Primate Behavior: Evolution, Sociality, and Reproduction
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Presentation Transcript
Chapter 7 Primate Behavior
Chapter Outline • Primate Field Studies • The Evolution of Behavior • Why Be Social? • Primate Social Behavior • Reproduction and Reproductive Strategies • Mothers, Fathers and Infants
Importance of Primate Studies • Modern African apes and humans last shared a common ancestor between 5 and 8 m.y.a. • Only within the last 4 decades have nonhuman primates been studied. • Many species, such as arboreal monkeys have scarcely been studied at all.
Primate Socioecology • Socioecology studies the relationship between social behavior and the natural environment. • One assumption is that components of ecological systems evolved together. • To understand how one component works, it is necessary to determine the species relationships with their environment.
Environmental Factors • Quality and quantity of foods • Distribution of food resources, water, predators and sleeping sites • Activity patterns (diurnal, nocturnal) • Relationship with other species • Impact of human activities
Socioecology and Predation • Environmental factors influence on group size and structure. • Multimale and multifemale groups have an advantage when predation pressure is high. • Adult males may join forces to attack predators. • Savannah baboons have been known to kill domestic dogs and attack leopards and lions. • Solitary foraging may be due to distribution of resources or predator avoidance.
Evolutionary Perspective Natural selection acts on behavior just as it acts on physical characteristics. • Behavior is a phenotypic expression and genes code for specific behaviors. • Natural selection has a role in shaping primate behavior.
Criticism of the Evolutionary Perspective Little data on: • The social behavior of large groups of animals. • Genetic relatedness through the male line. • Assigning reproductive costs and benefits to particular behaviors. • The genetics of primate social behavior.
Dominance Status • Factors that influence status: • Sex • Age • Aggression • Time in the group • Intelligence • Motivation • Mother’s social position.
Communication • Raised body hair is an example of an autonomic response. • Vocalizations and branch shaking are examples of deliberate communication. • Reassurance is communicated through hugging or holding hands. • The fear grin, seen in all primates, indicates fear and submission. • Displays communicate emotional states.
Affiliative Behaviors • Grooming reinforces social bonds. • Hugging, kissing and grooming are all forms used in reconciliation. • Relationships are crucial to nonhuman primates and the bonds between individuals can last a lifetime.
Patterns of Reproduction • In most primate societies, sexual behavior is tied to the female’s reproductive cycle. • Permanent bonding is not common among nonhuman primates. • Male and female Bonobos may mate even when the female is not in estrus, a behavior that is not typical of chimpanzees.
Reproductive Strategies • Behavioral patterns that contribute to individual reproductive success. • Primates produce only a few young in whom they invest a tremendous amount of parental care. (k –selected) • Male competition for mates and mate choice in females are both examples of sexual selection.
Mothers and Infants • The basic social unit among all primates is the female and her infants. • Except in species in which monogamy or polyandry occur, males do not participate in rearing offspring. • Monkeys raised without a mother were not able to form lasting affectional ties. • The mother-infant relationship is often maintained throughout life.
