Diet and dental caries among later stone age inhabitants of the Cape Province South Africa.код для вставкиСкачать
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 88:123-134 (1992) Diet and Dental Caries Among Later Stone Age Inhabitants of the Cape Province, South Africa J.C. SEALY, M.K. PATRICK, A.G. MORRIS, AND D. ALDER Departments of Archaeology (J.C.S., M.K.P., D.A.) and Anatomy and Cell Biology (A.G.M.), University of Cape Town, Private Bag, Rondebosch, 7700, South Africa KEY WORDS S13C, Hunter-gatherers, Africa, Fluoride ABSTRACT Stable carbon isotope measurements and incidences of dental caries are presented for three groups of prehistoric human skeletons from different regions of the Cape Province, South Africa. The isotopic analyses of bone collagen demonstrate the importance of marine foods in the diet and vary through time, across space, and according to sex. The incidence of dental caries ranges from 0% among heavily marine-dependent individuals from the south-western Cape coast, to 17.7% among skeletons from an archaeological site on the south coast. The extremely high incidence of caries in a huntergatherer population may be related to lack of fluoride in the water. 0 1992 Wiley-Liss, Inc. The health and nutritional status of hunter-gatherers may vary widely in populations living in different environments, exposed to different pathogens, and consuming different diets. This paper documents such variability among Later Stone Age inhabitants of the Cape Province, South Africa. Three Holocene groups are compared: archaeological skeletons found i) along the south-western Cape coast, between Cape Town and Elands Bay (see Fig. l),ii) at the site of Faraoskop (about 30 kilometres inland from Elands Bay), and iii) at the site of Oakhurst, about 450 kilometres to the south-east. All these sites are coastal or near-coastal. We expect that their inhabitants consumed marine foods, such as shellfish, and the meat of whales, seals, fish, and seabirds, in addition to terrestrial meat and plants. Analyses of excavated food-waste from archaeological sites indicate that plant foods, particularly the starchy underground corms of members of the iris family, and the meat of small bovids, tortoises, hyrax, and similar animals were staples (H.J. Deacon, 1976; J. Deacon, 1984; Sealy, 1986; Parkington et al., 1988).Although archaeologists know the kinds of foods likely to have been consumed 0 1992 WILEY-LISS. INC by Holocene hunter-gatherers, there remain a number of questions about the way that these resources were integrated into diets. How important were particular food items or classes of foods, such as marine resources? Do different sites, with different kinds of food-waste, represent the varied subsistence round of mobile bands of hunter-foragers, or did separate groups of people tend to exploit particular resources, perhaps in separate territories? Were Later Stone Age diets nutritionally satisfactory? What can we deduce about the health status of these people? Two methods which reflect the impact of diet on the biology of the population are employed here as a first step towards answering these questions. Measurements of the stable carbon isotope ratio (13C/12C)of bone collagen provide information about the relative importance of different classes of foods in the diet. The incidence of dental caries is determined at least partly by the nature of the diet. To deepen our understanding of prehistoric lifeways, we seek correlations between these observations on human skel- Received April 23,1991; accepted December 18,1991. 