Primate Social Behavior

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Dominance Hierarchies, Grooming, Mother-Child Bonds, and other Nonhuman Primate Behavior.

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Primate Social Behavior

  1. 1. Primate Social Behavior Are Chimps Like Us?
  2. 2. Why Study Primate Behavior? <ul><li>Sociobiology: Do genes govern our behavior? </li></ul><ul><li>Ant society as genetically determined </li></ul><ul><li>“ Instincts” among nonprimate mammals </li></ul><ul><li>Humans are guided by culture </li></ul><ul><li>Product of learning </li></ul><ul><li>Involves language, lacking in all other species </li></ul><ul><li>Can nonhuman primate behavior give us a clue to our own? </li></ul>
  3. 3. Primatology: Basic Concepts <ul><li>Ethology : Study of any animal’s behavior </li></ul><ul><li>Primatology: Study of nonhuman primates; subfield of ethology </li></ul><ul><li>Field Research: To avoid influencing primate behavior </li></ul><ul><li>Provisioning: Providing food to primates to shorten time in field </li></ul><ul><li>Drawback: Provisioning does influence primate behavior </li></ul>
  4. 4. Social Groups <ul><li>Primates form social groups </li></ul><ul><li>Primate behavior is the most complex among nonhuman animals </li></ul><ul><li>Why groups? </li></ul><ul><li>Defense of resources </li></ul><ul><li>Defense against predators—safety in numbers </li></ul><ul><li>Social control: dominance hierarchies </li></ul><ul><li>Group cohesion: grooming </li></ul><ul><li>Protection and raising of young: mother-infant bonds </li></ul>
  5. 5. Types of Social Groups <ul><li>Fusion-fission society: Groups come and go; chimpanzees ( Pan troglodytes) </li></ul><ul><li>Harems (gorillas): one male, several females </li></ul><ul><li>A few other, related males </li></ul><ul><li>Multimale (baboons): several males and females </li></ul><ul><li>Male dominance hierarchies are rigid </li></ul>
  6. 6. Mother and Infant Bonds <ul><li>Mother-infant bonds are strong among all primates (monkey and apes) </li></ul><ul><li>Top: baboon mother pulls leg of reluctant infant </li></ul><ul><li>Bottom: Chimp infants have long period of dependency </li></ul>
  7. 7. Social Behavior: Grooming <ul><li>All primates groom </li></ul><ul><li>One combs fur of another </li></ul><ul><li>Pick out dried skin, parasites </li></ul><ul><li>Main function: interaction to maintain social bonds </li></ul><ul><li>All primates but prosimians use fingers </li></ul><ul><li>We haven’t lost the grooming habit </li></ul>
  8. 8. Social Behavior: Territoriality <ul><li>Home range : area of cyclical migration </li></ul><ul><li>Core area: smaller unit which is the primary area of activity </li></ul><ul><li>Chimps defend their core area against other troops </li></ul><ul><li>These chimps are on patrol for that purpose </li></ul><ul><li>Baboons are more tolerant of baboons from other troops </li></ul>
  9. 9. Social Behavior: Communication <ul><li>Gibbon calls (like this one) are closed </li></ul><ul><li>Danger: high-pitched shouts </li></ul><ul><li>Assembling: clatters and clicks </li></ul><ul><li>Chimps have some aspects of language </li></ul><ul><li>Kanzi—bonobo capable of making requests by pressing computer keys with symbols </li></ul><ul><li>Chimpanzees—able to use American Sign Language </li></ul><ul><li>Language does not exist among nonhuman primates </li></ul>
  10. 10. Social Behavior: Dominance Hierarchies <ul><li>Dominance hierarchies: system of rank among nonhuman primates </li></ul><ul><li>Here, the alpha chimp touches the back of the lower ranked one (top) </li></ul><ul><li>Bonobo dominance behavior centers on females (bottom) </li></ul><ul><li>Sons’ hierarchy depends on that of their mothers </li></ul>
  11. 11. Communication: Threats <ul><li>Calls of greeting or threats when two troops meet </li></ul><ul><li>Threat gestures </li></ul><ul><li>Baboons: baring canines (top) </li></ul><ul><li>Chimpanzees </li></ul><ul><li>Slack jaw: sign of anger </li></ul><ul><li>Chimpanzee : Displays, screams (bottom), tearing vegetation </li></ul><ul><li>Reactions of target individuals : </li></ul><ul><li>Grimacing; crouching; presenting rear end </li></ul>
