geriatric mice are engineered to grow eggs and secrete estrogen into advanced old age -- the equivalent of delaying menopause in humans -- they remain strikingly youthful and robust. It is also plausible that the timing of first pregnancy resets, or at least plays interference with, a woman's biological clock. Mrs. Shandy of the 18th century novel "Tristram Shandy" may have been the first to connect conception with timepieces: "Pray, my dear," she inopportunely asked her aging husband, "have you not forgotten to wind up the clock?" Winding up our biological timepiece sooner could trigger early menopause and winding it up late in life could delay menopause and rejuvenate middle-aged parents. If so, older mothers who serenely assert that their children keep them young may be right. Sadly, for men, one of the sacred tenets of evolutionary psychology -- that men are naturally more promiscuous in order to propagate the species -- may also be fatal. Married men with decreased fecundity live longer, and their longevity is in fact correlated to that of their spouse. And like their fruit fly counterparts, those men who invest heavily in reproduction while young can expect, on average, shorter lives. We always knew men should share in the costs and benefits of parenthood; now the British study confirms they do, in a somatic sense. "Wee kill our selves to propagate our kinde," wrote 17th century poet John Donne. He was actually alluding to orgasm, the "little death," which at the time was believed to take years off men's lives. Read literally, however, Donne was expressing a form of Darwinian logic avant la lettre. As with most scientific research, the results of these studies will no doubt be modified. They are based on statistical associations, not the analysis of deterministic processes. They imply that a marriage of nature and nurture is involved in longevity -- and probably a big helping of chance. Certainly there are women -- Rose Kennedy and Queen Victoria immediately come to mind -- who have huge broods at an early age and live to ripe old age. And waiting until midlife to conceive is not necessarily the best way to ensure a successful pregnancy.
Besides, doing so also risks missing out on a few more IQ points! Another recent study, reported on at a meeting of the Society for Neuroscience in Los Angeles last November, suggests that women may get
smarter during pregnancy and lactation -- that is, if they are anything
like lab animals. Studies performed on rats showed that
brain structures called dendrites double during pregnancy and lactation, thus making learning more efficient. According to the team of researchers, led by Craig Kinsley of the University of Richmond, mothering rats learn mazes more quickly, make fewer mistakes and retain the new knowledge longer. The changes appear to mark the brain for a lifetime, suggesting that women's brains may be far more capable of change than those of men. Of course, some mothers have always believed this to be true.
Michele Y. Pridmore-Brown is a scholar with the Institute for Research on Women and Gender at Stanford University. |
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