Cover

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Title Page, Copyright

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Contents

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pp. v-viii

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Acknowledgments

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pp. ix-x

This book inevitably owes a great deal to a great many people, too many to mention all individually. John Crook provided the original stimulus for the project and I am grateful for his discreet guiding hand during the past decade and a half. I owe a special debt to my wife, Patsy, for her unstinting efforts in collecting the data. Among the many ...

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Introduction

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pp. 3-15

As our knowledge of the behavior of particular species has increased with time, it has become apparent that the traditional ethological notion of "species-specific behavior" is often inappropriate for social behavior. More than anything else, field workers have come to appreciate that the degree of variability in the behavior of natural populations of ...

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Structure of Gelada Populations

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pp. 16-23

The gelada social system is a complex arrangement of hierarchically organized social groupings, each of which corresponds to a different functional unit. These groupings are analogous to those of the hamadryas baboon, Papio hamadryas (see Sigg et al. 1982), these two species apparently being unique among the primates in the degree of organi ...

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Ecological Constraints

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pp. 24-31

In this chapter, I provide an overview of the more important aspects of gelada ecology. I draw on comparative data to show how the species' dietary specializations influence time budgets, population density, and ranging patterns. This specialization has important consequences for the animals' reproductive strategies since it limits and constrains their ...

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Demographic Processes

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pp. 32-38

This chapter summarizes the main demographic processes and life-history variables and provides the demographic information on which most of the analyses of reproductive strategies depend. The results pre sented here are based on analyses given by Dunbar and Dunbar (1975), Ohsawa (1979), Dunbar (1980a), and Ohsawa and Dunbar (1984). These ...

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Social Structure of Reproductive Units

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pp. 39-50

Gelada reproductive units are closed social microcosms (see Dunbar and Dunbar 1975, Mori 1979b). Consequently, an individual's social and reproductive strategies are constrained by the behavior of the other members of its unit. Understanding the principles that underlie social relationships between the adult members of a unit is thus critical for ...

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Constraints on Female Reproduction

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pp. 51-55

In this chapter, I consider some important reproductive consequences of the social relationships among females that were described in Chapter 5. These consequences provide the reproductive context within which females make their strategic decisions. It is thus in the constraints imposed by these consequences that explanations for the behavior of the ...

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The Female's Socio-Reproductive Strategies

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pp. 56-76

In order to understand what the females are trying to do, we need to know what the null condition is around which their strategies of repro duction are built (i.e. the constraint-free strategy). In the present case, this is the state that would result if females relied only on their intrinsic natural fighting abilities. Other things being equal, a female would ...

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A Decision Model of Female Reproductive Strategies

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pp. 77-89

The analyses in the previous chapter suggest that a female has six main strategies open to her: (1) to form coalitions with her mother and daughter(s), (2) to form a coalition with a sister, (3) to form a coalition with a less closely related female, (4) to become the harem male's social partner, (5) to become the new male's partner when the unit is ...

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The Female'sTactical Options

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pp. 90-105

Within the general constraints imposed by long-term strategic consid erations, females do have some freedom of movement in terms of the tactics they can pursue to offset losses in reproductive rate. There are three groups of tactical options open to females: behavioral tactics dur ing oestrus (aimed at improving the probability of impregnation on ...

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The Male's Loyalty Problem

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pp. 106-123

The female's problems relate strictly to intra-unit competition among females, with matrilineal coalitions forming a crucial basis from which she operates. The male, on the other hand, is effectively on his own and his problems are twofold. First, in order to breed at all, he has to gain control over a harem of females. Secondly, having gained a harem, ...

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Rules and Decisionsin Harem Acquisition

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pp. 124-144

In this chapter, I summarize the options open to a male and examine the decisions he makes during the process of acquiring a harem. In the following chapter, I undertake a simulation analysis of harem acquisi tion strategies aimed at determining whether the alternative strategies that males pursue are equally profitable. Chapter 13 explores the tac ...

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An Economic Modelof Male ReproductiveStrategies

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pp. 145-164

We have seen that a male has two main options in terms of harem acquisition and that these options commit him to lifetime strategies that are quite different. From a theoretical point of view, alternative solu tions to the same problem are most likely to arise when the costs of pursuing the constraint-free strategy become so great that an alterna ...

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Tactical Options Open to Males

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pp. 165-181

Although a male can expect to do as well by a takeover as by a follower entry, the values of the various parameters are by no means fixed. A male would gain a considerable advantage if he were able to manipu late any of them in his favor. In general, the initial values of most variables are extrinsically determined, being a consequence of various ...

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Dynamics of Strategy Choice

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pp. 182-207

The analyses of Chapters 12 and 13 refer specifically to the Sankaber population. They have also taken a rather static approach to strategy choice in that they tend to assume that the biological context within which the male is embedded is effectively neutral, or at least constant over time. This, of course, is a gross oversimplification: environmental ...

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Two Final Problems About Males

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pp. 208-222

Two questions have been left unanswered in the foregoing analyses. First, what becomes of the former harem-holders once they have been deposed? And secondly, is the set of alternative strategies evolutionarily stable? In this chapter, I try to answer these questions. In most species in which individual males hold harems that are taken ...

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Evolutionary Decisions Under Conflicts of Interest

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pp. 223-235

I have tried to show that the social behavior of gelada baboons can best be understood in terms of reproductive strategies, that these strategies involve decisions on the part of the individual, and that these decisions in turn are made in the context of a variety of constraints imposed by the biological and social environment within which the an ...

Appendices: Outline of Computer Programs

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pp. 236-244

References

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pp. 245-258

Author Index

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pp. 259-261

Subject Index

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pp. 262-266