Woman: An Intimate Geography (41 page)

Read Woman: An Intimate Geography Online

Authors: Natalie Angier

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past the fifth decade of life are such giants as elephants and finback whales. If you want to carry a lot of eggs, you need a very big basket.
Whatever the constraints, there is nothing precocious about the senescence of our ovaries, Hawkes says. On that score, she agrees with the artifactualists: women go through menopause because women outlive their follicles. But she parts company with the artifactualists in their insistence that old age is a modern invention. To the contrary, old age is old news. Call us
Homo maturus
. Yes, people used to die young routinely, of infectious diseases, in the jaws of a leopard, or while giving birth to a fat-headed, rear-facing baby. But those who survived illness and accident very likely thrived to a respectable old age. The Bible puts our allotment at three score and ten, and that's not a bad figure, biologically speaking. We're built to last about seventy to eighty years. Add on the overengineering needed to push a sizable number of people toward that mark, and you get a century. Wherever you go, whatever industrialized, agrarian, or nomadic population you consider, you will find that one hundred years is pretty much the upper limit for the human lifespan. "This is the human pattern," Hawkes says, "and there's no reason to think that it wasn't true for our ancestors as well."
What distinguishes women from other primates, then, isn't menopause but the long, robust life that women can lead after menopause. A chimpanzee at age forty-five or fifty not only has fading ovaries, she is fading globally. All her organs are faltering, and she is close to death. No matter that she has spent her life under the pampering ministrations of an American zoo, with the best medical care and all the bananas she can peel, a female chimpanzee will still be, at fifty, a decrepit animal. She will be the equivalent not of a menopausal woman but of a centenarian, blowing out the birthday candles to the cheers of Willard Scott.
So while natural selection may have been hamstrung by ovarian physiology, unable to augment a woman's follicular capacity beyond the standard primate model, it has flexed its muscles rather floridly on a woman's lifespan. And now we must emphasize the her-ness of human longevity. Let us return to the role of grandmother, and let us gloat. Yes, any wizened elder can, as Jared Diamond suggests, serve as memoirist, botanist, and toxicologist to the clan. But is a good hippocampus worth enough to account for the ascent of the centenarian? Not likely. Life is lived by the day, and most days aren't Christmas. Just as hunting is an

 

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irregular occupation, so is playing sage. We need food every day. We need women every day, day after day after year after decade after menopause. Let's build them to last.
By the new and expanded edition of the grandmother hypothesis, the rudiments of human longevity, and of human global domination, can be found in a ritual we take for granted: the family meal. A chimpanzee mother nurses her infant for four or five years. That's a long time, but afterward, there are no more free lunches at Mother's Café. The weaned apeling is expected to fend almost entirely for itself to find, pick, and eat its own food. On occasion its mother or another older chimpanzee will share foraged goods with the juvenile, particularly if the food is hard for young fingers to manage. But the offered item is a treat, a banana split if you will, and the young chimpanzee knows better than to expect routine handouts.
In food-sharing, though, lies a kernel of possibility. Chimpanzees and other social primates are restricted in their range. They must stay in an area where all members of the group can find enough to eat, and that includes the weaned young. The available resources must be accessible to even the fumbling hands and undeveloped strength of preadolescent animals. If the troop decided to migrate to an area where food was scarce and required adult skills to extract, the younger animals would soon die of malnourishment.
Unless, that is, the adults started sharing food with their weaned offspring on a regular basis. Adults means mothers. Among nearly all species of primates, fathers have little to do with their offspring and probably don't know quite who they are anyway. The males are busy with other things, like hunting. The mother must be the one to give to her children what they can no longer gather for themselves. And that's fine, and she will, but then comes a hitch. She gets pregnant again. She must breastfeed. Lactation is costly. She must eat more than ever. She can't provision the older children and nurse at the same time. Who's she going to call? We know the answer. Her mother. Her auntie. Her cousin Certain Age. Now the chance arises for the occasional robust older female to make a difference to her family's welfare. An aging chimpanzee has nothing to do in a society where the young are autonomous, so she might as well die right, Mother Nature, you beloved, cavalier, monomaniacal bitch? By contrast, in a setting where provisioning

