In 2008 MIT Press published Michael Tomasello’s book Origins of Human Communication, which was based on lectures that Tomasello gave in Paris in 2006. The book is a fascinating account of how human language may have evolved out of ape gestures. Based on the latest scientific knowledge on the use of gestures by apes and language development in human children, Tomasello makes a quite plausible and elegant argument that human language has had its origins in great ape gestural communication. This is because ape vocalizations are not learned. The vocalizations are used inflexibly, tied to the emotions that give rise to them. Great ape gestures, however, show much more flexibility and the use of gestures is learned during development. Great apes also use their gestures intentionally, they wait for a response from their conspecifics and will repeat or adjust the gestures if there has been no response. Though Tomasello has of course no clear-cut story of how exactly human language may have evolved, the argument for a gestural origin is solid, given these differences between great ape vocalizations and gestures. Tomasello divides great ape gestures into attention-getters and intention-movements. A gesture such as a mother asking her child to climb on her back, is an example of an intention movement: the movement of the gesture shows the intention that the mother wants to take place. The use of gestures by great apes is, however, limited to making requests to and demanding actions from others. In contrast, human communication includes motives for helping and sharing, which results in three basic motives of human communication: requesting (requesting help), informing (offering information) and sharing emotions and attitudes (bonding). These motives have come about because unlike nonhuman great apes, who have a comprehension of individual intentionality only (they know what the goals are of separate individuals), humans have skills for what is called shared intentionality: human individuals have a common conceptual ground, they have shared goals and attention and communicate with cooperative motives. These skills and motives arose in a context of mutualistic collaborative activities. Originally starting with pointing and using iconic gestures (pantomiming), humans experienced a “drift to the arbitrary,” eventually resulting in the linguistic conventions that we now know. Even grammar thus originated in human cooperative communication, because the human motives for informing and sharing needed the possibility to communicate about events displaced in time and space and to share further information about events and people that can only be expressed by certain aspects of grammar. mark the particular roles of participants and to relate events to one another as in stories and narratives. Grammatical constructions would have come about by a conventionalization process and there would thus be no need to infer a universal grammar such as Chomsky proposed: grammar is learned, not innate. The fact that grammar is part of every human language is because it is functional and necessary for our particularly human way of cooperative communication, not because grammatical rules are hard-wired in our brains.
I know this is a very short summary of Tomasello’s argument for the gestural origin of human language, so I advise you to read the book in order to understand his full argument. The book is written in a very clear and convincing style and is understandable for most lay persons with some academic background.
Chapter 6 is about the possible evolution of grammar and it is here that Tomasello gives ample space to discussing my work with the signing chimpanzees. He mentions that there has been a controversy about the lack of grammatical structure in the use of signs or lexigrams by the great apes in the language projects, because of a lack of systematic and quantitative data. My work with Washoe and the other signing chimpanzees has been exactly that: a large systematic analysis of the way the chimpanzees use their signs. My study is then presented by Tomasello on a par with the study of Sue Savage-Rumbaugh and Patricia Greenfield (published in 1990) of the way the bonobo Kanzi used his lexigrams. Both studies are the only ones in ape language research that systematically analyzed the videotaped behaviour of these ape subjects. Tomasello discusses the results of my study in several pages, presenting my conclusions on the communicative intentions or functions of the apes’ signed utterances and the lack of grammatical structure in the sequences of signs that the chimpanzees produced. He presents the only ordering that I found in the apes’ sign combinations: the chimps used object and action signs first, and a point (to the requested object or to the human) and signs that functioned as wild cards (pleasing the human) last. He quotes my 2005 conclusion in the Journal of Comparative Psychology:
“The object and action signs are produced first because these are the more important or salient signs of the (usually request) utterances, specifying what is requested. The request markers THAT/THERE/YOU/GOOD/HURRY are produced last because they are less important (not specifying what is requested) and function to add emphasis or to spur the human into action.” I feel great my work is being discussed in this great book and I’m grateful my hard work is now of use in theories and conclusions about ape communication and the evolution of human language.”
Michael Tomasello (1950) is a psychologist who originally worked at Emory University, Atlanta (where he did a lot of research on the apes at the Yerkes National Primate Research Center). Since 1998 he is professor at the Department of Developmental and Comparative Psychology of the Max Planck Institute for Evolutionary Anthropology (of which he is co-director) at Leipzig University, Germany. His research staff continues to do important studies on all four great ape species’ communicative behaviour and social cognition. The Koninklijke Nederlandse Akademie van Wetenschappen (Royal Dutch Academy of Sciences) has rewarded him the 2010 Dr. A.H. Heineken Prize for Cognitive Science.