Saers Jaap P P, Cazorla-Bak Yasmin, Shaw Colin N, Stock Jay T, Ryan Timothy M
PAVE Research Group, Department of Archaeology and Anthropology, Division of Biological Anthropology, University of Cambridge, Pembroke Street, Cambridge, United Kingdom.
PAVE Research Group, Department of Archaeology and Anthropology, Division of Biological Anthropology, University of Cambridge, Pembroke Street, Cambridge, United Kingdom.
J Hum Evol. 2016 Aug;97:97-108. doi: 10.1016/j.jhevol.2016.05.012. Epub 2016 Jul 13.
Trabecular bone is responsive to mechanical loading, and thus may be a useful tool for interpreting past behaviour from fossil morphology. However, the ability to meaningfully interpret variation in archaeological and hominin trabecular morphology depends on the extent to which trabecular bone properties are integrated throughout the postcranium or are locally variable in response to joint specific loading. We investigate both of these factors by comparing trabecular bone throughout the lower limb between a group of highly mobile foragers and two groups of sedentary agriculturalists. Trabecular bone structure is quantified in four volumes of interest placed within the proximal and distal joints of the femur and tibia. We determine how trabecular structures correspond to inferred behavioural differences between populations and whether the patterns are consistent throughout the limb. A significant correlation was found between inferred mobility level and trabecular bone structure in all volumes of interest along the lower limb. The greater terrestrial mobility of foragers is associated with higher bone volume fraction, and thicker and fewer trabeculae (lower connectivity density). In all populations, bone volume fraction decreases while anisotropy increases proximodistally throughout the lower limb. This observation mirrors reductions in cortical bone mass resulting from proximodistal limb tapering. The reduction in strength associated with reduced bone volume fraction may be compensated for by the increased anisotropy in the distal tibia. A similar pattern of trabecular structure is found throughout the lower limb in all populations, upon which a signal of terrestrial mobility appears to be superimposed. These results support the validity of using lower limb trabecular bone microstructure to reconstruct terrestrial mobility levels from the archaeological and fossil records. The results further indicate that care should be taken to appreciate variation resulting from differences in habitual activity when inferring behaviour from the trabecular structure of hominin fossils through comparisons with modern humans.
松质骨对机械负荷有反应，因此可能是一种从化石形态解读过去行为的有用工具。然而，有意义地解读考古和古人类松质骨形态变化的能力，取决于松质骨特性在整个颅后骨中整合的程度，或者是否因关节特定负荷而局部可变。我们通过比较一组高度活跃的觅食者和两组久坐的农业人群整个下肢的松质骨来研究这两个因素。在股骨和胫骨的近端和远端关节内放置的四个感兴趣区域中对松质骨结构进行量化。我们确定松质骨结构如何与推断出的人群间行为差异相对应，以及这些模式在整个肢体中是否一致。沿着下肢的所有感兴趣区域中，推断出的活动水平与松质骨结构之间发现了显著相关性。觅食者更大的陆地活动能力与更高的骨体积分数以及更厚且更少的小梁（更低的连接密度）相关。在所有人群中，整个下肢从近端到远端骨体积分数降低而各向异性增加。这一观察结果反映了由于肢体从近端到远端逐渐变细导致的皮质骨量减少。与骨体积分数降低相关的强度降低可能通过胫骨远端各向异性的增加得到补偿。在所有人群的整个下肢中都发现了类似的松质骨结构模式，在其上似乎叠加了陆地活动能力的信号。这些结果支持了利用下肢松质骨微观结构从考古和化石记录重建陆地活动水平的有效性。结果进一步表明，在通过与现代人类比较从古人类化石的松质骨结构推断行为时，应注意认识到因习惯性活动差异而产生的变化。
