Human evolution lecture

Human evolution lecture - Human evolution lecture: Why...

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Human evolution lecture: Why didn’t Darwin publish his documents in 1844 when the draft was completed? Afraid of people’s reactions. Social Darwinism has been used repeatedly to justify one ethnic group’s abuse or domination of another. Involves incorrect assumptions. Huxley vs. Wilberforce debate Where do humans fall in general classification? When did the human lineage diverge from other great apes. How diverse is the human lineage through time. When and where did homo sapiens first appear? 3 kinds of mammals ( 4000 species): monotremes (egg laying), marsupials (pouch maturing), placental mammals( develop inside uterus through placenta attachment). Four phylads of eutheria ( placental mammals). Some evolved in western and eastern portions of the northern hemisphere supercontinent Lausia? Primates are one of many groups belonging to the Euarchontoglires ( mid cretaceous 90-80 mya) Great apes appear in the fossil record about 20 mya. Hominids appears between 5-8 mya. The genus Homo is only about 2 mya. Modern humans appear in the fossil record about 195 000 years ago-= very recent. taxonomists fall into a continuum with the ends called lumpers and splitters. Splitters are more species. Different opinions on how many species, genera and families of great apes should be recognized. Whether a taxonomist is a lumper or splitter you can decipher how they classify species,
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The first great apes “dryopithecines”, lasted from 20-10 mya, gave rise to one African and asian branches. They were small aboreal primates about size of a dog. Ramapithecus was though to be directly in line with humans 14 mya BP. Additional data place it in the Pongid line ( Orangutans). We had a 4-5 million year gap in the fossil record because there weren’t any deposits. Links were missing. Until recently, before hte gap only drypith and pongids are known. After the gap, gorillas, chimps. ..Many important fossils have only been found the last 20 years. Bipedal locomotion, distinguishes us from the other apes. Gorillas knuckle walk, chimps can stand and walk on two legs but not efficiently. This is not as efficient or fast as quadrapedal locomotion/ So why has it evolved? All early hominid fossils come from the Rift Valley of east Africa. Gorillas and chimps at west of Africa. What happened 8 mya that caused east and west to be different. Chimps stayed in the forests while species that became homo sapiens moved into savannahs. Changing habitat in the rift valley, 8 mya the river disappeared. Changing habitat resulted in new selection pressures that favoured bipedal locomotion. Became a better solution to walk on two feet? How? When selection favoured feet, free hands could develop skills and traits like hunting, toolmaking. Diet change required a different kinds of organism that a great ape. Greater divergence between the eastern and western apes.
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This note was uploaded on 09/28/2011 for the course BIOL 301 taught by Professor Pickard during the Spring '09 term at Waterloo.

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Human evolution lecture - Human evolution lecture: Why...

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