This document discusses primate social behavior and compares human behavior to that of other primates. It covers topics like why primates form social groups, different types of social structures, communication methods, dominance hierarchies, and behaviors like grooming, territoriality, and tool use. The document also compares the social behaviors of chimpanzees and bonobos, noting that chimpanzees exhibit warfare while bonobos are more peaceful and promote conflict resolution.

1. Primate Social Behavior Are Chimps Like Us?

2. Why Study Primate Behavior? Sociobiology: Do genes govern our behavior? Ant society as genetically determined “ Instincts” among nonprimate mammals Humans are guided by culture Product of learning Involves language, lacking in all other species Can nonhuman primate behavior give us a clue to our own?

3. Primatology: Basic Concepts Ethology : Study of any animal’s behavior Primatology: Study of nonhuman primates; subfield of ethology Field Research: To avoid influencing primate behavior Provisioning: Providing food to primates to shorten time in field Drawback: Provisioning does influence primate behavior

4. Social Groups Primates form social groups Primate behavior is the most complex among nonhuman animals Why groups? Defense of resources Defense against predators—safety in numbers Social control: dominance hierarchies Group cohesion: grooming Protection and raising of young: mother-infant bonds

5. Types of Social Groups Fusion-fission society: Groups come and go; chimpanzees ( Pan troglodytes) Harems (gorillas): one male, several females A few other, related males Multimale (baboons): several males and females Male dominance hierarchies are rigid

6. Mother and Infant Bonds Mother-infant bonds are strong among all primates (monkey and apes) Top: baboon mother pulls leg of reluctant infant Bottom: Chimp infants have long period of dependency

7. Social Behavior: Grooming All primates groom One combs fur of another Pick out dried skin, parasites Main function: interaction to maintain social bonds All primates but prosimians use fingers We haven’t lost the grooming habit

8. Social Behavior: Territoriality Home range : area of cyclical migration Core area: smaller unit which is the primary area of activity Chimps defend their core area against other troops These chimps are on patrol for that purpose Baboons are more tolerant of baboons from other troops

9. Social Behavior: Communication Gibbon calls (like this one) are closed Danger: high-pitched shouts Assembling: clatters and clicks Chimps have some aspects of language Kanzi—bonobo capable of making requests by pressing computer keys with symbols Chimpanzees—able to use American Sign Language Language does not exist among nonhuman primates

10. Social Behavior: Dominance Hierarchies Dominance hierarchies: system of rank among nonhuman primates Here, the alpha chimp touches the back of the lower ranked one (top) Bonobo dominance behavior centers on females (bottom) Sons’ hierarchy depends on that of their mothers

11. Communication: Threats Calls of greeting or threats when two troops meet Threat gestures Baboons: baring canines (top) Chimpanzees Slack jaw: sign of anger Chimpanzee : Displays, screams (bottom), tearing vegetation Reactions of target individuals : Grimacing; crouching; presenting rear end

12. Communication: Reconciliation Embracing Extending hand for reassurance (top) Grooming (to curry favor) Even kissing

13. Sexual Behavior: Individual Estrus: cyclical female receptivity Swelling of sexual skin among monkeys and some apes (such as this hamadryas baboon) Receptivity longer among bonobos and humans Sexual positioning in copulation Most primates: male copulates with female from rear Bonobos and human: frontal (ventro-ventral) copulation, as between this couple

14. Sexual Behavior: Partners Gibbons form lifetime monogamous pairs (top) Other species: Harems among baboons and gorillas (such as these two females, bottom) Multiple male-female sexuality among chimpanzees and especially bonobos “ Homosexual” behavior found among bonobos

15. Phases of Growth Newborns: cling to mother’s stomach Up to a year: start riding mother’s back Juveniles form play groups, a good to learn basic skills Juveniles may also show empathy, as with this distressed adult Imitative behavior gradually integrates subadults into troop

16. Foraging and Sharing Prosimians: insects and plant foods Most anthropoids: roots, fruits, seeds—some species eat meat of small animals Gorillas: strict vegetarians Chimpanzees: often cooperate in stalking, killing prey, and sharing the meat Bonobos: Share food of all kinds

17. Yes, Chimps do eat meat Chimps feeding on red colobus monkey About 10% of these monkeys are killed by chimps in the Gombe reserve

18. Tool Making and Tool Use Chimpanzees at Gombe are famous for termite fishing with twigs They also use leaves as sponge May be culturally derived: Chimps in West Africa crack nuts but don’t fish for termites

19. Tool Making and Use: Other species: Bonobos make rain hats from leaves Orangutans also use tools Gorillas and gibbons do not make or use tools—so far as we know!

20. Agonistic Behavior and Warfare Agonistic behavior characteristic of all species mostly over mating females competing for dominance Primates were once thought incapable of killing their own kind.

21. Conflict: Comparing Chimps and Bonobos Chimpanzees Warfare actually was observed between one troop and a breakaway group. Cannibalism observed and reported Bonobos Philosophy: “Make love, not war” Frequent sexual contact between sexes and within one sex

22. Primate Behavior and Fossil Hominid Behavior Inferring the past Similarities between nonhuman primate and human behavior Tool making before the Paleolithic Interaction without language: kinesics and paralanguage When did language become necessary?

23. Interpreting the evidence Nature of prehominid and early hominid society Child rearing techniques Was hierarchy inevitable? Was warfare inevitable? Bonobos versus chimps