American Scientist

Foraging for Survival: Yearling Baboons in Africa. Stuart A. Altmann. 622 pp. University of Chicago Press, 1998. $70.

This is a story about how 11 juvenile baboons feed themselves. The setting: Amboseli National Park, Kenya. This is, however, much more than a simple story. Stuart Altmann engages the reader with his elegant analysis—rich with ecological detail—of the costs and benefits primates must negotiate in their daily pursuit of requisite nutrients and energy. Although baboons are exemplary eclectic omnivores, Altmann reminds us that there is no such thing as a free lunch. Bearing this in mind, he sets out to evaluate the balancing act baboons must achieve in maximizing nutrient intake while minimizing toxic accumulation of plant secondary metabolites.

At the outset, Altmann describes what foods the baboons ate, how they ate them and what they avoided during the study period in the middle 1970s. He also identifies what baboons should eat. A foraging strategy is an endpoint, achieved via an array of potential tactical routes. Altmann evaluates both the feeding tactics and the eclectic foraging strategy of his young baboons by identifying the degree to which they deviate from an optimum model of adaptive feeding traits. The baboons' actual dietary intake is compared to the specifications of adequate and optimal diets; this is done both for an average yearling's diet as well as for individual variance from the predicted diets.

Deviations from the optimum are viewed as indicators of potential differences in reproductive fitness. Altmann takes advantage of the two succeeding decades since his study year to relate differences in juvenile diets to fitness later in life and to longevity. This historical depth is particularly valuable because it tests the model by evaluating whether those baboons that come closer to the optimum as juveniles have higher fitness as adults.

Altmann expands on the extreme selectivity exhibited by baboons, providing details on the load of toxin, protein, carbohydrate, water content and fiber for various plants and the manner in which baboons maximize (or minimize) intake. Finally, he assesses the anatomical and behavioral attributes that may contribute to making baboons one of the most successful and broadly distributed primate species. Altmann includes a series of appendices and tables in which he evaluates various methodological and definitional issues that relate to calculating feeding bouts and dietary intake. Here he presents additional detail on diet composition and the nutritional and toxic attributes of plant foods.

The work's emphasis on juvenile feeding behavior is an unusual yet valuable feature. The developmental stage is often overlooked in studies of nonhuman primate behavior and ecology, despite the fact that this period and the transition from a milk diet to an adult diet are undoubtedly crucial to our understanding of adult fitness and life history patterns.

Caution is warranted: This book is not for the casual student of animal feeding behavior nor for those new to optimal-foraging theory. Altmann's models, food-intake calculations and feeding-bout formulae are exacting and quite abstract. Before embarking into this volume, non-modelers will have to review the technical terminology that necessarily accompanies optimization theory. In addition, Altmann's generalizations based on the relationships among body size, patch size and dietary selectivity are not particularly illuminating, and too many exceptions exist for these generalizations to be of much use.

Nonetheless, this book is destined to become a classic in primate feeding behavior. It is exhaustive and a pleasure to read, and it sets the standard for amalgamation of modeling theory and ecological observation.—Joanna E. Lambert, Anthropology, Southwest Missouri State University