Book Reviews Baboon Metaphysics: The Evolution of a Social Mind. By Dorothy Cheney and Robert Seyfarth. x 1 347 pp. Chicago: The University of Chicago Press. 2007. $27.50 (cloth). In a primatological tour de force surpassing even their previous classic, How Monkeys See the World (1992, Univer- sity of Chicago Press), Dorothy Cheney and Robert Seyfarth summarize 15 years of research on the social relationships, cognition, and communication of the baboons of the Oka- vango Delta. The book begins with Darwin (‘‘He who under- stands baboon would do more towards metaphysics than Locke’’—Notebook M, 1838) and a brief history of scientific thinking regarding the operations of primate minds, from Aristotle to the present. Next, the authors explore views of cercopithecine minds specifically, by pulling accounts of monkey behavior from European, Japanese, and ancient Egyptian texts, and adding more recent accounts by Afri- cans. The authors document baboons’ cognitive feats under unusual situations, when local people have employed them as goat-herders (who require no training to flawlessly match large numbers of lambs with their mothers), mechanic’s assistants, oxcart drivers, or railway signalmen. Chapters 3–5 introduce the reader to the sorts of chal- lenges that baboons must solve in the wild—predator attacks, deep water crossings to get from one island to another in the flooded delta, infanticidal immigrant males, dominance struggles, and the complexities of daily social life, in which each individual is competing with many rivals for access to food and preferred social part- ners. A notable strength of this research program is the inclusion of hormonal analysis. By extracting hormones from fecal samples, their research team was able to mea- sure changes in glucocorticoid levels as a function of the types of situations the baboons encountered. This meant that the researchers could know exactly how stressful par- ticular types of events were for the animals, rather than relying on intuition. Presumably, natural selection has shaped baboons’ minds such that they have stronger stress responses to those situations that have had the big- gest impact on their fitness over the course of evolution. One of the biggest strengths of Seyfarth and Cheney’s cog- nitive work is the fact that it is grounded in a detailed knowledge of the animals’ natural history. Their experi- ments are performed in the field, and they ask the ani- mals to solve those same types of problems that they face in daily life, solving the sorts of challenges that they have presumably been confronted by throughout their evolu- tionary history. For this reason, they surpass all other scholars in their ability to design experiments that have relevance to explaining the evolution of mind. In the latter half of the book, the authors delve into the main subject of their book. They start by documenting how baboons, like vervets, have an intricate knowledge of the rank, kinship, and alliance structure of their group. The authors postulate that in order to keep track of so many dyadic and triadic relationships (82,000 triads in a typical baboon group), the monkeys must be developing theories of social life—general expectations about how social interac- tions are likely to unfold (e.g. expectations about rank tran- sitivity, tendencies for kin to support one another, and expectations about how males and females will behave in consortships) rather than relying strictly on associative learning. In other words, baboons have an innate predisposi- tion to recognize certain features of others’ social relation- ships. This knowledge has a hierarchical structure. Further- more, baboons have an elementary theory of mind. That is, they seem capable of intuiting the motives and intentions of others (e.g. willingness to defend access to a resource), even though they seem not to attribute particular specific sorts of knowledge (or ignorance) to them. The authors show, via a series of ingenious experiments, how particular vocal sig- nals are interpreted differently by the animals, depending on who is producing them and what recent social interac- tions might have affected the motives of the vocalizers. Thus, mental representations of individuals, their inten- tions, and qualities of their dyadic and triadic relationships, are combined in ways that are somewhat analogous to human language. The authors propose that nonhuman pri- mates’ abilities to manipulate these mental representations in a discrete combinatorial fashion and to encode propositio- nal information are a sort of ‘‘language of thought’’ that pre- ceded and was a preadaptation for human language. They retain their earlier opinion that nonhuman primate vocal communication lacks many of the features of human lan- guage (e.g. nonhuman primates are remarkably inflexible when it comes to call production, though they are more plas- tic regarding vocal comprehension and usage). But they argue that in the quest to explain the evolution of language, too much emphasis has been placed on call production and too little emphasis on the cognitive aspects of language. This book is necessary reading for anyone interested in the evolution of language or intelligence. The writing is ac- cessible enough that any layperson interested in evolution or animal behavior would find it engaging, and yet it has enough new ideas and empirical facts to fascinate professio- nal primatologists as well. It would be an ideal supplemen- tary text for undergraduates studying primate behavior or cognition. This book includes highly cogent summaries of the theoretical issues relevant to the evolution of intelligence and language, complete with references to guide readers to additional reading. It also provides extensive detail on meth- odologies used for teasing apart the workings of the primate mind in the field. Cheney, Seyfarth and their colleagues approach cognitive issues from many angles, incorporating playback experiments, hormonal analysis, and standard ethological methods, to produce a highly convincing model of how baboons perceive and manipulate their social environ- ments. Surely even the most learning-resistant student could hardly fail to be charmed by the cleverness of the experiments, the humorous fieldwork anecdotes, and of course, the daily drama of baboon life. Descriptions of the research are peppered with enthralling nuggets of natural history that have never been published elsewhere, 45 superb photos, and amusing literary allusions to Jane Austen and Edith Wharton novels demonstrating parallels with the sorts of social challenges faced by baboons and humans. This is primatology at its best. SUSAN PERRY Department of Anthropology University California Los Angeles, California DOI: 10.1002/ajhb.20751 Published online 26 December 2007 in Wiley InterScience (www.interscience. wiley.com). AMERICAN JOURNAL OF HUMAN BIOLOGY 20:194–199 (2008) V V C 2007 Wiley-Liss, Inc.