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HOW DO ORGANISMS CHANGE OVER TIME?
•Why do giraffes have long necks?
•How did giraffes get long necks?
EARLY EVOLUTION IDEAS
•People did not know the true age of the Earth and thought that organisms did not change over time
•This idea did not explain why fossils were being found that looked very different than current organisms
EARLY EVOLUTION IDEAS
•Buffon (1760s) started noticing that some animals had similar bone structure and this lead him to believe that all these animals came from an ancient common ancestor
•His student Lamarck came up with the first idea of how this change happened
LAMARCK
•Came up with the idea of acquired traits to explain changes seen over time
•Changes in environment caused an organism’s behavior to change, creating a new trait
LAMARCK
•Organisms strive to improve themselves, the organism was responsible for its own changes
•Unused body structures waste away and are not passed on
•Once a structure is modified, it would be inherited by its offspring
CHARLES DARWIN
•One stop was the Galapagos Islands
•He noticed that the variations in animals were well suited to the environment they lived in
•Variation: differences in physical traits
DARWIN’S IDEAS
•The trait that is more beneficial for survival became more common (the environment was determining which trait was best,
not the organism)
•Ex. Giraffes with slightly longer necks survived and reproduced
Darwin’s Finches – 13 finch species that were each well adapted to their environment
-evidence suggests they descended from one original species from Ecuador