Mammalian Social Learning: Comparative and Ecological Perspectives
Strier, Karen B
Mammalian Social Learning: Comparative and Ecological Perspectives, edited by Hilary 0. Box and Kathleen R. Gibson. Symposia of the Zoological Society of London 72. Cambridge, UK: Cambridge University Press, 1999. 424 pp. $95.00 (hard cover).
Mammalian Social Learning is based on a 1996 conference jointly sponsored by The Zoological Society of London, The Mammal Society, and The Primate Society of Great Britain. Unlike many other edited conference-based volumes, this book is more than a convenient collection of previously published works. In fact, many of the contributors acknowledge the editors for stimulating them to think in new ways about social learning in the animals they study. A few of the contributors credit the editors for creating the incentive to think about social learning at all. The sense of discovery, which includes large doses of thoughtful speculation, makes for refreshing reading.
The 21 chapters are divided into six parts, corresponding, for the most part, to perspectives on social learning in primates, terrestrial herbivores, communal-dwelling mammals like rats and bats, terrestrial carnivores, cetaceans, and hominoids including great apes and humans. As displayed in these chapters, the state of knowledge about social learning, or how different mammals acquire the skills for success in their respective physical and social environments, is extremely uneven. Some mammals, including primates, European rabbits, bats, and cats, have been the targets of systematic studies on information transfer. Others, such as arctic herbivores like caribou and muskox, bears, and marsupials, are discussed in terms of the different kinds of opportunities for social learning that exist in their societies. All of the chapters include detailed descriptions of the natural histories of the mammals represented, and all offer stimulating ideas for future research.
The editors have done an outstanding job of introducing each of the book’s six parts. These “editors’ comments” serve as blueprints for navigating the chapters that follow them, and add a necessary measure of integrity to the divergent approaches that the contributors bring to their respective study subjects. In their concluding remarks, the editors synthesize these approaches, as well as what they reveal about mammalian social learning.
Among the common themes that emerge from the chapters are the opportunities that young mammals have to learn from their mothers and other group members during their extended periods of dependence from birth through weaning. For social mammals, these opportunities often extend beyond weaning and into adulthood, but even more solitary mammals, such as bears, can augment the prolonged social contact between mothers and cubs by associating with their siblings after weaning (B. K. Gilbert, chapter 13). Sex differences in developmental trajectories are considered specifically in the chapter on African elephants by P. C. Lee and C. J. Moss (chapter 6). Species differences are the focus of comparisons in chapters such as those by K. Higginbottom and D. B. Croft on marsupials (chapter 5), D. R. Klein on arctic herbivores (chapter 7), A. C. Kitchener on feuds (chapter 14), J. A. J. Nel on canids (chapter 15), and R. W. Byrne on great apes (chapter 18).
Two of the central questions addressed in this volume are what mammals must learn and the variety of means by which essential information is communicated. Primary skills to be learned involve obtaining food, whether by foraging or hunting; detecting and avoiding predators; and recognizing mates, species, and colony membership. It is not surprising that different mammals acquire these skills in different ways. For visually oriented mammals, like primates, social opportunities to observe experienced individuals are key. For the less visually inclined, olfactory and auditory cues play a much larger role. Thus, young European rabbits rely on a nipple-search pheromone to get milk from their mothers (R. Hudson, B. Schall, and A Bilko, chapter 8), and naked-mole rats use odor trails laid down by their colony mates to find their way to food and to discriminate members of their colonies from others (C. G. Faulkes, chapter 12). By contrast, vocalizations in acoustically sensitive mammals like bats (G. S. Wilkinson and J. W. Boughman, chapter 11) and bottlenose dolphins (V. M. Janik, chapter 17) are critical to their success at foraging and maintaining their social relationships, respectively.
Several of the authors appropriately emphasize the process of information transfer that underlies social learning. For example, R. M. Sibly (chapter 4) distinguishes between the “receiver” and the “transmitter” of information, and models social learning based on the expectation that transmitter behaviors should be uniform whereas receiver behaviors should be polymorphic throughout a population. Transmission chain experiments with Norway rats (K. N. Laland, chapter 10) include evidence that information can be both lost and gained in the process of transmission, and that the amount of information that can be transmitted in a population is influenced by factors such as group size and stability. In their model of Paleolithic tool-making tradi-; tions, S. J. Shennan and J. Steele (chapter 20) also point to the population consequences when skill transfer is predominantly from parent to offspring, and thus follows genetic lineages.
B. J. King (chapter 2) goes further to suggest that social learning is nonlinear, and that it might best be viewed as an emergent process that reflects the interaction between individuals that “donate” information and those that acquire it. Individual differences in temperament (H. 0. Box, chapter 3) and standardized definitions of groups and populations (T. E. Rowell, chapter 1) are clearly variables that must be taken into account when comparing social learning across taxa. Less clear, however, is what evidence of social learning means about the cognitive abilities of the individuals involved. As described by D. M. Brown (chapter 9), domesticated animals such as cattle and pigs exhibit cognitive abilities that extend social facilitation into the realm of strategically controlling their lives. How different are the learning processes employed by domestic pigs when they select the same trough after feeding demonstrations at that trough from those employed by male humpback whales, who change their songs in response to feedback among singers (Boran and Heimlich, chapter 16)?
The question becomes even trickier when applied to the evolution of hominid cognition. K. R. Gibson’s (chapter 19) review of what distinguishes the modern human brain focuses on its size and the social demands associated with meeting a large brain’s metabolic demands. Mithen (chapter 21) suggests a two-step difference in the evolution of human social learning abilities based on his analysis of the archaeological record. According to his analysis, the consistency with which handaxes were produced over a 200,000-year time span implies that hominids employed imitative, observational, learning long before the appearance of anatomically modern humans and the technological innovations they introduced. Considering Byrne’s (chapter 18) examples of imitative learning in object manipulation by great apes, the distinctive cognitive abilities of humans, at least as reflected by our capacity for social learning, appear to be a relatively recent evolutionary phenomenon. Nonetheless, considering the other examples presented in this book, it is evident that origins for human social learning are deeply rooted in our heritage as mammals.
Including such an eclectic range of species and approaches in one volume comes with risks as well as strengths. Some anthropologists may not care much about nonprimate mammals, and some biologists may find the discussions of fossil hominid behavior too speculative. It would be a mistake, however, to rule out this book based on preconceived biases about appropriate comparisons or disciplinary differences in methodology. The breadth of examples contained in these pages will challenge established researchers to rethink their assumptions about what counts-or doesn’t count-as social learning, and new students of behavior to think about ways of addressing the many as-yet unanswered questions about social learning. The readership for this book should be as diverse as the mammals and modes of social learning it depicts.
Copyright Wayne State University Press Dec 2000
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