Primate Behaviors Two Paradigms of Study I. A. B. C. Socioecology Sociobiology Sociobiology Criticisms Important Primate Behaviors II. A. B. C. D. E. F. G. H. Dominance Communication Aggression Affiliative Behaviors Reproduction and Reproductive Strategies Mothers and Infants Nonhuman Primate Cultural Behavior Primate Cognitive Abilities I. Two Primate Study Paradigms A. Socioecology focuses on the relationship between social behavior and the natural environment. Favors selection for the individual’s daily survival. B. Sociobiology focuses on the genetic predisposition to behaviors and those behaviors’ enhancement of reproductive success. 1. One of the underlying assumptions is that various components of ecological systems evolved together. 2. To understand how one component works, it is necessary to determine the species relationships with numerous environmental factors. I A. Socioecology Primatologists consider the following environmental factors: 1. a. b. c. d. e. Quality and quantity of different foods Distribution of food resources, water, predators and sleeping sites Activity patterns (diurnal, nocturnal) Relationship with other species Impact of human activities I A. Socioecology, cont. 2. 3. Environmental factors such as resource availability and predation have a strong influence on group size and structure. Multimale and multifemale groups have an advantage when predation pressure is high. Adult males may join forces to chase and attack predators. Savannah baboons have been known to kill domestic dogs and to attack leopards and lions. 4. Solitary foraging may be related to diet and distribution of resources or predator avoidance. I B. Sociobiology 1. 2. 3. Natural selection acts on behavior in the same way it acts on physical characteristics. Behavior is a phenotypic expression and genes code for specific behaviors. This approach provides an opportunity to study the effects natural selection has had in shaping primate behavior. I C. Criticism of Sociobiology 1. 2. 3. 4. 5. Lack of long-term data on the demography and social behavior of large groups of animals. Lack of long-term data on the distribution of resources in time and space. Nearly complete absence of information on genetic relatedness through the male line. Difficulty in assigning reproductive costs and benefits to particular behaviors. Almost total ignorance of the genetics of primate social behavior. II A. Dominance Many primate societies are organized into dominance hierarchies. Dominance hierarchies impose a degree of order within the group. Dominant animals have priority access to food and mating partners. Many factors influence dominant status: sex, age, level of aggression, time spent in the group, intelligence, motivation and sometimes the mother’s social position. II B. Communication Communication is universal among animals: 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. II C. Aggression Home range is the area where a primate lives permanently. Within this is the core area that a primate might defend. Jane Goodall and her colleagues witnessed unprovoked and brutal attacks of chimpanzees by other chimpanzees. Territoriality and acquisition of females are the motives suggested for chimpanzee male aggression. II D. Affiliative Behaviors These behaviors reinforce bonds between individuals and enhance group stability: 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. Altruism, behaviors that benefit another while posing risk to oneself, are common in primate species. II E. Patterns of Reproduction In most primate societies, sexual behavior is tied to the female’s reproductive cycle (perineal swelling). Permanent bonding is not common among nonhuman primates. The temporary relationship for mating purposes is called a consortship. Male and female Bonobos may mate even when the II E. Reproductive Strategies Reproductive strategies are behavioral patterns that contribute to individual reproductive success. Primates are k-selected; they produce only a few young in whom they invest a tremendous amount of parental care. Male competition for mates and mate choice in females are both examples of sexual selection. II F. Mothers and Infants The basic social unit among all primates is the female and her infant(s). Except in species in which monogamy or polyandry occur, males do not participate in rearing. Monkeys raised with no mother are not able to form lasting affectional ties. The mother-infant relationship is often maintained throughout life. II G. Primate Cultural Behavior Biological anthropologists use the term culture in referring to nonhuman primates as well as humans. Cultural behavior is learned and passed from one generation to the next. Chimpanzee culture includes tools such as termite fishing sticks and leaf sponges. II H. Primate Cognitive Abilities Primate social interactions and problem-solving abilities demonstrate their intelligence. Vervet monkeys have three different vocalizations to indicate types of predators. The fact that apes can’t speak has more to do with the anatomy of the vocal tract and the language related structures of the brain than intelligence. The Primate Continuum Although human brains are larger than primate brains, the neurological processes are functionally the same. The fact that humans are part of an evolutionary continuum is the basis for animal research, yet we continue to cage nonhuman primates with little regard for the needs they share with us. Nonhuman primates should be maintained in social groups and introduced to habitat enrichment programs.