ANTH 1102 1ST Edition Lecture 9 Outline of Last Lecture I Hominin II Timeline of Hominin Evolution a Miocene b Pliocene c Pleistocene III IV Important Trends in Hominin Evolution Signs of Bipedalism Outline of Current Lecture V Trends Important in Hominin Evolution a Molecular Clock VI Fossil Records a The Afar b Lucy c Earliest Ancestor Evidence of Bipedalism a Brain Size b Stone Tools VII VIII Environmental Factors Associated with Traits a Rainforest Depletion b Radical African Climate Change Current Lecture Film NOVA Becoming Human Trends Important in Hominin Evolution All but one species died out Homo sapiens Change in posture lead to change in brain Molecular Clock These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Rate of change in DNA sequence otherwise known as a mutation Calculate how long humans and chimps diverged Fossil Records The Afar A face of a child skeleton is discovered in Dikika Ethiopia Volcanic ash helps determine date of fossil Dated to be 3 3 million years old Named Selam Australopithecus afarensis same as Lucy Died at the age of three Age of death determined by adult teeth in CDC scan Suggest adaptation to walking upright Known by shine bone and knee cap Skeletal features matched those of Lucy Bipedal pelvis shape However had chimp like shoulder blades o Used for swinging climbing in trees o Described half chimp half human Earliest Ancestor Michel Brunet French Paleontologist Led 2001 Northern Chad 26TH Expedition Found deformed skull of a late Miocene Hominin nicknamed Toumai Dated 6 million years old Classified as first Sahelanthropus tchadensis Used particle accelerator for a virtual image and reproduced skull Found skull connected to the spine with eyes forward Believed to be a biped and earliest known Hominin Evidence of Bipedalism Brain Size 4 million years ago brain size plateaued did not change However other things changed Selam was found to have only 75 of adult brain size at age three Where chimps at age three have already 90 of adult brain size This suggested a slower rate of growing up Key difference of chimps and humans length of childhood Lunate sulcus in chimps not in humans o Moved back for larger neo cortex thinking part of brain Stone Tools Evidence of smarter species Era of genus homo Homo habilis Nicknamed Handy Man Dexterous hands allowed better tool making Expansion in brain size Environmental Factors Associated with Traits Rainforest Depletion Rainforest shrank and Africa dried out Fossils showed landscape used to be grassy have lakes rivers and forests When the environment changed so did ancestors Trees died out no more need to climb or swing greater need to walk on ground Bipedalism formed o To see over tall grass o Pick fruit o Cool more efficiently o Save energy Mutation is the ONLY source of new variation Radical African Climate Change Rapid change catalyst for our change Climate change caused adaptation Compared our time to climate found we changed when climate instability happened
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