124 J.C. SEALY ET AL. Fig. 1. Map showing localities mentioned in the text. Skeletons included in the “south-western Cape coast” category come from the coastline between the Cape Peninsula and Elands Bay. Horizontal hatching represents areas where more than 90% of the grass species are C,, small circles show mixed C&, grasses, in shaded areas more than 90% of grasses are C, (after Vogel, 1978). etons and reconstructions of diet based on excavated food-waste. MATERIALS AND METHODS The skeletal sample Three sets of Holocene human skeletons are compared. The first group (74 southwestern Cape coastal skeletons) have been assembled and dated for intensive archaeometric analysis (Sealy, 1989). Most were not recovered under controlled circumstances, but in the course of building operations or other developments, and have little associated documentation. They are generally isolated burials in shell middens or sand dunes. Direct radiocarbon dating of bone collagen therefore provides a n essential archaeologicalkhronological context for the observations reported here. Inland of the shifting dunes and highly visible shell middens of the coast, fewer human skeletal remains have been recovered. Recently, a series of skeletons were found at the site of Faraoskop, about 30 kilometres inland of Elands Bay. Initially, material was collected by a local farmer, but subsequent controlled excavations were carried out by Manhire and others (Manhire et al., in preparation).At least twelve individuals are represented (Alder, 1988; Table 11, although some are very fragmentary. Six have been radiocarbon dated, all the dates falling between 2,300 and 1,900 B.P. (at two standard deviations, corrected for 613C). It seems likely that the remaining undated skeletons also fall into this time range. The site of Oakhurst in the southern Cape was excavated in the 1930s, and many skeletons recovered (Drennan, 1938a,b). Recent re-analysis suggests that at least 48 individuals are represented, 27 of them juveniles (Patrick, 1989; Table 1).In this respect the Oakhurst sample differs from that from the south-western Cape, where the skeletons selected for analysis include few juveniles. Fifteen individuals have been radiocarbon dated by direct measurements of bone collagen. Fourteen dates fall between 10,000 and 4,000 B.P.; one skeleton is circa 2,000 years old (Table 1; Patrick, 1989). Agriculture was not introduced into this region until after European settlement in the seventeenth century A.D.; all skeletons discussed here pre-date this event. Pastoralism first appeared about 2,000 years ago, so DIET AND DENTAL CARIES IN STONE AGE SOUTH AFRICA that skeletons less than 2,000 years old (in this sample, from the south-western Cape coast only) may be the remains of pastoralists or of residual hunter-gatherers. There are very few sites a t the Cape known to have been occupied by pastoralists. Only one excavation has yielded a human skeleton in association with large numbers of domesticated animals, and a slaughtering pattern indicative of stock management. Other fauna from the same site, however, include numerous seal bones and remains of other wild animals also utilised by hunter-gatherers (Klein and Cruz-Uribe, 1989). The degree of economic and social differentiation between pastoralists and hunter-gatherers is contentious (Schrire, 1980; Elphick, 1985; Parkington et al., 1986; Smith, 1986). We have no way of ascertaining the importance of domesticated animal-derived foods in the diets of isolated skeletons from the last two millennia. Carbon and nitrogen isotope analyses (Sealy et al., 1987; Sealy, 1989) have not helped us to answer this question. Thus the most recent skeletons from the south-western Cape coast may reflect diets somewhat different from those of the other individuals in this study; hunted and gathered foods, though, continued to be important. The majority of the skeletons discussed here, however, date to the period before 2,000 years ago and therefore must be the remains of hunter-gatherers. Dietary tracing using 13C/'*C ratios in bone collagen The basis of this technique has been reviewed elsewhere (van der Merwe, 1982; DeNiro, 1987). Briefly, plants utilising different photosynthetic pathways incorporate different proportions of I3C and "C from the atmosphere. These differences are inherited by animal and human consumers higher in the food web and are reflected in their bones. Measurement of 13C/12C of human bone can therefore reveal the proportions of food consumed in life derived from C3 or Calvin pathway plants (grasses adapted to temperate climates, most shrubs and trees) as opposed to C, plants (tropical grasses). In the sea, the situation is complex but marine organisms, on average, have I3C/l2C more similar to C, than to C3 systems. 