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Week of 10 October 1997

Vol. I, No. 7

Feature Article

Talking the talk

In the beginning was the idea, argues CAS prof

by Jim Graves

Where did our minds come from? What is the source of our unique capacity to speak? To experience self-consciousness? To appreciate art and music? To reason out moral questions? In other words, how did we get to be human beings, the creatures of whom Sophocles says that "nothing is more wondrousÓ? In a new book that is selling briskly, these and other perennial stumpers are answered by a Boston University scientist in ways that revise significant areas of linguistics, biological anthropology, and cognitive neuroscience.

Terrence Deacon examines film of a brain. The CAS associate professor of anthropology's new book, The Symbolic Species: The Co-Evolution of Language and the Brain, sheds fresh light on the origin of language and what it means to be human. Photo: Vernon Doucette

Terrence W. Deacon's fluent 527-page multidisciplinary study The Symbolic Species: The Co-Evolution of Language and the Brain (W. W. Norton) is being hailed by colleagues as a major academic event. The author, a CAS associate professor of anthropology and neurobiological researcher at Harvard Medical School/McLean Hospital, rejects competing theoretical paradigms of the origin of language (including MIT linguist Noam Chomsky's famous innate universal grammar theory). Instead, he argues that human brains and language evolved over the same time and that many of the traits people display today are the result of ideas conceived by our ancestors around two million years ago, which changed the conditions under which natural selection affected our brains.

Language did not arise because human brains were larger or had developed certain structures, Deacon says. "The reverse occurred. Symbolic communication actually changed the shape and size of the brain, forging new pathways of neural connection and encouraging growth of the prefrontal cortex."

Symbolic communication refers to the ability to communicate indirect relationships among symbol tokens (as when words take on particular meanings by modifying other words in a sentence). Such relationships, which cannot be learned by rote, distinguish human language from other forms of communication. It was this ability to think in symbols, Deacon says, that triggered the evolution of Homo sapiens from hominids.

The need for symbolic communication probably developed in response to social challenges created when early stone tools enabled the taking of game for food. "Symbolic communication,"Deacon says, "was the only way for a group of humans to make agreements that would ensure that a hunter's catch was used to raise a child that carried his genes. The regulation of mating behaviors by marriage relationships was likely the first social function of symbolizing. Only through the use of linguistic symbols can one talk at all about the future, let alone make a commitment to remain faithful to one partner."

Beyond the origins of language, The Symbolic Species goes on to explore technical details of the nature of the brain's development and function, which have, Deacon says, "made our species the evolutionary marvel that it is."Likewise marvelous from his standpoint have been a number of enthusiastic apprasisals of his achievement in The Symbolic Species. Notre Dame University philosopher of science A. Edward Manier, for instance, nominates Deacon as the "best neurophilosopher on the planet."Philosophers, Deacon says, "seem especially to like the book. I've already received invitations to speak at two philosophical conferences."

Yet, in a controversial field laced with older, more deeply entrenched theories, it is not surprising that a distinguished figure such as MIT cognitive scientist Robert C. Berwick, in a Los Angeles Times review, rejects Deacon's conclusions about language learning. But Berwick is far from rejecting the book as a whole. To the contrary, he writes that The Symbolic Species "holds out possibly the best hope we have to understand the mystery and miracle of language and how it is that we became creatures able to walk the walk and talk the talk."

Already a science best-seller in the United States, The Symbolic Species is currently climbing the sales charts in Great Britain, where it was released three weeks ago. "For a fat and difficult book on science, that's pretty good,"says Deacon.

To what practical uses can Deacon's work be put? "Obviously,"Deacon says, "new knowledge about the brain has potential medical applications. But beyond that, it makes clear that we're approaching a point where the development of scientific tools and the accumulation of hard comparative data on human and animal brains can enable breakthroughs on the age-old, plaguing problem of what makes man a special animal. I think the answer to that, which may provide a more mature understanding of humanness, will at once demystify and deepen our appreciation of what we are."