 

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weaned children is essential, Grandmother too becomes essential. The stalwart older female succeeds in keeping her kin alive. The moribund older female does not. Selection favors robustness after menopause, and the human lifespan begins exceeding the primate norm like a pair of outstretched arms, strong and sweet and there to hold you.
Now, with Grandma's help, early humans are free. They can go where other primates, and possibly competing hominids, cannot. They can invade adults-only habitats, where they must dig to unearth tubers and cook many food items to make them edible. (Tubers, incidentally, are fairly rich in protein and calories, and they compose a large part of the diet among many traditional human cultures but are only rarely eaten by great apes.) Mothers can provision their progeny much of the time, but when they give birth they know they'll have help. An elder relative can assume responsibility for weaned children. In fact, with a grandmother's help, a mother can get that new baby off her breast sooner than she might otherwise. Chimpanzees breastfeed for four to five years, the length of time required for the young to reach self-sufficiency. But if a child does not need to be autonomous before leaving the teat, why keep suckling? Even in traditional societies where Similac is unknown and breastfeeding expected, women nurse for an average of only 2.8 years, less time than for other higher primates. Shortened lactation means greater fecundity, and indeed women in traditional cultures have more offspring with their primate ovaries than chimpanzees or gorillas do. The intervals between children are comparatively briefer. More grandchildren enhance the genetic fitness of the senior female. Through food-sharing, then, an older woman becomes a genetic czarina, dynastic in her reach.
As Grandmother grows stronger, children get weaker. It is a developmental rule of thumb that the greater an animal's lifespan, the later the onset of its sexual maturation; if a body is to endure, it must be built with care. Hence the genetic changes that foster life past menopause end up keeping children small and prepubescent comparatively longer. On all fronts, then, children are being infantilized. They are dragged into habitats where meals are beyond a juvenile's means, and then their genes delay their coming of age. Not to despair; instead, gild the cage. The lengthening of childhood opens a window of opportunity for cerebral experimentation. The brain has time to ripen, its synapses to

 

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lace and interdigitate and loop back lazily to do it again. For the first two or three years of life, a human child is not that different from a chimpanzee. Both creatures are astonishingly clever and curious, passionate students of life. But within short order the chimpanzee must drop out of school and work for a living, whereas the child let's be predictable and call her a girl remains in most cultures in the luxury of the nanny state. The child has all those postmammary years when she is still getting fed and thus can devote her energies to her intellectual and social education. In fact, she is well advised to do so, because even as extended dependency offers opportunity, it poses risks. The young chimpanzee can feed itself. The child cannot. An adult, unlike a fig tree, is not particularly responsive to being shaken or plucked, but instead must be ever so subtly fleeced. That means the child must learn the trade of enchantment: the strategic smile, the well-timed whimper, the feckless eye-bat. She must become a symbiotic parasite, an organism that takes and takes and depletes, as a parasite does, but that conveys to its host a sense of reciprocity, of being pleasant, worthy, useful; and that's a hard behavioral feat to manage, requiring a flow chart of routines and subroutines. Another whetstone to a young wit is the nattering chorus known as her sisters and brothers. Mother is fertile. She's having many children. She's weaning them young, and they're loitering at home. All those children are dependent on their elders, and all must beguile and connive to be noticed. Adults may like you soft, but your siblings whittle you sharp. No wonder children are so desperate to grow up: Kinder Garten is infested with snakes.
To review our story: Early humans took a preexisting primate hobby, food-sharing, and professionalized it. By shouldering the burden of feeding children, adults freed themselves to infiltrate whole new lands. But they couldn't have moved without Grandmother's help. Young women needed older women. Robustness after menopause became the rule, as did its corollary, delayed puberty. With Grandma in stride and children in tow, no land was too bleak, no tuber too deep, to dampen humanity's imperial zeal. The more hostile the terrain, the greater the dependency of child on elder. Peter Pan set down roots. Childhood expanded. And with world enough and time, the conditions converged for another revolutionary expansion of intelligence. Our minds hurtled outward in all directions. We became absurdly creative,
Homo

