DARWIN & Evolution

Darwin Darwin’s Journey Charles Darwin took trip on HMS Beagle as a naturalist. Five year trip took him to shores of Australia & S. America

Darwin Galapagos islands miles off coast of South America. forms of life lived there that could not be found anywhere else –ex giant tortoises & swimming iguanas they were unique yet similar to common animals in South America

Darwin Galapagos islands –

Darwin Before Darwin James Hutton (1795) published detailed theory about geological forces that shaped Earth, layers of rock form slowly some rocks are moved by forces under the surface other rocks are buried; forced from ocean floor to form mountain ranges Darwin concluded that these processes would take far longer than a few 1000 years

Darwin Before Darwin Charles Lyell (1830) book Principles of Geology stressed that scientists must explain past events in terms of process that they can actually observe since these same processes still occur on Earth ex: volcanoes, earthquakes, etc Darwin got book prior to trip on Beagle

Darwin Before Darwin Charles Lyell 1830 book Principles of Geology led Darwin to think –if Earth has changed over time – why can't animals –if life were to change over time then it would take a while Therefore, Earth must be old

Darwin Before Darwin Jean-Bantiste Lamarck (1809) French naturalist prior to Darwin 1809 publication proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during lifetime these traits could be passed on to offspring over time this process led to change in a species turns out that he was wrong about - inheritance of acquired traits

Darwin Before Darwin Thomas Malthus (1797) English economist observed that babies being born faster than people were dying he reasoned that if human population grew unchecked then eventually there would be insufficient food, space, etc for everyone

Darwin Before Darwin Thomas Malthus Darwin realized that this also applied to animals & plants he had observed. –Why didn't they overrun the Earth? –eventually led to ideas on natural selection

Darwin Natural selection –process by which best adapted individuals in a population survive & produce similarly adapted offspring

Darwin Darwin's Theory of Natural Selection 1) in nature there is a tendency to overproduce 2) not all offspring produced survive 3) variations exist in a population 4) variations are inherited 5) those with variations that are suitable for environment will live longer & leave more offspring on average 6) resulting population as a whole will change as it becomes better adapted to environment

Darwin Origins of life Early Ideas spontaneous generation –living things can come from nonliving material Francisco Redi (1668) –experiments with rotting meat disproved spontaneous generation

Darwin Origins of life Early Ideas Louis Pasteur (1878) –showed microorganisms only develop in broth when exposed to air

Darwin Origins of life Early Ideas the work of Redi and and Pasteur led to the idea of biogenesis biogenesis –life comes from life

Darwin Origins of life Modern Ideas How did life first appear on Earth? 2 major events had to happen before life could appear –organic molecules had to form –these molecules had to come together to form more complex molecules ex: amino acids, nucleotides, lipids, sugars

Darwin Origins of life Modern Ideas Aleksandr Oparin (1930) –proposed lightning struck Earth’s early atmosphere of methane, ammonia, hydrogen, & water to produce first organic molecules

Darwin Origins of life Modern Ideas Stanley Miller & Harold Urey (1953) –tested Oparin’s hypothesis

Darwin Origins of life Modern Ideas Stanley Miller & Harold Urey (1953)

Darwin Origins of life Modern Ideas Stanley Miller & Harold Urey (1953) – were able to create organic compounds necessary for life from compounds found in the primitive Earth atmosphere

Darwin Origins of life Modern Ideas Sidney Fox (1955) –created protocells(proteiniod microspheres) –protocells can grow and divide

Darwin Origins of life Modern Ideas Lynn Margulis (1960) –developed Endosymbiont Theory –eukaryotic cells arose from communities of prokaryotic organisms

Darwin Origins of life Modern Ideas evolution of cells possible time line –organic molecules (in water) –protocell –anaerobic respiration - eurobacteria –heterotrophic prokaryotes - archaebacteria –eukaryotes