EMG of the human flexor pollicis longus muscle: implications for the evolution of hominid tool use.
EMG of the human flexor pollicis longus muscle: implications for the evolution of hominid tool use.
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DOI：
10.1006/jhev.1997.0177
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发表时间：
1998-02
影响因子：
3.2
通讯作者：
M. Hamrick;S. Churchill;D. Schmitt;W. Hylander
中科院分区：
文献类型：
--
作者：
M. Hamrick;S. Churchill;D. Schmitt;W. Hylander
现代人类拥有独特且发达的拇长屈肌，这是一种外在拇指屈肌，在类人猿中“要么不成熟，要么不存在”（Straus，1942，第 228 页）。先前的研究人员（例如，Napier，1962；Susman，1988）将发达的拇长屈肌的起源与早期原始人类获得精确抓握和石器制造能力联系起来。然而，所提出的拇长屈肌活动、精确抓握和石器制造之间的功能关联从未经过实验测试。本研究使用肌电图技术 (EMG) 来研究拇长屈肌在各种工具制作、工具使用和操作行为中的作用，以确定人类拇长屈肌的功能和进化意义。我们的研究结果表明，在用力使用工具和石器制作行为期间，无论用于握持工具的力量或精确度如何，拇长屈肌都会被募集。特别是，使用三爪和四爪卡盘精密夹具的石器工具使用和石器制造都会引发持续高水平的 FPL 活动。在这些锤击、切割和敲击行为期间，当拇指掌侧垫的阻力增加时，拇长屈肌的活动增加最多。相比之下，我们在精细操作食品、制作细长的木制探针以及使用这些探针作为工具时观察到相对较低水平的拇长屈肌活动。古生物学、考古学和实验数据表明，在原始人类谱系中，发达的拇长屈肌最初发挥作用，以稳定拇趾末节指骨，以抵抗在频繁而有力地使用未经修饰的石头作为工具时施加到拇指根垫上的负载。
Modern humans possess a distinct and well-developed flexor pollicis longus muscle, an extrinsic thumb flexor which is "either rudimentary or absent" in great apes (Straus, 1942, p. 228). Previous workers (e.g., Napier, 1962; Susman, 1988) have related the origin of a well-developed flexor pollicis longus muscle to the acquisition of precision grasping and stone tool making capabilities in early hominids. The proposed functional association between flexor pollicis longus activity, precision grasping, and stone tool manufacture has, however, never been tested experimentally. This study uses electromyographic techniques (EMG) to investigate the role of flexor pollicis longus during a variety of tool making, tool using, and manipulatory behaviors in order to determine the functional and evolutionary significance of the human flexor pollicis longus muscle. Our results indicate that flexor pollicis longus is recruited during forceful tool using and stone tool making behaviors, regardless of the power or precision grip used to hold the tool. In particular, both stone tool use and stone tool making employing three- and four-jaw chuck precision grips elicit consistently high levels of FPL activity. Flexor pollicis longus activity increases most when resistance is increased to the thumb's volar pad during these hammering, cutting, and knapping behaviors. In contrast, we observed relatively low levels of flexor pollicis longus activity during the fine manipulation of food items, the making of slender wooden probes, and the use of these probes as tools. The paleontological, archaeological, and experimental data suggest that a well-developed flexor pollicis longus muscle functioned initially in the hominid lineage to stabilize the terminal pollical phalanx against loads applied to the thumb's apical pad during the frequent and forceful use of unmodified stones as tools.