Evolution and Lamarc1 - The classic example used to explain...

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Evolution and Lamarck Lamarck: The theory of transformation Though he was building on the work of his mentor, Count George-Louis Leclerc de Buffon , Jean-Baptiste Lamarck (1744-1829) is often credited with making the first large advance toward modern evolutionary theory because he was the first to propose a mechanism by which the gradual change of species might take place. Also, he extended the definition of the change over time, saying that life started out simple and became more complex. In 1809 he published Philosophie Zoologique, in which he described a two part mechanism by which change was gradually introduced into the species and passed down through generations. His theory is alternatively referred to as the theory of transformation or simply Lamarckism. Though today Lamarck's work is considered a major step forward, in his lifetime he did not receive much recognition.
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Use and Disuse
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Figure%: Use and disuse in the evolution of the neck of the giraffe
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Unformatted text preview: The classic example used to explain the concept of use and disuse is the elongated neck of the giraffe. According to Lamarck's theory, a given giraffe could, over a lifetime of straining to reach high branches, develop an elongated neck. A major downfall of his theory was that he could not explain how this might happen, though he discussed a "natural tendency toward perfection." Another example Lamarck used was the toes of water birds. He proposed that from years of straining their toes to swim through water, these birds gained elongated, webbed toes to better their swimming. These two examples demonstrate how use could change a trait. By the same token, Lamarck believed that disuse would cause a trait to become reduced. The wings of penguins, for example, would be smaller than those of other birds because penguins do not use them to fly....
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