Quantitative historical analysis uncovers a single dimension of complexity that structures global variation in human social organization.

Do human societies from around the world exhibit similarities in the way that they are structured, and show commonalities in the ways that they have evolved? These are long-standing questions that have proven difficult to answer. To test between competing hypotheses, we constructed a massive repository of historical and archaeological information known as "Seshat: Global History Databank." We systematically coded data on 414 societies from 30 regions around the world spanning the last 10,000 years. We were able to capture information on 51 variables reflecting nine characteristics of human societies, such as social scale, economy, features of governance, and information systems. Our analyses revealed that these different characteristics show strong relationships with each other and that a single principal component captures around three-quarters of the observed variation. Furthermore, we found that different characteristics of social complexity are highly predictable across different world regions. These results suggest that key aspects of social organization are functionally related and do indeed coevolve in predictable ways. Our findings highlight the power of the sciences and humanities working together to rigorously test hypotheses about general rules that may have shaped human history.

Evidence that a West-East admixed population lived in the Tarim Basin as early as the early Bronze Age.

BACKGROUND: The Tarim Basin, located on the ancient Silk Road, played a very important role in the history of human migration and cultural communications between the West and the East. However, both the exact period at which the relevant events occurred and the origins of the people in the area remain very obscure. In this paper, we present data from the analyses of both Y chromosomal and mitochondrial DNA (mtDNA) derived from human remains excavated from the Xiaohe cemetery, the oldest archeological site with human remains discovered in the Tarim Basin thus far. RESULTS: Mitochondrial DNA analysis showed that the Xiaohe people carried both the East Eurasian haplogroup (C) and the West Eurasian haplogroups (H and K), whereas Y chromosomal DNA analysis revealed only the West Eurasian haplogroup R1a1a in the male individuals. CONCLUSION: Our results demonstrated that the Xiaohe people were an admixture from populations originating from both the West and the East, implying that the Tarim Basin had been occupied by an admixed population since the early Bronze Age. To our knowledge, this is the earliest genetic evidence of an admixed population settled in the Tarim Basin.

A western Eurasian male is found in 2000-year-old elite Xiongnu cemetery in Northeast Mongolia.

We analyzed mitochondrial DNA (mtDNA), Y-chromosome single nucleotide polymorphisms (Y-SNP), and autosomal short tandem repeats (STR) of three skeletons found in a 2,000-year-old Xiongnu elite cemetery in Duurlig Nars of Northeast Mongolia. This study is one of the first reports of the detailed genetic analysis of ancient human remains using the three types of genetic markers. The DNA analyses revealed that one subject was an ancient male skeleton with maternal U2e1 and paternal R1a1 haplogroups. This is the first genetic evidence that a male of distinctive Indo-European lineages (R1a1) was present in the Xiongnu of Mongolia. This might indicate an Indo-European migration into Northeast Asia 2,000 years ago. Other specimens are a female with mtDNA haplogroup D4 and a male with Y-SNP haplogroup C3 and mtDNA haplogroup D4. Those haplogroups are common in Northeast Asia. There was no close kinship among them. The genetic evidence of U2e1 and R1a1 may help to clarify the migration patterns of Indo-Europeans and ancient East-West contacts of the Xiongnu Empire. Artifacts in the tombs suggested that the Xiongnu had a system of the social stratification. The West Eurasian male might show the racial tolerance of the Xiongnu Empire and some insight into the Xiongnu society.

Mitochondrial DNA analysis of human remains from the Yuansha site in Xinjiang, China.

The Yuansha site is located in the center of the Taklimakan Desert of Xinjiang, in the southern Silk Road region. MtDNA was extracted from fifteen human remains excavated from the Yuansha site, dating back 2,000-2,500 years. Analysis of the phylogenetic tree and the multidimensional scaling (MDS) reveals that the Yuansha population has relatively close relationships with the modern populations of South Central Asia and Indus Valley, as well as with the ancient population of Chawuhu.

Molecular genetic analysis of remains from Lamadong cemetery, Liaoning, China.

The Xianbei existed as a remarkable nomadic tribe in northeastern China for three dynasties: the Han, Jin, and Northern-Southern dynasties (206 BC to 581 AD) in Chinese history. A very important subtribe of the Xianbei is the Murong Xianbei. To investigate the genetic structure of the Murong Xianbei population and to address its genetic relationships with other nomadic tribes at a molecular level, we analyzed the control region sequences and coding-region single nucleotide polymorphism markers of mtDNA from the remains of the Lamadong cemetery of the Three-Yan Culture of the Murong Xianbei population, which is dated to 1,600-1,700 years ago. By combining polymorphisms of the control region with those from the code region, we assigned 17 individuals to haplogroups B, C, D, F, G2a, Z, M, and J1b1. The frequencies of these haplogroups were compared with those of Asian populations and a multidimensional scaling graph was constructed to investigate relationships with other Asian populations. The results indicate that the genetic structure of the Lamadong population is very intricate; it has haplogroups prevalent in both the Eastern Asian and the Siberian populations, showing more affinity with the Eastern Asian populations. The present study also shows that the ancient nomadic tribes of Huns, Tuoba Xianbei, and Murong Xianbei have different maternal genetic structures and that there could have been some genetic exchange among them.