Swan Karen R, Tsegai Zewdi J, Ives Rachel, Humphrey Louise T
Centre for Human Evolution Research (CHER), Natural History Museum, London, UK.
Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA.
Am J Biol Anthropol. 2025 Jan;186(1):e25045. doi: 10.1002/ajpa.25045. Epub 2024 Nov 30.
Chimpanzees are altricial in terms of their locomotor development and transition from being carried to engaging in suspensory and arboreal locomotor behaviors to eventually relying on terrestrial quadrupedalism as their main form of locomotion. Here, we consider the mechanical implications of femoral cortical bone restructuring during growth and locomotor development in wild chimpanzees.
Cortical bone structure was examined in an ontogenetic sample of wild chimpanzees from a single subspecies (P. t. verus) spanning in age from 2 weeks to 12.6 years. Diaphyseal cross-sections were extracted from micro-CT scans of the femur at 35%, 50%, and 65% of total intermetaphyseal length and variation in cortical bone structure was assessed based on bending rigidity (Imax/Imin, Ix/Iy), relative medullary area, and cortical bone porosity.
Diaphyseal shape is relatively circular with a high amount of cortical bone porosity and a large relative medullary area during early infancy. Distinct shifts in cortical bone structure occurred for each studied parameter with the biggest changes occurring within the first 5 years. Values appear to stabilize as quadrupedal walking increases in frequency and is established as the main form of locomotion.
Collectively, the results suggest a degree of integration in which cortical bone restructures in response to rapid changes in locomotion in addition to nonmechanical influences such as hormonal, and growth factors, without compromising function and structural integrity. The extent of influence of each factor varies throughout growth and highlights the need for caution in functional interpretations of cortical bone geometry.
黑猩猩在运动发育方面属于晚成动物，它们从被携带过渡到进行悬吊和树栖运动行为，最终以地面四足行走作为主要运动形式。在此，我们探讨野生黑猩猩生长和运动发育过程中股骨皮质骨重塑的力学意义。
对来自单一亚种（黑猩猩指名亚种）、年龄从2周龄至12.6岁的野生黑猩猩个体发育样本进行皮质骨结构检查。从股骨的微计算机断层扫描（micro-CT）中提取骨干中段35%、50%和65%处的横截面，并基于弯曲刚度（Imax/Imin、Ix/Iy）、相对髓腔面积和皮质骨孔隙率评估皮质骨结构的变化。
在婴儿早期，骨干形状相对呈圆形，皮质骨孔隙率高，相对髓腔面积大。每个研究参数的皮质骨结构都发生了明显变化，最大变化发生在最初5年内。随着四足行走频率增加并成为主要运动形式，这些值似乎趋于稳定。
总体而言，结果表明存在一定程度的整合，即皮质骨除了受激素和生长因子等非机械影响外，还会因运动的快速变化而进行重塑，同时不损害功能和结构完整性。每个因素的影响程度在整个生长过程中各不相同，这突出了在对皮质骨几何形状进行功能解释时需谨慎的必要性。
