Subadult age estimates of an Early Bronze Age charnel house at Bab edh-Dhra’, Jordan 1; JM Ullinger, MA 2; SG Sheridan, Ph. D 3 Catalina I Villamil 1 Dept. of Anthropology, Univ. of Pennsylvania; 2 Dept. of Anthropology, 3 Dept. of Anthropology, Univ. of Notre Dame The Ohio State University; INTRODUCTION Table 1. Comparative collections (# refers to the x-axis of each graph below) This study sought to determine a subadult age distribution based on left proximal femora from the Early Bronze Age site of Bab edh-Dhra', Jordan. The site had a permanent settlement from the Early Bronze Age IB (EBIB: beginning in 3050 BCE), through 2000 BCE in the Early Bronze Age IV (EBIV). A large cemetery near this settlement has burials from Early Bronze Age IA (EBIA: 3150 -2950 BC) through EBIV (2300 -2010 BC). Notably, there were several shifts in mortuary practices, starting with multiple chamber shaft tombs in the EBIA, changing to above-ground charnel houses in the Early Bronze Age II-III (EBII-III; 2800 -2300 BC), and returning to subterranean tombs in EBIV (Schaub and Rast 1989). METHODS Long bone length may not represent accurate chronological ages because of variation in health and stature among subadults (Johnston and Zimmer 1989, Perry 2002, Saunders 2000) but by using broader age categories some of the error can be accounted for. These stages permit greater accuracy (Buikstra and Ubelaker, 1994) and allow what may be a more meaningful determination of a child's role and activities (Wiley and Pike, 1998). These stages include: fetal (not yet born), infant (0 -1. 99 years), young child (2 -5. 9 years), old child (6 -11. 9 years), and adolescent (12+ years), and are related to tooth eruption (Ubelaker, 1999) and brain development (Johnson 2001, Caviness et al. 1996). Finally, the age distribution was compared to numerous other archaeological collections, and to a distribution generated from EBII-III dental eruption patterns (Di. Mucci and Mc. Clellan, 2009). The comparative data ranged in geographical area & time (Table 1). RESULTS The 95% range of femoral lengths were compiled for each sample and age category (Figures 1 -3). Different femoral length ranges, based on the highest, lowest, intermediate, and Bab edh-Dhra' EBIA means for each age category, gave age distributions for EBII-III femora as in Figure 4. The age categorizations for the EBII III femora based on the Bab edh-Dhra' EBIA mean length data gave the best age estimates when compared to those derived from the Bab edh-Dhra' EBII-III mandible dental data (Figure 5, 2=2. 14 p=0. 54, df =3), though the age categorizations based on the intermediate means gave estimates that were not significantly different from those of the dental data ( 2=6. 32, p=0. 097, df=3) as did the categorizations based on the highest means ( 2=3. 47, p=0. 18, df=2). These were, however, significantly different from the categorizations based on Bab edh-Dhra' EBIA length means ( 2=10. 49, p=0. 015, df=3 for intermediate estimates, 2=15. 67, p=0. 0013, df=3 for highest mean estimates). Of the comparative data, there were only significant differences between the Bab edh-Dhra' EBII-III age distributions determined from Bab edh-Dhra' EBIA means and age distributions of the Arikara ( 2=51. 06, p<0. 001, df=3), the Belleville cemetery ( 2=30. 28, p<0. 001, df=2), & the K 2 site (p=0. 028, Fisher's exact test). When the EBII-III age distribution, based on the EBIA means, was compared to the subadult age distribution of the Bab edh-Dhra' EBIA femora determined using the same methods, there was a statistically significant difference from Bab edh-Dhra' EBII-III (Figure 6, 2=6. 65, p=0. 036, df=2). Length (mm) 350 300 250 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 11 Figure 1. Femur lengths, infants 450 400 Length (mm) 350 300 250 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 11 Figure 2. Femur lengths, young children 450 400 350 estimated because of the small range of femoral length estimates for this category due to smaller sample size (Figure 3). However, the femoral results are very different from those reported by Ortner and Frohlich (2008) for the Bab edh-Dhra' EBIA cemetery taking into account all skeletal elements, where the majority of remains were fetal or infant remains. Since the EBIA femoral data provided estimates more similar to those of EBII-III A 22, it may be that the determined age distribution for EBII-III is due to a problem with sampling and is not a real age distribution for those who died or were buried. Taphonomic processes may have played a major role in creating the assemblage. This may be especially important in A 22, which are fire-burned, broken and commingled. Alternatively, it may be that cultural practices led to differential burial practices between time periods (Ortner and Frohlich, 2008), wherein fewer neonates and infants were buried with older children and adults in EBII-III. Finally, there may have been a real difference in mortality between the Bab edh-Dhra' EBIA and EBIII periods, following the shift in settlement and subsistence patterns. This project illustrated that age distributions can be estimated from fragmentary remains, particularly when considered in conjunction with multiple age indicators. 