DFG Center for Advanced Studies "Words, Bones, Genes, Tools", Department of Geosciences, Eberhard Karls University of Tübingen, Tübingen, Germany.
Department of Early Prehistory and Quaternary Ecology, Eberhard Karls University of Tübingen, Schloss Hohentübingen, Tübingen, Germany.
Am J Biol Anthropol. 2024 Nov;185(3):e25019. doi: 10.1002/ajpa.25019. Epub 2024 Sep 2.
The appearance of early lithic industries has been associated with the gradual development of unique biomechanical and cognitive abilities in hominins, including human-like precision grasping and basic learning and/or communicating capacities. These include tools used for activities exclusively associated with hominin contexts (cutting flakes) and hammerstones utilized for behaviors shared with non-human primates (e.g., nut-cracking). However, no previous experimental research has focused on comparing the factors affecting efficiency between these two key behavioral patterns and their evolutionary implications.
Here, we address this gap with an experimental design involving participants with varying tool-related experience levels (i.e., no experience, theoretical-only experience, and extensive practical knapping expertise) to monitor their success rates, biometrics, and surface electromyography (sEMG) recordings from eight important hand and forearm muscles.
Our results showed that practical experience had a substantial impact on flake-cutting efficiency, allowing participants to achieve greater success rates with substantially less muscle effort. This relationship between success rates and muscle effort was not observed for the nut-cracking task. Moreover, even though practical experience did not significantly benefit nut-cracking success, experts exhibited increased rates of self-improvement in that task.
Altogether, these experimental findings suggest that the ability to practice and retain tool-using knowledge played a fundamental role in the subsistence strategies and adaptability of early hominins, potentially providing the cognitive basis for conceptualizing the first intentional tool production strategies.
早期石器工业的出现与人类独特的生物力学和认知能力的逐渐发展有关，包括类似人类的精确抓握能力以及基本的学习和/或交流能力。这些工具包括专门用于人类活动的工具（切割石片）和与非人类灵长类动物共享的工具（例如，砸坚果的石锤）。然而，以前的实验研究都没有集中比较这两种关键行为模式的影响效率的因素及其进化意义。
在这里，我们通过一项涉及具有不同工具相关经验水平（即无经验、仅有理论经验和广泛的实际剥片专业知识）的参与者的实验设计来解决这一差距，以监测他们的成功率、生物力学和来自八个重要手部和前臂肌肉的表面肌电图（sEMG）记录。
我们的结果表明，实际经验对石片切割效率有很大影响，使参与者能够以更少的肌肉努力获得更高的成功率。这种成功率和肌肉努力之间的关系在砸坚果任务中并不明显。此外，尽管实践经验并没有显著提高砸坚果的成功率，但专家在该任务中表现出了更高的自我改进率。
总的来说，这些实验结果表明，练习和保留使用工具知识的能力在早期人类的生存策略和适应性方面发挥了重要作用，可能为概念化第一批有目的的工具生产策略提供了认知基础。
