From these radiographs the combined cortical thickness (CCT) of the bones ... A significant reduction in CCT values of both sheep and goats was found in the.
Journal
of Archaeological
Science
1984, l&467-475
Radiographic Evidence for Changing Patterns of Animal Exploitation in the Southern Levant Patricia Smith” and Liora Kolska Horwitzh (Received 24 July 1983, Accepted 4 July 1984) Radiographs were taken of sheep (Ovis aries) and goat (Cap-a hircus) metacarpals from archaeological sites in Israel dating from the Pre-Pottery Neolithic B (PPNB) to recent times. From these radiographs the combined cortical thickness (CCT) of the bones was measured, and used to estimate sample variation in bone mass. The samples were compared by species and period, and further compared with CCT values obtained for a recent sample of ibex (Capra ibex nubianu) from the same region. For all periods studied, CCT values in goats were comparable with those of recent ibex. A significant reduction in CCT values of both sheep and goats was found in the Early Bronze to recent samples as compared with the Chalcolithic and PPNB samples. It is proposed that this reduction in CCT values is associated with the presence of older, female animals in the later samples studied, and may be indicative of an emphasis on milk herds. Keywords:
THICKNESS,
CAPRINES, MILKING,
DOMESTICATION, METACARPALS, SOUTHERN LEVANT
CORTICAL
Introduction
Methods currently in use to determine the presence, of domesticated animals in archaeological contexts largely concentrate on the initial stages of domestication. Such studies have emphasized changes in the age and sex composition of fauna1 assemblages, that are considered to reflect selective hunting or culling of herded animals. Morphological changes in fauna1 remains have also been interpreted as evidence of human intervention in breeding patterns and/or environmental constraints on the domesticates (Zeuner, 1963 ; Uerpmann, 1973 ; Payne, 1972 ; Higgs & Jarman, 1972; Ducos, 1978; Hecker, 1982). A third approach has been the use of microscopic techniques to investigate changes in bone structure (Drew et al., 1971; Pollard & Drew, 1975; Zeder, 1978; Ostergard, 1980; Dyson, 1973). The results have been inconclusive (Payne, 1968; McConnell & Foreman, 1971; Watson, 1975) and this can be explained by the fact that the microstructure of bone remains unchanged, even in conditions of extreme stress and dietary deficiency, although total bone mass may be reduced (ElMaraghi et al., 1965; Geiser & Trueta, 1958; Norden et al., 1975). Less attention has been paid to the identification of more subtle changes associated ODepartment of Anatomy and Embryology, Hebrew University Medicine and Dental Medicine, Jerusalem, Israel. “Institute of Archaeology, Hebrew University of Jerusalem, Israel.
School of
467 0305S4403/84/060467+09$03.00/O
0 1984 Academic Press Inc. (London) Limited
468
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with secondary resource utilization. Sherratt (1981) suggested that secondary product utilization took place in the Old World only some 4 millennia after the initial phase of animal domestication. He characterized this stage by the exploitation of animals for labour, transport and secondary products such as milk and wool. Payne (1973) proposed that age and sex distribution in herds kept for milk production would differ from that of herds kept primarily for meat, with younger males being culled and females kept to an older age (that is 510 years) to maximize milk yields. Baker (1978) and Baker & Brothwell (1980) have also suggested that pathological lesions present in the fauna1 remains may in themselves be diagnostic of specific conditions under which animals were kept or used. They also discussed the effect of poor diets and intestinal parasites on bone composition of ruminants kept in crowded conditions. Disturbances in calcium metabolism are known to occur in lactating ruminants and their young when they graze in areas with a low mineral content in the soil, or when they are affected by parasites such as Trichostrongylus colubr{formis or Ostertagia circumcincta larvae. The former directly affect mineral uptake, while the latter reduces protein absorption, and either may cause reduction of up to 30% in growth (Wilson & Field, 1983). The greater susceptibility of the immature animals and lactating ewes is due to their greater need for calcium and phosphorus as well as greater energy requirements. In immature animals rickets may develop, and even in less severe instances