The human lineage is marked by a transition in hand use, from locomotion towards increasingly dexterous manipulation, concomitant with bipedalism. The forceful precision grips used by modern humans probably evolved in the context of tool manufacture and use, but when and how many times hominin hands became principally manipulative remains unresolved. We analyse metacarpal trabecular and cortical bone, which provide insight into behaviour during an individual's life, to demonstrate previously unrecognized diversity in hominin hand use. The metacarpals of the palm in Australopithecus sediba have trabecular morphology most like orangutans and consistent with locomotor power-grasping with the fingers, while that of the thumb is consistent with human-like manipulation. This internal morphology is the first record of behaviour consistent with a hominin that used its hand for both arboreal locomotion and human-like manipulation. This hand use is distinct from other fossil hominins in this study, including A. afarensis and A. africanus.

中文翻译：

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化石人参在化石人手中的位置利用多样性。

人类血统的特点是手的使用从运动到越来越灵巧的操纵，同时伴随着两足动物的过渡。现代人类使用的有力的精密握柄可能是在工具制造和使用的背景下发展起来的，但何时以及多少次人的手主要成为操纵手，这一问题仍未解决。我们分析了掌骨小梁和皮质骨，这些骨洞提供了人们一生中行为的真知灼见，以证明以前在人参手使用中无法识别的多样性。南方古猿手掌的掌骨具有小梁的形态，最像猩猩，与手指的运动能力相吻合，而拇指的手指与人的操纵相吻合。这种内部形态是行为的第一个记录，与人类素相一致，人类素将其手用于树木运动和类似人的操纵。这种手工用途不同于本研究中的其他化石人参素，包括A. afarensis和A. africanus。