Social Conventions, Sexual Selection, and Acoustic Signals in Wild Brown Capuchins

将物体组合起来并将其作为工具使用的能力被认为是人类的主要成就之一，在我们对人类智力和行为进化的神话、哲学、文化和学术解释中，这一能力有着深刻的意义。许多研究人员认为，物体操纵、语言、社交技能和大脑结构在人类进化中是相互联系的。在过去的40年里，卷尾猴（capuchin猴属的新世界灵长类动物）经常被认为是人类智力和工具使用进化的模型。在灵长类动物中，只有黑猩猩和人类在组合和操纵物体的频率和复杂性上超过了卷尾猴。尽管对圈养卷尾猴的观察具有启发性，但很少有来自野生种群的证据来验证关于为什么特殊的操纵能力在自然环境中是有利的以及个体如何获得这些技能的假设。中央苏里南自然保护区（CSNR）的棕色卷尾猴（Cebus apella）使用复杂物体操纵的比率在野生卷尾猴中是最高的。更具体地说，CSNR的雄性卷尾猴会使用一系列被称为打击的物体组合和操作：用棍子或坚硬的水果击打坚硬的表面，折断树枝。打击乐产生机械（非声音）的声音，在这种茂密的森林环境中，这种声音比基于视觉显示的社会信号传播得更远、更可靠。初步观察表明，卷尾猴将雄性打击乐发出的声音结构作为雄性力量和活力的可靠指标，这在雄性配偶竞争和雌性配偶选择中很重要，即雄性打击乐越强，噪音越大。本研究项目评估了以下假设：(1)棕色卷尾猴打击乐行为的功能，重点关注在性选择与觅食中积累的相对利益；(2)打击乐的表达与个体发育状态和社会环境的关系。无论研究结果如何，理论意义都是重要的，涵盖了人类学、生物学、生态学和心理学。在CSNR的卷尾猴社会的独特生态背景下，撞击行为将得到最充分的理解。首先，与其他新热带地区相比，贵南高原的生物群具有能量和养分流极低的特点。其次，这些地区的生态特征由于前哥伦布时期的美洲印第安人在现在被CSNR包围的地区所进行的未曾预料到的景观土方工程而变得更加复杂。Boinski及其同事最近的探索工作证实，CSNR中存在普遍的考古特征；这些地点与卷尾猴优先使用的竹林和藤本林栖息地相同。这个灵长类动物和群落生态学研究项目自1998年以来一直在CSNR进行，并且自暴力内乱结束（20世纪70年代末- 90年代初）以来一直是苏里南森林内部唯一的多年生态项目。博因斯基和她的团队与生物学家、教育家、苏里南的野生动物和保护官员、国际非政府组织以及和平队合作。苏里南公园管理局与研究小组之间建立了长期的支持关系，导致该项目对苏里南科学基础设施的教育和保护的推广和贡献远远超出了直接的研究成果。由研究磁带制作的教育录像将在网上免费提供。在国内和外国利益集团寻求扩大对这些森林的经济开发的历史时刻，CSNR项目正在向苏里南人提出有关其无与伦比的森林的文化和生物意义的挑衅性问题。

The capacity to combine objects and employ objects as tools is considered one of the major achievements of our species and figures deeply in our mythological, philosophical, cultural, and academic explanations for the evolution of human intelligence and behavior. Many researchers hold that object manipulation, language, social skills, and brain structure are been linked in human evolution. For the past 40 years capuchins monkeys, New World primates in the genus Cebus, have often been suggested as models for the evolution of intelligence and tool use in humans. Among primates, only only chimpanzees and humans exceed capuchins in the frequency, complexity with which objects are combined and manipulated. Although suggestive observations come from capuchins in captivity, scant evidence from wild populations is available to test hypotheses as to why exceptional manipulative abilities can be advantageous in natural settings and how individuals acquire these skills. Brown capuchins (Cebus apella) in the Central Suriname Nature Reserve (CSNR) use complex object manipulation at the highest rates yet documented among wild capuchins. More specifically, male capuchins at CSNR employ an array of object combinations and manipulations labeled as percussion: striking sticks or hard fruit against hard surfaces and breaking off tree limbs. Percussion generates mechanical (non-vocal) acoustic sounds that transmit farther and more reliably in this densely forested environment than social signals based on visual displays. Preliminary observations suggest that capuchins evaluate the acoustic structure of the noises males produce in percussion as honest indicators of male strength and vigor important in male-mate competition and female mate choice, i.e., the stronger the male percussing, the louder the noise. This research project evaluates hypotheses about (1) the functions of brown capuchins' percussive behavior, focusing on the relative benefits accruing in sexual selection versus foraging, and (2) the expression of percussion in relation to an individual's developmental status and social circumstances. Whatever the findings, the theoretical implications are important and encompass anthropology, biology, ecology, and psychology. Percussive behavior will be most fully understood against the distinctive ecological background of capuchin society at CSNR. First, the biota of the Guianan Plateau is characterized by extremely low energy and nutrient flow relative to other Neotropical regions. Second, these regional ecological characteristics are compounded by previously unsuspected landscape earthworks by pre-Columbian Amerindians populations in the area now encompassed by the CSNR. Recent exploratory work by Boinski and colleagues confirms that pervasive archeological features are present in CSNR; these sites covary with the bamboo and liana forest habitats preferentially used by capuchins. This primate and community ecology research program has been ongoing in the CSNR since 1998 and remains the only multi-year ecological project within Suriname's forested interior since the end of violent civil uprisings (late 1970's - early 1990's). Boinski and her team work with biologists, educators, and wildlife and conservation officials of Suriname, international NGOs, and Peace Corps. Long-term supportive relations have developed between Surinamese Park Service and the research team, leading to educational and conservation outreach and contributions to the scientific infrastructure of Suriname by this project far beyond the immediate research products. Educational videos produced from research tapes will be made freely available on the web. The CSNR project is engaging the Surinamese with provocative questions about the cultural and biological significance of their matchless forests at a moment in history when national and foreign interests seek to expand economic exploitation of these same forests.