Mammalian Social Learning: Comparative and Ecological Perspectives. Edited by Hilary O. Box & Kathleen R. Gibson. Cambridge: Cambridge University Press (1999). Pp. xiv+424. Price UKP 60.00. This volume is often about what we don't know rather than what we do. Around half of the 21 chapters describe the natural history of a species or group of species with particular attention to their social organization. Each author then discusses the likely opportunities for the animals to learn from their conspecifics, presenting field studies and anecdotes that may be highly suggestive of social learning but fall short of providing definitive evidence for it. The chapter by Lee and Moss on elephants, and that by Gilbert on bears, exemplify this approach. The observations reported are the fruits of persistent and ingenious fieldwork, but the reader is nevertheless left with a sense of how much more needs to be done before we really understand social learning in that animal. Some chapters review both field observations and controlled experiments, and these contributions lead to a more fleshed-out picture. For example, Kitchener's chapter, on young learning from their mothers among the Felidae, integrates field observations of big cats with experimental work on domestic cats. Kitchener establishes that social learning is important in allowing young cats to identify appropriate prey species and to perfect their killing techniques. A few chapters describe original, well-constructed experiments that really pin down an instance of social learning. Laland's chapter describes a series of transmission chain experiments using rats, and establishes that a novel foraging technique can be passed along a sequence of animals. Hudson, Schaal, and Bilko look at the ways in which young European rabbits learn food preferences from their mothers, and show that multiple mechanisms exist: transmission occurs in utero, through suckling, and via faecal pellets. The first four chapters of the book are theoretical or position pieces, including Box's argument that individual differences in temperament will mean different opportunities for social learning, and a piece by Sibly applying some rudimentary cost-benefit results from signalling games to the social learning case. The editors are aware that humans, hominids, and apes are mammals too, and the book covers these groups in the concluding four chapters. For example, Byrne discusses the ability of apes to imitate behavioural programs, and Mithen makes the surprising claim that the archaeological record, specifically the manufacture of handaxes, shows that imitation doesn't always lead to cultural evolution. The volume succeeds in the editors' stated goal of extending the comparative database on mammalian social learning. In more than one instance a chapter appears to represent the first time that social learning has even been addressed in a species or group (e.g., Higginbottom and Croft's chapter on marsupials). The editors believe that field studies are necessary in showing the likely functions or survival value of social learning, whereas controlled experiments are better suited to teasing out specific mechanisms. King argues in her chapter that identifying mechanisms of social learning is a near-impossible task for most field researchers, and that a functional perspective based on the acquisition and donation of information is preferable. It follows that the many field studies summarised here stand as a useful testing ground for theoretical work that looks at the conditions under which social learning should be selected for (e.g., Laland, Richerson and Boyd, 1996). On the negative side, the book's origin as a collection of conference papers is sometimes a little too obvious. The editors have prepared introductory comments for each section that go some way towards linking the different chapters. However, it would seem that many of the authors did not have a chance to read each other's contributions: there are few cross-references between chapters. Furthermore, the inclusion of 21 chapters in a book of about 400 pages means that the average chapter is quite short. Perhaps as an inevitable result of this brevity, those authors who focused on their own work (as opposed to presenting a review) have tended to simply summarize previously published material rather than offering a novel or extended treatment. Phrases such as "much more research is needed in this area" occur often in this collection. This is not a criticism per se; indeed, such phrases occur throughout the scientific literature. However, in an area like social learning, where we know so little about so many taxa, some strategic thinking about realistic future research is probably called for, and this is largely absent from the book. For example, given a lot of time, an unlimited budget, and various technological advances in focal animal tracking and video-recording, it is easy to conceive of experiments and fieldwork that would allow us to fully explore social learning in a difficult species such as the lion. But this is unlikely to happen. If our goals are to find out more about the functions and mechanisms of social learning in general, perhaps the most prudent course would be to focus on species where both field studies and naturalistic laboratory work is practicable: the chapters by Hudson et al., Laland, and Faulkes on rabbits, rats and naked mole rats respectively are inspiring in this regard. The book also exhibits differing perspectives on how much cognitive complexity we should ascribe to an animal that is shown to be capable of social learning. For example, Broom claims that the social learning seen in domestic animals can only be explained in terms of conscious awareness and cannot be reduced to "automatic responses." In contrast, Hudson et al. (p. 152) emphasise that isolating the mechanisms involved in social learning "can help counterbalance more mentalistic accounts." Ultimately this is an empirical question, but it seems likely that in many cases investigators have overestimated the cognitive machinery required for one animal to learn from another (Noble & Todd, in press). In summary, this book would be useful to anyone who needs to be reminded of just how little we know about social learning in most mammals. Readers seeking a more integrated treatment of theoretical and experimental work in the area of social learning might do well to start with Heyes and Galef (1996) before reading this volume. Jason Noble Center for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94, 14195 Berlin, Germany noble@mpib-berlin.mpg.de References Heyes, C. M. & Galef, Jr., B. G. 1996. Social Learning in Animals: The Roots of Culture. San Diego, CA: Academic Press. Laland, K. N., Richerson, P. J. & Boyd, R. 1996. Developing a theory of animal social learning. In Heyes & Galef (1996), pp. 129-154. Noble, J. & Todd, P. M. In press. Imitation or something simpler? Modelling simple mechanisms for social information processing. In Dautenhahn, K., & Nehaniv, C. (Eds.) Imitation in Animals and Artifacts. Cambridge, MA: MIT Press.