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, 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.