Our Own Devices: How Technology Remakes Humanity
Page 8
Despite all these possible biases there is evidence—sometimes limited and controversial—of long-term benefits of breast-feeding. Breast-fed children may develop slightly higher intelligence than bottle-fed contemporaries. A number of chemicals that appear in human milk but not in formula, including arachidonic acid (AA) and docosahexaenoic acid (DHA), are known to promote brain growth. Longer-term breast-feeding has been linked in one study to faster motor and cognitive development. In another, premature infants tube-fed with human milk had an 8.3-point IQ advantage over their formula-fed counterparts at the age of seven and a half—this after downward adjustment to reflect their mothers’ educational and social status. Some studies show only weak or insigificant gains after adjustment for family background, but the very first study of feeding method and mental development, published in 1929, showed advantages for breast-feeding at a time when formula-feeding was chic and breastfeeding associated with immigrants and the working class.26
The immune system also may be affected by infant feeding. The nutrition researcher Alan Lucas has pointed out that studies of other animals show effects of prenatal and postnatal nutrition on indicators of health from size and metabolism to obesity, hardening of the arteries, and longevity. There is evidence, if not yet proof, that there are critical periods in human development, “programming windows” for stimuli that enable or inhibit later behavior. Very early in their lives, chicks, mallard ducklings, and some infant mammals become attached to the first thing they encounter, in nature nearly always a parent but in the laboratory sometimes a human being, another animal, or even an object. Since the 1960s, scientists have been able to produce lifelong changes with brief early interventions; rats receiving less nourishment in their first three weeks remain smaller than others. Baboons overfed in infancy gain weight in early adulthood as though by a delayed causal mechanism. Lucas believes nutritional programming may have effects on human health.27
Are we not only what we eat, but what we ate? Fragmentary but intriguing evidence exists. Inflammatory bowel diseases may be linked to very early nutrition. Studies have shown that ulcerative colitis and Crohn’s disease (a chronic inflammatory disease of the intestines) are less common among those raised on breast milk. Another study suggests that artificial feeding has been responsible for the long-term increase in juvenile diabetes; the authors attribute a quarter of all cases to bottle-feeding. Because childhood infections of the ear and the lower respiratory tract may lead to chronic respiratory illness, the early benefits of breast-feeding can carry through to later life. There are also indications that breast milk may reduce the risk of malignant lymphomas, multiple sclerosis, and coronary artery disease. Exclusive breast-feeding for at least four months after birth has been shown to reduce the risk of childhood asthma significantly. The number of studies in each case is small, and breast-feeding advocates in medicine also acknowledge that human milk is no panacea; it probably only delays the onset of allergies, for example. But the studies have still contributed to medical organizations’ overwhelming support for extended breast-feeding.28
Industrial and postindustrial culture also affects the timing of feeding. For most of human history, there was no supplementary feeding, and infants were allowed access to milk frequently, with short intervals between feeds. Most of today’s breast-feeding mothers, especially in economically advanced nations, nourish their infants fewer times each day. The original style is healthier for babies, helps prevent jaundice, and it’s less likely that overenthusiastic sucking by hungry infants will cause the mother pain. While the standard U.S. breast-feeding handbook now recommends nursing “at least every two or three hours,” this is not feasible for many employed mothers, though their stored milk may be fed to their infants by sitters.29
Breast-feeding may also protect mothers in ways that are not fully understood because our culture—even among most breast-feeding mothers—departs from many of the patterns present during the evolution of our species. Katherine Dettwyler has argued persuasively that human infants follow a “hominid blueprint” for extended nursing. Studies of other living primate species have established a formula linking weight at maturity to age of weaning. For human weight, the formula predicts, conservatively, a natural age of weaning of from 2.8 to 3.7 years, varying with adult female weight. Studies of gestation time and weaning suggest that in humans, as in chimpanzees and gorillas, breast-feeding would last at least six times as long as gestation rather than for nine months, as many medical texts assert. Other primate studies link weaning strongly with the eruption of the first permanent molar; this happens to human children, regardless of nutritional status, at the age