125 In temperate environments, where there are no C, grasses, 13C/12Cratios in the bones of hunter-gatherers reflect the proportions of marine and terrestrial foods eaten in life (Tauber, 1981; Chisholm et al., 1982, 1983; Hobson and Collier, 1984; Sealy and van der Merwe, 1985, 1986; Hayden et al., 1987; Yesner, 1988). Stable carbon isotopes and the Later Stone Age of the Cape Province, South Africa Distinguishing marine from terrestrial resources is of value in the Later Stone Age of the south-western Cape, where the role of marine foods in the diets of coastal and nearcoastal dwellers has been a major topic of research (Parkington, 1972, 1976; Parkington et al., 1988; Smith, 1987; Robertshaw, 1977,1979).Stable carbon isotope measurements of modern representatives of important food species for indigenous Later Stone Age people confirm the distinct isotopic character of the terrestrial foodweb (which is largely based on C, plants) and the marine system. Hence in this area, as in other winter-rainfall regions, we can use 13C/12C measurements of human skeletons a s a n index of marine food consumption. The situation in the southern Cape, at the site of Oakhurst, is more complicated. This region receives year-round rainfall, and the terrestrial flora includes a n appreciable C, component (Vogel et al., 1978). We expect, therefore, that the separation in 13C/12Cbetween marine and terrestrial foods will be less clear-cut than in the western Cape. Dental caries and tooth-wear Dental caries result from a complex interaction of dietary, hereditary, and environmental factors. There have been a number of studies in which the incidence of dental caries is reported for prehistoric populations, and correlations sought with dietary factors. Some foods, particularly starchy andlor sugary ones, are known to be cariogenic. It is widely reported that caries rates among hunter-gatherers are low, but that people with access to agricultural products, with their (usually) higher carbohydrate intake, are more susceptible to caries (Cohen and Armelagos, 1984; Drennan, 1929; Goldstein, ~ ~~ UCT 199 UCT 200 UCT 201 UCT 201 UCT 202 UCT 203 UCT 203 UCT 204 UCT 204 UCT 204 (3 individuals) UCT 205 UCT 205(2) UCT 206(1) UCT 206(2) UCT 206(3) UCT 207(G) UCT 207(H) UCT 207(I) UCT 208' ' UCT 208(Gr9) UCT 208(Gr10) UCT 209 UCT 209 UCT 210(10ci UCT ~- 211 UCT 212 UCT 212 UCT 213 UCT 213(G) UCT 213(Gr16/2) IJCT 214 - _ _ -~~ UCT 215(Gr10) UCT 215(D) UCT 215(I) UCT 215'(P/Q?) UCT 216(5) UCT lZS(Q/D?) Oakhurst skeletons -10.4 - -15.7 -11.7 -13.8 -16.4 -15.9 - - -12.4 -13.9 - -15.4 -10.9 -12.3 - -11.1 -13.8 -14.1 - -12.6 -12.4 -12.3 - - -13.6 -14.5 - -13.4 -16.6 - -14.2 -12.4 -14.0 613C (Oleo) male male female juvenile male female juvenile femaIe juvenile indeterminate juvenile male male female female juvenile juvenile juvenile female juvenile juvenile male juvenile juvenile male female juvenile juvenile juvenile juvenile male juvenile juvenile juvenile juvenile juvenile juvenile Sex 30-39 20-29 30-39 0-1 40+ 30-39 0-1 30-39 4-5 indeterminate 5-9 20-29 30-39 30-39 20-29 1-4 5-9 1-4 25-45 1-4 5-9 20-29 0-1 1-4 30-39 30-39 1-4 1-4 0- 1 15-19 20-29 5-9 1-4 1-4 0-1 0- 1 0- 1 Age at death 4995 f 215 5330 f 60 - AA-2116 - Pta-4467 - AA-2117 Pta-3719 - 2065 f 105 - 4900 k 60 - - - 4880 i 70 - - 4830 i 250 - 4880 f 70 5450 I 70 - - 9100 f 90 4100 i 60 4870 f 210 4530 5 70 AA-2115 Pta-4348 - Pta-4347 Pta-4367 - - Pta-3724 Pta-4431 AA-2119 Pta-4449 6180 f 70 7120 f 60 5990 f 70 Radiocarbon date Pta-3718 Pta-4354 Pta-4426 TABLE 1 . Skeletons from Oakhurst and Faraoskop No. of carious teeth per total teeth UCT 217(K) - - -17.7 -16.5 - -17.5 -16.9 -16.8 -18.8 femur: -17.2 cranium: -18.0 -17.8 -16.9/-18.2 - *Multiple lesions on one tooth are treated as one occurrence. Total UCT 391/389 UCT 392/387 UXT 393 UCT 394 UCT 395 UCT 396 UCT 397 UCT 398 UCT 385 UCT 386 UCT 388 UCT 390 FaraoskoD skeletons Total UCT 217(M) UCT 217(N) UCT 218 UCT 218D (2 individuals) UCT 2 1 7 i ~ j - -14.1 -15.4 -14.4 -15.9 -13.3 -12.0 female male juvenile male female indeterminate female