Evolution of Communication Systems: A Comparative Approach. D. Kimbrough Oller and Ulrike Griebel, eds. MIT Press, Cambridge, MA, 2004. 338 pp., illus. $45.00 (ISBN 0262151111 cloth).
Evolution of Communication Systems: A Comparative Approach, the fourth volume in the Vienna Series in Theoretical Biology published by the MIT Press, addresses a hallmark feature of human evolution—our unparalleled facility for complex symbolic communication. The advanced status of human symbolic communication, exemplified by spoken and written language, is well articulated by contributing author Charles T. Snowdon: “Nothing that nonhuman animals can do approaches the complexity of our vocabulary, our grammar, the concepts and ideas, both concrete and abstract, that we can express; our playfulness and creativity as we devise new words like Xerox and fax; as we pun, write poetry or novels, or express our love for one another” (p. 131).
Reconstructing the evolution of human symbolic communication presents serious conceptual and methodological challenges. Did human languages evolve gradually from more primitive signal precursors? If so, how similar to these precursors are “primitive” communication systems in present-day nonhuman animals? Are there general rules for symbolic communication that cut across all species? And why have other species not evolved similarly advanced communication systems? These and related questions, many of which trace back to Charles Darwin and George Romanes, are the focus of 16 chapters penned by cognitive and behavioral psychologists, linguists, biologists, and a philosopher. The editors, D. Kimbrough Oller and Ulrike Griebel, from the University of Memphis, Tennessee, have done admirable work integrating a diverse population of chapters into a fairly cohesive unit. Introductory and closing chapters provide helpful guides, and liberal cross-referencing highlights common themes. I had one minor complaint: the title and cover photographs (of cuttlefish and a walrus) imply that the book will address communication in nonhuman animals on its own terms. This is not the case.
Most chapters address, and some as their raison d'être, the constituent properties and infrastructure of complex symbolic language. Numerous authors also suggest sequences by which symbolic language may evolve. Be ready here for challenging terminology; the semantics of semantics, in which language is both medium and content, can be alarmingly complex. Several chapters on this front, notably those by Ruth Garrett Millikan, William F. Harms, and Chris Sinha, were virtually unreadable, at least to this biologist.Yet other chapters offered clear and interesting insights. It was fascinating to see how behavioral scientists (Snowdon, Irene M. Pepperberg, Jennifer A. Mather) placed their work on nonhuman animals in the broader context of the book. I was particularly impressed by Peter Gärdenfors's hypothesis about how humans differ from other animals in communication abilities. Gärdenfors suggests that humans are unique in that we use symbolic language to refer to objects, actions, and goals that are not necessarily present in our immediate environments, but that may exist purely in our own “inner worlds.” Such capacity for “detached representation,” a term coined by Gärdenfors, enables humans to plan future events that are not cued by immediately available stimuli.With this comes an ability to construct abstract symbolic categories, for example to group individual referents (names) into categories based on shared properties (nouns). Human language thus stands apart from other complex communication systems, such as those of bees, which may appear symbolic on the surface but only address immediate stimuli or situations, and which appear not to be categorical. The concept of representations used by Gärdenfors is refreshingly consistent with its normal, familiar usages in cognitive ethology and neuroethology.
And what of language evolution? One observation of central interest, discussed by numerous authors, is that language evolved in concert with vocal learning and advanced cognitive capacities. Vocal learning provides humans an ability to develop otherwise arbitrary “sound-meaning mappings” (James R. Hurford, p. 302), and advanced cognitive capacities set the context in which fine-resolution symbolic representations are articulated. Other species, however, may also possess similar traits but have not evolved symbolic language. Vocal learning, for example, has evolved in songbirds, and advanced cognitive capacities have evolved in African grey parrots; but neither uses symbolic communication. What, then, is so special about people?
Traditionally, answers to this question have been mostly of an “environmental or technical” nature (R. I. M. Dunbar, p. 257), addressing, for example, unique features of human vocal physiology, or how advanced vocal learning or cognitive abilities delimit universal “rules” or “grammar” on which language is built. Such approaches were pioneered by Noam Chomsky; see Marc Hauser's 1996 book The Evolution of Communication (Cambridge, MA: MIT Press) for a helpful overview of this literature. But, as evident in both Hauser's and the present book, the focus is now shifting to stress how human language evolution may have been catalyzed by our unique ancestral social circumstances.
A common emerging theme is the importance of cooperation, and this is where the book excels. I particularly recommend the quartet of chapters by Dunbar, Gärdenfors, W. Tecumseh Fitch, and Snowdon. Dunbar reviews his “gossip” theory of language evolution, which argues that symbolic language evolved as a means by which our ancestors maintained social bonds as group sizes increased during hominid evolution. This task was previously accomplished by grooming, but became unmanageable in larger groups because time required for grooming encroached on other critical tasks such as foraging. Gärdenfors further suggests that symbolic language enabled our ancestors to plan future actions, and that such planning revolved largely around selection for cooperative ventures. Fitch takes these ideas to a more detailed level of resolution, arguing that language, being both cheap and honest, carries the imprint of kin selection. Thus the ability to share complex information among kin, with regard to behavioral ventures such as group foraging, would favor kin groups with comparatively strong language proficiency. Fitch's focus on the importance of language within family groups concurs well with data on language ontogeny and function. Snowdon reviews work on communication and cooperative breeding in New World primates. Of particular interest is his research on vocalizations in tamarin families, in which changing patterns of adult vocal behavior were shown to guide food choice by juveniles. Even more intriguing are data that suggest that adult tamarins teach their infants about which vocalizations they should use in which contexts.
The conceptual emphasis of Evolution of Communication Systems, then, is on cooperation. Perhaps selection for cooperative behavior, playing out on a receptive “biological platform” (Snowdon, p. 145) of vocal, imitative, and cognitive proficiency, indeed powered language evolution. The level of agreement among authors on the importance of cooperation is impressive. The editors report that the workshop “resulted in an extremely lively exchange of these ideas, filled with probing questions and much laughter” (preface, my italics). Is, then, the study of linguistics, a field long rife with controversy, itself entering a new age of civility?