军都山古游牧人群股骨功能状况及流动性分析

Femoral function and patterns of mobility amongst the Jundushan Bronze Age pastoralists

为了解北京延庆军都山东周时期游牧人群下肢功能状况和流动性,对其股骨干中部断面外轮廓几何形状的生物力学参数进行了分析.与定居、低流动性的清代君子村墓地出土股骨比较表明,军都山古代游牧人群的流动性存在明显性别差异,男性具有较高流动性和下肢功能活跃度,而女性下肢功能活跃度较弱与君子村相似.这说明军都山古代居民男、女性之间存在明显的与劳动分工有关的下肢运动模式的差异.古人生活所处地形会影响股骨载荷及粗壮度,生活于山地人群股骨要较平原地区更为粗壮.但生活于山地的军都山股骨粗壮度与平原地区君子村同性别大致相当,并未明显体现出二者所处地形环境上的差异.文化因素如马匹的使用等可能对此有所影响.股骨生物力学分析为了解中国古代北方游牧民族下肢功能状况及运动模式提供了直接的证据.

Jundushan cemeteries are key sites of the Bronze Age nomadic Yuhuangmiao Culture in North China, dated between the 8th to 4th century BC. Nomadic pastoralists specialize in animal herding that requires periodic mobility. This high mobility is one of the most basic adaptive strategies of pastoralists. However, there is enormous variability in subsistence strategies, degrees of mobility, and social organization in pastoral societies. Despite this, till date, there is sparse information on the mobility patterns of Bronze Age pastoralists in North China. Data on the biomechanical properties of the external femoral midshaft cross-sections of Jundushan Bronze Age pastoral groups, was collected, and compared with a sample from the sedentary Junzicun, of the Qing Dynasty（16–19th century AD）, in order to investigate lower limb functions and patterns of mobility amongst the former group. Diaphyseal cross-sectional geometric properties such as the total area of section（TA）, polar moments of area（J） and ratio of anterioposterior to mediolateral second moments of area（Ix/Iy） were collected for comparison. Ix/Iy provides a good indicator of the shape of the diaphysis cross-section that relates to the degree of mobility. Analysis of Ix/Iy provides evidence of high sexual dimorphism amongst Jundushan pastoralists. There is a similarity in the degree of mobility between females of both pastoral and sedentary groups; while males of the Jundushan pastoralists show a greater degree of mobility than that of the sedentary Junzicun group. Results suggest a distinct sexual division of labor amongst the Jundushan pastoralists, with men primarily performing high mobility pastoral tasks, while women were engaged in time-consuming sedentary tasks. Differences in the cultural material excavated in cemeteries, such as proportions of different kinds of sacrificed domesticated animals and weapons, also support gender-based differentiation of activities. Standardized TA and J results provide a robust estimate of diaphyseal rigidity. Although the Jundushan group lived in a mountainous territory that may have increased lower limb robusticity, according to previous studies, this study did not find any differences of robusticity between Jundushan and Junzicun for both sexes. Cultural factors—such as activities like horse riding—that can decrease the total mechanical loading on the femur in the case of the Jundushan pastoralists may explain this result.