growth-arrest may be reflected in the presence of transverse radio-opaque lines on the long bones (Spense et al., 1982). In lactating ewes, osteoporosis, in which bone mass is reduced, takes place (Nisbet et al., 1970). A number of studies carried out on sheep have further shown that even where no deleterious changes are seen in lambs, older lactating ewes still tend to develop osteoporosis because of the continued drain on calcium resources (Silver, 1963; Nisbet et al., 1970; Sykes & Field, 1972; Wenham, 1977, 198 1). Osteoporosis results from resorption of both trabecular and cortical bone. The number of trabeculae are decreased and the cortical bone is reduced in quantity appearing thinner on radiographs (Dequeker, 1976). Given its association with dietary deficiency, parasite infestation and the presence of older lactating ewes, its presence in the archaeological record may be used to monitor changing patterns of animal exploitation. When osteoporosis is present in older animals, together with rickets or growth arrest lines in immature animals, dietary deficiencies and/or infection may be the cause. Its presence in older animals without rachitic juveniles may be considered diagnostic of full scale milk production and/or breeding. We have accordingly examined the evidence for reduction in cortical thickness of caprine metacarpals from fauna1 assemblages in Israel covering a period of 9000 years, that is, from the initial phase of animal domestication, until the present. We propose that a more pronounced reduction in cortical thickness will be found in milking herds comprising a higher frequency of older female animals that are subject to continued calcium drain through prolonged milking and repeated pregnancies. The findings on cortical thickness may then be used to determine when in the archaeological record caprine milk herds became established. Materials and Methods
This study was carried out on goat (Cap-a hircus), sheep (Ovis aries) and Nubian ibex (Capra ibex nubiana) metacarpals from the collections of the Hebrew University of Jerusalem. They included six goats from the Pre-Pottery Neolithic B (PPNB) site of Beisamoun (Davis, 1978); eight goats and three sheep from the Chalcolithic site of Ghassul (Davis, 1983); four goats and two sheep from the Early Bronze Age site of
ANIMAL
EXPLOITATION
Figure 1. Diagram of radiographed A-A, width; B, medullary width.
IN THE SOUTHERN
metacarpal
showing
LEVANT
measurements
469
taken.
Arad (Davis, 1976); six sheep from the Middle Bronze Age site of Sasa (Horwitz, in prep.); and 20 goats from the Late Bronze Age site of Tel es-Sharia (Davis, 1983). In addition 23 recent goats, eight recent sheep and nine Nubian ibex, from various localities in Israel, were also studied. Pottery Neolithic sites with fauna1 remains are scarce in the area and none have yielded complete sheep or goat metacarpals. The metacarpal was chosen for this study because it provides good diagnostic criteria for identification, some indication as to the height of the animal, and good discrimination between cortical and medullary bone on radiographs. It has a further advantage in being relatively well represented in the archaeological assemblages. We examined 98 metacarpals of which 68 were adult and 30 belonged to immature animals. They included right and left sides of the same animal where present. The immature metacarpals were radiographed to check for the presence of lines of arrested growth but were not analysed further. The adult bones, with fully fused epiphyses, were measured to the nearest 0.1 mm using vernier calipers. Greatest length was measured after von den Driesch (1976) and trochlear and condyle width were measured after Payne (1968) to determine species identification. The bones were then placed with their flat surface on the X-ray cassette and radiographed with the X-ray source at 1.0 M using 60 KV and exposure times varying according to the density of the bone from 0.5 to 1.5 s. The developed radiographs were measured on a light table using the vernier calipers. We measured minimal shaft width and medullary cavity width along a line constructed at right angles to the long axis of the bone (Figure 1). Medullary cavity width was then subtracted from minimal shaft width to obtain the combined cortical thickness (CCT). Since no difference was found between right and left sides of the same animal only one side was included in the analysis. The Mann-Whitney test for intergroup variation was used in the analysis of the material (Mann & Whitney, 1947).
