新疆下坂地墓地人骨的C,N稳定同位素分析：3500年前东西方文化交流的启示

Carbon and nitrogen stable isotope ratio analysis of Bronze Age humans from the Xiabandi cemetery,Xinjiang,China:Implications for cultural interactions between the East and West

公元前2千纪下半叶,以蒙古人种、粟作农业（包括粟和黍）、彩陶等为特征的东方人群已到达新疆中部,并与安德罗诺沃文化等西方文明发生碰撞、交流甚至融合.然而,受益于新的考古发现,以粟黍为代表的东方文化要素在公元前3千纪~前2千纪时已传播至哈萨克斯坦、希腊、意大利等地.作为文化传播十字路口的帕米尔高原,其人群何时开始食用粟黍,东西方文化交流是否存在更早的迹象,尚缺乏佐证.为此,本文通过对新疆下坂地墓地青铜时代（公元前1500~前600年）出土的人骨进行C,N稳定同位素分析,发现下坂地墓地先民的食物结构,虽以C_3类的动物蛋白为主,但也不乏少许C_4类,在个别个体中,C_4类甚至占较大比例.结合考古资料,研究结果显示：先民的主要生活方式为畜牧或半游牧业,但麦作及粟作农业也是其不可或缺的一环.下坂地墓地的部分先民可能已开始食用粟类作物,这暗示了东方文化因素在帕米尔高原东端,即新疆西南部出现的时间可早至公元前1500年前后.

The Andronovo culture of Central Asia is characterized by wheat agriculture and sheep/goat and cattle animal husbandry. Sometime during the beginning to the middle of the 2nd millennium BC, the Andronovo migrated from the Kazakh Steppe into the moderu-day Xinjiang Uyghur Autonomous Region of China and became one of the most important archaeological complexes in this area. At about the same time or earlier, populations from the East characterized by： millet agriculture, Mongolian race, and painted pottery spread westward from northern China along the mountain ranges of the Gansu Corridor and met the Andronovo culture in the central part of Xinjiang. It is not known how and when these cultures originating from the East and West first started to interact with each other in Xinjiang, and this is especially true in the southwest region of Xinjiang, which is a crucial transport corridor between the Eurasian Steppe and the populations of Central Asia. The analysis of stable isotope ratios of carbon （δ13C） and nitrogen （δ15N） permits an investigation of human diets and lifeways and has the potential to shed light on cultural interactions between the East and the West. Here δl3C and δ15N results of human bone collagen （n=27） are presented to reconstruct dietary patterns and cultural communications at the Xiabandi cemetery site in the Xinjiang Uyghur Autonomous Region of China. The Xiabandi AII cemetery site is located along the Taxkorgan River and is currently one of the earliest Bronze Age archaeological sites in southwest Xinjiang. Influenced by the Andronovo culture, Xiabandi is believed to have been occupied from 1500 BC to 1300 BC and was likely abandoned by approximately 600 BC based on radiocarbon dating evidence. Bone collagen from the 27 humans was extracted from femurs （representing diet from the last ＋10 years of life） and 26 out of 27 individuals yielded acceptable collagen. The δ13C values ranged from -15.2‰ to -19.0‰ with a mean ＋SD value of -18.2‰±0.8‰. The results suggested that the human diet was mainly based on C3 resources but that there was also some consumption of C4 based foods. The δ15N values ranged between 9.8‰ and 14.5‰and had a mean ±SD value of 12.3‰±1.0‰, indicating that a large quantity of animal protein was consumed （sheep/goats） as well as the arid climate of the region （Taklamakan Desert）. The large range of δ13C and δ15N values at Xiabandi, demonstrates dietary diversity and possible human migration and interactions between the cultures of the East and West. Although the majority of the Xiabandi individuals consumed C3 based foods, six individuals show evidence of 13C-enriched values indicative of millets （either foxtail millet （Setaria italic） or common millet （Panicum miliaceum）. In particular, two individuals, M46 and M48, had diets that included significant amounts of millets being consumed. Botanical discoveries in Central Asia indicate that millet cultivation can be dated to the late 3rd millennium BC or the beginning of 2nd millennium BC in Central Asia. Carbonized millet grains have been found at sites such as Begash （2200 BC） in Kazakhstan, Ojakly （1600 BC） in southern Turkmenistan and Babar Kot （2200-1700 BC） in the Indus Valley. When the isotopic results are considered with the archaeological evidence, it is likely that the inhabitants of Xiabandi were pastoralists or semi-nomadic pastoralists that supplemented their diets with millets, but were mainly practicing the cultivation of wheat. In addition, comparison of the Xiabandi isotopic results with previously published isotopic results from the Minusinsk Basin of southern Siberia, and the Semirech＇ye region of southeast of Kazakhstan, indicates that there was an increase the consumption of millets during the early to middle of 2nd millennium BC in the southwest of Xinjiang. Thus, this consumption of millets by the inhabitants at Xibandi is evidence of possible East-West cultural interactions and communications in far western end of the Tarim Basin.