Why We Get Sick (23 page)

H
uman nature was formed in what anthropologists have recently termed (following a 1966 suggestion by psychiatrist John Bowlby) the
environment of evolutionary adaptedness
, or
EEA
. Despite their frequent reference to the EEA, anthropologists differ widely about what it was like. They cannot
directly observe the ways of our ancestors of tens of thousands of years ago or the effects of environmental conditions on the human genetic makeup. They must base their conclusions on indirect evidence: skeletal remains, stone tools, cave paintings, and information about modern groups with seemingly primitive economies and social conditions.

The shortage of information is serious. What are the historically normal conditions of human childbirth? This is just one of many basic questions for which there is no assured answer. We suspect that the correct answer to many such questions is,
it was highly variable
. Attitudes toward childbirth differ enormously among different cultures today, and there is no reason to believe they were any less variable a hundred thousand years ago. They must also have been quite variable within social groups. The solicitude offered to a chiefs wife no doubt differed from that proffered a concubine captured from a hostile tribe. Giving birth during times of plenty in a settled camp might have been rather different from giving birth in leaner times or during travel to a new location.

We also suggest that the correct answer to other important questions is,
it varied
. What sorts of rewards went to gifted poets, artists, or others of high intellectual attainment, compared to those who were good hunters or warriors? How stratified, by family connections or merit, were the socioeconomic conditions? Was inheritance matrilineal or patrilineal? What were the child-rearing customs? What were the religious doctrines and constraints, and how strong a factor was religion? These questions would have vastly different answers in different societies in the EEA. There is no one “natural” way of human life.

Despite great variation in the human adaptations to a variety of EEA conditions, the available evidence does support some generalizations. Social systems were constrained by economics and demography. No elaborately stratified societies with hereditary class structures were possible in the Stone Age, because groups that had to gather their food from within walking distance necessarily remained small. Likewise, no chief of a nomadic band can have dozens of wives when the band only includes a few dozen people. Prior to the development of agriculture, no chief could control enough land, wealth, and people to build cathedrals or pyramids.

Social systems were also constrained by the physiological and structural differences between the sexes. The physiological costs of
reproduction involved in pregnancy and lactation are borne entirely by women. By what rules were the economic costs of reproduction apportioned? Again, we suggest,
they varied
. On the basis of what we know about current human groups, husbands no doubt contributed significantly in most cultures, but in others a mother’s brothers and other relatives made a greater contribution. Likewise, the gross physical differences between the sexes imply behavioral differences. The greater size and strength of men suggest that these attributes provided important competitive advantages, especially in the competition for mates. We discuss this and related matters in
Chapter 13
.

Economic necessity often demanded that adults and older children of both sexes spend much of their time searching for and preparing food. It is usually assumed that men did the hunting and women the gathering in hunter-gatherer societies, although the antiquity and importance of big-game hunting have been exaggerated in fictional accounts of Stone Age life. Archery and other weapons effective against such animals as deer were in fact not invented until late in the Stone Age. Dogs, which can play crucial roles in many hunting techniques, were not common human associates before about fifteen thousand years ago. Meat or hides from large animals may often have been procured not by hunting but by scavenging or stealing from other predators.

The mainstay foods in the Stone Age would seem to us inedible or too demanding of time and effort. We would find most of the game strong-tasting and extremely tough. Most of us have little appreciation of the tedious skinning and butchering it takes to turn a wild animal carcass into a serving of meat. Many wild fruits, even when fully ripe, are sour to our tastes, and other plant products are bitter or have strong odors. We find them unpleasant thanks to our adaptations that make us avoid toxins, as discussed in
Chapter 6
. Most natural human foods require a far greater labor of preparation and chewing than the foods we eat now. Domesticated animals and plants have been artificially selected to be tender, nontoxic, and easily processed.

