ANTH1102 Lecture 13 Outline of Last Lecture I Allen and Bergman s Rules continued adaptation II Why Anthropologists Study Non Human Primates A Reasons B Origins of the Human Species C Tendencies of Primates Outline of Current Lecture I Bipedalism A History B How Do We Know They Were Bipedal C Hominin Species D Why bipedal Current Lecture History Hominids primates Hominins human lineage Many hominin fossils have been found in Africa Taphonomy study of how decaying organisms became fossilized possible reasons scavengers weather floods solarization bioturbation geologic forces diagenesis Uniformitarianism paleoecology fossil associations and modern proxies can all lead to inferences about how the hominins lived How do we know they were bipedal anatomy foramen magnum hole in skull where spine connects curved vertebral column pelvis femur knees the foot components orthograde upright walking center of mass directly above hips and to what effect on efficiency speed swiftness flexibility vision solar exposure vs facultative bipedalism not necessary to walk upright only sometimes The foramen magnum is posterior in primates because the vertebral column is at an angle while it is less far back in humans whose vertebral column is vertical Great ape quadruped C curved spinal column hominin bipeds S curved spinal column sacral vertebra more robust I e thicker bones for more support Hominin pelvis is wider and shorter and the birth canal can accommodate larger skulls angle of femur socket is different hominins walk with legs closer together than primates do knees are more robust for inward support and ankles less flexible no need to climb trees as much as primates have in the past Laetoli tracks proved bipedalism and non opposable hallux big toe and human like arch they were obligatory bipeds opposable big toe abducted in line big toe adducted Hominin Species The oldest acknowledged hominins are the sahelanthropus tchadensis 6 5mya Ardipithecus ramidus kadabba 4 4mya had an opposable hallux though the femur and pelvis were bipedal like also they were arboreal with long arms compared to the legs Australopithecus afarensis Lucy 3 6 2 9mya was very small about 3 ft very similar to modern humans though Homo erectus 1 8mya 100 000ya were probably the most successful hominins went unchanged for a very long time Why bipedal hypotheses savannah vision ability to see predators feeding arboreal bipedality most popular sex and reproduction climate technology efficiency not one is completely true some may be true simultaneously
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