of 5.5 to 6 years, about the time they acquire adult immune competence. Thus infants are biologically inclined to continue nursing until their third or fourth year or even longer. Katherine Dettwyler believes there may be benefits for both mothers and infants in prolonged lactation; she cites research that suggests that small but significant numbers of mothers in industrial societies continue suckling their children discreetly well beyond the second and third year. Indeed, in 1999 a Chicago newspaper found a local four-year-old preschooler with his own computer who scandalized guests at a parental party by taking such a milk break, raising his fists “Muhammad Ali—style, and declar[ing], ‘That was sooooo good.’” And despite the reservations of some psychologists, there seem to be no physical or mental ill effects among late-nursing children. One of them in Chicago grew up to be a massive offensive linesman at Texas A&M who says he has not been sick since eighth grade and has no memories of nursing.30
Because this ancient pattern of breast-feeding is difficult to study in Western societies, we still are not sure of its effects on maternal health. There is some evidence that prolonged breast-feeding has protective value against breast cancer, especially among premenopausal women. Societies in which breast-feeding is widespread tend to have lower rates of breast cancer, and when infants are fed unilaterally, the suckled breast is significantly less likely to develop cancer. Breast-feeding is also thought to reduce ovarian and endometrial cancer. Since the choice of whether to bottle-feed or breast-feed may be associated with so many differences in diet and other practices, these findings are more suggestive than conclusive. But it still seems likely that future clinical studies will confirm some significant long-term differences in the health of breast-feeding and bottle-feeding women.31
There is a clear benefit for women in natural regulation of birth patterns. In developing countries where mechanical or chemical contraceptives may be unavailable or too costly, prolonged breast-feeding—because it often inhibits ovulation—can space children naturally three or four years apart, the pattern among early hunter-gatherers. There are good evolutionary reasons for this pattern: sibling competition for a mother’s milk endangers the survival of both infants and hence of their genes. The hormone prolactin, which stimulates milk production, is produced by the hypothalamus in response to the infant’s suckling. Prolactin also suppresses ovulation and menstruation (the medical term for this effect is lactational amenorrhea). Because they generally gave their children to wet nurses rather than breast-feeding them, upper-class women in early modern Europe had much larger families than poorer women did. Swedish peasant women, and no doubt many others, were aware of this contraceptive benefit. But even in cultures where breast-feeding remains the norm, ovulation sometimes resumes while a mother is still nursing. Suckling at longer intervals appears to allow prolactin levels to sink; it is more frequent, on-demand suckling that keeps prolactin levels elevated.32
THE OUTLOOK FOR THE BOTTLE
What seemed to be an elementary chemical and mechanical challenge— duplicating the constituents of mother’s milk and making it available to infants—has become a ubiquitous technology that changes both the bodies and the social lives of most men and women in industrial societies. Nineteenth- and twentieth-century technology did not begin humanity’s cultural tinkering with ancestral patterns of infant feeding; we have seen that wet nursing and feed
ers were widespread in Europe. A baby nourished today with the latest version of infant formula may lack many nutrients and hormones unique to mother’s milk, but it is certainly better off than its ancestors might have been with the often deadly mixes of their time and has far better prospects for health than an eighteenth-century child farmed out to a wet nurse miles away. And even breast-feeding advocates have made some room for artificial feeders. Bottles and other feeding devices are now recommended for administering the stored milk of nursing mothers while they are at work. While the medicalization of infant feeding a hundred years ago introduced some dubious concepts and practices—for example, strictly scheduled breast-feeding—that interfere with infants’ natural demands and the beneficial synchronization of mothers’ and infants’ sleeping cycles, scientific research has also corrected errors. For example, in Europe and elsewhere, yellow early milk, called colostrum, was once discarded as poisonous to infants. While until recently some hospitals gave newborns sugar water solutions instead, English physicians had discovered the excellent nutritional value of colostrum by the early eighteenth century. Some historians believe those physicians’ publications helped shape modern forms of family affection with maternal breastfeeding at their core.33
