The Cultural Origins of Human Cognition

  • Michael Tomasello
Harvard University Press: 1999. 248 pp.$29.95, £18.50

Human language and thought elevate us mentally to a grade far removed from anything known in other animals. Yet it has happened in just a twinkling of evolutionary time. Less than six million years separate us from the non-human, non-verbal ancestor we share with chimpanzees. So, suggests Michael Tomasello, we are faced with a puzzle: how could human minds vault this high so quickly? The question becomes more acute if one acknowledges little sign of any accomplishment beyond basic ape mentality until two million years ago or even less. Tomasello's solution — given how far he wants to push the idea — is a radical one. Depending on the reader, I suspect it will elicit excitement, irritation or incredulity. These different reactions may be more or less appropriate according to the evolutionary timescale Tomasello truly aspires to address.

The key proposition is that there was just one critical step in biological evolution which transformed our ancestors' capacity to sustain culture. A new ‘ratchet’ effect arose, in which cultural advances were built upon progressively in a way not seen in the social traditions of other animals. Human cognition would thenceforth become increasingly complex and differentiated, eventually achieving modern levels of sophistication without need of further biological change.

To see how radical a proposition this is, consider the case of language. Tomasello is arguing that the structures of our highly elaborated language capacities today have nothing to do with the evolution of a dedicated and, in some views, highly structured language instinct (he gives short shrift to the idea of innate mental modules, of any kind). Instead, he proposes that syntax and all the other complex aspects of human language have simply been built up over the generations, by cumulative, ratcheted, cultural evolution. The biological substrate did not need to change. What makes such a scenario plausible, according to Tomasello, is evidence that, quite early on, the human child demonstrates a capacity to translate between the perspectives of self and other that goes beyond anything seen in apes. Perceiving others as intentional agents, in particular, permits the child to become the kind of ‘imitation machine’ needed to participate in the powerful ratchet effect.

Tomasello's ambitious thesis requires accounts of changes on three very different timescales; evolutionary, historical and ontogenetic. To this task he brings almost unrivalled authority, based on an influential suite of both comparative and developmental studies; he cites more than 40 observational and experimental studies conducted by his group on monkeys, apes and children. These studies, mostly conducted in the 1990s, cover an impressive array of socio-cognitive capacities, including imitation, joint attention, theory of mind and language acquisition.

This substantial empirical base is coupled with a sophisticated grasp of the theoretical issues at stake, particularly when it comes to Tomasello's prime area of expertise, the development of language. Written with refreshing simplicity and directness, the product is a slim volume that nevertheless packs in a richly articulated and challenging model of mind, backed by a wealth of pithily summarized comparative and developmental studies.

At least two-thirds of the book is devoted to tracing the origins and development of components of cultural learning in children, with a particular emphasis on language. This is a masterly survey, covering pre-linguistic scaffolding for language, the acquisition of symbol and syntax use, discourse and the implications of internalization for other aspects of cognition.

Certain features of Tomasello's thesis are less compelling. He considers the possibility that the vital change may have happened two or even six million years ago. But his argument appears to neglect enormous changes in the brain, which has tripled in size since six million years ago and roughly doubled in the past two million. It seems more likely that whatever elaboration of social and cultural practices occurred in this period, it was underwritten by equally massive and rapidly driven neural changes.

A predominant role for cultural change becomes more likely in the context of the past quarter of a million years of Homo sapiens' existence. If the greater part of existing language structure arose over this period, the idea that this happened through cultural learning and ratcheting processes still constitutes a major challenge to those who argue for innate language systems. Tomasello notes that the main diversification of the Romance languages occurred in a few hundred years; so why could not cultural processes of syntacticization turn an embryonic language into a vastly more complex one over hundreds of thousands of years?

A further doubt is whether Tomasello has correctly identified the critical cognitive step that elevated our ancestors' social sophistication over existing anthropoid psychology. His conclusion is largely founded on experimental findings in captive apes far removed from the rich inputs of their natural environments. Field researchers tend to perceive more advanced cultural processes at work, although these perceptions are difficult to substantiate without experimental controls. Accordingly, we are at something of an impasse on this question. Tomasello's thesis probably depends less than he implies on the exact difference between chimpanzee and human cultural propensity, especially if the thesis gets its main application in the recent rise of Homo sapiens.

Nevertheless, students of primate behaviour are one of several groups who should read this important book. It spells out forcefully what appears to make human development so distinctive, and does so from the perspective of an expert in language acquisition who has also devoted much time to comparative work with apes. It is strong medicine for anybody in danger of romanticizing the similarity of ape to child. Developmental psychologists will find here a well-articulated account of the ontogeny of cultural learning, which challenges alternative accounts from the vantage point of extensive research. The book should also be a thought-provoking read for cognitive psychologists, many of whom seem to disregard social and cultural processes. Of course, we have ‘cultural psychology’, but that is about cultural differences. Tomasello is instead talking about universals, an aspiration of most cognitive psychology. If he is even half-right, the field suffers a serious omission indeed.