Latest findings on human remains at Xiaohe Cemetery

By NIE ZHONGZHI / 04-13-2023 / Chinese Social Sciences Today

Xiaohe Cemetery Photo: COURTESY OF ZHU HONG

The rich archaeological discoveries of the Xiaohe Cemetery indicate the existence of a unique Bronze Age archaeological culture. Commissioned by the Xinjiang Institute of Cultural Relics and Archaeology, the team of researchers at Jilin University led by Professor Zhu Hong has studied the human remains unearthed at the Xiaohe Cemetery, making notable achievements in recent years.

Paleodemographic study

Currently, in the field of archaeological studies on human bones, the gender of adult individuals is mainly identified by the physical characteristics of pelvises and skulls. Among 130 human bone specimens unearthed from the Xiaohe Cemetery, 50 male individuals and 61 female individuals have been identified, with a sex ratio of 0.82:1. From a biological perspective, the sex ratio within the same population should be approximately to 1:1, so the ratio of the Xiaohe population is close to ideal.

The physical characteristics of human teeth and bones change with age according to predictable patterns. Of the 130 individuals, the ages of 56 of them have been identified. Middle age (36-55) accounted for the largest proportion (41.38%) of the age of death, followed by the prime of life (24-35), approximately 34.48%. These proportions may have had something to do with the daily lives of the Xiaohe people, such as inadequate nutrition caused by harsh living conditions, poor medical care, and frequent natural disasters and wars.

A comparison of the age of death between males and females in the Xiaohe Cemetery reveals that the death rates of the two genders were relatively balanced. The death rates of males were higher than that of females in adolescence (7-14), youth (15-23), and middle age. In the prime of life, the proportion of female deaths was higher than that of males. Preliminary analysis suggests that most women in prime age were in the reproductive stage, and had a high death rate due to difficult childbirth or poor postpartum living conditions. Although there is no certain reason for the higher death rate of males in adolescence, youth, and middle age, modern medicine finds that males usually have lower resistance to diseases than females, and males undertake more high-risk behaviors and heavy manual labor. Therefore, we believe that physical differences and social roles may be the cause of different death rates between the Xiaohe males and females.

The average age of death of all individuals in the Xiaohe Cemetery was 26.27 years old, among which the average age of death of male individuals was 29.62 and that of female individuals was 26.91. The average life expectancy of the Xiaohe population was 33.29, with an average life expectancy of 33.80 for males and 32.88 for females. From a modern perspective, the lifespan of this population was very short. However, considering the natural and social environment at that time, the average life expectancy of the Xiaohe population was rather high compared to other populations [of the same period].

Dental analyses

Due to the close relationship between human teeth and human genetics, teeth play an important role in exploring relationships between and within populations. It has been found that the ancient Xiaohe population didn’t completely belong to other East Asian populations in terms of dental features, but rather exhibited a closer morphological match with West Eurasian populations. They also shared similar features with populations in central Asia and southern Siberia. These similarities were closely related to the special geographical location of the Xiaohe Cemetery. As a hub of East-West cultural exchange in ancient China, the Xinjiang region has always been characterized by genetic exchanges and fusions between East and West.

Paleopathological research

Paleopathology mainly involves the medical examination of human bones excavated from archaeological sites to determine the causes and frequency of diseases within a population during a certain period. Studies show that the Xiaohe people had much higher levels of tooth wear than other ancient peoples from different periods, regions, and with different lifestyles. They also suffered from a high incidence of temporomandibular arthritis and tooth fractures, and presented minimal differences between anterior and posterior tooth wear. Researchers believe that one reason for this phenomenon was poor food processing technology, which resulted in rough and hard food. Another cause may have been the complex diet structure of the Xiaohe people, where different foods caused different degrees of wear on anterior and posterior teeth. In addition, the frequent sandstorms in the Xiaohe region had a significant impact on the rate of tooth wear.

In addition to tooth wear, researchers also examined the dental calculus deposits of the Xiaohe individuals, which exhibit strong evidence that the local diet was rich in protein and carbohydrates. The Kongque River, on which the Xiaohe population relied heavily, had high mineral concentration. Influenced by these factors, severe dental calculus deposits were common in the Xiaohe population. There were significant differences in the wear of the canine teeth between males and females, suggesting the possibility of gendered division of labor in some handicrafts. However, the other teeth showed no obvious differences between males and females in terms of tooth wear or dental calculus deposits. Combined with the local burial traditions, this indicates that the differences in social status between males and females may have not resulted in significant differences in diet structure and food distribution between them during that period.

Molecular archaeological study

Using techniques of molecular archaeology, the research team conducted whole genome sequencing on 19 human bones unearthed from the cemeteries at Xiaohe, Gumugou [located on the north bank of the Kongque River, 70 kilometers east of Lop Nur], and Beifang [located 595 kilometers southwest of the Xiaohe Cemetery, considered to belong to the same cultural type as the Xiaohe Cemetery]. The results showed that although the samples came from three different sites, the genetic structures of the three populations were quite similar, indicating a possible shared ancestry. This provides new evidence for further exploring the relationship between the archaeological cultures represented by Xiaohe, Gumugou, and Beifang. Additionally, researchers found that the Xiaohe population had experienced long-term genetic isolation due to the unique desert environment. No evidence shows that the early population of the Xiaohe region had genetic exchanges with other ancient populations in the surrounding areas. Through calculation, the researchers discovered that the Xiaohe population genetically represented an old lineage of the Eurasian continent, formed by a mixture of two ancient autochthonous Asian genetic groups between approximately 10,000-6,000 years ago: the ancient North Eurasian (ANE) and ancient Northeast Asians [according to an article titled “The genomic origins of the Bronze Age Tarim Basin mummies” published in Nature in 2021, the earliest individuals of the Xiaohe horizon belong to an ancient and isolated autochthonous Asian gene pool. This autochthonous Ancient North Eurasian (ANE)-related gene pool is likely to have formed the genetic substratum of the pre-pastoralist ANE-related populations of Central Asia and southern Siberia]. The Xiaohe population may be one of the earliest populations in Xinjiang. Moreover, researchers found no genetic connection between the early Xiaohe population and the Eurasian steppe population or the Central Asian agricultural population during the Bronze Age, which refutes the previous hypotheses that the Xiaohe people were genetically connected with people who roamed the Eurasian grasslands and those who lived in oases in Central Asia.

Height of Xiaohe individuals

Studies reveal that the height of the male individuals in the Xiaohe region varied between 161.582-178.828 cm, with an average height of 167.93 cm. The females’ height varied between 146.560-168.755 cm, with an average height of 155.49 cm. A comparison of the height between the Xiaohe population and other ancient populations reflects that Xiaohe males were generally taller, while Xiaohe females were shorter on average.

Based on current archaeological research, the Xiaohe population is believed to have lived in Lop Nur around 4,000 years ago as an independent group. The harsh environment of the Xiaohe region may have formed a barrier to gene flow. In order to survive such living conditions, men and women may have had different social roles but enjoyed a relatively fair distribution of resources. Dental analyses suggest that the Xiaohe population may have shared ancestry with ancient populations that once lived in southern Siberia. This suggests that we should carefully consider southern Siberia in future research regarding the origin of the “Xiaohe culture.” The latest molecular archaeology research suggests that the early Xiaohe population was formed by a mixture of ANE and ancient Northeast Asians around 10,000 to 6,000 years ago. They had already been a relatively independent population before reaching Xinjiang.

Nie Zhongzhi is from the School of Archaeology at Jilin University.