indeterminate female male juvenile male juvenile juvenile juvenile juvenile juvenile juvenile male indeterminate 25-35 35-45 2-3 40+ 20-30 30-35 40+ indeterminate 25-35 40-45 6-7 30-40 20-29 indeterminate 0-1 5-9 1-4 0- 1 0-1 0-1 Pta-4965 Pta-4967 - Pta-4964 - Pta-5284 - Pta-5281 Pta-5283 ~~~ + 2090 60 2130 rt 45 2150 + 70 - 2110 rt 70 - + 60 * 50 - 2130 2000 - 1/28 Loose teeth 12/138 - - - 017 7/26 1/17 1/30 - 2/30 - .14/192 2/11 5/12 4/21 Skull UCT 192* 4/16 Loose teeth 128 J.C. SEALY ET AL. 1932; Morris, 1984; Pedersen, 1938; Powell, 1985; Schwartz, 1946; Turner, 1979; van Reenen, 1966; Walker and Hewlett, 1990). Caries and tooth-wear data presented here are for individuals with fully adult dentitions only. Since juveniles are excluded, and some skeletons do not have dentitions preserved, fewer individuals are represented than in the case of the isotopic analyses. Wear values are scored according to Morris' (1984) adaptation of the system used by Brothwell (1981). Wear observations have been recorded on the left side of the mouth, and the right side used only when both maxillary and mandibular teeth on the left side are missing. The numerical values for maxillary and mandibular teeth are combined; if the two values are different the average is given. If unusual wear is obviously due to ante-mortem tooth loss and subsequent abnormal occlusion, this part of the dentition is treated a s absent. The five categories are: 0 (unworn), 1(wear on enamel only), 2 (dentin exposed, but some occlusal enamel remains), 3 (heavily worn, enamel rim only remains), 4 (entire tooth crown lost, pulp cavity exposed). The presence of carious lesions has been recorded for both left and right sides, and upper and lower jaws. Multiple lesions on one tooth are treated as one occurrence. RESULTS AND DISCUSSION Coastal dwellers in the south-western Cape Carbon isotopes Stable carbon isotope measurements of 74 prehistoric human skeletons from the southwestern Cape coast (between the Cape Peninsula and Elands Bay; see Fig. 1)have recently been completed. All these skeletons were recovered from shell middens or other contexts in the immediate vicinity of the coastline. The aim of this study was to investigate the role of marine foods, viz, To what extent did coastal people rely upon marine foods? Are there geographical differences in the use of seafoods along this 200 kilometre stretch of coastline? Is there change through time? Can one detect differences within populations, that is, between men and women, or adults and children? A -I2 -I4 -16 .* i . i 1 A A A I _ _ 6000 DATE (RADIOCARBONYEARS B.P.) Fig. 2. 6'"C values for male (squares),female (triangles) and neutraUjuvenile (stars) skeletons from the south-western Cape coast, plotted a s a function of radiocarbon date. 6'"C values are calculated as follows: p cr 3 'C2 '/C, 1 y y %standard Results are reported relative to the internationally accepted standard, PDB. This i s a marine limestone, arbitrarily assigned a 6% value of O"/oo (parts per milk, or parts per thousand). values reported here are bone collagen measurements. The laboratory procedures used isolate collagen "pseudomorphs" of whole bone: All samples have C/N ratios within the range of variation of modern collagen (Hassan and Hare, 1978; DeNiro, 1985). Isotopic values are therefore unlikely to have been altered by post-mortem degradation. The answers to these questions are discussed in some detail elsewhere (Sealy, 1989). Briefly, it seems that there was considerable variability in the extent to which people relied upon marine foods: some individuals ate large amounts, others relatively little. There is no correlation between geographical location and the amount of seafood consumed. There is, however, marked chronological patterning in the carbon isotope ratios (and hence the marine food intake) of these people (see Fig. 2). All but one of the 74 southwestern Cape coastal skeletons discussed here have been directly dated by radiocarbon measurements of bone collagen. Only twelve skeletons pre-date 3,000 B.P., too few for us to be able to draw any firm conclusions about lifestyles at that time. Values of S13C (see caption to Fig. 2) for these individuals span almost the entire range from figures indicative of a large marine food intake (number approaching -ll0/oo) to those rep- DIET AND DENTAL CARIES IN STONE AGE SOUTH AFRICA resenting little reliance on seafood (numbers approaching - l8"/oo). Between 3,000-2,000 BP, the picture is very different. Stable carbon isotope readings generally are enriched (x = -12.82 ? 