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Lecture 03 Outline Chapter 22

Lecture 03 Outline Chapter 22 - Lecture 3 DARWINIAN...

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Lecture 3: DARWINIAN EVOLUTION On earth : 1.4 – 1.6 million described species Maybe 30 million or more species WHAT ARE THE MECHANISMS FOR THE DIVERSIFICATION OF LIFE? 1. NON EVIDENCE-BASED (NON-SCIENTIFIC) EXPLANATIONS: Creationism: The belief that humanity and other species were created In their original form by a deity e.g. MAYAN creation account in Popl Vuh e.g. JUDAEO-CHRISTIAN creation accounts in Genesis Modifications by clerics to creationism: .. shift away from literal interpretation of genesis But. Shift back towards this by modern creationists. 2006 Gallup poll asked Americans if they believed “God created human beings pretty much in their present form at one time within the last 10,000 years or so” 46% said yes: Despite incontrovertible scientific evidence against this hypothesis e.g. Southern Germany 30 – 33,000 year old cave art e.g. fossil skulls of Homo: 160,000 years. Based on GENETIC EVIDENCE: DIVERGENCE OF modern Homo sapiens FROM A NOW-EXTINCT SISTER SPECIES H. neanderthalensis ca. 500,000 YEARS AGO. Last common ancestor with our most closely related LIVING relative (bonobos and chimpanzees) - approximately 6.5 MYA. 2. EVIDENCE-BASED (SCIENTIFIC) EXPLANATIONS: Evolution by natural selection. 1859. On the Origin of Species by Natural Selection, or the Preservation of Favored Races in the Struggle for Life. Charles Darwin. All species (including humans) are descended from a distant common ancestor through a process of evolution by natural selection 1st convincing hypothesis for how evolutionary change could occur to produce adaptations Descent by modification: All organisms, including humans, are descended from a common ancestor via a long series of intermediates as part of a “NATURAL PROCESS” : i.e. one that does not involve divine intervention . Darwin called this ‘descent by modification’ We call Darwin’s ‘descent by modification’ evolution by natural selection Evolution was not a new word: Anything that changes evolves . . e.g. clouds Even Descent by modification was not new in 1859 Darwin’s grandfather: Erasmus Also believed in descent by modification VIA natural laws: HE BELIEVED IN THE INHERITANCE OF ACQUIRED CHARACTERISTICS… AND SO DID MANY SCHOLARS IN THE EARLY 19 th Century The notion of biotic evolution goes back much earlier… Aristotle: 384 BC – 322 BC Jean Baptiste Pierre Antoine de Monet, Chevalier de La Marck
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Lamarck: Only previous model on how life evolved that made any sense Good parts: used fossil record related extinct species to extant species proposed changes due to environmental adaptation Lamarck’s Ideas on Evolution Use and disuse : body organs used a lot become bigger and stronger, organs not used deteriorate
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Lecture 03 Outline Chapter 22 - Lecture 3 DARWINIAN...

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