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Download 3.1 Origin of life
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Evolution • The development of life in geological time. • Today evolution refers to the origin from earlier life forms – the process that has transformed life from its earliest beginning to the vast diversity that has and does exist today. The Big Bang Theory George Lemaitre First proposed ‘big bang theory’ Edwin Hubble All galaxies are moving away from us The Hubble Telescope 3.9 billion years old Where did life come from? Special Creation •Life created by a super natural being at a particular time Archbishop Ussher • 1654 • Life began on earth at 9am, 23rd October, 4004 BC • He based this on calculations form the bible William Paley (1802) • The fact that such complicated things exist is evidence for the existence of a creator! Panspermai • Life arrived form outer space Comet storms Fred Hoyle Life originated in outer space and came to earth riding on light beams Svente Arrhenius • Life originated in the form of spores and was then driven through space by the pressure of light from the sun. Watson and Crick • Crick – life has evolved twice. • Once from molecules to intelligent people elsewhere. • Once from bacteria to humans Evidence • Experiments have shown that when ammonia, methane and carbon dioxide are mixed with ice crystals in a vacuum and UV light applied – hundreds of organic molecules are formed. • Presence of bacteria in meteorites • Survival of bacteria in space 20 million year old Bee Bacterai found in the resin were still alive! Cosmozoan Theory Life arrived from outer space • UFO’s • Cave drawings of dinosaurs • Kangaroos in SA Britney Spears • Alien? Spontaneous Generation Aristotle (384BC-322BC) • Believed that certain particles contained an ‘Active ingredient’ which could produce life Van Helmont (1577-1644) • Recipe for spontaneous generation of mice • • • • Dirty shirt Dark cupboard Wheat grains Active ingredient - sweat Francisco Redi • This experiment asked questions about spontaneous generation Pasteur • Disproved the idea of spontaneous generation (1860) Biochemical Evolution • The formation of organic molecules from inorganic material Oparin – The Russian J.B.S. Haldane The Brit Jupiter • Atmosphere • • • • Methane Ammonia Hydrogen Water vapour • CO2 Miller and Urey Miller and Ureys Experiment 1953 Fred Hoyle • Life assembling from inorganic substances is – • “as improbable as a tornado blowing through a junk yard and assembling a 747” Protobionts Protobionts • Proto – First • Biont – life form • These are specialized droplets whose internal chemical characteristics differ markedly form their surroundings. • Capable of growth by engulfing other droplets • These were probably the precursors to prokaryotes • RNA could provide means of transferring information Bacteria – Clostridium tatani First life forms appear on earth around 3.5 billion years ago Prokaryote Bacteria - Prokaryotes So how do we get from Prokaryotes to Eukaryotes? Endosymbiotic Theory Amoeba – Protist First Eukaryotes around 2.1 billion years ago Euglena • Could chloroplasts have once been free living prokaryotes? Paramecium - Protist Were mitochondria once free living prokaryotes Theories for the origin of life • • • • • • Special creation Panspermia Cosmozoan Stready State Biochemical Evolution Spontaneous Modern science evaluates theories in many ways. For a theory to be scientifically credible it must: – – – – fit with the known facts Overlap with other known scientific theories Lead to testable predictions Not rely on supernatural explanations So which fit with scientific theory • • • • • • Special creation Panspermia Cosmozoan Stready State Biochemical Evolution Spontaneous – fit with the known facts – Overlap with other known scientific theories – Lead to testable predictions – Not rely on supernatural explanations
