Review of Philip Lieberman's Human Language and our Reptilian Brain

Philip Lieberman, Human Language and our Reptilian Brain: The Subcortical Bases of Speech, Syntax, and Thought. Harvard University Press, Cambridge, Mass, 2000.

James R Hurford,
Language Evolution and Computation Research Unit,
Linguistics Department, University of Edinburgh

(This review appeared in Quarterly Review of Biology, 76,3 p.383, September, 2001).

This is Philip Lieberman's fifth book on the evolution of language. Inevitably, it echoes many of the messages of the earlier books, especially the emphasis on the evolution of speech as holding the key to the evolution of language as a whole, and a concomitant opposition to the dominant Chomskyan paradigm, which sees syntax as central to language. The book is approachably written. No reader could be unclear about Lieberman's main claims, crisply set out in his introduction. He argues that language is a learned skill, rather than an innate instinct. The human capacity for language is based on a ``functional language system'' (FLS), distributed across many subsystems of the brain, many of which link directly to the subcortical basal ganglia. Lieberman opposes a Fodorean modular view of human cognition and ``algorithmic'' accounts of human language capacities. To Lieberman, ``algorithmic'' seems to mean implemented by symbolic operations in a sequential machine: he does not discuss determinism or whether algorithms can be implemented in neural nets, though he seems to believe that they cannot.

After the introduction, Chapter 1 gives a readable and useful brief survey, for a relative layperson, of the basic architecture and functioning of the brain, along with an account of investigative procedures, including microelectrode studies with monkeys, modern scanning techniques with humans, and experiments of nature. Chapter 2 is a quick survey of fundamentals of speech production and perception, selected for their relevance to Lieberman's main theme, and pitched at a level of intermediate technicality; a scheme of representation in the brain common to both production and perception is emphasized. In Chapter 3, Lieberman ventures away from speech, to argue that lexical storage in the brain is integrated with non-linguistic knowledge, and in many areas outside the traditional ``language areas''. Chapter 4, the longest, surveys a wide range of neurological studies pointing to the crucial involvement of the subcortical basal ganglia in language processing; in this chapter, a reader may lose sight of the wood for the mass of trees. Chapter 5 speculates as to how the human functional language system could have evolved, after strongly critical sections on the speculations of others, especially evolutionary psychologists such as Tooby and Cosmides, and Chomskyans such as Bickerton and Pinker. In opposition to the former, Lieberman emphasizes the importance of finding neural mechanisms corresponding to proposed adaptive traits. In opposition to the Chomskyans, he proposes a gradual evolution of language capacity stretching over at least two million years (with roots orders of magnitude older) neurally integrated with nonlinguistic cognitive and motor capacities.

The book is mainly lively reading, citing a rich range of scientific literature. The strong polemical tone sometimes adopted is symptomatic of a schism in modern Linguistics which I hope can soon be resolved.