Gorilla Society
Conflict, Compromise, and Cooperation Between the Sexes
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9780226316024
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Gorilla Society
Conflict, Compromise, and Cooperation Between the Sexes
Societies develop as a result of the interactions of individuals as they compete and cooperate with one another in the evolutionary struggle to survive and reproduce successfully. Gorilla society is arranged according to these different and sometimes conflicting evolutionary goals of the sexes. In seeking to understand why gorilla society exists as it does, Alexander H. Harcourt and Kelly J. Stewart bring together extensive data on wild gorillas, collected over decades by numerous researchers working in diverse habitats across Africa, to illustrate how the social system of gorillas has evolved and endured.
Gorilla Society introduces recent theories explaining primate societies, describes gorilla life history, ecology, and social systems, and explores both sexes’ evolutionary strategies of survival and reproduction. With a focus on the future, Harcourt and Stewart conclude with suggestions for future research and conservation. An exemplary work of socioecology from two of the world’s best known gorilla biologists, Gorilla Society will be a landmark study on a par with the work of George Schaller—a synthesis of existing research on these remarkable animals and the societies in which they live.
416 pages | 33 halftones, 68 line drawings, 9 tables | 6 x 9 | © 2007
Anthropology: Physical Anthropology
Biological Sciences: Behavioral Biology, Conservation, Ecology, Evolutionary Biology, Natural History, Tropical Biology and Conservation
