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15-1: The Puzzle of Life’s Diversity. Evolution – change over time Theory – well-supported, testable explanation of something that has occurred in the natural world. Charles Darwin. Born February 12 th , 1809. Joined the crew of the H.M.S. Beagle in 1831
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15-1: The Puzzle of Life’s Diversity • Evolution – change over time • Theory – well-supported, testable explanation of something that has occurred in the natural world.
Charles Darwin • Born February 12th, 1809. • Joined the crew of the H.M.S. Beagle in 1831 • Collected samples from everywhere he visited.
What Darwin Saw • Many, many, many different species • Different animals in similar environments • Fossils very similar to living animals • Fossils totally unlike living animals • The Galapagos Islands • Tortoises • Finches
15-2: Ideas That Shaped Darwin’s Thinking • Life without evolution • Nothing changed • Fossils were of animals before some unidentified mass extinction event • Darwin thought so, too, when he left. • What changed his mind?
Hutton and Lyell • Hutton – Explained that the Earth’s landscape has changed over time and that the Earth is very old. • Lyell – Principles of Geology – Said that scientists must focus on what is observable. • Geology is constantly changing.
What that meant for Darwin • If the Earth changes over time, might life change to adapt to it?
Lamarck • Lamarck’s Hypotheses on Evolution: • Tendency Toward Perfection • Use and Disuse • Acquired Traits Passed On • Lamarck was wrong, but he made people think about evolution.
Malthus • Said that if a human population got too large, then there would be increased competition for food and space. • Darwin realized that this applied to all organisms.