Paleoanthropology, Senckenberg Centre for Human Evolution and Palaeoenvironment, Institute for Archaeological Sciences, Eberhard Karls University of Tübingen, Rümelinstraße 23, Tübingen D-72070, Germany.
Paleoanthropology, Senckenberg Centre for Human Evolution and Palaeoenvironment, Institute for Archaeological Sciences, Eberhard Karls University of Tübingen, Rümelinstraße 23, Tübingen D-72070, Germany; DFG Centre of Advanced Studies 'Words, Bones, Genes, Tools', Eberhard Karls University of Tübingen, Rümelinstraße 23, Tübingen D-72070, Germany.
J Hum Evol. 2024 Nov;196:103591. doi: 10.1016/j.jhevol.2024.103591. Epub 2024 Oct 4.
The evolution of the human hand is a topic of great interest in paleoanthropology. As the hand can be involved in a vast array of activities, knowledge regarding how it was used by early hominins can yield crucial information on the factors driving biocultural evolution. Previous research on early hominin hands focused on the overall bone shape. However, while such approaches can inform on mechanical abilities and the evolved efficiency of manipulation, they cannot be used as a definite proxy for individual habitual activity. Accordingly, it is crucial to examine bone structures more responsive to lifetime biomechanical loading, such as muscle attachment sites or internal bone architecture. In this study, we investigate the manual entheseal patterns of Australopithecus afarensis, Australopithecus africanus, and Australopithecus sediba through the application of the validated entheses-based reconstruction of activity method. Using a comparative sample of later Homo and three great ape genera, we analyze the muscle attachment site proportions on the thumb, fifth ray, and third intermediate phalanx to gain insight into the habitual hand use of Australopithecus. We use a novel statistical procedure to account for the effects of interspecies variation in overall size and ray proportions. Our results highlight the importance of certain muscles of the first and fifth digits for humanlike hand use. In humans, these muscles are required for variable in-hand manipulation and are activated during stone-tool production. The entheses of A. sediba suggest muscle activation patterns consistent with a similar suite of habitual manual activities as in later Homo. In contrast, A. africanus and A. afarensis display a mosaic entheseal pattern that combines indications of both humanlike and apelike manipulation. Overall, these findings provide new evidence that some australopith species were already habitually engaging in humanlike manipulation, even if their manual dexterity was likely not as high as in later Homo.
人类手部的进化是古人类学中一个非常有趣的话题。由于手部可以参与到各种各样的活动中，因此了解早期人类如何使用手部可以为推动生物文化进化的因素提供关键信息。以前对早期人类手部的研究主要集中在整体骨骼形状上。然而，虽然这些方法可以提供有关机械能力和操作的进化效率的信息，但它们不能作为个体习惯性活动的明确替代指标。因此，检查更能响应终生生物力学负荷的骨骼结构至关重要，例如肌肉附着点或内部骨骼结构。在这项研究中，我们通过应用经验证的基于附着点的活动重建方法，研究了南方古猿阿法种、南方古猿非洲种和南方古猿源泉种的手部附着点模式。通过对后来的人类和三个大型猿类属的比较样本进行分析，我们分析了拇指、第五掌骨和第三中间指骨上的肌肉附着点比例，以深入了解南方古猿的习惯性手部使用情况。我们使用一种新的统计程序来解释总体大小和射线比例的种间变异的影响。我们的研究结果强调了第一和第五指的某些肌肉对于类人手法使用的重要性。在人类中，这些肌肉对于在手中进行可变操作以及在制作石器时非常重要。 A. sediba 的附着点表明肌肉激活模式与后来的人类相似，与类似的习惯性手动活动套件一致。相比之下，A. africanus 和 A. afarensis 显示出混合的附着点模式，结合了类人手法和类人手法的指示。总体而言，这些发现提供了新的证据，表明一些南方古猿物种已经习惯性地进行了类人手法的使用，即使它们的手部灵巧性可能不如后来的人类高。
