ANTH 1102 1ST Edition Lecture 9 Outline of Last Lecture I.HomininII. Timeline of Hominin Evolutiona. Mioceneb. Pliocenec. PleistoceneIII. Important Trends in Hominin EvolutionIV. Signs of BipedalismOutline of Current Lecture V.Trends Important in Hominin Evolutiona.Molecular ClockVI. Fossil Records a. The Afarb. “Lucy”c. Earliest AncestorVII. Evidence of Bipedalisma. Brain Sizeb. Stone ToolsVIII. Environmental Factors Associated with Traitsa. Rainforest Depletionb. Radical African Climate ChangeCurrent LectureFilm- 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 bladeso Used for swinging, climbing in treeso 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 humanso 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 formedo To see over tall grasso Pick fruito Cool more efficientlyo 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
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