Van Schaik C P, Knott C D
Department of Biological Anthropology and Anatomy, Duke University, Durham, North Carolina 27708-0383, USA.
Am J Phys Anthropol. 2001 Apr;114(4):331-42. doi: 10.1002/ajpa.1045.
Geographic variation in the presence of skilled behavior may reflect geographic variation in genetic predispositions or ecological conditions (accompanied by reliable expression during development), or it may reflect the vagaries of invention and the appropriate social conditions for persistence. In this study, we compare the feeding techniques and tool-using skills used by orangutans to extract the nutritious seeds from Neesia fruits between Suaq Balimbing on Sumatra and Gunung Palung on Borneo, and map the distribution of Neesia tool use in Sumatran swamps. We show that neither genetics nor ecology is sufficient to explain the distribution of this tool use, confirming earlier findings on chimpanzees. We conclude that the ability to learn to use tools determines the geographic distribution. It is impossible to distinguish between the history of invention and the conditions for social transmission as the causal factors, but the high density and the social tolerance at Suaq Balimbing create propitious conditions for the maintenance of the skill as a tradition once it has been invented. High orangutan densities in the other Sumatran coastal swamps with Neesia tool use support the conclusion that suitable transmission conditions are the critical factor to explain the geographic distribution of skills such as feeding tool use.
熟练行为的地理差异可能反映了遗传倾向或生态条件的地理差异（在发育过程中伴有可靠的表现），也可能反映了发明的偶然性以及技能得以持续存在的适当社会条件。在本研究中，我们比较了苏门答腊岛的苏阿克巴利明和婆罗洲的古龙帕伦两地的猩猩从内西亚果实中获取营养种子时所使用的取食技术和工具使用技能，并绘制了苏门答腊沼泽地内西亚工具使用的分布图。我们发现，遗传因素和生态因素都不足以解释这种工具使用的分布情况，这证实了先前关于黑猩猩的研究结果。我们得出结论，学习使用工具的能力决定了其地理分布。虽然无法区分发明的历史和社会传播条件作为因果因素，但苏阿克巴利明的高密度猩猩群体以及社会容忍度为该技能一旦发明后作为一种传统得以维持创造了有利条件。其他使用内西亚工具的苏门答腊沿海沼泽地中猩猩的高密度群体支持了这样一个结论，即合适的传播条件是解释诸如取食工具使用等技能地理分布的关键因素。
