Recent discoveries in archaeology and palaeoanthropology highlight that stone tool knapping could have emerged first within the genera Australopithecus or Kenyanthropus rather than Homo. To explore the implications of this hypothesis determining the physical demands and motor control needed for performing the percussive movements during the oldest stone toolmaking technology (i.e. Lomekwian) would help. We analysed the joint angle patterns and muscle activity of a knapping expert using three stone tool replication techniques: unipolar flaking on the passive hammer (PH), bipolar (BP) flaking on the anvil, and multidirectional and multifacial flaking with free hand (FH). PH presents high levels of activity for Biceps brachii and wrist extensors and flexors. By contrast, BP and FH are characterized by high solicitation of forearm pronation. The synergy analyses depict a high muscular and kinematic coordination. Whereas the muscle pattern is very close between the techniques, the kinematic pattern is more variable, especially for PH. FH displays better muscle coordination and conversely lesser joint angle coordination. These observations suggest that the transition from anvil and hammer to freehand knapping techniques in early hominins would have been made possible by the acquisition of a behavioural repertoire producing an evolutionary advantage that gradually would have been beneficial for stone tool production.

考古学和古人类学的最新发现强调，石器敲击可能首先出现在南方古猿或肯尼亚人而不是人属中。探索这一假设的含义，确定在最古老的石器制造技术（即 Lomekwian）期间执行敲击运动所需的物理需求和运动控制将有所帮助。我们使用三种石头工具复制技术分析了敲击专家的关节角度模式和肌肉活动：被动锤 (PH) 上的单极剥落、砧座上的双极 (BP) 剥落以及徒手多向和多面剥落 (FH) . PH 为肱二头肌提供高水平的活动和腕伸肌和屈肌。相比之下，BP 和 FH 的特点是前臂旋前的高度要求。协同分析描述了高度的肌肉和运动协调。尽管两种技术之间的肌肉模式非常接近，但运动模式的变化更大，尤其是对于 PH。FH 表现出更好的肌肉协调性，相反，关节角度协调性较差。这些观察表明，早期人类从砧和锤子到徒手敲击技术的转变是通过获得一种行为曲目而成为可能的，这种行为曲目产生了逐渐有利于石器生产的进化优势。