Despite the abundance of foods available in the EEA much of the time, the village elders would have been able to remember times of severe famine. Actual starvation may have been rare, but deaths from the combined stresses of disease, malnutrition, and poisoning by the excessive consumption of marginally edible plants were probably
common. These same stresses also would have caused abortion of fetuses, curtailment of lactation, reduced fertility, and actions such as infanticide and the abandonment of the old or impaired.

In addition to xenophobic conflict with other groups, social strife within groups, famines, and toxic diets, there were many other environmental stresses. Our ability to tolerate the atmospheric pollution of modern cities may owe much to our many thousands of years of exposure to smoke toxins from woods and other fuels. Imagine living in a hut with a fire on the floor and only a small hole in the roof. Atmospheric pollution was different in the EEA, but it was substantial and real. We would find the odors of a Stone Age settlement most unpleasant. There were no soaps or deodorants, no flush toilets, or readily cleanable chamber pots, or any installations worthy of the term latrine. Wastes of various kinds were taken away to some customary distance and no further. Other wastes simply accumulated where they were produced. The average Stone Ager lived in a dump and moved away when conditions got really bad.

Children grew up, and adults lived out their lives, in the constant awareness, and sooner or later the personal experience, of woeful illness, painful injury, physical handicaps, debilitation, and death. There were no antibiotics, tetanus shots, or anesthetics, no plaster casts, corrective lenses, or prosthetic devices, no sterile surgery or false teeth. Our remote ancestors had few cavities, but they had many other dental problems. Teeth could be injured or lost in accidents, and they could literally wear out before what we call middle age. Abrasive plant products can wear molars down to gum level, as seen in some fossil skulls and even in some contemporary groups.

Lest it seem that our account of the EEA is merely a selection of items for a catalog of horrors, we should emphasize that we are discussing our fully human ancestors, with a fully human capacity for pleasure as well as pain and a fully human intellect. The bonds of kinship and friendship could be strong and a source of great pleasure and security. In seasons of plenty there would be abundant time for play: games, music and dancing, storytelling and poetry recitals, intellectual and theological disputes, and the creation of ornamental artwork. The cave paintings at Lascaux, France, created perhaps 25,000 years ago, have been described by anthropologist Melvin Konnor as
“a Paleolithic Sistine Chapel” that impresses a sensitive observer “whether religious or not—whether expert or not—with a strong sense of the holy.” And our ancestors also had the ability to look on the bright side in times of adversity and to find reasons for laughter. Mark Twain’s hero Sir Boss in A
Connecticut Yankee in King Arthur’s Court
lamented having to listen, at a sixth-century campfire, to the same jokes he had already found tiresome in the nineteenth. We suspect that if he had gone back to the Stone Age he would have groaned at many of the same jokes.

Y
ou have now spent several hours reading this book. Do you realize how much thoroughly abnormal use of your eyes this feat required? Was the light source the sun, with its normal spectrum? Probably not, at least not entirely. How much muscular exertion did you expend during those hours of reading? How could you be so inactive for that much time without jeopardizing your well-being, perhaps your life, by having spent inadequate time and effort in vigilance against enemies and in foraging for food? But you are in fact well fed? How long did it take to pick or dig or hunt or fish for your last meal? How much shelling and grinding and butchering? If the food was cooked, how long did it take you to gather the fuel and kindle the fire? How much sweating and shivering have you done in the last twenty-four hours? What’s that about thermostatically controlled heating and air conditioning? How bizarre! And what are the long-term consequences of such meager challenge to your body’s built-in temperature controls?

As the last chapter (we hope) made clear, only the grossly uninformed or irrationally romantic would think we were ever better off than we are now. Rousseau’s noble savage and the Flintstones’ merry capers are delightful in escapist fiction, but the reality was painful and sad compared to our lives today or even to when farming first replaced nomadic scrounging. Agriculture led to urban civilization, with its durable architecture and associated fine arts, and the nautical and other technological advances that permitted exploration of distant
lands. The domestication of hoofed animals enabled one worker to do jobs that would previously have required several. It also contributed to revolutionary advances in transportation. Continuing technological advances have led to ever greater freedom from want and freedom of movement for ever larger numbers of people.

