Stuart A. Altmann. Foraging for Survival: Yearling Baboons in Africa. The University of Chicago Press, Chicago, 1998, xii + 609 pp, ISBN 0-226-01595-5 Reviewed by: Cheryl D. Knott Department of Anthropology Harvard University 11 Divinity Avenue Cambridge, MA 02138 USA This book is destined to become required reading for any student or researcher undertaking a study of primate nutrition and foraging. Stuart Altmann provides an exhaustive analysis of the diets of 11 yearling baboons in Amboseli National Park, Kenya between August 1975 and July 1976. In intricate detail he discusses the decisions that were made in his analysis, the constraints of the study and the possible shortcomings. Those studying other species will doubtless make different decisions in certain instances, but Altmann's treatment of the subject provides a roadmap of considerations for any study of primate diet. Altmann's approach is to use linear modeling to derive 'optimal' baboon diets and to use these to evaluate the baboon's actual diet. Assessing how far each yearling baboon's diet varies from an optimal diet that maximizes daily energy intake while remaining above the minimum for nutrients and below the maximum for various constraints such as time limits and gut capacity gives him a measure with which to compare individual fitness. The outstanding conclusion is that the diets of these young baboons are highly predictive of adult survivorship and reproductive success. After introducing the book, Altmann describes how baboons meet the challenge of finding nutritious, low toxic items in their environment through 'eclectic omnivory.' He makes the compelling argument that dietary items cannot be easily ranked by nutrients, calories or toxins. As he says, "Neither nutrients nor toxins occur with the same abundance or even have the same abundance rank in all foods, nor do all nutrients rank inversely with all hazards. Consequently, the 'value' of a food is neither an independent property nor a scalable one. It's value depends on what other foods in the diet provide and fail to provide. As a result, no one-dimensional scaling of foods combined with a top-down rule will lead systematically to the set of adequate and optimal diets." This 'packaging problem' of foods how to get enough nutrients without incurring too high a cost guide's Altmann's approach. The next chapter details Altmann's field methods for estimating dietary intake. Using a very self-critical eye he describes how each decision was made. His discussion provides a very useful guide to any dietary study. I read this section with the objective of assessing how Altmann's methods could be applied to other studies. In many cases, study of other species will be more constrained than Altmann's. However, in other instances it may be possible to collect additional types of data where Altmann was restricted. For example, Altmann was not able to record the feeding rate for each feeding bout due to the high number of bouts and their often short length. Instead, Altmann took intake rates opportunistically and needed to pool rates from different individuals to derive a mean rate for each food. Recording individual feeding bout rates will be possible in some other species where bout lengths are typically long and much fewer in number compared to baboons. Altmann needed to use sampling to extrapolate to total bout lengths to account for periods when the animals were out of sight this will, of course, vary dependent on the species in question. Due to the types of items consumed, Altmann derived mean food weights by combining food items and then dividing by the number of food items weighed. An alternative approach, particularly appropriate for the consumption of large fruits, is to weigh several items separately, deriving a mean weight as well as a measure of the variance. On the other hand, the excellent habituation and viewing conditions of these baboons, necessary to collect this kind of data, will be hard to replicate in quite a few other species. The results of this meticulous field work are provided in the following chapter on dietary diversity where he gives us a detailed discussion of what the baboons ate. Using linear programming, in Chapter 5 Altmann presents the linear optimization model he used to generate ideal diets based on total energy content, total protein and time spent foraging. This model takes into consideration an animal's energy requirements, nutrient requirements, presence of secondary compounds and other risks to develop verifiable predictions about what individuals should be eating. Ten diets are generated based on maximizing energy, maximizing protein, minimizing feeding time, maximizing energy intake rate and maximizing protein intake rate. One set of diets only allows for a few foods, whereas the other set incorporates a broader spectrum. Altmann provides a thorough discussion of this method that should enable others to follow his lead. Other types of optimal diets could, of course, be created. For species that have a more lipid-rich diet than baboons, modeling the diet that maximizes lipid intake would be an obvious choice. Although time consuming, Altmann's approach is an excellent way to incorporate the many factors primates must consider in their foraging decisions. When 'real' diets are compared to ideal diets in Chapter 6 he finds that the baboons do not eat, or even approach, any of these optimal diets. For example, the diet of yearlings totaled 1.79 Mj/day well short of the 4.69 Mj/day of energy maximizing diet. On average, yearlings consumed 11.1 g of protein which is 181% above requirement of 3.94 g /day but below the optimum of 31.0 g/day. These yearlings spent 240.5 min/day foraging far more than the 50.9 min/day possible in the 'optimal' diet. The point, though, that he discusses later, is not that the baboons were expected to reach these optimums, but to evaluate how far individuals varied from these ideal diets. Altmann's discussion of milk consumption is quite informative. Luckily, studies have already been done on rates of milk consumption in baboons which allowed him to estimate baboon milk consumption. Unfortunately, this information is only available for a limited number of species. In the next chapter Altmann discusses the individual differences between the different yearlings. He primarily uses two time-budget comparisons: feeding bout durations and bout rates and assumes that bite rate and size did not differ appreciably between individuals. This assumption may not be the case in other species. The preceding chapters lead us up to the impressive results presented in Chapter 8 that each of the seven measures of a female's lifetime reproductive success is predictable from what she ate as a 30-70 week old yearling, although age at menarche and age at first conception also required information on play frequency and mother's rank. Mean energy shortfall or how far each baboon strayed from the optimum diet was the best predictor for most of these reproductive measures. This is quite remarkable that by 70 weeks of age "a female baboons lifetime fitness if largely established as is the likelihood of males and females of surviving to adulthood." These results demonstrate the merits of conducting long term field research on one group of animals Altmann can actually test the effect of early diets and behavior on later reproduction and survivorship. This is quite a remarkable feat for a study of such a long-lived species as baboons. The last two chapters discuss "why be choosy" and "how to be an eclectic omnivore." Altmann discusses in details why particular foods were selected or discarded. It would also be interesting to examine the lignin and cutin fractions of the fiber since these affect food preference. Altmann measured Total Non-Structural Carbohydrates. Measurement of Water Soluble Carbohydrates (a measure of the sweetness of a food) would strengthen the discussion comparing baboon and vervet food preference. The last chapter provides interesting discussion of the implications of several important features of baboon omnivery: their size and strength, sexual dimorphism, fighting ability, locomotor and manipulative abilities, cheek pouches, binocular color vision, sense of taste and smell, memory and intelligence, and their social groups. This book stands as a testament to the value of collecting detailed data on primate diet and conducting nutritional analysis of foods. Combining this with long term field data on individual animals allows Altmann to do what is rare in studies of long lived primates actually test the affect of predictor variables on reproductive success. The book is sure to become a classic one that warrants close study by all those interested in this primate diet and foraging. Primate-Science Book Revews are supported in part by grant RR15311-01 for the National Center for Research Resources, National Institutes of Heatlh. P-S Book Reviews may be reposted or republished, but must cite the author and Primate-Science. This review should be cited as follows: Knott, Cheryl D. Review of Foraging for Survival: Yearling Baboons in Africa by Stuart A. Altmann. University of Chicago Press, 1998. Primate-Science Book Reviews, Primate-Science List Serve [primate-science@primate.wisc.edu] (October 10, 2000). ******************************************************************************
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