300 Length (mm) Femoral head diameter and mediolateral neck breadth were measured using digital calipers when possible. A standard osteometric board or Paleo-Tech Mini-Osteometric Board was used for complete femoral lengths. When length and at least one other measure were available, they were used to determine regression equations that were then used to estimate the lengths of broken femora in the collection. Subadult femora (without epiphyseal fusion) from both Bab edh-Dhra' Early Bronze Age IA and II-III were measured. The lengths and estimated lengths were compared to measurements from other groups to determine ages, and these were grouped into broader age categories or stages. 400 250 200 ACKNOWLEDGEMENTS 150 100 This research was supported by the NSF-REU (SES 0649088) Summer Research 0 in Biological Anthropology program at the University of Notre Dame. We would 0 1 2 3 4 5 6 7 8 9 10 11 like to thank: Elizabeth Studer for her work during the first part of this study; Hiba Figure 3. Femur length, old children Ahmed, Mary De. Agostino, and Lesley Gregoricka for their time and patient advice; Dr. Brenda Baker for her invaluable expertise in counseling the direction of our 70 Lowest mean project; Dr. Donald Ortner for allowing us to work with the Bab edh-Dhra' EBIA Intermediate mean 60 Highest mean collection under his care; Dr. Robert Hoppa for his timely replies and assistance in Bab edh-Dhra' EBIA means 50 developing our methods; and Dr. Janusz Piontek for his kind support and interest in our research, as well as for sending us invaluable data. 40 50 Percent of total (n=56) numerous than proximal epiphyses or distal femoral elements. Of all measurements possible on the proximal femur, the femoral head diameter were the least variable in relation to femoral length because it is an articular surface (Lieberman et al. 2001, Ruff 1988 ). Measurements and regression equations from Hoppa and Gruspier’s (1996) study of a large Canadian ossuary sample were used to assess age. 450 30 20 REFERENCES 10 0 Fetal Infant Young Child Old Child Adolescent Figure 4. Age distribution based on mean femoral length/age category 45 Danforth ME, Wrobel GD, Armstrong CW, and Swanson D. 2009. Juvenile age estimation using diaphyseal long bone lengths among ancient Maya populations. Lat Am Antiq 20: 3 -13. Hoppa R, Gruspier K. 1996. Estimating diaphyseal length from fragmentary subadult skeletal remains: implications for paleodemographic reconstructions of a Southern Ontario ossuary. Am J Phys Anthropol 100: 341 -354. 27 25 21. 4 20 Caviness V, Kennedy D, Richelme C, Rademacher J, and Filipek P. 1996. The human brain age 7 -11 years: a volumetric analysis based on magnetic resonance images. Cereb Cortex 6: 726 -736. Johnston F, Zimmer LO. 1989. Assessment of growth and age in the immature skeleton. In: Iscan MY, Kennedy KAR, editors. 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Unpublished manuscript on file at the Laboratory for Biocultural Anthropology, University of Notre Dame. 42 Bab edh-Dhra' EBIII dental estimates, n=71 40 Percent of total The sample was composed of subadult femora from numerous EBIA shaft tombs, as well as from Charnel House A 22, a rectangular mudbrick structure dating to EBII-III, housing at least 219 individuals whose remains were commingled and burnt in antiquity. There are at least 102 subadults (based on the femora in this study), but because the remains are commingled it is impossible to assign individual ages using dental development or skeletal maturation. Proximal femoral metaphyses were chosen for measurement because they were more Maresh MM. 1943. Growth of major long bones in healthy children, a preliminary report on successive roentgenograms of the extremities from early infancy to twelve years of age. Am J Dis Child 89: 725 -42. Merchant VL, Ubelaker DH. 1977. Skeletal growth of the protohistoric Arikara. 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DISCUSSION & CONCLUSIONS Our results indicate that the femora represent 10. 7% fetal or infant bones, 30. 4% young children, 37. 5% older children, and 21. 4% adolescents in the Bab edh-Dhra' EBII-III A 22 charnel house. These results are consistent with those obtained from dental data (Di. Mucci and Mc. Clellan, 2009. There was a significant difference between the Bab edh-Dhra' EBIA and EBII-III periods when using only femoral aging, but in this case it may be that the Bab edh-Dhra' EBII-III proportion of older children was over- Percent of total Sundick RI. 1978. Human skeletal growth and age determination. Homo 29: 228 -249. 38. 6 40 Ubelaker, DH. 1999. Human skeletal remains: excavation, analysis, interpretation. Washington DC: Taraxacum. Wall CE. 1991. Evidence of weaning stress and catch-up growth in the long bones of a Central Californian Amerindian sample. Ann Hum Biol 18: 9 -22. Wiley AS, Pike IL. 1998. An alternative method for assessing early mortality in contemporary populations. Am J Phys Anthropol 107: 315 -330. 30 23. 3 20. 0 20 10 0 6. 7 6. 8 Fetal A copy of this poster is available for download at: http: //www. nd. edu/~nsfbones/Posters_Presentations. html 6. 8 Infant Young Child Old Child Figure 6. Age distributions for the Bab edh-Dhra’ EB IA vs IIB femora
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