The long-term consequences of the soft and gratifying lives we now enjoy are mostly beneficial or harmless, but many of the advantages we enjoy today are mixed blessings. Benefits have costs, and even the most worthwhile benefits can be costly to our health. For a good example we need look no further than the effects of lower mortality rates in early life. Because fewer people die young from smallpox, appendicitis, childbirth complications, and hunting accidents, the death rates from old-age afflictions like cancer and heart failure are much higher now than they were a couple of generations ago. This is largely because a higher proportion of people live to the ages at which the body becomes especially vulnerable to these illnesses. The price of not being eaten by a lion at age ten or thirty may be a heart attack at eighty. Modern practices of food production, medicine, public health, and industrial and household safety have drastically improved the prospects of surviving to old age. Unfortunately, the increased effects of aging are not the only bad aspects of the good life.

Novel environments often interact with previously invisible genetic quirks
to
cause more variation in phenotypes, some of it outside the normal range. As described already in the chapter on genetics, these abnormalities arise only when a vulnerable genotype encounters an environmental novelty. Novel physical, chemical, biological, and social influences will cause problems for some people and not others or will have different effects on different individuals depending on their specific genetic makeup. We have already discussed some human examples; for instance, the genetic quirks that cause myopia impose problems in literate societies, but they caused no difficulties for our ancestors.

Our ways of getting food changed the environment in ways that created new problems. Thousands of years ago some of our ancestors hunted wild goats or cattle. Hunters followed herds for hours in the hope of killing one of the animals for food, hide, and other resources. Sometimes they may have found, early in the morning, the same herd they had been following the day before. If animals can be followed for two days, why not three, or a week, or a month? How long would this go on before the hunters would start thinking of the herd as their
own, driving off wolves or rival groups of hunters or other predators and chasing strays back into the group to maintain a large herd? This process gradually converted hunters into nomadic herdsmen.

Other ancestors were more vegetarian and found that some plants could produce a lot more food if they were intentionally planted for later harvest. Plowing, weeding, fertilizing, and selecting variants with the highest yields soon became standard practice and resulted in steadily greater and more reliable food production. It has been supposed that local increases in population may have encouraged the invention of agriculture or its adoption from neighboring peoples. Whether this is true or not, agriculture permitted the maintenance of much denser and more sedentary populations than could be supported by hunter-gatherer economies. Increased population density then became a source of other problems, some of which will be discussed in this, others in the next four chapters.

P
aradoxically, the increased food production made possible by herding and agriculture resulted in nutritional shortages. There are more calories and protein in a bushel of wheat than in a handful of wild berries, but there is more vitamin C in the berries. If wheat provides most of the calories and protein for a farming community, deficiencies of vitamins and other trace nutrients are much more likely to arise than they would be with the more diversified diets of hunter-gatherers. If the wheat or other agricultural produce is also used as feed for the domestic animals that provide meat or eggs or milk, the farmers’ meals are much improved, but shortages, especially of vitamin C, remain a threat.

Iceland is a good example, with a vitamin C problem that lasted well into this century. Icelandic farmers raised mainly sheep, which grazed the wild grasses of the countryside. The more successful families might have had a dairy cow, but mutton provided a large part of the diet, and wool was the chief commercial export, sold mostly to Danish colonials. The money so earned allowed the farmers to import flour and such luxuries as coffee and sugar. Nothing in the list so far contains vitamin C, which was provided mainly by blueberries and other wild plant foods. Unfortunately, the supply of these commodities
was strictly seasonal. During winter and spring, when diets were notably lacking in vitamin C, many a seemingly robust and healthy Icelandic farmer would start bleeding from the gums and feeling lethargic and depressed, the usual symptoms of scurvy. Some members of a family would sicken and others not, with the severity of scurvy varying greatly.