Fletcher Alison W
Department of Biological Sciences, University of Chester, Chester, United Kingdom.
Am J Primatol. 2006 Nov;68(11):1081-8. doi: 10.1002/ajp.20308.
An increased understanding of spontaneous bimanual tasks performed by chimpanzees would enhance the ongoing debate on population handedness in this species, and thus shed light on the evolution of hemispheric lateralization in humans. However, documentation of such bimanual activities has been largely absent in the literature because such behavior is infrequently observed in the natural repertoire of this species. This study presents data on a simple, spontaneous bimanual gesture-"clap"-that was investigated in a naturalistic group of 26 chimpanzees (Pan troglodytes). Sixteen individuals exhibited a total of 657 bouts of clapping directed toward humans, usually in the context of food availability. Most individuals were exclusive in their dominant hand preference, but since there was no population bias to the right or the left, the population is placed at level 3 of McGrew and Marchant's [Yearbook of Physical Anthropology 40:201-232, 1997] laterality framework. This is the first reported evidence of level 3 laterality in a non-tool-using task. Clapping increased in frequency with age, being common in adults, present at lower rates in adolescents, and absent in infants and juveniles. There was no effect of rearing or sex. The lack of population bias to the left or right for this bimanual gesture has implications for the debate on the evolution of language.
对黑猩猩自发进行的双手任务有更深入的了解，将有助于推动关于该物种群体用手习惯的持续争论，从而为人类半球侧化的进化提供线索。然而，此类双手活动的记录在文献中基本缺失，因为这种行为在该物种的自然行为中很少被观察到。本研究展示了关于一种简单的自发双手手势——“鼓掌”的数据，该研究在一个由26只黑猩猩（黑猩猩属）组成的自然群体中进行。16只个体总共展示了657次针对人类的鼓掌行为，通常是在有食物供应的情况下。大多数个体在优势手偏好上是排他性的，但由于群体中没有偏向右侧或左侧的倾向，该群体处于麦克格鲁和马钱特[《体质人类学年鉴》40:201 - 232，1997]侧化框架的第3级。这是在非工具使用任务中首次报道的第3级侧化证据。鼓掌频率随年龄增加，在成年个体中常见，在青少年中出现频率较低，在婴儿和幼年个体中不存在。饲养方式或性别没有影响。这种双手手势在群体中没有偏向左侧或右侧的倾向，这对语言进化的争论具有启示意义。
