新疆石人子沟遗址出土家马的DNA研究

ANCIENT DNA ANALYSIS OF ANCIENT HORSE REMAINS FROM SHIRENZIGOU SITE,XINJIANG,CHINA

运用古DNA技术对新疆石人子沟遗址的墓葬中出土的古代家马样本进行遗传学分析。共选取5匹家马骨骼样本,从中提取DNA并对线粒体DNA控制区和毛色控制基因的核DNA进行PCR扩增。全部样本获得了线粒体DNA序列,在这5个序列中共检测出3个不同的单倍型,可以归属到3个不同的谱系A,B和E。毛色控制基因的SNP检测结果显示石人子沟遗址古代家马有栗色(chestnut)、枣色(bay)和金黄色(palomino)3种不同毛色。尽管样本量很小,但是线粒体DNA和毛色控制基因的核DNA研究均显示出石人子沟遗址的古代家马具有较高的遗传多样性。结合古代文献记载和新疆的特殊地理位置,支持新疆是家马引入中国的一个重要通道的观点。此外,金黄色马与墓主人同葬于墓室,可能是当时特殊的选择,表明马在古代人类社会中具有着重要的地位。

This research aims to use an ancient DNA approach to genetically characterize ancient horse remains （400- 120 BC）from Shirenzigou site in Barkol County, Xinjiang, China. Excavated in 2006- 2007, Shirenzigou site （43° 31＇12.8＂-43° 34＇28.9＂N,93° 13＇ 44.8＂-93° 16＇49. 1＂E） is 5km long from north to south and 3.5km long from east to west,with an area of 8.75km2. DNA was successfully extracted from five ancient horse samples in dedicated ancient DNA labs following vigorous protocols for maximal contamination prevention. Both mitochondrial DNA （mtDNA）and single nucleotide polymorphic （SNP）markers for coat colors were targeted for PCR amplification. The results show a high success rate（100%） of DNA recovery due to the superior DNA preservation conditions in the region. The mtDNA reveals three haplotypes belonging to three haplogroups（A, B and E）while the amplified SNP markers indicate three different coat colors（ chestnut,bay and palomino）. While the sample size is relatively small,it is clear that the analyzed remains have a high genetic diversity as demonstrated by both the mtDNA and SNP results. The relatively recent antiquity of the horse remains and the nature of the archaeological contexts strongly indicate that these skeletal remains represent domesticated horses instead of wild horses. Although this study cannot provide any direct evidence as to how these remains are linked to older horse remains in Central China, it is clear that the remains analyzed did not originate from Central China. These results are consistent with the hypothesis that Chinese domesticated horses were imported via Xinjiang of Northwest China. The high genetic diversity of the analyzed horse remains in this study can be adequately explained by the fact that this geographic region represents an easy exchange area for horses traded in from other regions. One extremely rare coat color of palomino （light golden color）was detected in this study, marking the first time it has been reported in ancient horses. It is worth noting that the horse skeleton with the palomino coat was buried together with a human skeleton,while two other chestnut colored horse skeletons（ a common coat color）were buried in sacrificial pits（ animals only）. While more studies are needed to fully understand this burial practice, it is clear that horses must have played extremely important roles in human life then. This study demonstrates the unique contribution that ancient DNA analysis can make, when combined with archaeology,to our understanding of human-animal interactions in the past. Ancient DNA in this study reveals not only a high genetic diversity of ancient horse populations but also a rare coat color that is found to be associated with special cultural implications in the region.