Hand-me-down speech. (Human Evolution).

From Hand to Mouth: The Origins of Language. Michael C. Corballis. xiv + 257 pp. Princeton University Press, 2002. $27.95.

No one really knows where human language comes from. One possibility is that language evolved from the hand gestures of our ape and hominid ancestors and not from their vocalizations. The view promoted by Michael Corballis in From Hand to Mouth is that our ancestors used both vocalizations and hand gestures to communicate, but that--particularly after the evolution of bipedalism and an increase in brain size--gestural communication became more complex and acquired the characteristics of a language, including symbolic referents, grammar and a syntax. Eventually there was a shift from gestures to speech as the main medium for expression.

One of the first to propose the gestural theory of language origins was the 18th-century French philosopher Abbe Etienne Bonnot de Condillac; it was then resurrected by the American anthropologist Gordon W. Hewes in the 1970s. Corballis expands the theory and integrates many research findings from disciplines such as paleoanthropology primatology, linguistics, developmental psychology and neuroscience.

He does a good job: From Hand to Mouth is informative and entertaining. It shows that many serious scholars are involved in research on human evolution and language origins--and also that there is a great deal of wackiness. Take, for example, the proposal by Julian Jaynes that until about 3,000 years ago, human behavior was guided by hallucinations generated by a "bicameral" brain, which were interpreted as the voices of "the Gods." According to Jaynes, some floods and earthquakes in the second millennium B.C. caused the brain to become lateralized, leading to the emergence of self-consciousness and individual responsibility for action, mediated by the left hemisphere. As a result, people no longer waited for the Gods to tell them what to do but started making their own decisions.

Corballis makes his own small contribution to the wackiness sometimes found in the field of paleoanthropology by suggesting that human bipedalism may have evolved as an adaptation to wading through water, or perhaps to swimming. If he is right, one may wonder why the wildebeest of the Serengeti do not walk bipedally and why humans not evolve fins, too.

Some readers of From Hand to Mouth may have difficulty discerning the boundary between facts and fiction in the book. The problem is that much of the research discussed by Corballis has little or no relevance ...