| Abstract: |
Human skeletal remains coming principally from the Kerma necropolis were studied for the carbon (d13C) and nitrogen (d15C) isotopic composition of skin and bone collagen to reconstruct the dietary regimens of these populations. The majority of samples belong to the Kerma cultural period that is subdivided into three phases: Ancient (44504000 ), Middle (40003700 ) and Classic (37003450 ). A few additional samples, belonging to the Meroitic (2300 350) and Christian ( 5001400) periods, have been measured for comparison. The isotopic compositions of fossil and recent mammal and freshwater fish bones from the same area were also taken into account along with a few fossil plants considered to be representative of the Nubian population's diet. On average, the measured d13C and d15N values suggest a mixed dietary regimen including C3and C4plants (C4plants being more important during the Ancient Kerma period), proteins from caprine and cattle (cattle being more important during the Ancient Kerma period), and freshwater fish. \bIntroduction\b On average, the measured delta<sup>13<\sup>C and delta<sup>15<\sup>N values suggest mixed dietary regimen including C\-3\- and C\-4\- plants, proteins from caprine and cattle, and freshwater fish. The human bones samples analyzed come from the Northern Sudan 6km east of the Nile. The delta<sup>13<\sup>C in the area is variable because of the differences in the relative importance of C\-3\- and C\-4\- plants. \bMaterials & Methods\b 25 individuals represented mainly by fragments of phalanges and ribs, and fragments of skin recovered from the same bone sample Analysis included 18 fossil remains of animals found in the human burials of the necropolis, represented by bone, coprolites and keratin horn sheaths.
mammals
freshwater fish
turtle plate
and fossil plants were also used. <sup>14<\sup>C used performed on the skin and bone from 8 samples but this does always correlate with the cultural period of the tombs. Environment is desert except along the Nile which provides the only source of water. Area characterized as less than 50mm per year. This environmental condition is suggest to have been the same for the last 4000 years based on palynological analysis. \bResults\b A preliminary check of the presence of extractable organic matter was out by measuring the nitrogen content (weight %) of the total bone with a CHN elementl analyser. Thereafter, chunks of about 1 g of bone were demineralized in a 0.5 M EDTA-buffered solution at about 25\[6,36]C, pH 7.2 {Tuross et al 1988}. Collagen repeated washed and freeze-dried. \bResults & Conclusions\b To check for the degree of preservation of problems that may arise from diagenesis they measured each bones carbon and nitrogen conent (wt%) and calculated its carbon/nitrogen ratio (C/N). This should range from 2.9 to 3.6 {DeNiro 1985}. In the case of smaple of modern bone collagen the wt% of C should be about 40-47%, while the wt% of N should be about 12-15%
well preserved collagen from fossil or subfossil material should yield C or N contents lower than 13% and 5% respectively {Ambrose 1990
Ambrose 1993}. Results of preservation testing for the human and animals remains suggest that good preservation was prevented by burial in a warm and dry environment. \uAnimal results\u Coprolites refer directly to the value of the last meals and therefore shiggest shifts in food habits that may ovcurred recently before fecal excretion {Tieszen & Fagre 1993}. \uHuman results\u No dietary differences between sexes. Middle period has lower delta<sup>13<\sup>C values than Ancient Period. \ucarbon\u The diets of the Middle Period indicates that diets were mainly based on the consumption of C\-3\- platns, with minor quantities of C\-4\- plants. During the Ancient Period the food intake was quite rick in C\-4\- plants, the proportion intake was quite rich in C\-4\- plants. May be realted to the increasing importance of caprine in the diet during the Middle Phase: goat and sheep show delta<sup>13<\sup>C values lower than cattle. C\-3\- plants increase in importance during the Classic Period. \unitrogen\u delta<sup>15<\sup>N linked to the consumption of proteins coming from terrestrial animals, fish, or legumes. During the Middle Period, a significant increae in the consumption of C\-3\- plants is evident, the delta<sup>13<\sup>C values being similar to those already found in Egyptian populations. C\-4\- plants are indigenous in the area due to better arid environments. Nitrogen isotope ratios indicate that protein reousrces throughout the Kerma civilization included fish in addition to protein from caprine and cattle, cattle consumption probably being more importnat during the Ancient Period. \bMiscellaneous Comments\b Carbon and nitrogen isotope studies provide direct information about the average diet of an individual over the last 25-30 years of his life {Stenhouse and Baxter 1979
Van der Merwe 1982
DeNiro 1987}. C\-3\- plants include wheat, barely and most fruits and vegetables, showing delta<sup>13<\sup>C values centered around -26 to -28 {Smith and Epstein 1971
Vogel and Van der Merwe 1978}. C\-4\- plants show delta<sup>13<\sup>C values higher than those of C\-3\- plants, centered around -12 and -14 {Bender 1971
Smith et al 1979}. Even while the diet may primarily have/is C\-3\- by eating herbivores whose diet is primarily C\-4\- the human <sup>13<\sup>C values can be greater. Trophic values of Nitrogen vary as a result of differences in the delta<sup>15<\sup>N of the primary source of nitrogen for the plants at the base of the food chain, which may vary according to ecological parameters {Mariotti et al 1980
Rodiere et al 1996}. \bEcological Factors\b Climate, Precipitation and/or relative humidity {Cheng et al 1964}
Heaton 1987}, rainfall (herbivores have a higher delta<sup>15<\sup>N values in areas with less than 400mm of rain per annum {Sealy et al 1987}. This is due, at least partially, to the regulation of urea excretion in response to water stress {Ambrose and DeNiro 1986
Ambrose and DeNiro 1987}.
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