  12. 12. Communication: Reconciliation <ul><li>Embracing </li></ul><ul><li>Extending hand for reassurance (top) </li></ul><ul><li>Grooming (to curry favor) </li></ul><ul><li>Even kissing </li></ul>
  13. 13. Sexual Behavior: Individual <ul><li>Estrus: cyclical female receptivity </li></ul><ul><li>Swelling of sexual skin among monkeys and some apes (such as this hamadryas baboon) </li></ul><ul><li>Receptivity longer among bonobos and humans </li></ul><ul><li>Sexual positioning in copulation </li></ul><ul><li>Most primates: male copulates with female from rear </li></ul><ul><li>Bonobos and human: frontal (ventro-ventral) copulation, as between this couple </li></ul>
  14. 14. Sexual Behavior: Partners <ul><li>Gibbons form lifetime monogamous pairs (top) </li></ul><ul><li>Other species: </li></ul><ul><li>Harems among baboons and gorillas (such as these two females, bottom) </li></ul><ul><li>Multiple male-female sexuality among chimpanzees and especially bonobos </li></ul><ul><li>“ Homosexual” behavior found among bonobos </li></ul>
  15. 15. Phases of Growth <ul><li>Newborns: cling to mother’s stomach </li></ul><ul><li>Up to a year: start riding mother’s back </li></ul><ul><li>Juveniles form play groups, a good to learn basic skills </li></ul><ul><li>Juveniles may also show empathy, as with this distressed adult </li></ul><ul><li>Imitative behavior gradually integrates subadults into troop </li></ul>
  16. 16. Foraging and Sharing <ul><li>Prosimians: insects and plant foods </li></ul><ul><li>Most anthropoids: roots, fruits, seeds—some species eat meat of small animals </li></ul><ul><li>Gorillas: strict vegetarians </li></ul><ul><li>Chimpanzees: often cooperate in stalking, killing prey, and sharing the meat </li></ul><ul><li>Bonobos: Share food of all kinds </li></ul>
  17. 17. Yes, Chimps do eat meat <ul><li>Chimps feeding on red colobus monkey </li></ul><ul><li>About 10% of these monkeys are killed by chimps in the Gombe reserve </li></ul>
  18. 18. Tool Making and Tool Use <ul><li>Chimpanzees at Gombe are famous for termite fishing with twigs </li></ul><ul><li>They also use leaves as sponge </li></ul><ul><li>May be culturally derived: </li></ul><ul><li>Chimps in West Africa crack nuts but don’t fish for termites </li></ul>
  19. 19. Tool Making and Use: Other species: <ul><li>Bonobos make rain hats from leaves </li></ul><ul><li>Orangutans also use tools </li></ul><ul><li>Gorillas and gibbons do not make or use tools—so far as we know! </li></ul>
  20. 20. Agonistic Behavior and Warfare <ul><li>Agonistic behavior characteristic of all species </li></ul><ul><li>mostly over mating females </li></ul><ul><li>competing for dominance </li></ul><ul><li>Primates were once thought incapable of killing their own kind. </li></ul>
  21. 21. Conflict: Comparing Chimps and Bonobos <ul><li>Chimpanzees </li></ul><ul><li>Warfare actually was observed between one troop and a breakaway group. </li></ul><ul><li>Cannibalism observed and reported </li></ul><ul><li>Bonobos </li></ul><ul><li>Philosophy: “Make love, not war” </li></ul><ul><li>Frequent sexual contact between sexes and within one sex </li></ul>
  22. 22. Primate Behavior and Fossil Hominid Behavior <ul><li>Inferring the past </li></ul><ul><li>Similarities between nonhuman primate and human behavior </li></ul><ul><li>Tool making before the Paleolithic </li></ul><ul><li>Interaction without language: kinesics and paralanguage </li></ul><ul><li>When did language become necessary? </li></ul>
  23. 23. Interpreting the evidence <ul><li>Nature of prehominid and early hominid society </li></ul><ul><li>Child rearing techniques </li></ul><ul><li>Was hierarchy inevitable? </li></ul><ul><li>Was warfare inevitable? Bonobos versus chimps </li></ul>

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