Characteristics of Disease and Sickness Pictures

Infections

A nomadic society of family-level foragers and hunters can be infected only by certain types of parasites (Black 1975; Cohen 1989; Eaton,

Shostak, and Konner 1988; Fiennes 1978; Lovejoy 1981; McNeill 1976). Infectious organisms must rely on plants or animals as a way of maintaining themselves and sporadically intrude on humans, producing the so-called zoonoses; or, they can live within humans, affording themselves a long time to bring about transmission from person to person, in which case they account for slow-acting, chronic diseases.

The kinds of zoonotic diseases that might have affected early humans (and do affect contemporary hunter-gatherers) are protean in their physiological effects, long term and short term. These diseases include the following: rabies, tularemia, toxoplasmosis, brucellosis, salmonellosis, trichinosis, tapeworm infestations, typhus, yellow fever, malaria, and encephalitis. As outlined by Mark N. Cohen (1989), the zoonotic and soil-borne diseases have the following characteristics: (1) they do not claim many victims; (2) they can have a severe impact on the body; (3) their rarity precludes individual immunity or resistance; (4) their independence from humans means that there has taken place no selection for less virulent forms compatible with human life; (5) they are more likely to strike adults and productive members (as compared to children) who venture into the wild, away from the camp, with severe economic and demographic consequences for the group; and (6) they have limited geographic distribution. There are a number of theoretical and informative summaries of the ecological balances that have existed between early human (and, later, fully human) communities and parasites and microorganisms of environments located in different regions of the world (Boyden 1970, 1987; Dunn 1968; Eaton, Shostak, and Konner 1988; Fiennes 1978; McNeill 1976; Wadsworth 1984).

Early family-level foragers and hunters were less vulnerable to infections that were based on a fecal-oral mode of transmission since they moved frequently and accumulated less human wastes at any one site. However, their nomadic mode precluded elaborate housing structures, rendering them more vulnerable to extremes of precipitation and temperature.

Dietary Factors and Health Implications

As discussed in chapters 1 and 2, early hominid groups undoubtedly inherited an array of food procurement practices and dietary preferences that reflected evolved "health maintaining" routines. These were complemented by other innate biological traits involving physiological responses and disposition to form learned conditioned avoidances of plant toxins and contaminated food substances, whether of plant or animals. These processes, mechanisms, and reactions that account for the healthy maintenance of an organism's chemical ecology have been viewed as constituting a biological predisposition toward or antecedent of medicine (Johns 1990). Here, it is only necessary to add that special food preparation technologies (e.g., leaching, washing, pounding, cooking) constituted extra protections against noxious effects of ingested plant and animal material.

The foraging subsistence mode is said to constitute a comparatively efficient way of producing food (Cohen 1989; Eaton, Shostak, and Konner 1988; Lee and Devore 1968). Provided population density remains low and large game animals are not scarce or exhausted, hunters and gatherers are able to obtain a high caloric yield of foodstuffs per hour of expenditure of effort at procurement. The quality of diet associated with foragers is said to be healthful, characterized as offering varied, balanced intakes of nutrients, vitamins, and minerals (Wadsworth 1984). Signs of malnutrition are generally mild and not very common, but the adequacy of caloric intake can be uncertain. Although controversial, it is generally believed that societies showing this mode of subsistence have reliable and ample sources of foodstuffs but depending on local supplies are subject to periods of famine and deprivation.

The foods eaten by family-level subsistence foragers are ordinarily coarse and tough. This produces a heavy wear on teeth, protects against caries, and can prove problematic to individuals with few or no teeth, namely, the very young and the very old. There probably existed a high reliance on human breast feeding to supply the nutritional needs of infants and toddlers, with weaning onto foods prechewed by parents. While this provided healthy diets for the child, it contributed to a heavy caloric and mineral drain on the mother with possible deleterious health consequences or at least vulnerabilities. Despite these factors, contemporary hunter-gatherers are relatively successful in rearing their children to adulthood, although life expectancy is low compared to modern standards.

In general, the relatively low caloric yield of the high-volume diets of foragers limits the accumulation of body fat, which means that leanness as compared to obesity was common. Thus their generally varied, healthful diet plus its high fiber content means that diseases such as atherosclerosis, diabetes, and cancer are comparatively rare. The relative lack of energy body reserves in the form of fat, the low energy yields of diets, and a reliance on prolonged breast feeding means that fertility among family-level subsistence foragers is comparatively low.

Other Types of Medical Problems

A figure of around 200 deaths per 1,000 infants is cited as the average rate of survival among family-level subsistence foragers (Cohen 1989). This means that approximately 50 to 65 percent of all babies are reared to adulthood. These figures naturally vary in relation to the physical environment. Although the figures do not compare favorably with those of contemporary industrial societies (infant mortality averages around 10 deaths per 1,000 infants), they match and in some instances are better than levels achieved in the historical past, especially in urban settings of civilizations. The pattern of mortality in hunter-gatherers varies in relation to the physical habitat. It is appropriate to here quote Cohen: "[There

is] a changing distribution of causes of death with latitude. In the tropics, indigenous infections are a significant source of mortality, but by most accounts starvation is rarely a cause of death, and accidents are relatively unimportant. Malaria and other diseases of greater antiquity account for a significant fraction of deaths in some societies. Hunting accidents appear surprisingly unimportant as causes of death. Such accidents as falls, burns, and (more rarely) snakebites are mentioned more frequently. In high latitudes, in contrast, famine and accidental death are significant sources of mortality" (Cohen 1989: 102).

Studies of contemporary family-level foragers indicate that so-called degenerative diseases (heart diseases, cancers, hypertension, diabetes, and bowel disorders such as peptic ulcer and diverticulitis) are comparatively rare, as are also epidemic virus diseases (influenza, parainfluenza, mumps, measles, polio, whooping cough, rubella, tuberculosis, and smallpox); the former largely a result of diet and the latter of the small size, isolation, and migratory lifestyle of the group. Studies of contemporary hunter-gatherer societies (which rely on some agriculture to be sure) strongly suggest that skin diseases, either due to insect bites or to infected injuries with resulting abscess and ulcer formation and chronicity, were an important consideration.

Given the size, social organization, and cultural ecology of small-scale forager groups, one can surmise that any number of medical events and circumstances special to such groups will influence the character of healing in them. The high level of parasitic infestations and exposure to toxins that is found in these groups (particularly among those living in low latitude) suggests that short-lasting episodes of acute illness are common. The group would have acquired experience in coping with and treating such illnesses, in the process acquiring tolerance for their manifestations. It is likely that skin lesions were common, as were secondary infections with ulceration and chronicity. Upper and lower respiratory tract infections as well as gastrointestinal infections were likely to be common. The latter were probably a result of improper cooking and contamination, although it is likely that fecal oral contamination within the group did not play a significant role.