1 . 2 8 ° i ~n~= 27), reflecting high marine food consumption. This is in accordance with the archaeological evidence from the west coast site of Elands Bay, where food waste from the third millennium B.P. consists almost entirely of marine shells which have accumulated in open middens, often near shellfish-rich rocky areas of the shoreline (Parkington et al., 1988). It seems from the isotopic data, however, that heavy reliance on marine foods at this time is characteristic not only of Elands Bay, but of much of the south-western Cape coast. Skeletons post-dating 2000 BP have more depleted 13C/12C ratios, (x = -14.80 l.6lo/oo n = 271, reflecting diets which incorporated a larger proportion of terrestrial foods. The distributions of SI3C readings in the 3,000-2,000 and post-2,000 B.P. periods are significantly different (Mann-Whitney approximate Z-value = 4.2, P < 0.001. Only skeletons with dates falling into these time brackets a t two standard deviations have been included). This picture corresponds with that gained from the excavated sites, where post-2,000 B.P. food-waste includes large numbers of the bones of small terrestrial animals and markedly increased quantities of plant food remains. Such a pattern has been tentatively interpreted as an enforced shift towards the use of less desirable, and probably more labour-intensive foods as population density increased and large parts of the landscape of the south-western Cape were occupied by pastoralists and so unavailable to hunter-gatherers (Parkington et al., 1986,1988).Skeletons post-dating 2,000 B.P. probably include pastoralists, a s well as hunter-gatherers. Thus there is clear evidence of chronological patterning in the carbon isotope ratios (and hence the marine food intake) of prehistoric human skeletons from the southwestern Cape coast. In the main, these patterns are consistent with those reported for food-waste excavated from archaeological sites. The chronological patterning may, however, be different for male and female skele- * 129 tons. Over the entire time range in Figure 2, there is no linear trend in the association of 613C and radiocarbon date for female skeletons (r2 = 0.00001, d.f. = 26) while there is for male skeletons (r2 = 0.34, d.f. = 31, P < 0.01). Women's diets underwent less change during the period under consideration than did those of men. Male skeletons, on the whole, have more positive S13C values (i.e., they are enriched in the heavy isotope) compared with female skeletons (Mann-Whitney approximate Z-value = 2.43, P < 0.01). Men appear to have consumed more marine foods, and women more terrestrial foods. It seems likely that these latter were mostly plant foods, perhaps consumed in the course of gathering expeditions. Dental caries and tooth-wear A total of 948 teeth were examined, of which 25 (2.6%) were carious (Table 2). This is similar to the averge value (1.6%) for 12 hunter-gatherer populations for which Turner (1979) compiled data. (The range was 0-5.3%.) Comparisons of the number and proportion of carious teeth in male and female skeletons is of some interest, given the more depleted S13C values, possibly representing a higher intake of carbohydraterich terrestrial plant foods among women. Of the teeth from female skeletons, 11 out of 438 (2.5%) are carious, compared with 13 out of 504 (2.6%) for males. More than half the carious teeth of the males are from one individual (SAM-AP 5091) with advanced dental disease. If this skeleton is excluded, the incidence of carious teeth among male skeletons drops to 6 out of 474 (1.3%).Unfortunately, the numbers of carious teeth are so small that comparison of caries incidences in males and females gives a value of the approximate