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Communication skills The Design of Animal Communication edited by Marc D. Hauser and Mark Konishi, MIT Press, 1999. $70.00 (xi + 679 pages) ISBN 0 262 08277 2
This book stems from the symposium in honor of Peter Marler, and brings together chapters from leaders in the field of animal communication. Two immediate, and telling, testimonials to Marler are evident from simply browsing the table of contents. The first is the high proportion of contributors that are academic offspring (i.e. either children or grandchildren) of Marler himself, which testifies to his generous spirit and capacity for inspiration. The second is the variety of taxa, approaches, and perspectives represented – this diversity speaks volumes about the extraordinary breadth of ideas and interests with which Marler is associated. This breadth of representation is a strength of the book, since it is unusual in this age of ever-increasing specialization to have neural, behavioral, developmental, and evolutionary perspectives represented in a single volume. For example, vocal behavior in songbirds (one area of research in which Marler was a pioneer) is discussed, in various chapters, from the perspective of the physical nature of vocal sounds and individual variation, peripheral motor production, auditory processing, neural and hormonal mechanisms, comparative and genetic analyses, and ecological relevance and selection. Marler’s own chapter reviews some of the evidence from his lab for innate influences on vocal behavior and learning in sparrows. The iconoclastic nature of this work lies in its contrast to the preoccupation of many students of the song system (present company included) with the role of experience in vocal learning. Abundant evidence attests to the fact that the genome exerts fundamental predispositions and constraints on vocal learning in songbirds, but these issues have not been active topics of research for those chauvinists (such as myself) who have a certain degree of tunnel vision for the role of experience in shaping brain and behavior. This relative neglect of innate factors is surprising, because greater emphasis in this area would provide fundamental advances in our understanding of nature–nurture issues http://tins.trends.com
TRENDS in Neurosciences Vol.24 No.5 May 2001
generally, and would bear on the unresolved debate of similar issues regarding the acquisition of human language. Marler’s chapter concludes with a typically thought-provoking discussion concerning the pitfalls of describing vocal behavior as ‘learned’ or ‘innate’, arguing that it is not enough to realize that interpretations of behavior based on a dichtomy of these two terms is overly simplistic. Rather, as a heuristic, it is preferable to view the development of phenotypic plasticity in terms of Waddington’s epigenetic landscapes: genomic instructions for alternative ontogenetic patterns that are environmentally influenced. By this strategy, almost any behavior develops according to both genetic factors and accrued experience. The challenge for the future might be to explore how experience can alter the range of genetically based ontogenies available to an organism as development unfolds, and vice versa. Another strength of this book, as indicated above, is the range of model systems represented. Browsing through the chapters presents a golden opportunity for those unfamiliar with neuroethological systems to appreciate the power and beauty of studies that focus on the neural basis of naturally occurring behaviors, particularly when combined with comparative and phylogenetic approaches. Such studies exploit behaviors that organisms do well, presumably because such behaviors have been selected for during evolution and are associated with large and well-localized neural substrates. Studies of dancing honeybees (including a robotic bee!), echolocating bats, electric fish, calling crickets, rapping frogs, and emoting primates (both human and nonhuman), among others, are brought together to address basic issues in mechanisms and evolution of behavior. A nice example is provided by studies of categorical perception in field crickets in the chapter by Wyttenbach and Hoy. The question of how perceptual systems parse, or categorize, incoming signals into meaningful units of information is one that transcends the immediate and interesting question of classification of natural signals, and extends to fundamental issues regarding neural processing underlying perception and behavior. The approach espoused by Ron Hoy and colleagues puts the analysis of categorical perception in an evolutionary
303
framework. Their work shows that an ethological perspective is essential for ultimately understanding the adaptive benefit (and potential costs) associated with ‘collapsing’ perceived stimuli into relatively broad categories. Another example is provided by the powerful approach pursued by Mike Ryan and colleagues, who have combined molecular phylogenetic analysis, comparative behavioral testing, neurobiology, and computer modeling neural network studies in their analysis of acoustic mate recognition systems in túngara frogs. Their studies indicate that females have acoustic biases that exert selective pressures on males, such that male calls come to exploit female acoustic preferences. They examine phylogenetic relationships of frogs to deduce the evolutionary history of vocal calls, and show that females of one species can prefer calls modified to mimic those of a different (but related) species if the call contains an ancestral characterisitic (i.e. an ancient sensory bias, or ‘neural sweet spot’ in the words of editor Marc Hauser). Thus, the evolutionary history of the communication system generates response biases that are not present in the repertoire of all frogs in this species group. Ryan et al. use the phylogeny of this group to recreate ancestral calls; digitally synthesized renditions of these predicted calls show that female preferences are dictated by evolutionary history, suggesting that ancestrally derived preferences could provide starting points of sexual selection for new signals. The range of systems covered in this volume also means that not only are vocalacoustic communication systems well represented, but also communication based on recognition of emotions and facial signals, electrosensory processing, visual processing, and echolocation. As such, this volume seems mandatory for all students of communication. However, students of many disciplines will find this book well worth exploring because the study of communication, as pioneered by Marler, addresses basic questions crossing many areas of research in neural systems and behavior. S. Bottjer Dept of Biology, University of Southern California, Los Angeles, CA 90080 2520, USA. e-mail: [email protected]