 

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artifactus
, intolerant of bare cave walls and naked clay pots. We built better tools, better spears, better mastodon traps. The earth that we were fast overrunning was no longer enough, and we laid claim to the heavens, peopling the terrible, silent dome above us with an exuberant divinarium of advisers, legislators, coaches, and entertainers. We lived so long and so self-consciously that we assumed we must live forever, and we buried our dead with enough talismans and spare change for eternity.
Think of it: the grandmother hypothesis inverts all the conventional sequences; it brays at the party line of human evolution. We usually assume that we got smart first and then had to have an extended childhood to cultivate the circuitry of that smartness, and then had to live long enough as adults to care for our smart, slow-growing kids. As Hawkes plays it out, the order of events is just the opposite. We got old, we got young, we got smart. She takes a thwack at the familiar figurine of Man the Hunter, questioning the role of the male in provisioning the young and allowing children to be children. The original division of labor, as she sees it, was between childbearing women and postmenopausal women. Mothers bred what grandmothers fed. Through that compact, human fecundity and human mobility knew no limits.
But what of men? They live a long time too. If longevity arose to benefit the female, what of the superannuated male? The answer to that can be explained mostly by the mechanisms of genetics. Women have no exclusive patent on any particular gene. Unlike genes located on the Y chromosome, which will be passed only from fathers to sons, mothers apportion all their genes to sons and daughters alike. Genes that enhance robustness postmenopausally when a female inherits them will find their way into male zygotes as well. The male lifespan gets dragged along. Still, it is possible that somatic robustness operates at its peak against a female background. Men do not live as long as women do, after all, and the disparity in lifespan applies globally. Maybe they don't have to live as long. Or maybe they don't want to. Maybe they get tired of losing their hair, and of the political pomp of the hunt, and of making bad jokes about their mothers-in-law.
If we accept the grandmother as the bedrock of our past and life after menopause as an ancestral right rather than a modern gratuity, then we

 

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can examine with a certain tempered skepticism the concept of "estrogen deficiency." Assuming that our bodies were built to senesce slowly, what should we make of the decline in estrogen that accompanies menopause? More to the point, should we treat it? Does the grandmother hypothesis tell us anything about whether or not we should take exogenous hormones when our follicles cease to burst cyclically and bless us unasked? The answer is . . . complicated. On the one hand, nature is imperfect. She is a slapdash engineer whose motto is "It'll do." The body after menopause certainly looks like an example of "It'll do.'' Nasolabial canyons, liver spots, the occasional embarrassing sneeze-leak sequence. Hey, nature barks, you've got a pulse, haven't you? In other words, even if our somas persist in the absence of ovarian estradiol, that doesn't mean we can't do better and live stronger by taking estrogen tablets. There's a principle in evolutionary thinking called the naturalistic fallacy making the mistake of assuming that what is, is for the best. Murder and infanticide are "natural," in our species as well as in most others, but they are not defensible human strategies. The same may be true for menopause. Living without ovarian estradiol may be natural but far from ideal. After all, if the senescence of our primate ovaries is not an adaptation per se but merely the result of evolutionary constraints on follicular supply, then the concomitant loss of ovarian estrogen may be an example of "Sorry, this was the best we could come up with. It'll have to do. You'll muddle through." Muddling unnecessarily is stupid. We're clever. We have organic chemistry. We have gynecology, cardiology, endocrinology. We have evidence that hormones help. Take your Premarin, darling if we're clever by nature, it's the natural thing to do.
On the other hand . . . the old pink Cadillac still drives. Nature is slapdash, yet the engine turns over and sometimes purrs. The analogy that many doctors make between menopause and hormone deficiency disorders such as diabetes and hypothyroidism doesn't hold up. If I were to stop taking my thyroid supplements, I would begin falling apart within days or weeks. My thyroid has failed me; I have a disease, I admit it, and I have no choice but to seek outside assistance. Menopause is not so dire. A woman's bones don't crumble or her blood vessels shatter once she has run out of eggs. Most women do extraordinarily well for years or decades after menopause without taking hormones. We might

 

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