chi-squared statistic (D2 = 1.9, d.f. = 1)that is not statistically significant. The teeth of individuals who ate large amounts of marine foods (S13C values equal to or more positive than -13'/00) are somewhat more heavily worn than those of people with S13C values of - IV/oo or less (Table 3). A study of dental attrition among the prehistoric inhabitants of the Santa Barbara Channel of California also found that greater reliance upon seafood was associated with increased toothwear, and attrib- 130 J.C. SEALY ET AL. TABLE 2. Numbers of carious teeth per total teeth' No. of individuals Incisors Canines Premolars Non-id. I/C/PM First molars Second molars Third molars Non-id. molars Total Percentage ~ ~~~~~ ~ ~ Cape West Coast total Cape West Coast -13 5 6I3C 5 - 1 0 Cape West Coast -18 5 6I3C 5 -15 Faraoskop Oakhurst 49 0/184 0/118 2/235 017 6/148 8/141 5/110 4/5 25/948 2.6 18 0/60 0/35 0/75 0/3 0/55 0/50 0/30 011 0/309 0 13 0153 0/31 1/59 0/1 2/34 4/36 4/35 5 0/35 0/19 2/34 13 0/36 1/27 9/52 7/16 1/19 2/15 11/249 4.4 12/138 8.7 8/25 9/28 6/23 1/1 34/192 17.7 - - - - 'Multiple lesions on one tooth are treated as one occurrence. TABLE 3. Average toothwear scores Cape West Coast (total) Cape West Coast (-13 5 6% 5 -10) Cape West Coast (-18 5 6I3C 5 -15) Faraoskop Oakhurst I1 12 C PI P2 M1 M2 M3 2.8 2.9 2.6 3.4 2.8 2.6 2.7 2.4 3.1 2.8 2.5 2.6 2.3 2.8 2.7 2.3 2.1 2.1 2.5 2.6 2.2 2.1 1.7 2.2 2.4 2.3 2.2 2.1 2.5 2.2 2.0 1.9 1.7 2.0 2.1 1.7 1.8 1.4 1.2 1.4 uted this to sand and grit in foods from the littoral zone (Walker, 1978). The slightly greater degree of wear in the heavily marine-dependent group at the Cape is, however, probably not sufficient to account for the marked absence of caries in these individuals. Not one tooth (out of 309) from individuals with SI3C 2 - 13%0 is carious. Skeletons with -18 s 613C G -15 yielded 11 carious teeth out of a total of 249. These frequencies are significantly different (D2 = 13.9, d.f. = 1, P < 0.005). Comparisons of caries incidences based on total numbers of teeth examined may be misleading. Some individuals have several carious teeth. The presence of an initial carious lesion increases the chances of additional lesions developing, and thus violates the assumption that the observations are independent. It may be more appropriate to compare the numbers of dentitions with caries, even though most have suffered postmortem losses. None of the eighteen individuals with S13C 2 -13"/00 have caries, compared with five out of thirteen skeletons with -18 4 S13C G -15. These frequencies are significantly different (D2 = 8.2, d.f. = 1, P < 0.01). At least two factors may contribute to the lower incidence of caries among individuals who ate diets rich in marine foods: lower carbohydrate intake andlor the possible cariostatic effects of seafood. The influence of carbohydrates on caries has been mentioned above. One possible explanation for the lack of carious lesions in individuals who ate a great deal of seafood (Walker and Erlandson, 1986; this study) may simply be that they ate relatively little carbohydrate food. It has also been suggested that marine foods, particularly fish, contain high levels of fluoride and inhibit the development of caries (Sognnaes, 1941; Pu and Lilienthal, 1961; Hadjimarkos, 1964). This effect has been challenged, however, by analysis of non-carious teeth from a strongly fish-dependent population, which contained less fluoride than expected (Holloway et al., 1965). The relationship between marine food intake and dental caries probably requires further investigation. Non-coastal dwellers in the south-western Cape Carbon isotopes Stable carbon isotope measurements are available for nine of the Faraoskop skeletons. They range from -16.8 to -18.8"/00. These values are similar to those obtained DIET AND DENTAL CARIES IN STONE AGE SOUTH AFRICA previously for skeletons from the Olifants River Valley, approximately 30 kilometers further inland than Faraoskop (Fig. 1). Values of 613C for all sixteen non-coastal skeletons range from -16.0 to -19.0°/oo. This sample is too small to provide the chronological or social information obtained from