P. SMITH
470
AND
L. K. HORWITZ
Cl7pra
OViS
(a) 100
115
68
150
-El
(b) II
9
EG
17
-
MW El 4
8
Figure 2. Bar diagrams showing the range of measurements taken (a) length, (b) minimum shaft, (c) width CCT (in mm). Capra: I, Capra ibex nub&ma (n = 7); N, PPNB (n = 6); C, Chalcolithic (n = 4); EB, Early Bronze (n : 4); LB, Late Bronze (n = 16); 9, Recent (n = 9); D, dwarf goat (n = 7); (Total n = 53). Oris: C, Chalcolithic (n = 5); EB, Early Bronze (n = 2); MB, Middle Bronze (n = 4); R, Recent (n = 4); (Total n = 15).
f---q
iYq
Figure length,
3. Bar diagrams showing (b) lOO.CCT/width. Key
the range of measurements as in Figure 2.
taken
(a) lOO.CCT/
Results
No lines of arrested growth were found on the immature or mature metacarpals. Metacarpals of the 68 adult caprines were measured. The range of values found for length, shaft width and CCT is shown in Figure 2. From Figure 3, it is obvious that sheep metacarpels tended to be longer than those of goats but had similar values for shaft width and CCT. Sheep/goat differences in proportions were emphasized when
ANIMAL Table
EXPLOITATION
1. SigniJicance
IN THE SOUTHERN
of intergroup
differences
(Mann-
Whimey
Width
PPNB-Chalcolithic PPNB-Early Bronze PPNB-Late Bronze PPNB-Recent Chalcolithic-Early Bronze Chalcolithic-Middle Bronze Chalcolithic-Late Bronze Early Bronze-Middle Bronze Middle Bronze-Recent Late Bronze-Recent
100x CCT/length
CCT
Length
Width
CCT
0.05
0.025 0.025 0.01 -
0.025 0.025 0.01 0.05
-
0.05
-
-
~ 0.05 -
Width
= minimum
0.01
shaft
rest) Goat
Sheep
Length
471
LEVANT
width;
0.01
100x CCT/length
0.05 0.05 0.05 0.05
- = not significant.
CCT/length ratios were used to compare the two groups. In the recent samples, CCT/ length ratios in sheep averaged 43.2, in goats 50.6 and in ibex 60.0. In Chalcolithic sheep, CCT/length ratios averaged 51.4 and in Chalcolithic goats CCT/length ratios averaged 69.4. That is, CCT values in sheep were lower than those of goats when metacarpal length was taken into consideration. In goats, a statistically significant reduction in length was observed between the PPNB and Early Bronze Age samples (Table 1). However, no statistically significant differences were found between the PPNB and Late Bronze Age or recent goat sample. Metacarpal length in the Nubian ibex was similar to that of the recent goats but dwarf goat metacarpals were significantly shorter than those of all other groups studied. Shaft width in the PPNB goats was significantly greater than that of all other goats (P -KO-025). Differences in CCT were also similarly pronounced with CCT values in the Early Bronze Age to recent samples significantly lower than those of the Chalcolithic and PPNB samples. The recent Nubian ibex had relatively wide shafts for their length, and CCT values intermediate between those of the Chalcolithic and PPNB goats. In the dwarf goat, shaft width and CCT values were lower than those of the recent goats but the differences were not statistically significant. No PPNB sheep metacarpals were available for study and no statistically significant differences were found in metacarpal length between Chalcolithic to recent sheep. Diachronic changes were observed in CCT, and Chalcolithic sheep had significantly thicker CCT than any of the other samples (PcO.01). Shaft width was somewhat more variable with values observed in the Middle Bronze Age sample comparable to i those of the Chalcolithic sample. Discussion
Zeuner (1963) and Payne (1968) have emphasized the functional basis of morphological differences between sheep and goats. Payne (1968) described sheep metapodia as longer and more slender than goat metapodia. He considered this difference a reflection of differences in preferred habitat. Sheep prefer open flattish areas while goats prefer steeper, rockier habitats. The first are then better adapted for fast running, the second for jumping. The results obtained here for metacarpal length and shaft width conform to these observations, and are further reflected in the differences present in CCT values.
