COMPARATIVE STUDY ON THE DEVELOPMENT OF MANIPULATIVE SKILLS IN CHIMPANZEES AND HUMANS
Authors: Misato Hayashi and Hideko Takeshita
Abstract: Manipulative activity is based on both manual motor skills and cognitive development. Humans and chimpanzees, the closest living relatives of human beings, share manual dexterity in manipulating objects in their daily lives. Chimpanzees are also known to use tools in their natural habitat to achieve a variety of goals. This chapter reports the findings gained by assigning tasks using identical objects conducted in a faceto- face situation for chimpanzees and human children. Manipulative skills in both species were analyzed as a non-verbal scale for direct comparison by focusing on their manipulative patterns. Tasks using blocks of different shapes were designed to test physical understanding involved in making a vertical stack. The subjects were required to selectively use appropriate orientation of differently-shaped blocks in order to stack them efficiently. The subjects acquired the solution of manually changing the orientation of the blocks to the appropriate one. The results illuminated a fundamental similarity between chimpanzees and humans. Tasks using nesting cups were originally designed to assess cognitive development in human children by analyzing the behavioral strategies of combining multiple cups into a nesting structure. The manipulation of nesting cups was described in a form of sequential codes in both chimpanzees and humans to illuminate the patterns of making a hierarchical combination among objects. Some of the subjects from both species succeeded in making a nesting structure with nine cups. The subjects tried to solve the task by reducing the number of cup units and by combining cups in an appropriate order. In sum, manipulative behavior revealed high levels of physical intelligence shared by chimpanzees and humans.