Notes for primate social behavior and evolution Primate Social Behavior (1) live in social groups (different species, different types of groups) division of labor--different sexes and ages do different tasks in the group dominance and hierarchy...sometimes inherited from parents.  NOT simply based on size and strength individuals will form "friendships" and "alliances" with others "family" groupings, at least mother and children (sometimes males are long-term members) (2) territoriality groups occupy and defend territory within territory, groups set up "home bases" (3) communication use sight, vocalizations, and touch to communicate grooming--establishes bonds and expresses status (lower groom higher) vocalizations--use different sounds for different kinds of information/threats (some primates can be taught human symbolic language) sight and touch--look at, hold hands, "kiss" others (4) extended childhood childhood can last 5-10 years, so long periods to build emotional relationships and to learn can learn and share new behaviors--culture? (5) eat meat and even hunt for meat some primates eat meat as well as plants (even hunt other primates) hunting requires cooperation and planning meat increases protein in diet (6) aggression primates will defend group and territory some even seek out other groups to attack and kill (war?) (7) use--and even make--tools chimps for example will tear off a twig, prepare it, and use it to fish ants out of ant-hills tool=any natural object that is modified to do a specific job tool use and tool making requires intelligence, foresight, manual dexterity, and learning In other words, at least some primates have the ability to think ahead, to discover new solutions and behaviors, and to learn and share those behaviors. That is, they have at least some "cultural" capabilities Primate physical characteristics make primate behavior and "culture" possible Primate Evolution First primates appears ~65 mya, about the time the dinosaurs went extinct.  Known as plesiadapiforms. Example: Purgatorius--discovered in Dakotas, size of mouse/rat, still had primitive rodent-like teeth, claws instead of nails, but better vision than rodents and flexible wrists and ankles. Probably not a direct ancestor to humans.  Today, not even considered a primate but a member of a related species. 50-40 mya first prosimians Example: Adapis--cat-sized, quadrapedal, incisor teeth smaller and less specialized, nails instead of claws, eye sockets facing forward.  Lemur-like. ~30 mya first anthropoids Example: Aegyptopithecus (33 mya)--(many jaw fossils, some limbs, 1 nearly complete skeleton) size of monkey, 2-1-2-3 tooth pattern, primitive teeth, brain size between prosimian and anthropoid Also Propliopithecus (30 mya)--2-1-2-3 tooth pattern, typical molar shape of hominoids! ~20 mya Age of Hominoids (ape-like primates) over 500 individuals recovered from Africa, Asia, and Europe Example: Proconsul--up to 150 pounds (size of large chimp), flat palate and V-shaped jaw of ape Environment of Africa was continuously cooling and drying through this period--forests shrinking and being replaced by grassland. Dryopithecus continued to live in trees--probably quadrapedal, tooth shape of hominoids Ramapithecus adapted to live on ground--appear ~14 mya, incisors very large, molars very thick, face like orangutan.  Originally believed to be first hominid, but probably ancestor to orangutan.  Very successful species--only humans more widely distributed, found throughout Eurasia) No true undisputed hominids until 5-4 mya.