Reviews
Table of Contents
Acknowledgments
PART. INTRODUCTION
CHAPTER 1 INTRODUCTION
PART. INTRODUCTION
CHAPTER 1 INTRODUCTION
Summary
The Book’s Aim
1.1. What Is a Society? What Is Socioecology?
1.2. Why Primate Socioecology?
The Book’s Aim
1.1. What Is a Society? What Is Socioecology?
1.2. Why Primate Socioecology?
1.2.1. The tropics are little known
1.2.2. Primates are relatively well known
1.2.3. Primates are diverse
1.2.4. Primate males and females live together
1.2.5. The study of primates
1.2.2. Primates are relatively well known
1.2.3. Primates are diverse
1.2.4. Primate males and females live together
1.2.5. The study of primates
1.3. Why Gorilla Socioecology?
Structure of the Book
Figure Details
Structure of the Book
Figure Details
CHAPTER 2 PRIMATE SOCIOECOLOGY: A BRIEF INTRODUCTION
Summary
2.1. Socioecology
2.1. Socioecology
2.1.1. Introduction
2.1.2. Females to food, males to females
2.1.2. Females to food, males to females
2.2. Food and Society
2.2.1. Body size, food, and society
2.2.2. Food and competition
2.2.2. Food and competition
2.2.2.1. The nature of the food affects the nature of competition
2.2.2.2. The nature of competition affects the nature of the society
2.2.2.2. The nature of competition affects the nature of the society
2.2.3. Food, competition, cooperation, and grouping
2.2.3.1. Grouping increases competition
2.2.3.2. Food and the benefits of cooperation in competition as a cause of grouping
2.2.3.2. Food and the benefits of cooperation in competition as a cause of grouping
2.3. Predation and Society
2.3.1. Primates are preyed upon and have evolved antipredator strategies
2.3.2. Body size and predation
2.3.3. Predation and grouping
2.3.3. Predation and grouping
2.3.3.1. Grouping within species protects from predation
2.3.3.2. Grouping evolved for protection from predation?
2.3.3.3. Grouping with a male for protection from predation
2.3.3.2. Grouping evolved for protection from predation?
2.3.3.3. Grouping with a male for protection from predation
2.4. Mating and Society
2.4.1. Mating competition among males and sexual dimorphism
2.4.1.1. Sexual dimorphism and body size
2.4.1.2. Sexual dimorphism and group size
2.4.1.2. Sexual dimorphism and group size
2.4.2. Male-male mating competition and access to females: Male-female association
2.4.2.1. Association for male care
2.4.2.2. Association without active care?
2.4.2.3. Association to mate-guard
2.4.2.4. Association to guard against infanticide
2.4.2.5. More than one male associating
2.4.2.6. Breaking the association—emigration
2.4.2.7. No association—roving males
2.4.2.2. Association without active care?
2.4.2.3. Association to mate-guard
2.4.2.4. Association to guard against infanticide
2.4.2.5. More than one male associating
2.4.2.6. Breaking the association—emigration
2.4.2.7. No association—roving males
2.4.3. Male-male mating competition and infanticide: Male-female conflict
2.4.4. Female and male responses to mating competition
2.4.4. Female and male responses to mating competition
2.4.4.1. Female responses to harassment and infanticide
2.4.4.2. Male responses to female responses
2.4.4.2. Male responses to female responses
2.5. Rearing and Society
2.5.1. Need for help: Male-female association
2.5.2. Female competition to rear
2.5.2. Female competition to rear
Conclusion
Statistical Details
Statistical Details
PART GORILLAS, ECOLOGY, AND SOCIETY
CHAPTER 3 INTRODUCING GORILLAS: SOME BACKGROUND
Summary
3.1. Distribution, Taxonomy, and Study Sites
3.1. Distribution, Taxonomy, and Study Sites
3.1.1. Distribution: Where gorillas live
3.1.2. Taxonomy: How many species?
3.1.3. Study sites
3.1.2. Taxonomy: How many species?
3.1.3. Study sites
3.1.3.1. Mountain gorillas
3.1.3.2. Eastern lowland, or Grauer’s gorillas
3.1.3.3. Western gorillas
3.1.3.2. Eastern lowland, or Grauer’s gorillas
3.1.3.3. Western gorillas
3.1.4. Comparison with Pan and Pongo
3.2. Life History and Reproduction
3.2.1. Introduction
3.2.2. Body size and sexual dimorphism
3.2.3. Maturation and reproduction
3.2.2. Body size and sexual dimorphism
3.2.3. Maturation and reproduction
3.2.3.1. Infants to subadults
3.2.3.2. Maturity and reproduction in males
3.2.3.3. Maturity and reproduction in females
3.2.3.2. Maturity and reproduction in males
3.2.3.3. Maturity and reproduction in females
3.2.4. Mortality
3.2.4.1. Mortality rates
3.2.4.2. Causes of mortality
3.2.4.2. Causes of mortality
3.2.5. Life span
3.2.6. Lifetime reproduction
3.2.7. Comparison with Pan and Pongo
3.2.6. Lifetime reproduction
3.2.7. Comparison with Pan and Pongo
Conclusion
Table Details
Figure Details
Table Details
Figure Details
CHAPTER 4 GORILLA ECOLOGY AND SOCIETY: A BRIEF DESCRIPTION
4.1. Gorilla Ecology
Summary: Gorilla Ecology
Introduction: Gorilla Ecology
Summary: Gorilla Ecology
Introduction: Gorilla Ecology
4.1.1. Body size and diet
4.1.2. General habitat and food preferences
4.1.3. Diet, altitude, and season
4.1.2. General habitat and food preferences
4.1.3. Diet, altitude, and season
