Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Intro to Evolution
Transcript
Introduction to Evolution Earth History Origin of Life Central Questions • What was the early Earth like? • What were the first cells like? • What is the Endosymbiotic Theory? • What is spontaneous generation? What experiments were used to disprove it? Early Earth • Earth was formed approximately 4.6 billion years ago • It was covered in boiling oceans, volcanoes, storms and a poisonous atmosphere that contained no oxygen Starting Life • Where would the first organic molecules come from? • Alexander Oparin hypothesized that life could come from Chemical Evolution • Miller and Urey passed electricity through a simulation of the early atmosphere and made organic compounds. 1 Early Life • Earliest fossils are about 4 billion years old- simple prokaryotic cells (bacteria) • They were anaerobic (didn’t use oxygen) heterotrophs that fed off of organic compounds (remember no oxygen or photosynthesis) More Complex Life • Mutations over time lead to the development of photosynthesis and more oxygen in the atmosphere (equation for photosynthesis ) • Endosymbiont theory larger cells absorbed cells that could photosynthesize or use oxygen to break down food, making the first eukaryotes Endosymbiont theory General Timeline of Evolution • • • • • 4.54 BYA 4 BYA 4 -3.8 BYA 3.5 BYA 2.4 BYA • 1.7 – 1.2 BYA • 1 B - 580 MYA • 530 MYA • 490 MYA • • • • • • 370 MYA 300 MYA 250 MYA 230 MYA 200 MYA 180 MYA Animals Cambrian Explosion Land Plants Land invertebratess Land vertebrates Pangaea forms P-TR Extinction (biggest) Dinosaurs Tr-J Extinction Pangaea breaks up • 150 MYA • 130 – 90 MYA • 65 MYA • • • • 6 MYA 2.5 MYA 200 KYA 100 KYA Formation of the Earth End of Heavy Bombardment First Life Photosynthesis Oxygen rich atmosphere Eukaryotes Multicellular Life Plants Fungi Sexual Reproduction Avian evolution Angiosperms Social Insects K-T Extinction (dinosaurs die off, mammals emerge) Great Apes Diverge Stone tools Human migration “Great leap forward” 2 Spontaneous Generation • Spontaneous Generationidea that life came from nonliving material, like maggots from dead meat • Also called abiogenesis (beginning from no life) Experiments • Francisco Redi (1668)- Put meat under a lid to prove no maggots would grow (disprove spontaneous generation) • Incorrect theory, how might you disprove it? Louis Pasteur (1861)- Used Sshaped flasks to finally disprove spontaneous gen. • Spontaneous Generation was finally proven wrong by Pasteur’s experiments • Science supports the idea of biogenesis. Bio=life, genesis=beginning • Biogenesis- life comes from other life (like the cell theory) Central Questions • What was the early Earth like? • What were the first cells like? • What is the Endosymbiotic Hypothesis? • What is spontaneous generation? What experiments were used to disprove it? 3