the much larger number of coastal skeletons; it is of interest mainly for the light it throws upon the more terrestrially-based subsistence patterns of inland people (Sealy, 1986; Sealy and van der Merwe, 1985; 1986; but see also Parkington, 1986,1987,1991). These S13C values overlap with those of the coastal skeletons, but all lie towards the more negative end of the range, indicating largely terrestrial diets. It has been argued that inland individuals followed a different subsistence round from that of coastal people (Sealy, 1986; Sealy and van der Merwe, 1985,1986,1987). Such comparisons have previously focussed on coastal skeletons from Elands Bay and individuals from the Olifants River Valley. As noted above, the site of Faraoskop is almost half-way between these two areas, only about 30 kilometres from Elands Bay. The presence of significant quantities of marine shell in the Faraoskop deposits is evidence of contact with the coast. Skeletons from Faraoskop, however, like those from the Olifants River Valley, have S13C values which reflect only a small marine food intake. We do not yet have skeletons from Elands Bay which date to exactly the same period as those from Faraoskop. This period is a particularly interesting one in the coastal sequence, marking as it does the end of the “megamidden” period, during which evidence of human occupation at Elands Bay is found almost entirely in huge openair shell middens located near shellfish-rich rocky outcrops (Parkington et al., 1988). Contemporary coastal skeletons from further south are often enriched in 13C compared with the Faraoskop skeletons, indicating large intakes of marine foods (Sealy, 1989; Sealy and van der Merwe, 1988).Why did the people whose skeletons are buried a t Faraoskop not eat more marine foods, if they were only 30 kilometres from the coast? One possibility is that there was an intervening social boundary, so that restricted access to 131 another group’s territory may have limited the availability of seafoods. Dental caries and tooth-wear Data on caries and tooth-wear are available only for five adult skeletons from Faraoskop (Tables 1 and 2). Of 138 teeth examined, 12 (8.7%)were carious. The average tooth-wear scores for the anterior teeth are slightly higher than in the case of the coastal skeletons; for the posterior teeth the values are similar. Based on total number of teeth examined, the incidence of dental caries is not significantly different from that seen in coastal skeletons with comparable S13C values (-18 s S13C 4 -15) (D2 = 2.9, d.f. = 1).If numbers of dentitions with caries are compared, the conclusion remains the same (D2 = 2.5, d.f. = 1). Thus, on the currently available sample, the Faraoskop results are consistent with the picture for those coastal individuals who ate more mixed diets, probably including a greater proportion of terrestrial carbohydrate foods. If a larger sample were available, statistically significant differences might emerge. Four out of five of the Faraoskop dentitions show caries, and the one that does not is that of an elderly individual with only seven anterior teeth remaining. The sample is, however, very small and subject to bias: it is possible that all the individuals were related to one another, and their susceptibility to caries influenced by genetic factors. Oakhurst (Southern Cape) Carbon isotopes Thirty S13C values have been obtained for skeletons from Oakhurst. They range from -10.4 to - l6.6%0. These numbers are difficult to interpret, since enriched 13C/12C measurements in areas such as the southern Cape may indicate marine foods in the diet, or alternatively C,-based terrestrial food (e.g. the meat of grazing animals). Marine shells and fish-bones have been identified from the Oakhurst deposits (but not quantified), so we know marine foods were consumed (Patrick, 1989).The complex ecology of the southern Cape, however, precludes confident interpretation of 613C values without extensive monitoring of the 132 J.C. SEALY ET AL surrounding areas. There does not appear to be any marked shift in SI3C with time (Patrick, 1989). much greater incidences (up to 5%)in areas where the fluoride level is currently less than 2 ppm, Dental caries and tooth-wear C0NCLUSI 0NS The relative importance of marine and terrestrial foods (as revealed by SI3C measurements) in the diets of coastal and near- One hundred and ninety-two adult teeth were available for examination. Tables 1,2, and 3 show the incidence of caries, and average toothwear scores. The toothwear values are not markedly different from those for the south-western Cape skeletons discussed above. 