Nutrition and Diet. Damage from Agriculture. Iron Deficiencies

The degree to which this sequence of declining fallow/ crop ratios represents a historical sequence, as opposed to mere use of different environmental potentials, is debated. What is clear is that significant agriculture involves massive inputs of labor well in advance of any rewards for that labor.

Extensive systems of agriculture can damage land if population density forces people into fallow/crop ratios that the soil cannot tolerate, especially if people do not understand the increasing inputs involved. It is also clear that irrigation has, over long periods of time, resulted in the elimination of farming and sometimes of all plant growth in some areas because of the build-up of salt in soil from evaporation. Increasing exploitation of fossil fuels and chemical fertilizers or the expansion of irrigation systems beyond the capacity of freshwater supplies may do the same in the long run.

The processes of agricultural intensification were once theorized largely as a series of inventions (hoe, plow) permitting more sophisticated and more efficient use of resources. The alternate theory suggests that the behavioral-ecological succession probably resulted from increasing demand, motivating the development of technology to increase supply, rather than the other way around. The question of the primacy of population growth or technological innovation as the major force for change depends on resolution of a disputed question: What was the relative efficiency of long-fallow and short-fallow agriculture, and hence would the succession have been desirable?

What is clear, however, is that the intensification first of hunting and gathering and then of farming appears to have resulted in a decline in the quality of human nutrition. This decline can be documented in several ways: by the known ecology and nutritional value of certain foods, by observations of the diets of various populations, by medical examination of living individuals, and by paleopathology (observation of the comparative frequency of certain pathologies in human skeletons from different times).

Modern hunter-gatherer diets, largely deprived of large game, still match affluent Western diets in consumption of meat protein and far exceed modern Third World diets in meat consumption. Modern hunter-gatherers are generally far better nourished in other respects (vitamins, minerals) than contemporary small-scale farmers and modern Third World populations.

Compared to modern hunter-gatherers, farmers—particularly peasants in the modern Third World—widely display increased signs of poor nutrition as a consequence of overdependence on various cereals and root crops associated with declining dietary variety because all of the major crops provide incomplete nutrition.

Kwashiorkor (malnutrition) and marasmus (chronic undernourishment), as well as vitamin deficiencies, occur far more frequently among farmers than among remnant hunter-gatherers in the modern world. (Because their diets are lean, hunter-gatherers also avoid the problems of overconsumption of fats, calories, and salt that plague modern affluent populations and result in conditions such as obesity, diabetes, and high blood pressure, all unheard of among “primitives.")

The problem is compounded by an increasing load of parasites accompanying sedentism, storage, domestication of animals, and increased population density of both animals and people. For example, hookworm, a clearly density- and sedentism-dependent parasite, is a major cause of blood and iron loss; and tapeworms associated with animal domesticates also rob the body of nutrients. Domestic animals are also blamed for the appearance of most of the major modern plagues such as tuberculosis and many others that can cause major drains on nutrition.

Iron Deficiencies. The skeletons of prehistoric hunter-gatherers do show occasional signs of iron deficiency and some vitamin deficiencies, but subsequent populations almost always show significant declines in nutritional status. The overall (although irregular) tendency in human evolution displayed by skeletons since the emergence of Homo sapiens has been for stature to decline during the broad-spectrum revolution and the adoption in farming and during much of the rest of history until the last 150 years or so.

In fact, the shortest populations in human history have lived in the last few centuries and in the modern world. Signs of iron deficiency and other dietary deficiencies increase dramatically with the origins of agriculture. Signs of increasing in-utero and juvenile malnutrition include delayed juvenile growth and juvenile osteoporosis.

Signs of infection, including periostitis, osteitis, and osteomyelitis as well as specific infections such as yaws/syphilis and tuberculosis, also increase through time. Specific episodes of stress recorded in teeth show an increasing frequency with farming, which is consistent with a decline, not an improvement, in the reliability of food supplies.

The evolution of state-level societies (usually called "civilizations"—a vague reference to "progress"—but, in fact, better defined by cities, specialists, class stratification, extensive trade, limited or exclusive ownership of land or other major resources, and government control by force) poses additional nutritional problems. In fact, the poor of civilized societies display a higher level of undernutrition or malnutrition than do earlier or less-complex societies.

Trade associated with civilizations has resulted in the dissemination of staple crops from their centers of origin around the world (corn, wheat, barley, potatoes, and others) to the benefit of recipient populations. On the other hand, trade and transport of food have often resulted in taking nutrients from areas where they are needed. They have also resulted in processing, reducing bulk and weight in transport but also reducing the content of all nutrients except calories. Moreover, trade itself can be fragile for natural or political reasons.

Areas of the world have seen their local economies distorted by colonial powers or by the need to sell foods on fickle international markets. Countries relying increasingly on specialized crops to sell in order to import food often trade quality for quantity, and they often suffer from poor exchange ratios, contributing to undernutrition and malnutrition. Some countries have seen their land converted from their own subsistence needs to the production and export of beef or other cash crops for consumption in wealthy nations.