4.1.3.1. Western gorillas
4.1.3.2. Eastern lowland, or Grauer’s gorillas
4.1.3.3. Mountain gorillas
4.1.3.2. Eastern lowland, or Grauer’s gorillas
4.1.3.3. Mountain gorillas
4.1.4. Diet and daily ranging: Variation in foraging effort
4.1.5. Diet and home range size
4.1.6. Ecology and group cohesion
4.1.7. Ecology and population density
4.1.8. Comparison with Pan and Pongo
4.1.5. Diet and home range size
4.1.6. Ecology and group cohesion
4.1.7. Ecology and population density
4.1.8. Comparison with Pan and Pongo
4.1.8.1. Pan
4.1.8.2. Pongo
4.1.8.2. Pongo
Conclusion: Gorilla Ecology
4.2. Gorilla Society
Summary: Gorilla Society
Introduction: Gorilla Society
4.2. Gorilla Society
Summary: Gorilla Society
Introduction: Gorilla Society
4.2.1. Social structure and social processes
4.2.1.1. Group size and composition; population structure
4.2.1.2. Dispersal; group formation, transition, and demise
4.2.1.3. Infanticide
4.2.1.4. Interunit encounters
4.2.1.2. Dispersal; group formation, transition, and demise
4.2.1.3. Infanticide
4.2.1.4. Interunit encounters
4.2.2. Social relationships
4.2.2.1. Relationships between adult males and females
4.2.2.2. Relationships between adult females
4.2.2.3. Relationships between adult males
4.2.2.4. The social relationships of immature animals
4.2.2.2. Relationships between adult females
4.2.2.3. Relationships between adult males
4.2.2.4. The social relationships of immature animals
4.2.3. Comparison with Pan and Pongo
4.2.3.1. Pan
4.2.3.2. Pongo
4.2.3.2. Pongo
Conclusion: Gorilla Society
Figure Details
Statistical Details
Figure Details
Statistical Details
PART FEMALE STRATEGIES AND GORILLA SOCIETY
Summary
CHAPTER 5 FEMALE STRATEGIES AND SOCIETY: FOOD AND GROUPING47
Summary
Introduction: Gorillas; Food, Competition, and Cooperation
5.1. Female Strategies: Food, Competition, and Grouping
Introduction: Gorillas; Food, Competition, and Cooperation
5.1. Female Strategies: Food, Competition, and Grouping
5.1.1. Do gorilla females compete over food?
5.1.2. Is the competition important?
5.1.3. Conclusion: Food, competition, and grouping
5.1.2. Is the competition important?
5.1.3. Conclusion: Food, competition, and grouping
5.2. Female Strategies: Food, Cooperation, and Emigration
5.2.1. Do gorilla females cooperate in competition over food?
5.2.2. Is the cooperation important?
5.2.3. Conclusion: Food, cooperation, and emigration
5.2.3. Conclusion: Food, cooperation, and emigration
5.3. Comparison with Pan and Pongo
Conclusion
Figure Details
Statistical Details
Conclusion
Figure Details
Statistical Details
CHAPTER 6 FEMALE STRATEGIES: MALE INFLUENCES ON FEMALES’ COMPETITION, COOPERATION, AND GROUPING
Summary
6.1. The Male Is a Major Competitor
6.2. The Male Mitigates Competition Among Females
6.3. The Male Mitigates the Benefits of Females’ Cooperation
6.4. Comparison with Pan and Pongo
Conclusion
Figure Details
Statistical Details
6.1. The Male Is a Major Competitor
6.2. The Male Mitigates Competition Among Females
6.3. The Male Mitigates the Benefits of Females’ Cooperation
6.4. Comparison with Pan and Pongo
Conclusion
Figure Details
Statistical Details
CHAPTER 7 FEMALE STRATEGIES: MALE INFLUENCES; JOINING A PROTECTIVE MALE87
Summary
7.1. Protection from Predation
Summary: Protection from Predation
7.1. Protection from Predation
Summary: Protection from Predation
7.1.1. Female gorillas associate with a male for defense against predators88
7.1.2. Females join males
7.1.3. Gorillas are preyed upon
7.1.4. Males protect females
7.1.2. Females join males
7.1.3. Gorillas are preyed upon
7.1.4. Males protect females
7.1.4.1. The male protects females (and their offspring) against predators
7.1.4.2. Females (and immature animals) act as if they perceive that the male is a protector against predators
7.1.4.2. Females (and immature animals) act as if they perceive that the male is a protector against predators
7.1.5. Comparison with Pan and Pongo
Conclusion: Escaping Predation as the Cause of Females’ Association with a Male
7.2. Protection from Infanticide
Summary: Protection from Infanticide
7.2. Protection from Infanticide
Summary: Protection from Infanticide
7.2.1. Infanticide in gorillas
7.2.2. Female gorillas associate with a powerful male for protection against infanticide by other males
7.2.2. Female gorillas associate with a powerful male for protection against infanticide by other males
7.2.2.1. Males protect against infanticide
7.2.2.2. Females associate with a male for protection against infanticide
7.2.2.3. Females associate with a male for protection against infanticide: A model
7.2.2.4. The model’s conclusions
7.2.2.5. Criticism of the model
7.2.2.2. Females associate with a male for protection against infanticide
7.2.2.3. Females associate with a male for protection against infanticide: A model
7.2.2.4. The model’s conclusions
7.2.2.5. Criticism of the model
7.2.3. Comparison with Pan and Pongo
Conclusion: Escaping Infanticide as the Cause of Females’ Association with a Male
