Is paleopathology a relevant predictor of contemporary health patterns? • 15 



skeletal estimators of age at death to underestimate the age of 

 old adults. Hence, there is reason to question the common 

 proposition that the amount of bone lost by modern groups 

 from ages 20 to 90+ years was lost over only three or four 

 decades in archeological native samples (Ericksen 1982). 

 Nevertheless, measures of cortical thickness from such sam- 

 ples show lower values than cither archeological black sam- 

 ples or modem cadaver collections. PfciiTer and King (1983) 

 studied femora, metacarpals, and lumbar vertebrae of pre- 

 historic American Indians using a cross-sectional approach, 

 and argued that mean adult values for all measures were 

 below expected normal values. 



High incidences of vertebral compression fractures have 

 been demonstrated among prehistoric lnuit(Merbs 1983) and 

 Iroquoians (Pfeiffer 1984). Indeed, such compression frac- 

 tures appear to be relatively common among all northern 

 native skeletal samples in which they have been studied. 

 Note that such samples are believed to represent primarily 

 young adults, with very few survivors over age 55. 



This phenomenon of low cortical mass has been explored 

 in modem Inuit populations. While initial study of Alaskan 

 Eskimos suggested that these lower bone densities were tied 

 to a high-protein, high-phosphate, low-calcium, sea mam- 

 mal diet (Mazess and Mather 1974), subsequent studies of 

 Canadian Inuit (Mazess and Mather 1975) and southern 

 Alaskan Eskimos ( Harper et al . 1 984) show that the bone loss 

 is not associated with a very specific dietary regime. Among 

 these ;groups there is some variability in young adult peak 

 bone mass, but all show an accelerated rate of bone loss with 

 aging. Harper et al. note that, despite the potential, these 

 Eskimo groups do not display a high incidence of osteoporo- 

 tic fractures. They postulate that this might be due to short 

 life expectancy. 



Among Indians, a small cross-sectional study of southem 

 Ontario natives demonstrated significantly lower cortical 

 bone density in postmenopausal Indian women (N = 34) than 

 in postmenopausal white women (N = 43) (Evers et al. 

 1985). However, no osteoporotic fractures had occurred 

 among the Indian women (Evers, pers. comm.). There was 

 no attempt to identify compressed vertebrae, which can func- 

 tion as an early, asymptomatic indicator of osteoporosis. 



If low adult bone mass is a predictable characteristic of 

 native populations, it may be relevant to predicting an in- 

 crease in the incidence of senile osteoporosis as native life 

 expectancy increases. Low peak adult bone mass has been 

 observed for other Asiatic-origin populations, through both 

 growth studies (Gam et al. 1964; Eveleth 1979) and adult 

 radiographic screening (Nordin 1966; Yanoet al. 1984). De- 

 pending on geographic location, Asiatics may show os- 

 teoporotic fracture rates that are extremely low, or higher 

 than those of whites (Wong 1966; Chalmers and Ho 1970). 

 Certainly diet, intensity of physical work, and the presence 

 of confounding diseases such as tuberculosis will influence 

 the probability of fracture in these groups. Obesity has been 

 demonstrated to have a protective effect, helping to maintain 



Zagreb Paleopathology Symp. 1988 



postmenopausal bone mass (Ribot et al. 1988). Many native 

 populations currently show high weights for height (cf. Nu- 

 trition Canada 1 980), and so may not experience the expected 

 magnitude of postmenopausal bone loss. However, future 

 public health measures are likely to emphasize weight re- 

 duction as a generally desirable goal. Should populations 

 achieve that goal, the paleopathological evidence of Native 

 Americans is consistent with a prediction of a relatively high 

 incidence of osteoporotic fractures as the contemporary pop- 

 ulation ages. 



There is thus far no metabolic mechanism known to link 

 low cortical bone mass to diabetes mellitus or any other 

 component of the "New World Syndrome." Women with 

 non-insulin-dependent diabetes may be at risk for bone loss, 

 possibly because of the adverse effect of insulin deficiency 

 on protein synthesis (Nordin 1983). Diabetics may also show 

 high cortical bone mass (Meema and Meema 1967). Obesity, 

 diabetes, and gallstones may all be directly associated with 

 abnormalities in protein metabolism. Insofar as protein and 

 calcium metabolism are interactive, consideration of a link 

 with bone mass maintenance is not unreasonable. 



Population differences in endocrinological activity have 

 not been oriented toward explaining differences in adult peak 

 bone mass or rates of bone loss. However, apparent popula- 

 tion differences in steroid control are consistent with ob- 

 served pattems of bone mass acquisition and loss (Purifoy 

 198 1 ). Blacks, who appear to tend toward a set point favoring 

 an increased ratio of androgens to glucocorticoids, exhibit 

 increased peak bone density, and frequently a slower rate of 

 bone loss. Asiatics, conversely, show decreased androgens 

 (both groups described relative to whites) and increased 

 glucocorticoids. Such fundamental differences could explain 

 the observed tendency toward lower peak bone mass in Asia- 

 tics. 



Conclusions 



The contribution that paleopathology can make directly to 

 the health of Native Americans is limited by the perspective 

 of modem health sciences. When population dilTercnces in 

 disease prevalence are associated solely with ethnic atTilia- 

 tion, there is a tendency for researchers to look for behavioral 

 or environmental causation, ignoring the more difficult mat- 

 ter of genetic predisposition. The research necessary to iden- 

 tify a racial or genetic component is extremely difficult to 

 design, owing to the difficulty of identifying Mendelian pop- 

 ulations in the past or present and the lack of information on 

 the genetic basis of most diseases. Nevertheless, the ac- 

 knowledged need for race-specific standards of child devel- 

 opment plus acknowledged racial differences in morphology, 

 physiology, and biochemistry will continue to push popula- 

 tion health studies in this direction (Watts 1981). The quan- 

 tification of contemporary native groups' genetic link with 

 pre-European native populations will allow a clearer weigh- 

 ing to be placed on paleopathological evidence. 