34/192 teeth (17.7%) showed caries. This is an extraordinarily high incidence of caries; higher than any of the published values we have seen reported for hunting-andgathering societies (e.g. Cohen and Armelagos, 1984; Drennan, 1929; Goldstein, 1932, Morris, 1984; Pedersen, 1938; Powell, 1985; Schwartz, 1946; Turner, 1979; van Reenen, 1966; Walker and Erlandson, 1986; Walker and Hewlett, 1990),or for the European Mesolithic (Meiklejohn et al., 1984, 1988). Skeletons with S13C more positive than - 13*/00may have carious teeth, in contrast to the situation in the south-western Cape. Although we cannot be sure that enriched carbon isotope ratios at Oakhurst necessarily reflect marine foods in the diet, the marine shells and fish bone found at the site strongly suggest that such items were eaten. Any cariostatic properties of these foods were inadequate to prevent or arrest dental decay in the inhabitants of Oakhurst. The explanation for the high prevalence of caries is almost certainly related to the extremely low fluoride content of the groundwater in the southern Cape. Fluoride concentrations are below 1 ppm in the area surrounding Oakhurst, and contemporary populations with limited access to dental care suffer rampant caries (Ockerse, 1949). Fluoride in the groundwater of the southwestern Cape, on the other hand, varies from less than 1 to more than 6 ppm. The northern Cape and the Kalahari have relatively high levels of fluoride in the groundwater, no doubt a contributing factor in the low incidence of caries (0.7%) reported for the Kalahari San (van Reenen, 1966). Morris’ (1984) analysis of late prehistoric skeletons from the northern Cape shows similar low caries rates for high fluoride zones, and coastal hunter-gatherers from three areas of the Cape Province, South Africa is discussed. The degree of tooth-wear and incidence of dental caries has been recorded for these same skeletons, and correlations sought between diet and pathology. The incidence of dental caries is different in each of the three areas: It is lowest (2.6%) among coastal skeletons in the south-western Cape, intermediate (8.7%)in individuals from the non-coastal site of Faraoskop, also in the south-western Cape, and highest (17.7%) among skeletons from Oakhurst in the southern Cape. In the sample of coastal skeletons from the south-western Cape, individuals who ate large amounts of seafood have a lower incidence of caries than do people who ate more mixed marine and terrestrial diets. In the southern Cape, the high incidence of caries probably results from low levels of fluoride in the groundwater. This paper highlights the substantial variability in diet and caries rates among hunter-gatherers in a fairly limited area. ACKNOWLEDGMENTS Drs. Graham and Margaret Avery and Mr. Mike Wilson of the South African Museum arranged access to the physical anthropological collections in their care. Mr. John Lanham provided invaluable laboratory and computer assistance. We thank Dr. John Vogel and staff of the Department of Earth and Marine Science and Technology at the Council for Scientific and Industrial Research in Pretoria for numerous radiocarbon dates, without which this work would be meaningless. Additional dates were provided by Dr. Timothy Linick of the Department of Physics, University of Arizona, Dr. Robert Hedges and staff of the carbon-14 accelerator laboratory at the Research Laboratory for Archaeology and the History of Art at Oxford University; and Mr. H. DIET AND DENTAL CARIES IN STONE AGE SOUTH AFRICA Krueger and staff of the Geochron Laboratories, Cambridge, Massachusetts. 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