Schilling Ann-Marie, Tofanelli Sergio, Hublin Jean-Jacques, Kivell Tracy L
Department of Biology, University of Pisa, Pisa, 56126, Italy.
J Morphol. 2014 May;275(5):572-85. doi: 10.1002/jmor.20238. Epub 2013 Dec 10.
Trabecular (or cancellous) bone has been shown to respond to mechanical loading throughout ontogeny and thus can provide unique insight into skeletal function and locomotion in comparative studies of living and fossil mammalian morphology. Trabecular bone of the hand may be particularly functionally informative because the hand has more direct contact with the substrate compared with the remainder of the forelimb during locomotion in quadrupedal mammals. This study investigates the trabecular structure within the wrist across a sample of haplorhine primates that vary in locomotor behaviour (and thus hand use) and body size. High-resolution microtomographic scans were collected of the lunate, scaphoid, and capitate in 41 individuals and eight genera (Homo, Gorilla, Pan, Papio, Pongo, Symphalangus, Hylobates, and Ateles). We predicted that particular trabecular parameters would 1) vary across suspensory, quadrupedal, and bipedal primates based on differences in hand use and load, and 2) scale with carpal size following similar allometric patterns found previously in other skeletal elements across a larger sample of mammals and primates. Analyses of variance (trabecular parameters analysed separately) and principal component analyses (trabecular parameters analysed together) revealed no clear functional signal in the trabecular structure of any of the three wrist bones. Instead, there was a large degree of variation within suspensory and quadrupedal locomotor groups, as well as high intrageneric variation within some taxa, particularly Pongo and Gorilla. However, as predicted, Homo sapiens, which rarely use their hands for locomotion and weight support, were unique in showing lower relative bone volume (BV/TV) compared with all other taxa. Furthermore, parameters used to quantify trabecular structure within the wrist scale with size generally following similar allometric patterns found in trabeculae of other mammalian skeletal elements. We discuss the challenges associated with quantifying and interpreting trabecular bone within the wrist.
小梁骨（或松质骨）在整个个体发育过程中已被证明会对机械负荷产生反应，因此在对现存和化石哺乳动物形态的比较研究中，它能够为骨骼功能和运动提供独特的见解。手部的小梁骨可能在功能方面具有特别的信息价值，因为在四足哺乳动物的运动过程中，与前肢的其余部分相比，手部与基质有更直接的接触。本研究调查了一组在运动行为（以及手部使用情况）和体型上存在差异的灵长目简鼻亚目动物腕部的小梁结构。对41个个体和8个属（智人属、大猩猩属、黑猩猩属、狒狒属、猩猩属、合趾猿属、长臂猿属和蛛猴属）的月骨、舟骨和头状骨进行了高分辨率显微断层扫描。我们预测，特定的小梁参数将：1）基于手部使用和负荷的差异，在悬荡型、四足型和两足型灵长类动物中有所不同；2）按照先前在更大样本的哺乳动物和灵长类动物的其他骨骼元素中发现的类似异速生长模式，与腕骨大小成比例变化。方差分析（分别分析小梁参数）和主成分分析（一起分析小梁参数）表明，在三块腕骨的小梁结构中均未发现明显的功能信号。相反，在悬荡型和四足型运动群体内部存在很大程度的变异，并且在一些分类单元中，特别是猩猩属和大猩猩属，属内变异也很高。然而，正如预测的那样，很少用手进行运动和支撑体重的智人，与所有其他分类单元相比，其相对骨体积（BV/TV）较低，这一点很独特。此外，用于量化腕部小梁结构的参数通常与大小成比例变化，遵循在其他哺乳动物骨骼元素的小梁中发现的类似异速生长模式。我们讨论了在量化和解释腕部小梁骨时所面临的挑战。