7.3. Conclusion: Predation or Infanticide?
7.3. Conclusion: Predation or Infanticide?
7.3.1. Predation is the primary cause of association
7.3.2. Infanticide is the primary cause of association
7.3.3. The hypotheses cannot yet be separated?
7.3.2. Infanticide is the primary cause of association
7.3.3. The hypotheses cannot yet be separated?
Figure Details
CHAPTER 8 FEMALE STRATEGIES: MALE INFLUENCES; EMIGRATION AND CHOICE OF MALES5
Summary
Introduction
8.1. Female Emigration and Mate Choice: Finding a Better Protector
8.2. Female Emigration and Mate Choice: Avoiding Inbreeding
Introduction
8.1. Female Emigration and Mate Choice: Finding a Better Protector
8.2. Female Emigration and Mate Choice: Avoiding Inbreeding
8.2.1. Evidence for avoidance of inbreeding
8.2.2. Incest in gorillas: Inbreeding is not always avoided
8.2.3. Minimal costs to inbreeding?
8.2.2. Incest in gorillas: Inbreeding is not always avoided
8.2.3. Minimal costs to inbreeding?
8.3. Comparison with Pan and Pongo
Conclusion
Figure Details
Statistical Details
Conclusion
Figure Details
Statistical Details
CHAPTER 9 FEMALE STRATEGIES: CONFLICT, COMPROMISE, AND COOPERATION BETWEEN THE SEXES
Summary
9.1. Gorilla Female Society
9.1. Gorilla Female Society
9.1.1. Food and society
9.1.2. Protection and society: The male’s influence
9.1.3. Emigration by females: The male’s influence
9.1.2. Protection and society: The male’s influence
9.1.3. Emigration by females: The male’s influence
9.2. Gorilla Society: An Unusually Strong Influence of Males?
9.3. Gorilla Society: An Unusual Product from Interaction of Usual Rules
Statistical Details
9.3. Gorilla Society: An Unusual Product from Interaction of Usual Rules
Statistical Details
PART MALE STRATEGIES AND GORILLA SOCIETY
Summary
CHAPTER 10. MALE STRATEGIES AND SOCIETY: INFLUENCES OF THE ENVIRONMENT AND OF FEMALES
Summary
10.1. Association as a Means of Access to Females
CHAPTER 10. MALE STRATEGIES AND SOCIETY: INFLUENCES OF THE ENVIRONMENT AND OF FEMALES
Summary
10.1. Association as a Means of Access to Females
10.1.1. Means of access to females
10.1.2. Gorillas cannot be territorial as a mate access strategy
10.1.3. Gorillas cannot roam, but must associate permanently
10.1.3. Gorillas cannot roam, but must associate permanently
10.2. Predation, Infanticide, and Association with Females
10.3. Comparison with Pan and Pongo
10.3. Comparison with Pan and Pongo
10.3.1. Finding females: Roam or stay?
10.3.2. Predation and association
10.3.2. Predation and association
Conclusion
A robust model, and therefore the right answer?
Added variations
Are female strategies irrelevant to males?
Figure Details
A robust model, and therefore the right answer?
Added variations
Are female strategies irrelevant to males?