412
P. SMITH
AND
L. K. HORWITZ
While sample sizes used in this study were small, all samples except those of the Early Bronze Age show a wide range of values. This factor was responsible for the use of the Mann-Whitney test rather than more rigorous parametric tests. Since only fully fused bones were used, age related differences in length should not be expected. Size variation is then attributable either to differential representation of males and females, or genetic factors, or differing husbandry practices affecting growth. Ryder (1982) stated that there was reduction in metapodial length of sheep following domestication, but fluctuations in the withers height of sheep in Hungary, from the Neolithic to recent times. He reported peaks of 7&80cm in the Bronze, Roman and recent periods in contrast to low values of 50-60 cm for sheep from the Neolithic, Iron Age and Middle Ages. Our data do not support the hypothesis that there has been a statistically significant reduction in leg length, between PPNB and recent caprines. Davis (1978) also found no reduction in size between PPNB and recent caprines but did report on significant reduction in size between Aurignacian wild goats and pre-pottery Neolithic goats from Israel. It is not definitely known if the PPNB goats from Beisamoun were domesticated (Ducos, 1973; Davis, 1978, 1983) but our data show that the PPNB metacarpals very closely resemble those of the recent Nubian ibex in overall proportions. They further show that the Chalcolithic goats resemble these two samples much more closely than they do the Early Bronze Age or later goat samples. In both sheep and goats, a slight, non-significant, tendency towards reduction in metacarpal length is associated with a very much greater reduction in shaft width and CCT. This differential pattern of reduction does not seem to be the result of allometric differences in size, as shown by the contrast between the dwarf goats and other recent goats. In these two groups, the differences are most pronounced in length and least pronounced in CCT. The observed changes in CCT over time are not therefore really a function of reduced length or shaft width. There is a shift in the entire range of values, rather than a trend towards more homogeneous values as would be expected were the problem one of general factors affecting all members of the population. The most extreme changes are to be found at the lower end of the observed range in each sample, suggesting differential stress on individuals represented. As previously mentioned, no signs of pathology such as rickets or lines of arrested growth were found on the immature or mature specimens. Neither dietary deficiencies nor disease seem then to have affected any of the animals studied. Very thin cortical bone in some adult individuals from the Early Bronze Age and later sites, without associated signs of calcium stress affecting immature individuals, is consistant with the alternative model presented in the Introduction. That is to say, females were kept until old age, and suffered from calcium depletion as a result of continued intensive milking. This in contrast to herds kept for meat, where all animals were killed at an earlier age (Payne, 1973). Supportive evidence for our conclusions can be found in the examination of age and sex profiles from PPNB Beisamoun and the Chalcolithic site of Bir Es-Safadi published by Ducos (1973) and those from the Early Bronze Age site of Arad published by David (1976). Ducos showed that less than 5% of adult caprines were older than 33 years at PPNB and Chalcolithic sites studied by him, whereas Davis reported that 22% of the 72 caprines studied from Early Bronze Age Arad were aged between 6 and 10 years old. The differences in mortality profiles is considerable, with Davis’ findings comparable to those proposed by Payne (1973) for Bronze Age Greece and considered by him to reflect full scale milking practices. Pictorial representations of milking practices in the Old World are best known from Mesopotamia (Hilzheimer, 1936) and Egypt (Sherratt, 1981) and date to the third
ANIMAL
EXPLOITATION
IN THE SOUTHERN
LEVANT
473