By 2000, the bottle and formula industry had achieved a paradoxical relationship with medical leaders and breast-feeding advocates. The boycott of Nestlé for its Third World marketing remained in effect but was less visible in the press. The manufacturers, for their part, conceded the superiority of human milk for infants in principle but still promoted their products through hospitals and encouraged supplemental feeding. Medical authority, once firmly on the side of the bottle, now supports breastfeeding. After declining in the 1980s, the proportion of breast-fed newborns in the United States rose to 59.7 percent by 1995, nearly equal to its 1982 level, but now the rate of breast-feeding is highest among more affluent and older women. Even in 1995, only 21.6 percent of infants were still breast-feeding at six months. There is still a vast domestic and international market for bottles and infant formula, $3 billion annually in the United States alone.34
The infant formula industry has achieved a curious symbiosis with its foes, the breast-feeding advocates. Even with the best lactation counseling and banked human milk from volunteers, at least a small number of infants will need formula. Our knowledge of the new revival of breastfeeding in the 1990s comes not from the U.S. Census Bureau or the Public Health Service but from a survey conducted by the Ross Products Division of Abbott Laboratories, a major producer of formula. Formula companies not only sponsor conferences on breast-feeding but fill a gap in consumer information: in Britain one formula maker sent out to parents 300,000 articles in support of breast-feeding. Companies openly acknowledge the superiority of breast milk and try to approach its composition more closely, though they obviously cannot replace the mother’s enzymes and antibodies. But this research and improvement are also controversial, and not just because they may encourage bottle-feeding.35
The long-chain fatty acid DHA, present naturally in mother’s milk, is known to help develop infants’ brain cells. The WHO and the Commission of the European Community have endorsed it, and premium formulas overseas include it. The U.S. Food and Drug Administration approved it for inclusion in formula in 2001. Yet there are more than 160 other fatty acids in breast milk that do not appear in formula, and scientists are still unsure whether synthetic and natural nutrients are equivalent. The formula makers’ goal has changed; where Liebig aimed to duplicate human milk, manufacturers now seek to match the “performance” of breast-fed babies. The position of the U.S. Food and Drug Administration appears in a headline in its consumer magazine: “Second Best but Good Enough.”36
And as formula makers extol and emulate breast milk, even scientific advocates of breast-feeding are adding cautions. Alan Lucas, the infant nutrition scientist whose work on nutritional programming is some of the most powerful evidence against the bottle, recently called attention to studies concerning the long-term effects of early feeding on heart disease. When adult baboons were fed a typical Western high-fat “unphysiologic” diet, those that had been breast-fed in infancy developed more fatty arterial streaks than those that had been formula-fed. Human studies also suggest that prolonged breast-feeding increases the risk of cardiovascular disease in men. And environmental hazards may create new risks. In the 1960s, strontium-90 was found in Americans’ breast milk, and dioxin was found in the 1980s. A Dutch study in the late 1990s revealed that polychlorinated biphenyls (PCBs), a neurotoxic threat to intelligence and learning, appeared in the bloodstreams of breast-fed children at a concentration 3.6 times higher than that found in the bloodstreams of their bottle-fed counterparts. Though these results are tentative and Lucas cautions against drawing any inference against breast-feeding, they do show that as we change our environment inadvertently, we modify ourselves unexpectedly as well.37
Despite all the evidence against it, the bottle is likely to remain the first technology of a substantial part of humanity. It gives fathers a nurturing opportunity denied them by nature. (In the 1980s, a prominent American male physician even invented the Baby Bonder, a bib of terrycloth and fleece with nipple openings through which men could nourish their children.) Formula is certainly superior to the animal milk that traditional societies used as a breast-milk substitute. Because American physicians still have limited training in helping with breast-feeding technique, but extensive information on prescribing formula, and because American insurers are reluctant to pay for lactation consultants, mothers are likely to breastfeed for a matter of months rather than the year or more that medical societies as well as evolutionary biologists and epidemiologists recommend.38
