Functional comparisons of cortical bone strength properties between hominoid hallucal and pollical metapodials (Mt1 and Mc1, respectively) are lacking. Determining which of these two elements is stronger, and by how much, could be informative because the hallux and pollex are used differently both within and among extant hominoids during locomotion and manipulation (i.e., functional differentiation between autopod pairs). Here, we compare Mt1 and Mc1 midshaft cortical area, polar section modulus, and polar second moment of area, calculated from high-resolution computed tomography images in humans (n = 21), chimpanzees (n = 47), gorillas (n = 24), orangutans (n = 20), siamangs (n = 8), and gibbons (n = 21). Intraindividual comparisons between bones within species were made using paired t-tests. Log10-transformed Mt1:Mc1 ratios were created to assess relative strength asymmetry between bones, and interspecific comparisons of these proportions were made using analyses of variance. Absolute strength differences between the Mt1 and Mc1 for all variables were significantly larger in the Mt1 for all species (p < 0.05). Significant differences across species in Mt1:Mc1 proportions were also found, thereby demonstrating that strength asymmetry between bones differs among taxa (p < 0.05); asymmetry was lowest in orangutans, intermediate in gorillas, and greatest in humans, chimpanzees, siamangs, and gibbons. These findings support the hypothesis that the Mt1 is better adapted structurally than the Mc1 for bearing mechanical loads during weight support of locomotion in all extant hominoids and that pedal hallucal grasping likely engenders higher loads than manual pollical grasping in nonhuman hominoids. Thus, functional differentiation in autopod use within and among hominoids is reflected in hallucal and pollical metapodial strength properties.

中文翻译：

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现存的人类类幻觉和足部后掌骨的强度特性。

缺乏人类类比的幻觉和足突间足（分别为Mt1和Mc1）的皮质骨强度特性的功能比较。确定这两个元素中的哪一个更强，以及多少，可能是有益的，因为在运动和操纵（即，自足脚对之间的功能区分）期间，在现存的类人动物内部和之中使用了不同的拇指和地物。在这里，我们比较了根据人类（n = 21），黑猩猩（n = 47），大猩猩（n = 24）的高分辨率计算机断层扫描图像计算得出的Mt1和Mc1中轴皮质区域，极地截面模量和极地第二矩），猩猩（n = 20），暹罗猫（n = 8）和长臂猿（n = 21）。使用配对t检验对种内骨骼之间的个体内比较。Log10转换的Mt1：创建Mc1比率以评估骨骼之间的相对强度不对称性，并使用方差分析对这些比率进行种间比较。Mt1和Mc1之间所有变量的绝对强度差异在所有物种的Mt1中均显着更大（p <0.05）。还发现跨物种的Mt1：Mc1比例存在显着差异，从而表明不同类群之间骨骼之间的强度不对称性存在差异（p <0.05）；在猩猩中，不对称性最低，在大猩猩中是不对称性，在人类，黑猩猩，暹罗和长臂猿中，不对称性最大。这些发现支持以下假设：在所有现存类人动物运动的重量支持过程中，Mt1在结构上都比Mc1更好地适应了机械负荷，而在非人类类人动物中，脚掌幻觉的抓握可能比人工手法抓握产生更高的负荷。因此，在类人猿内部和类人猿之间的自足类动物使用中的功能差异反映在幻觉和花粉类足突强度特性上。