Transcript DARWIN
DARWIN
Darwin’s Journey
Darwin Charles Darwin
took trip on HMS Beagle as a naturalist. Five year trip took him to •shores of Australia & S. America
Galapagos
islands –ex giant tortoises & swimming iguanas •they were unique yet similar to common
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•600 miles off coast of South America. •forms of life lived there that could not be found anywhere else animals in South America
Galapagos islands –
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Before Darwin
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
Before Darwin
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
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
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Before Darwin
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
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
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eventually there would be insufficient food, space, etc for everyone
Before Darwin
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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
Natural selection
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–process by which best adapted individuals in a population survive & produce similarly adapted offspring
Darwin's Theory of Natural Selection
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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
Origins of life
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Early Ideas •
spontaneous generation
–living things can come from nonliving material •
Francisco Redi
(1668) –experiments with rotting meat
disproved
spontaneous generation
Origins of life
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Early Ideas •
Louis Pasteur
(1878) –showed microorganisms only develop in broth when exposed to air
Origins of life
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Early Ideas •the work of Redi and and Pasteur led to the idea of
biogenesis
•biogenesis –life comes from life
Origins of life
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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
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
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Origins of life Modern Ideas •
Stanley Miller & Harold Urey
(1953) –tested Oparin’s hypothesis
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Origins of life Modern Ideas •Stanley Miller & Harold Urey (1953)
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Origins of life
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Modern Ideas •Stanley Miller & Harold Urey (1953) – were able to create organic compounds necessary for life from compounds found in the primitive Earth atmosphere
Origins of life
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Modern Ideas •
Sidney Fox
(1955) –created
protocells
(proteiniod microspheres) –protocells can grow and divide
Origins of life
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Modern Ideas •
Lynn Margulis
(1960) –developed
Endosymbiont Theory
–eukaryotic cells arose from communities of prokaryotic organisms
Origins of life
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Modern Ideas •evolution of cells possible time line –organic molecules (in water) –protocell –anaerobic respiration - eurobacteria –heterotrophic prokaryotes - archaebacteria –eukaryotes