Dainton M, Macho G A
Department of Human Anatomy and Cell Biology, The University of Liverpool, UK.
J Hum Evol. 1999 Feb;36(2):171-94. doi: 10.1006/jhev.1998.0265.
Although African great apes share a similar quadrupedal locomotor behaviour, there are marked differences in hand morphology and size between the species. Hence, whilst all three species (two genera) of African ape frequently knuckle walk as adults, debate remains as to whether this behaviour is derived from a common ancestor or whether it evolved in parallel in chimpanzees and gorillas. This exploratory morphometric study of the sub-adult and adult wrist of these two genera aims to contribute to this debate. A total of twenty-seven dimensions of the lunate, triquetral, hamate and capitate of sub-adult and adult Pan troglodytes and Gorilla gorilla were analysed in order to determine whether carpal dimensions are generally ontogenetically scaled, and whether differences in growth trajectories, or length of growth, and adult morphologies can be explained by behavioural differences between the two species. Only 56% of all dimensions studied were ontogenetically scaled in sub-adults and some of these dimensions exhibit differing adult proportions between the two species. In general, the dimensions analysed fell into two categories: Pan and Gorilla either follow the same growth trajectories (Pattern A) or the Pan reduced major axis (RMA) regressions were significantly transposed above those of Gorilla (Pattern B). Additionally, it was found that Gorilla carpals appear to cease growing relatively earlier than those of Pan. While a small number of differences, notably those of the lunate, can be accounted for by differences in behaviour between the species, the majority of differences indicate heterochronic modifications of development during evolution, which correspond to kinematic differences in knuckle walking between the African great apes. In light of morphological, behavioural and ecological data currently available it is parsimonious to suggest that knuckle walking has evolved in parallel in the two lineages.
尽管非洲大型猿类具有相似的四足运动行为，但不同物种之间的手部形态和大小存在显著差异。因此，虽然所有三种非洲猿（两个属）成年后都经常用指关节行走，但关于这种行为是源自共同祖先还是在黑猩猩和大猩猩中平行演化，仍存在争议。这项对这两个属的亚成年和成年腕部进行的探索性形态测量研究旨在为这场争论提供参考。对亚成年和成年黑猩猩（Pan troglodytes）及大猩猩（Gorilla gorilla）的月骨、三角骨、钩骨和头状骨的总共二十七个维度进行了分析，以确定腕骨维度是否一般按照个体发育比例缩放，以及生长轨迹的差异、生长长度的差异和成年形态是否可以通过这两个物种之间的行为差异来解释。在亚成年个体中，所研究的所有维度中只有56%是按照个体发育比例缩放的，并且其中一些维度在两个物种的成年个体中呈现出不同的比例。总体而言，所分析的维度分为两类：黑猩猩和大猩猩要么遵循相同的生长轨迹（模式A），要么黑猩猩的简约主轴（RMA）回归明显高于大猩猩的（模式B）。此外，还发现大猩猩的腕骨似乎比黑猩猩的相对更早停止生长。虽然少数差异，特别是月骨的差异，可以由物种之间的行为差异来解释，但大多数差异表明在进化过程中发育的异时性改变，这与非洲大型猿类指关节行走的运动学差异相对应。根据目前可得的形态学、行为学和生态学数据，简约的推测是指关节行走在这两个谱系中是平行演化的。
