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Walking the Walk, Talking the Talk

Contending Views on Language and the Brain

THE SYMBOLIC SPECIES: The Co-Evolution of Language and the Brain.\o7 By Terrence W. Deacon\f7 . \o7 W.W. Norton: 528 pp., $29.95\f7

September 07, 1997|ROBERT C. BERWICK | Robert C. Berwick is co-director of the Massachusetts Institute of Technology's Center for Biological and Computational Learning and MIT professor of computer science. His most recent book, "Cartesian Computation," will be published by MIT Press this fall


Nearly 160 years ago, Charles Darwin wrote that "He who understands baboon would do more toward metaphysics than Locke." He tried. In his prescient two-volume "The Descent of Man and Selection in Relation to Sex" (1871), written 12 years after "Origin of Species," Darwin found that "the large size of the brain in man, in comparison with that of the lower animals, relatively to the size of their bodies, may be attributed in chief part . . . to the early use of some simple form of language, that wonderful engine which affixes signs to all sorts of objects and qualities, and excites trains of thought which would never arise from the mere impression of the senses." Language, then, produces a powerful stimulus for the brain or, as Darwin put it: "[T]he continued use of language will have reacted on the brain, and produced an inherited effect; and this again will have reacted on the improvement of language."

Sound familiar? It should. It's the exact model of a modern major evolutionary "Just So" story. As usual, Darwin's batting average bested those of most of our current players. Not only did Darwin get our "out of Africa" origin (probably) right, but he also spotted most of the currently debated evolutionary ingredients accounting for language: a ballooning brain expanded by an evolutionary "arms race"; and symbols that increased our ancestors' behavioral repertoire, thereby pushing the brain to keep pace and spurring further language development in an upward-spiraling direction--what biologists now dub "co-evolution."

What fueled this escalation? For Darwin, it was sexual selection: the same process of female choice or male competition that leads to ever-gaudier peacock feathers. Smooth-talking potential mates won the day. In a moment of extended Victorian reverie, Darwin speculates in "Descent" that our ancestors' "love songs" were the precursors to human language. Caruso lives!

It is testament to Darwin's triumph that this story of how speech divides us from the rest of creation seems so familiar. Whether you're talking about Desmond Morris and Richard Ardrey's 1960s work on the "naked ape," Edmund O. Wilson's 1970s sociobiological speculations linking language to hunting-plan competence and scratch-my-back-I'll-scratch-yours reciprocal altruism or Harry Jerison's brain expansion calculations, it's all rejuggled Darwin.

Even this decade's revivals--such as William H. Calvin's and Christopher Wills' "runaway brain," Michael Corballis' "lopsided ape" or psychologist Steven Pinker's language-as-Machiavellian offshoot (to win friends and influence people)--are just filigree adorning the same basic tale about brain-culture co-evolution. But it is when potboiler novels such as John Darnton's "Neanderthal" mix talk of telepathy with sophisticated byplay concerning whether or not the hyoid bone in early man's larynx was properly placed to hit Caruso's modern vowel tones, that you realize that the science writers have some catching up to do.

Luckily for us, Terrence Deacon's informative book makes a remarkable contribution. Most authors go awry by equating language development with communication. Darwin did. Our brains ballooned, bigger brains meant more smarts and, with more smarts, the wit for language. That much has dominated the quasi-theological discussion of language origins from before Aquinas to Hobbes' dictum "Homo rationale quid orationale" (man thinks because he speaks) and beyond. But this equation gets it wrong. As the linguist Derek Bickerton has noted, confusing "language" with "communication" is like confusing a car--the machinery itself--with the act of driving. Not so with Deacon. He dodges this misleading thought, along with many others. Gossip replaced grooming? Since animal communication systems can be so sophisticated, there's no obvious adaptive reason our ancestors ever needed anything more for hunting plans or "gossip." Bigger brains and machinery for speech?

Deacon argues that three, and only three, wildly divergent animal groups do all of the following: babble from birth, imitate the sounds of others and have (mostly) voluntary control of their breathing--humans, songbirds and parrots, and cetaceans (seals, whales, dolphins). Breath control is essential to speech: We speak only while exhaling (try saying this sentence while breathing in). Deacon observes that breath intake is yet another way that human speech differs from primate vocal calls which, like their human analogues of sobbing or laughter, are largely involuntary, contagious, and can involve rapid intakes of breath. Yet, being a literal bird-brain suffices for human-like breath control, and even children who are otherwise severely impaired, down 50% on normal IQ, still acquire language in the usual way.

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