Communication skills The Design of Animal Communication edited by Marc D. Hauser and Mark Konishi, MIT Press, 1999. $70.00 (xi + 679 pages) ISBN 0 262 08277 2
This book stems from the symposium in honor of Peter Marler, and brings together chapters from leaders in the field of animal communication. Two immediate, and telling, testimonials to Marler are evident from simply browsing the table of contents. The first is the high proportion of contributors that are academic offspring (i.e. either children or grandchildren) of Marler himself, which testifies to his generous spirit and capacity for inspiration. The second is the variety of taxa, approaches, and perspectives represented – this diversity speaks volumes about the extraordinary breadth of ideas and interests with which Marler is associated. This breadth of representation is a strength of the book, since it is unusual in this age of ever-increasing specialization to have neural, behavioral, developmental, and evolutionary perspectives represented in a single volume. For example, vocal behavior in songbirds (one area of research in which Marler was a pioneer) is discussed, in various chapters, from the perspective of the physical nature of vocal sounds and individual variation, peripheral motor production, auditory processing, neural and hormonal mechanisms, comparative and genetic analyses, and ecological relevance and selection. Marler’s own chapter reviews some of the evidence from his lab for innate influences on vocal behavior and learning in sparrows. The iconoclastic nature of this work lies in its contrast to the preoccupation of many students of the song system (present company included) with the role of experience in vocal learning. Abundant evidence attests to the fact that the genome exerts fundamental predispositions and constraints on vocal learning in songbirds, but these issues have not been active topics of research for those chauvinists (such as myself) who have a certain degree of tunnel vision for the role of experience in shaping brain and behavior. This relative neglect of innate factors is surprising, because greater emphasis in this area would provide fundamental advances in our understanding of nature–nurture issues http://tins.trends.com
TRENDS in Neurosciences Vol.24 No.5 May 2001
generally, and would bear on the unresolved debate of similar issues regarding the acquisition of human language. Marler’s chapter concludes with a typically thought-provoking discussion concerning the pitfalls of describing vocal behavior as ‘learned’ or ‘innate’, arguing that it is not enough to realize that interpretations of behavior based on a dichtomy of these two terms is overly simplistic. Rather, as a heuristic, it is preferable to view the development of phenotypic plasticity in terms of Waddington’s epigenetic landscapes: genomic instructions for alternative ontogenetic patterns that are environmentally influenced. By this strategy, almost any behavior develops according to both genetic factors and accrued experience. The challenge for the future might be to explore how experience can alter the range of genetically based ontogenies available to an organism as development unfolds, and vice versa. Another strength of this book, as indicated above, is the range of model systems represented. Browsing through the chapters presents a golden opportunity for those unfamiliar with neuroethological systems to appreciate the power and beauty of studies that focus on the neural basis of naturally occurring behaviors, particularly when combined with comparative and phylogenetic approaches. Such studies exploit behaviors that organisms do well, presumably because such behaviors have been selected for during evolution and are associated with large and well-localized neural substrates. Studies of dancing honeybees (including a robotic bee!), echolocating bats, electric fish, calling crickets, rapping frogs, and emoting primates (both human and nonhuman), among others, are brought together to address basic issues in mechanisms and evolution of behavior. A nice example is provided by studies of categorical perception in field crickets in the chapter by Wyttenbach and Hoy. The question of how perceptual systems parse, or categorize, incoming signals into meaningful units of information is one that transcends the immediate and interesting question of classification of natural signals, and extends to fundamental issues regarding neural processing underlying perception and behavior. The approach espoused by Ron Hoy and colleagues puts the analysis of categorical perception in an evolutionary
303
framework. Their work shows that an ethological perspective is essential for ultimately understanding the adaptive benefit (and potential costs) associated with ‘collapsing’ perceived stimuli into relatively broad categories. Another example is provided by the powerful approach pursued by Mike Ryan and colleagues, who have combined molecular phylogenetic analysis, comparative behavioral testing, neurobiology, and computer modeling neural network studies in their analysis of acoustic mate recognition systems in túngara frogs. Their studies indicate that females have acoustic biases that exert selective pressures on males, such that male calls come to exploit female acoustic preferences. They examine phylogenetic relationships of frogs to deduce the evolutionary history of vocal calls, and show that females of one species can prefer calls modified to mimic those of a different (but related) species if the call contains an ancestral characterisitic (i.e. an ancient sensory bias, or ‘neural sweet spot’ in the words of editor Marc Hauser). Thus, the evolutionary history of the communication system generates response biases that are not present in the repertoire of all frogs in this species group. Ryan et al. use the phylogeny of this group to recreate ancestral calls; digitally synthesized renditions of these predicted calls show that female preferences are dictated by evolutionary history, suggesting that ancestrally derived preferences could provide starting points of sexual selection for new signals. The range of systems covered in this volume also means that not only are vocalacoustic communication systems well represented, but also communication based on recognition of emotions and facial signals, electrosensory processing, visual processing, and echolocation. As such, this volume seems mandatory for all students of communication. However, students of many disciplines will find this book well worth exploring because the study of communication, as pioneered by Marler, addresses basic questions crossing many areas of research in neural systems and behavior. S. Bottjer Dept of Biology, University of Southern California, Los Angeles, CA 90080 2520, USA. e-mail: [email protected]