One reason is that breast-feeding, like many other techniques, conveys conflicting values. Many of its advocates consider it a feminist act, a rejection of the contemporary sexualization of the breast. It is an affirmation of women’s autonomy and unique capacity in the face of medical and commercial interests that initially sponsored “scientific” feeding, from the patriarchal Dr. Liebig onward. But breast-feeding, as we have seen, has also attracted male (and conservative female) campaigns to restrict married women to a nurturant domestic sphere. The health benefits of nursing for mothers appeal to liberals’ greener side, but if expressed too forcefully they can also appear to some progressives as holistic fascism. The bottle, and modern infant formula, are much easier to oppose in the developing world than in Western societies that do not seem prepared to pass legislation guaranteeing nursing mothers equality in careers, or even decent accommodation in public spaces. Even where breast-feeding could save money for governments, as in U.S. income-supplement programs for women, infants, and children, authorities have not promoted it vigorously. Bottle-feeding may exact a high price in medical costs, but as long as medications exist to treat the illnesses it increases, the technological treadmill will roll on.39
On balance, then, the twentieth century gave a scientific and moral victory to breast-feeding but a de facto social and economic victory to bottle-feeding after the first few months of life. But breast-feeding advocates, scientific and lay, have made remarkable gains in transmitting and improving a sometimes challenging technique over a technology that, for all its progress, has remained merely adequate. Now there is the prospect, equally heartening and disturbing, of cows genetically engineered to produce human milk. What Liebig’s chemistry was to the nineteenth century, molecular biology will surely be to the twenty-first. But even if the children are healthy and the cloned cows contented, and even if women could take safe medication that conferred on them the benefits nursing provides, could the transmission of one of the most profound human skills become threatened?40
CHAPTER THREE
Slow Motion
Zori
WHILE NURSING IS our first technique—and, for many of us, the bottle our first technology—the first rite of technical passage for the greater part of humanity is the use of footwear. We are not th
e only animal that uses external things to modify its body: hermit crabs, for example, inhabit discarded shells of other creatures. Nor are we the only animal that makes things to modify its body: chimpanzees sometimes use large leaves for walking, as they do for eating. But we are the only animal that both makes and needs these objects for its well-being. None changes us more significantly than shoes. Footwear alters the foot itself, sometimes disastrously, but it helps prevent conditions that may have even worse effects. It changes not only our contact with the world but our perception of it. And through the meanings which have been assigned it, it affects how we relate to others socially.
The footwear consultant and columnist Dr. William Rossi has identified seven and only seven styles of shoe: moccasin, sandal, boot, clog, pump, mule, oxford. The moccasin, a piece of leather wrapped around the foot and fastened with a leather thong or other material, is thought to be the oldest foot covering. But sandals—pieces of leather or other material held on the foot with straps or other devices—are almost as ancient. Other footwear forms are combinations or extensions of the moccasin and sandal. Our word sole is derived from the Latin solea, a sandal made of heavy leather or woven straw with loops for straps of plaited straw or rawhide, and many of our other shoe styles are moccasins sewn or bonded to a sandal platform. North American Indians had three styles: moccasins with continuous soft soles, hard-soled moccasins, and (especially in what is now the U.S. Southwest and parts of Central America) sandals of hide or plant materials.1
Because true moccasins are unsuitable for contemporary paved roads and sidewalks, the sandal remains the most ancient form of footwear in common use. In fact, rubber and plastic sandals are among the most plentiful manufactured objects on the earth’s surface. No official international statistics are available, but the Canadian shoe industry specialist Phillip Nutt estimates that in the last sixty years, the earth’s factories have produced fifteen billion to twenty billion pairs. The thong sandal, with two straps anchored at three points, forming a V with its apex between the first and second toes, is known to nearly every nation and social class. The variety of its names in English alone reflects its ubiquity: zori (zories is the official term of the U.S. Customs Service), thongs (originally Australian), flip-flops (originally New Zealand), slippers (Hawaii), slaps, flaps, beach walkers, and go-aheads. On one Caribbean luxury cruise, the writer David Foster Wallace counted over twenty makes. Used apparently independently by societies around the world for millennia, the thong, or zori, went into mass peacetime production more than fifty years ago thanks to new materials and manufacturing techniques. Like other body technologies, it helps shape body techniques. But to understand the zori, we must start by asking why people need even this simplest of footwear.2