Chirchir Habiba
Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20013; Center for the Advanced Study of Hominid Paleobiology, George Washington University, Washington, DC, 20052.
Anat Rec (Hoboken). 2015 May;298(5):797-809. doi: 10.1002/ar.23090. Epub 2014 Nov 19.
Skeletal design among cursorial animals is a compromise between a stable body that can withstand locomotor stress and a light design that is energetically inexpensive to grow, maintain, and move. Cursors have been hypothesized to reduce distal musculoskeletal mass to maintain a balance between safety and energetic cost due to an exponential increase in energetic demand observed during the oscillation of the distal limb. Additionally, experimental research shows that the cortical bone in distal limbs experiences higher strains and remodeling rates, apparently maintaining lower mass at the expense of a smaller safety factor. This study tests the hypothesis that the trabecular bone mass in the distal limb epiphyses of cursors is relatively lower than that in the proximal limb epiphyses to minimize the energetic cost of moving the limb. This study utilized peripheral quantitative computed tomography scanning to measure the trabecular mass in the lower and upper limb epiphyses of hominids, cercopithecines, and felids that are considered cursorial and non-cursorial. One-way ANOVA with Tukey post hoc corrections was used to test for significant differences in trabecular mass across limb epiphyses. The results indicate that overall, both cursors and non-cursors exhibit varied trabecular mass in limb epiphyses and, in certain instances, conform to a proximal-distal decrease in mass irrespective of cursoriality. Specifically, hominid and cercopithecine hind limb epiphyses exhibit a proximal-distal decrease in mass irrespective of cursorial adaptations. These results suggest that cursorial mammals employ other energy saving mechanisms to minimize energy costs during running.
奔跑动物的骨骼设计是一种折衷，既要拥有能够承受运动压力的稳定身体，又要具备轻盈的设计，以便在生长、维持和移动过程中消耗较少的能量。据推测，由于在远端肢体摆动过程中观察到能量需求呈指数级增长，奔跑动物会减少远端肌肉骨骼质量，以维持安全与能量消耗之间的平衡。此外，实验研究表明，远端肢体的皮质骨承受着更高的应变和重塑率，显然是以较小的安全系数为代价来维持较低的质量。本研究检验了这样一个假设，即奔跑动物远端肢体骨骺中的小梁骨质量相对低于近端肢体骨骺中的小梁骨质量，以将肢体移动的能量消耗降至最低。本研究利用外周定量计算机断层扫描来测量被认为是奔跑型和非奔跑型的人类、猕猴和猫科动物的下肢和上肢骨骺中的小梁骨质量。采用单向方差分析和Tukey事后校正来检验不同肢体骨骺中小梁骨质量的显著差异。结果表明，总体而言，奔跑动物和非奔跑动物在肢体骨骺中均表现出不同的小梁骨质量，并且在某些情况下，无论是否为奔跑型，都呈现出近端到远端质量的下降。具体而言，人类和猕猴的后肢骨骺无论有无奔跑适应性，均呈现出近端到远端质量的下降。这些结果表明，奔跑哺乳动物采用其他节能机制来将奔跑过程中的能量消耗降至最低。
