Nonspecific Indicators of Stress

Within the past two decades there has been an explosion of interest in applying the so-called nonspecific indicators of stress to questions of community health. These indicators range from those that apparently mark episodes of acute stress and recovery, such as Harris lines and dental defects, to those that are associated with chronic mal- or undernutrition. Each type of change has been observed to be associated with disadvantaged health status in modern clinical examples, with predisposing factors including nutritional inadequacy, infectious disease, and even severe emotional episodes. Working with ancient materials, the observer cannot precisely determine the cause of a specific condition, but instead assumes that a sample with more evidence of nonspecific stress is less advantaged than one with fewer indicators of poor health. The popularity of this approach has been influenced by an emphasis on population biology in physical anthropology, as well as by archaeological interest in human ecology (Buikstra and Cook 1980; Cohen and Armelagos 1984).

Harris lines, observed as radiopaque lines perpendicular to the cortex of limb long bones, result from episodic stress. Because the lines, which can also be visualized as disks in the affected diaphyses, can remodel, they are less satisfactory indicators of poor health than are dental defects that include both hypoplastic bands and microdefects such as Wilson's bands (Rose, Condon, and Goodman 1985). Even so, Harris lines have proved useful in documenting the presence of annual periods of growth arrest, which appear to be characteristic of archaic peoples in Illinois, Kentucky, and California (McHenry 1968; Buikstra 1981a; Cassidy 1984). Such repetitive patterning is not characteristic of sedentary groups, whose storage facilities may have buffered them from seasonal stress.

A number of North American studies have focused on the biological costs and benefits of increased dependence on maize agriculture. As noted at the beginning of this essay, maize cultivation represented a late prehistoric intensification of a trend in plant utilization begun many centuries before. Estimates of relative maize dependence suggest that maize comprised a very significant part of the diet for certain late prehistoric peoples, including the Fort Ancient Late Missis-sippian communities of Ohio and Kentucky.

These studies have employed various markers of health status, including stature attainment rates in juveniles, adult stature, sexual dimorphism, cortical thickness, demographic patterning, and porotic hyperostosis, as well as the Harris lines and dental defects mentioned previously (Lallo 1973; Lallo, Armelagos, and Rose 1978; Rose, Armelagos, and Lallo 1978; Cook 1979, 1981, 1984; Lallo, Rose, and Armelagos 1980; Buikstra 1984; Cassidy 1984; Goodman et al. 1984; Larsen 1984; Perzigian, Tench, and Braun 1984; Goodman and Armelagos 1985). In general, it is assumed that populations with disadvantaged health status will exhibit slower growth, depressed adult stature, less sexual dimorphism, reduced cortical thickness, elevated death rates, and increased frequencies of porotic hyperostosis when compared with closely related groups in advantaged situations. In this context, it should be noted that the cranial porosities termed porotic hyperostosis and cribra orbitalia are usually considered to be evidence for nutritional anemias in the New World. No convincing arguments have been made for the existence of anemias of genetic origin, such as sickle-cell anemia and thalassemia, in the prehistoric Americas.

The regional studies cited earlier generally support the notion that a certain health risk was associated with the development of maize agriculture. Late Woodland agriculturalists in West-Central Illinois, for example, present evidence of disadvantaged health status in juveniles, including such features as depressed growth curves, elevated weaning age, elevated death rates, and decreased cortical thickness (in juveniles). However, as Cook (1984) pointed out, the more recent and increasingly maize-dependent Mississippian peoples in the same region show less evidence of nonspecific stress. Their only liability appears to have been a tuberculosislike pathology (Buikstra and Cook 1981), a density-dependent disease, which is most closely linked to effective population size and only indirectly reflects subsistence base.

A. Goodman and co-workers (1984; see also Lallo 1973; Lallo et al. 1978, 1980; Rose et al. 1978; Goodman and Armelagos 1985) report deteriorating health for Mississippian peoples from Dickson Mounds, located in the central Illinois River valley. It is clear, however, that the shift to maize intensification in this region does not correlate tightly with the periods of extreme ill health (Buikstra and Milner 1988). The residential sites associated with Dickson Mounds are fortified during the Mississippian period, which suggests that socially mediated stresses may have been at least as important as diet in explaining the health status of the skeletal sample excavated from the Dickson Mounds cemeteries.

Farther to the east, there is evidence of extreme maize dependence among late prehistoric populations from Ohio, Kentucky, and Tennessee (Broida 1983, 1984; Buikstra et al. 1988). Disadvantaged health status is clear for many of these same groups (Cassidy 1984; Eisenberg 1986). In fact, the population profile for the Averbuch site (Eisenberg 1986) is consistent with the presence of disease epidemics (Buikstra et al. 1988). Thus, however probable it is that Western diseases caused severe depopulation during protohistoric times (Ramenofsky 1987), there is also convincing evidence for severe ill health in at least some American native populations that clearly predates Columbian contact.

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