Great Apes and Human Development: A Personal History

In this article, I recount my history of research with great apes. From the beginning, the idea was to compare apes to human children, with an eye to discovering facts relevant to describing and explaining processes of human development. The research went through three more or less distinct stages, focusing on communication and social learning, social cognition and theory of mind, and cooperation and shared intentionality. I conclude by identifying problems and prospects for comparative research in developmental psychology. KEYWORDS—evolution; development; apes I wish I could say it was all planned. But the fact is, I lucked into the opportunity to study great apes. Although from my first psychology course as an undergraduate at Duke University I thought about things evolutionarily, my graduate work at the University of Georgia was almost totally developmental. True, the focus was on Piaget, a biologist with an evolutionary perspective, but the research was all about children. It was pure luck that I happened to get a job (barely) at Emory University, home of the Yerkes Primate Center. Soon after arriving in 1980, I drove out to the Yerkes Field Station with a colleague. We were gushing enthusiastically about how incredibly similar chimpanzees were to humans—in their basic emotions, their playful social interactions, their clever use of tools—when one of them sitting atop a climbing apparatus began urinating. Another sauntered over and opened its mouth to catch the pee. Well, okay, maybe very similar to us, but not identical! At more or less that moment, I could dimly see how exciting it would be to directly compare great apes and human children on the kinds of phenomena that I and other developmental psychologists were studying. COMMUNICATION AND SOCIAL LEARNING At the time, I was studying language acquisition. Prominent researchers such as Bruner (1) and Bates (2) were emphasizing the pragmatics of the process, including the role of joint attention in word learning and the status of the pointing gesture as the most basic act of reference. So one thing that caught my eye on that first day was the way the young chimpanzees gestured to one another, especially during play. What was remarkable was that these gestures did not seem to be the kind of fixed action patterns characteristic of the phylogenetically ritualized communicative signals studied by ethologists. They seemed to be more under the intentional control of the individual for flexible use as needed in particular circumstances. What they looked like were human infants asking to be picked up using an arms-up gesture toward an adult. That is, they seemed similar to the intention movements studied by ethologists, except that individuals actually learned them from their social interactions and also had intentional control over them. Over a series of observational studies published in animal behavior journals, we established that chimpanzees had a number of gestures that were learned individually and used intentionally (see 3 for a review). They used these gestures flexibly (same gesture for different ends, same end effected by different gestures), even waiting for a response from the recipient, and repeated the gesture if the desired response was not forthcoming. And their use of the gestures was tailored to the recipients’ attentional state: When their intended recipient was not looking, their gestures were never visual but mostly auditory or tactile. Although these gestures were of the same type as human infants’ ritualizations, such as the arms-up gesture, they clearly differed from human infants’ pointing and iconic gestures. Pointing and Michael Tomasello, Duke University and Max Planck Institute for Evolutionary Anthropology. Correspondence concerning this article should be addressed to Michael Tomasello, Department of Psychology and Neuroscience, Duke University, Box 90086, Durham, NC 27708-0086; e-mail: michael.tomasello@duke.edu.