Vale Gillian L, Davis Sarah J, Lambeth Susan P, Schapiro Steven J, Whiten Andrew
Centre for Social Learning and Cognitive Evolution, and Scottish Primate Research Group, School of Psychology & Neuroscience, University of St Andrews, United Kingdom.
National Center for Chimpanzee Care, Michale E. Keeling Center for Comparative Medicine and Research, The University of Texas MD Anderson Cancer Center, United States.
Evol Hum Behav. 2017 Sep;38(5):635-644. doi: 10.1016/j.evolhumbehav.2017.04.007. Epub 2017 May 2.
Cumulative culture underpins humanity's enormous success as a species. Claims that other animals are incapable of cultural ratcheting are prevalent, but are founded on just a handful of empirical studies. Whether cumulative culture is unique to humans thus remains a controversial and understudied question that has far-reaching implications for our understanding of the evolution of this phenomenon. We investigated whether one of human's two closest living primate relatives, chimpanzees, are capable of a degree of cultural ratcheting by exposing captive populations to a novel juice extraction task. We found that groups ( = 3) seeded with a model trained to perform a tool modification that built upon simpler, unmodified tool use developed the seeded tool method that allowed greater juice returns than achieved by groups not exposed to a trained model (non-seeded controls; = 3). One non-seeded group also discovered the behavioral sequence, either by coupling asocial and social learning or by repeated invention. This behavioral sequence was found to be beyond what an additional control sample of chimpanzees ( = 1 group) could discover for themselves without a competent model and lacking experience with simpler, unmodified tool behaviors. Five chimpanzees tested individually with no social information, but with experience of simple unmodified tool use, invented part, but not all, of the behavioral sequence. Our findings indicate that (i) social learning facilitated the propagation of the model-demonstrated tool modification technique, (ii) experience with simple tool behaviors may facilitate individual discovery of more complex tool manipulations, and (iii) a subset of individuals were capable of learning relatively complex behaviors either by learning asocially and socially or by repeated invention over time. That chimpanzees learn increasingly complex behaviors through social and asocial learning suggests that humans' extraordinary ability to do so was built on such prior foundations.
累积文化是人类作为一个物种取得巨大成功的基础。声称其他动物没有文化棘轮效应的观点很普遍，但仅基于少数实证研究。因此，累积文化是否为人类所独有仍然是一个有争议且研究不足的问题，这对我们理解这一现象的进化具有深远影响。我们通过让圈养的黑猩猩群体接触一项新颖的果汁提取任务，来研究人类现存的两种最亲近的灵长类亲属之一——黑猩猩是否具备一定程度的文化棘轮效应。我们发现，那些引入了经过训练能进行工具改进的示范者的群体（ = 3），在基于更简单、未改进的工具使用基础上发展出了种子工具方法，与未接触经过训练的示范者的群体（非种子对照组； = 3）相比，这种方法能获得更多的果汁回报。一个非种子群体也通过结合非社会学习和社会学习或反复发明发现了行为序列。结果发现，没有具备能力的示范者且缺乏简单、未改进工具行为经验的额外黑猩猩对照组样本（ = 1组），无法自行发现这一行为序列。五只单独测试且没有社会信息，但有简单未改进工具使用经验的黑猩猩，发明了部分而非全部行为序列。我们的研究结果表明：（i）社会学习促进了示范者展示的工具改进技术的传播；（ii）简单工具行为的经验可能有助于个体发现更复杂的工具操作；（iii）一部分个体能够通过非社会学习和社会学习或随着时间的推移反复发明来学习相对复杂的行为。黑猩猩通过社会学习和非社会学习来学习越来越复杂的行为，这表明人类在这方面的非凡能力是建立在这样的先前基础之上的。