millennium. There are, however, no pictorial representations of milking from Israel. Elongated narrow necked ceramic vessels with handles on both sides that have been termed “churns” are associated with Chalcolithic sites in Israel. They are best known from Bir Es-Safadi and Bir Abou Matar but have also been found at Ghassul (Amiran, 1969). Kaplan (1954) has described them as resembling the goat skin containers used by Bedouin as liquid containers and milk churns. Since the Ghassulian vessels have double handles with holes, both Kaplan (1954) and Amiran (1969) have suggested that they may have been suspended and used as churns. There is, however, no definite evidence to show that these vessels were used for milk processing. In conclusion it should be emphasized that while our data is derived from relatively small samples they do show a similar pattern for both sheep and goats. A definite break appears between the Chalcolithic and Early Bronze Age samples with the Bronze Age to recent caprines having similar and lower CCT than the PPNB or Chalcolithic caprines. We propose that these changes are largely due to the predominance of older females in the Early Bronze to recent caprine assemblages, and that the similarity of CCT in them is indicative of a similar pattern of animal husbandry, namely full-scale milking. That is, caprine milking, on a similar scale to that practised today, was fully developed at the Early Bronze Age site of Arad and maintained through later periods, but was not practised at the Chalcolithic site of Ghassul. We hope that analysis of other sites using the rationale presented here may provide more detailed information regarding the origin and spread of caprine milking in the Levant. Acknowledgements We would like to thank Professor E. Tchernov, Dr C. Grigson and Dr S. Davis for their valuable comments on the earlier versions of this manuscript. Research was supported by the Israel Academy of Sciences and the Hebrew University Hadassah School of Dental Medicine. References Amiran, R. (1969). Ancient Pottery of the Holy Lund. Jerusalem: Masada Press. Baker, J. R. (1978). The differential diagnosis of bone disease. In (D. R. Brothwell, K. D. Thomas & J. Clutton-Brock, eds) Research Problems in Zooarchaeology, pp. 107-l 12. Occasional Publication No. 3. Institute of Archaeology, London. Baker, J. R. & Brothwell, D. R. (1980). Animal Diseases in Archaeology. London: Academic Press. Barnett, C. & Nordin, B. (1960). The radiological diagnosis of osteroporosis: a new approach. Clinical Radiology 11, 166174. Davis, S. J. (1976). Mammal bones from the early bronze age city of Arad, N. Negev, Israel. Some implications concerning human exploitation. Journal of Archaeological Science 3, 153164. Davis, S. J. (1978). Etude de la faune. In Mkmoirs et Truvailles du CNRS No. 2, 195197. Davis, S. J. (1981). The effects of temperature change and domestication on the body size of late Pleistocene to Holocene Mammals of Israel. Puleobiology 7, 101-l 14. Davis, S. J. (1983). Climatic change and the advent of domestication. Pal&orient 8, >15. Dequeker, J. (1976). Quantitative radiology: radiogrammetry of cortical bone. British Journal of Radiology 49,9 12-920. Drew, I. M., Perkins, D. & Daly, P. (1971). Prehistoric domestication of animals: effects on bone structure. Science 171, 28&282. Drew, I. M., Perkins, D. & Daly, P. (1971). Reply to McConnel and Foreman. Scknce 1972, 972-973. Driesch, A. von den. (1976). A Guide to the Measurement of Animal Bones from Archaeological Sites. Peabody Museum Bulletin (1) Harvard University.
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Ducos, P. (1973). Sur quelques problemes poses par l’etude des premiers tlevage en Asie du SudQuest. In (J. Matolcsi, Ed) Domestikatkms forschung und Geschichte a& Haustiere, pp. 77-85. Budapest: Akademai Kiado. Ducos, P. (1978). Methodology and results of the study of the earliest domesticated animals in the Near East (Palestine). In (P. J. Ucko & G. W. Dimbleby, Eds) The Domestication and Exploitation of Plants and Animals, pp. 265275. London: Duckworth. Dyson, R. H. (1973). The First Farmers. New York: Time-Life Series. El-Maraghi, N. R. H., Platt, B. S. & Stewart, R. J. C. (1965). The effect of the interaction of dietary protein and calcium on the growth and maintenance of the bones of young, adult and aged rats. British Journal of Nutrition 19,491-509. Geiser, M. & True& J. (1958). Muscle action, bone rarefaction and bone formation. Journal of Bone and Joint Surgery (Britain) 4, 282-3 11. Hecker, H. M. (1982). Domestication revisited: its implications for fauna1 analysis. Journal of Field