Figure Details
CHAPTER 11. MALE MATING STRATEGIES AND GORILLA SOCIETY
Summary
11.1. Competition to Be Sole Breeder
11.1. Competition to Be Sole Breeder
11.1.1. Gorilla society as a one-male mating system
11.1.2. The reproductive payoffs of infanticide
11.1.3. Male competitive tactics: Mate acquisition versus mate retention and offspring protection
11.1.2. The reproductive payoffs of infanticide
11.1.3. Male competitive tactics: Mate acquisition versus mate retention and offspring protection
11.1.3.1. Contests during interunit encounters
11.1.3.2. Why are there no male takeovers? The influence of females on the stability of male-female associations
11.1.3.2. Why are there no male takeovers? The influence of females on the stability of male-female associations
11.1.4. Mating competition in multi-male groups
11.1.4.1. Breeding success and mating competition: The importance of being dominant
11.1.4.2. Mating competition and male-female interactions: Coercion and mate-guarding
11.1.4.2. Mating competition and male-female interactions: Coercion and mate-guarding
11.1.5. Female choice and male mating competition
11.1.6. Long-term reproductive strategies
11.1.6. Long-term reproductive strategies
11.1.6.1. The wooing of females by subordinate males
11.1.6.2. Control of female aggression
11.1.6.2. Control of female aggression
11.2. Maturing Males: Stay or Emigrate?
11.2.1. Breeding tenure and number of mates
11.2.2. Why dominant males tolerate younger rivals?
11.2.3. Staying versus dispersing
11.2.4. Reproductive payoffs of different male strategies
11.2.5. Why leave?
11.2.2. Why dominant males tolerate younger rivals?
11.2.3. Staying versus dispersing
11.2.4. Reproductive payoffs of different male strategies
11.2.5. Why leave?
11.3. Variation Across Gorilla Populations
11.3.1. Differences in rates of male dispersal
11.3.1.1. Ecological constraints on group size, male mating competition, and male emigration
11.3.1.2. Interaction of male and female strategies and the perpetuation of group structure
11.3.1.3. Lower risk of infanticide
11.3.1.2. Interaction of male and female strategies and the perpetuation of group structure
11.3.1.3. Lower risk of infanticide
11.3.2. Differences in predictability of infanticide and nature of interunit encounters
11.3.2.1. Demographic influences on mating competition
11.3.2.2. Familiarity and relatedness between males and females of different groups
11.3.2.2. Familiarity and relatedness between males and females of different groups
11.4. Comparison with Pan and Pongo
11.4.1. Common chimpanzees
11.4.2. Bonobos
11.4.3. Pongo
11.4.3. Pongo
Conclusion
Figure Details
Statistical Details
Figure Details
Statistical Details
CHAPTER 12. MALE STRATEGIES AND THE NATURE OF SOCIETY: CONFLICT, COMPROMISE, AND COOPERATION BETWEEN THE SEXES
Summary
12.1. Gorilla Society: The Influence of Females on Males
12.2. Gorilla Society: The Influence of Males on Females
12.3. Gorilla Society: Conflict, Compromise, and Cooperation
12.4. Males and Society: A Familiar Case Study?
12.5. Males and Society: An Unfamiliar Case Study?
12.1. Gorilla Society: The Influence of Females on Males
12.2. Gorilla Society: The Influence of Males on Females
12.3. Gorilla Society: Conflict, Compromise, and Cooperation
12.4. Males and Society: A Familiar Case Study?
12.5. Males and Society: An Unfamiliar Case Study?
PART GORILLA SOCIETY: THE FUTURE
CHAPTER 13. GORILLA AND PRIMATE SOCIOECOLOGY: THE FUTURE
Summary
13.1. Gorilla Society Yesterday
13.2. Gorilla Society Today
13.3. Gorilla and Primate Society Tomorrow
13.1. Gorilla Society Yesterday
13.2. Gorilla Society Today
13.3. Gorilla and Primate Society Tomorrow
13.3.1. Phylogeny, environment, and society?
13.3.2. Diet, competition, cooperation, and grouping?
13.3.2. Diet, competition, cooperation, and grouping?
13.3.2.1. Frugivore-folivore differences
13.3.2.2. Cooperation
13.3.2.3. Some methodology
13.3.2.2. Cooperation
13.3.2.3. Some methodology
13.3.3. Intermale competition?
13.3.3.1. Number of males per group
13.3.3.2. Intergroup aggression and kinship
13.3.3.3. Duration of male tenure
13.3.3.2. Intergroup aggression and kinship
13.3.3.3. Duration of male tenure
13.3.4. The fate of dispersers?
13.3.5. Within-species community structure?
13.3.6. Sexual selection, environment, and society: Predation versus infanticide?
13.3.7. Schemas, quantification, modeling, and experiments?
13.3.5. Within-species community structure?
13.3.6. Sexual selection, environment, and society: Predation versus infanticide?
13.3.7. Schemas, quantification, modeling, and experiments?
13.3.7.1. Categorization, quantification, and definition
13.3.7.2. Modeling
13.3.7.3. Experimentation
13.3.7.2. Modeling
13.3.7.3. Experimentation
13.3.8. Communication between primate socioecology and human socioecology?
13.3.9. More fieldwork?
13.3.9.1. Three areas of ignorance
13.3.9.2. Gorilla socioecology
13.3.9.2. Gorilla socioecology
CHAPTER 14. SOCIOECOLOGY AND GORILLA CONSERVATION
Summary
Introduction
14.1. Conservation’s Five Questions: Why? What? How Much? Where? How?
Introduction
14.1. Conservation’s Five Questions: Why? What? How Much? Where? How?
14.1.1. Why conserve?
14.1.2. What to conserve?
14.1.2. What to conserve?
14.1.2.1. The Red List classification of the gorilla
14.1.2.2. Some reflections on the Red List
14.1.2.2. Some reflections on the Red List
14.1.3. How much?
14.1.4. Where?
14.1.5. How?
14.1.4. Where?
14.1.5. How?
14.1.5.1. Africa is poor
14.1.5.2. Protected areas and tourism?
14.1.5.2. Protected areas and tourism?
14.2. Socioecology and Conservation
14.2.1. Is biology necessary?
14.2.2. How can socioecology help?
14.2.3. Socioecology and demography
14.2.4. Socioecology and reaction to the environment
14.2.5. Socioecology of human use of the environment
14.2.6. Socioecology and active management
14.2.7. Socioecology and tourism: The relevance of socioecology
14.2.8. Socioecologists and conservation
14.2.9. Conservation and socioecology
14.2.2. How can socioecology help?
14.2.3. Socioecology and demography
14.2.4. Socioecology and reaction to the environment
14.2.5. Socioecology of human use of the environment
14.2.6. Socioecology and active management
14.2.7. Socioecology and tourism: The relevance of socioecology
14.2.8. Socioecologists and conservation
14.2.9. Conservation and socioecology
Conclusion
Table Details
Figure Details
Statistical Details
References
Author Index
Subject Index