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Theory of Evolution

Theory of Evolution. Before Darwin. At the beginning of the 1800s, scientists knew of some kinds of fossils and were aware of homologous and vestigial structures

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Theory of Evolution

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  1. Theory of Evolution

  2. Before Darwin • At the beginning of the 1800s, scientists knew of some kinds of fossils and were aware of homologous and vestigial structures • Many scientists suspected some type of evolution had given rise to living things around them, but they had no unifying theory to explain how it happened • Before Charles Darwin, Jean Lamarck presented the first theory of evolution

  3. Jean Lamarck • In 1809, French scientist Jean Lamarck put forth the first systematic presentation of evolution • Lamarck described a mechanism by which he believed evolution could occur • The mechanism was known as “the inheritance of acquired characteristics”

  4. Lamarck argued that salamanders living in grasslands had a hard time walking due to short legs not being able to trample tall grass/reach the ground • Over time, the salamanders began to slither on their bellies and their leg muscles wasted away from disuse and legs became small • Lamarck’s theory said the trait was passed on to the offspring and in time, salamanders legs became so rarely used that they disappeared • Legless salamanders (snakes) evolved from salamanders by inheriting the acquired characteristic of having no legs • Lamarck’s theory failed to catch on because he presented no experimental evidence or observations

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