A review of Unraveling The Population History of The Xiongnu to Explain Molecular and Archaeological Models Of Prehistoric Mongolia, by Ryan William Schmidt.
Ryan Schmidt’s dissertation is a comprehensive study of the population history and structure of the Xiongnu. The Xiongnu is arguably the world’s first known nomadic empire, which peaked in the second century BCE. While the influence of the Xiongnu on the historic trajectory of Eurasia is well recognized, we know very little about the origin of this nomadic group. In his dissertation research, Schmidt mainly compares cranial samples gleaned from places across Eurasia with a timespan of around 6000 years. By employing a method known as geometric morphometrics (GM), Schmidt differentiates at least two biologically distinct subgroups within the Xiongnu population. One of these two subgroups shows biological affinity with Bronze Age Mongolian population, while the other presents similarity with modern Mongolians and perhaps some other Siberian groups. Regarding population history, this research reveals a complex and dynamic picture of the Xiongnu population. Overall, Schmidt suggests the Xiongnu perhaps shared closer ties with northern Chinese and Siberian groups than with Central Asian populations.
Schmidt’s effort pioneers the research on large-scale population connections in the Eurasian steppe. It directly responds to previous bioanthropological work conducted by François-Xavier Ricaut, Christine Keyser-Tracqui and others. Also, this work enables Schmidt to join the long-lasting debate in archaeology and history on nomadic migration patterns and state formation processes in the Eastern Eurasia steppe.
This dissertation is divided into eight chapters. In the introductory chapter, Schmidt first briefly discusses a few key concepts for this research such as population history and structure. Schmidt then moves to a theoretical discussion of population genetic and quantitative genetic theories. In Chapter 2, Schmidt situates his research on quantitative genetic study and further on the broad realm of population genetic research. Schmidt concludes that much research supports a direct correlation between genetic variations and their phenotypic expressions for anthropometric traits. In addition, due to their extreme complexity both from anatomic and evolutionary perspectives, human skulls qualify as the best material for the study of population history and structure. This understanding justifies Schmidt’s employment of craniofacial traits as a proxy to investigate genetic variations, and ultimately to use it to elucidate the population history and structure of the Xiongnu.
Following the theoretical discussion, Schmidt reviews the status quo of our knowledge on the peopling history of greater Eurasia, which is characterized by a number of major migration events and continuous admixing process in Chapter 3. Then Schmidt combines archaeological, historical and genetic studies to provide a background for his research on the Xiongnu in Chapter 4. These review work not only contextualizes the following analysis but also points out the necessity of conducing more molecular and bioanthropological studies on regional population history, as well as preparing for the data interpretation in the meantime.
Chapter 5 focuses on introducing the crania series analyzed in this research. This massive crania series includes 1,158 adult cranial samples from Eurasia as well as other parts of the Old World for comparison reasons. Among this series 68 samples, assigned to the Egiin Gol valley and many other unknown sites in western Mongolia, are supposed to belong to the Xiongnu. To measure the cranial traits of these samples, Schmidt digitizes 44 landmarks for each crania sample, although this number shrinks to 24 homologous points in the later analysis due to reasons like missing data and such like.
Following the recent trend in morphometrics—shifting from linear measurement to Cartesian coordinates of anatomical features—Schmidt uses three-dimensional data of the cranial samples for the GM analysis in Chapter 6. By utilizing the GM methods, quantitative genetics, and various multivariate statistical analysis, Schmidt conducts intra-group analysis of Xiongnu samples and inter-group comparisons between the Mongolian cranial series and global, Chinese, Central Asian, Siberian cranial series. Chapter 7 presents the result of both direct (Relethford-Blangero model) and indirect (principal components analysis) methods used to assess the intra- and intergroup relationships among the Xiongnu cranial series and between the various populations mentioned in this research.
Schmidt interprets the analysis results and concludes this dissertation in Chapter 8. Based on the results, he argues that complex demographic processes have happened in modern-day Mongolia since the Palaeolithic period. The population history of the Xiongnu is but one episode of this complex population history. Accordingly, the population structure of the Xiongnu also renders a mixture between several biologically distinct groups of people. Therefore, Schmidt’s research provides a nuanced understanding of the relationship between the Xiongnu population and other contemporary nearby populations, historic population in Eurasia and modern Eurasia populations.
In sum, Schmidt’s research opens a new window for constructing a more nuanced understanding of the complex population history of Eurasia than before. Its publication will trigger more investment of scholarship in the research on Eurasian Steppe population history and structure.
Department of Anthropology
Washington University in St. Louis
Crania samples from Egiin Gol, northern Mongolia
Pooled crania samples from a number of Xiongnu sites in western Mongolia
Osteological collection of ancient northern Chinese population from Jilin University, Changchun, China
Prehistoric and Modern crania samples of a number of Siberian groups
Modern Central Asian crania samples
University of Montana Missoula, MT. 2012. 246 pp. Primary Advisor: Noriko Seguchi.
Image: Photo by Author.