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Primate Bodies and Movement 1
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Primates As Mammals •  There are approximately 230 species of nonhuman primates (prosimians, monkeys, and apes) •  Primates belong to the vertebrate class Mammalia and the subgroup of placental mammals. 3
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New World
Monkeys
Apes
Old World Monkeys
Gibbons
Orangutans
Chimps
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CharacterisEcs of Primates •  Primates share a number of traits with other placental mammals: •  Body hair •  Long gestaEon period followed by live birth •  Endothermy, the ability to maintain a constant body temperature through internal processes 5
Specific Primate CharacterisEcs •  Increased brain size •  Crucial evoluEonary characterisEc •  Capacity for learning and behavioral flexibility 6
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Limbs and LocomoEon •  Primates have a tendency towards erect posture. •  Hands and feet possess a high degree of prehensility or grasping ability. •  Movement for most primates involves both hands and feet. 7
Limbs and LocomoEon •  Features of the hands and feet include: •  5 digits on hands and feet •  Opposable thumb and parEally opposable great toe •  TacEle pads enriched with sensory nerve fibers at the ends of digits 8
Primate Hands 9
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Five Types of LocomoEon •  Terrestrial quadrupeds •  Baboons •  Arboreal quadrupeds •  Lemurs •  VerEcal climbers and leapers •  Bushbaby •  Brachiators, or suspensory quads •  Orangutans, gorillas, chimps •  Bipeds •  Humans 10
Intermembral Index •  Different ways of walking are reflected in the relaEve length of front and hind limbs. •  The intermembral index is a way of expressing this. •  Is the forelimb/hindlimb X 100 11
Terrestrial Quadrupeds •  Intermembral index: about 100 •  Most comfortable movement is on the ground, using all four legs. •  “Default se\ng” for mammals. •  Many mammals have specialized limbs designed exclusively for movement. 12
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Who am I? 13
Primate Terrestrial Quad: Baboon 14
Baboon 15
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Arboreal Quad: Lemur IM index: up to 85 16
Ring‐tailed Lemur 17
Lemur mom & baby 18
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VerEcal climber/leaper: Bushbaby 19
Bushbaby 20
Quad climber with prehensile tail: Squirrel Monkey 21
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Squirrel Monkey 22
Spider Monkey: suspensory quad with prehensile tail 23
Orangutan: brachiator IM index: 130 24
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Orangutan 25
Chimpanzee: our closest cousin Brachiator with an IM index of 106 26
Mom mediates a sibling dispute 27
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ContemplaEng by the river 28
Chimp using a termite fishing pole 29
3 Mystery Guests 30
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Bipedalism •  Humans are the only living primate with a habitually upright posture. •  Other primates are capable of walking upright, but are not as agile or adept at it as modern humans. 31
Physical Traits of Bipedalism •  Human anatomy differs from that of other apes, and these facilitate bipedalism. •  Differences go, literally, from head to toe. 32
Bipedal locomoEon •  Skeletal differences from quadrupedalism: •  Change in posiEon of foramen magnum: 33
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S‐curve of spine 34
Shape of pelvis 35
Longer lower limbs and Femur angled inward 36
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Foot and great toe 37
Development of Bipedalism •  EvoluEonary changes happened gradually, over millions of years •  Humans didn’t “evolve from” apes, but each species has its own history, arising from a common ancestor for all the great apes somewhere between 5 and 7 million years ago. •  Hominids were walking upright in Africa 3 to 4 million years ago. 38
Footprints at Laetoli 39
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Who walked at Laetoli? Australopithecus afarensis 40
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