Abstract: Xinjiang, the western-most province of China, was the area where the Oriental met the Occidental, and thus human groups in Xinjiang exhibit different ratios of population admixture and very high genetic diversity. However, few studies have been undertaken to determine when this population admixture began. In this paper, we studied 61 discontinuous traits of 20 skulls from the Bronze Age Liushui graveyard in Keriya County ( Katan) in southwestern Xinjiang to examine possible population admixture. Twenty discontinuous traits were used to compare the Katan samples with 53 population samples from various areas of Eurasia and North Africa. These traits included auditory exostosis, lambdoidal ossicle, occipito-mastoid bone, asterionic ossicle, parietal notch bone, accessory infraorbital foramen, hypoglossal canal bridging, tympanic dehiscence, accessory mental foramen, condylar canal patent, metopism, precondylar tubercle, paracondylar process, mylohyoid bridging, biasterionic suture vestige, jugular foramen bridging, transverse zygomatic suture vestiges, medial palatine canal, ovale-spinosum confluence and supraorbital nerve foramen.
As the data did not show significant difference between males and females in the same population, we pooled the data of both sexes for each population in the analyses. Frequency comparison indicated that the Katan samples have closer affinities to southeastern Asians, eastern Asians, and southern Asians than to Arctic populations and North Africans. Fisher's exact probability test for the 20 discontinuous traits was performed between the Katan samples and the pooled samples of 12 geographical regions respectively. Few significant differences between these populations were found suggesting that the Katan population might have various origins and be related with peoples from various areas in Eurasia. Genetic distances between the Katan samples and another 53 samples were also analysed using principal components analysis, neighbour-joining tree, and multidimensional scaling base on the Smith's mean measure of divergence. These results indicated that population sample of Katan was mixed by the western and eastern Eurasians with strong similarities to the South Asian population.
Therefore, we have demonstrated that population admixture between east and west Eurasia can be traced back to as early as 1000 BC in southwest Xinjiang.

Key words: Discontinuous traits; Keriya County; Katan; Physical anthropology