Archaeology 9, 217-236. Higgs, E. & Jarman, M. (1972). Papers in Economic Archaeology. Cambridge: Cambridge University Press. Hilzheimer, M. (1936). Sheep. Antiquity 10, 195-206. Hole, F., Flannery, K. V. & Neely, J. A. (1969). Prehistory and Human Ecology of the Deh Luran Plain. University of Michigan: Memoirs of the Museum of Anthropology 1. Horwitz, L. R. K. (In prep.). Sasa: Middle Bronze Age II Fauna. Kaplan, J. (1954). Two Chalcolithic vessels from Palestine. Palestine Exploration Quarterly, 97-100. Mann, H. B. & Whitney, D. R. (1947). On a test of whether one or two random variable is statistically larger than the other. Annals of Mathematical Statistics 18, 52-54. McConnell, D. & Foreman, D. W. (1971). Texture and composition of bone. Science 172, 971-972. Nisbet, D. I., Butler, E. J., Smith, B. J. W., Robertson, J. M. & Bannatyne, C. C. (1966). Ostodystrophic diseases of sheep. II. Rickets in young sheep. Journal of Comparative Pathology 76, 159169. Nisbet, D., Butler, E., Robertson, J. M. & Bannatyne, C. C. (1970). Osteodystrophic diseases of sheep. Journal of Comparative Pathology 80, 535-542. Norden, B., Wilkinson, R., Marshall, D. H., Gallagher, J. C., Williams, A. & Peacock, M. (1975). Calcium absorption in the elderly calcified tissues. In (S. Pors Nielsen & E. Hjorting-Hansen, Eds). Proceedings of 11th European Symposium on Calct$ed Tissues, pp. 442. Copenhagen: Fadls Forlag. Ostergard, M. (1980). X-ray diffractometer investigations of bones from domestic and wild animals. American Antiquity 45, 5963. Payne, S. (1968). The origins of domestic sheep and goats. A reconsideration in the light of fossil evidence. Proceedings of the Prehistoric Society 34, 368-384. Payne, S. (1972). On the interpretation of bone samples from archaeological sites. In (E. Higgs & M. Jarman, Eds) Papers in Economic Prehistory. pp. 6581. Cambridge: Cambridge University Press. Payne, S. (1973). Kill-off patterns in sheep and goats: the mandibles from Asvan Kale. Anatolian Studies 23, 281-303. Pollard, G. C. & Drew, I. M. (1975). Llama herding and settlement in prehispanic N. Chile: Application of analysis for determining domestication. American Antiquity 40, 296-305. Ryder, M. L. (1982). Sheep-Hilzheimer 45 years on. Antiquity 46, 15-23. Sheratt, A. (1981). Plough and Pastoralism: aspects of the secondary products revolution. In (I. Hodder, G. Isaac & N. Hammond, Eds) Patterns of the Past, pp. 261-305. Cambridge: Cambridge University Press. Silver, I. A. (1963). The ageing of domestic animals. In (D. R. Brothwell & E. Higgs, Eds) Science in Archaeology, pp. 250-268. London: Thames and Hudson. Spence, J. A., Mellor, D. J. & Aitckison, G. K. (1982). Morphology and radio-opaque lines in bones of foetal lambs. Journal of Comparative Pathology 92, 317-329. Sykes, A. R. & Field, A. C. (1972). Effects of dietary deficiencies of energy, protein and calcium on the pregnant ewe. Journal of Agricultural Science 78, 109117. Uerpmann, H. P. (1973). Animal bone finds and economic archaeology: a critical study of osteo-archaeological method. World Archaeology 4, 307-322.
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Wallace, L. R. (1948). The growth of lambs before and after birth in relation to the level of nutrition. Journal of Agricultural Science 2, 24>302. Watson, J. P. N. (1975). Domestication and bone structure in sheep and goats. Journal of Archaeological Science 2, 315-383. Wet-d-ram, G. (1977). Studies on reproduction on prolific ewes. 2. A radiographic study of the primary and secondary ossification centres in the foetus. Journal of Agricultural Science 88,553-566.
Wet&am, G. (1981). A radiographic study of early skeletal development in foetal sheep. Journal of Agricultural Science %, 394. Wilson, W. D. & Field, A. C. (1983). Absorption and secretion of calcium and phosphorus in the alimentary tract of lambs infected with doses of Trichostrongylus colubriformis and Ostertagia circumcincta larvae. Journal of Comparative Pathology 93, 61-71. Zeder, M. A. (1978). Differentiation between the bones of caprovines from different ecosystems in Iran by the analysis of osteological microstructure and chemical composition. In (M. A. Zeder & R. H. Meadows, Eds) Approaches to Fauna1 Analysis in the Middle East, pp. 69-84. Peabody Museum Bulletin (2) Harvard University. Zeuner, F. E. (1963). History of Domesticated Animals. London: Hutchinson.
