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Evolution and Lamarck


Lamarck: The theory of transformation

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Problem : What major additions did Lamarck make to the theory of his mentor, Buffon?

Lamarck supported Buffon's theory that species change over time. However, he extended this idea back through history, saying that life must have started out in simple forms that changed to become more complex and better suited to its environment. In addition, he was able to propose a mechanism by which this might occur.

Problem : Describe the way in which Lamarck believed giraffes came to have long necks.

Lamarck believed that animals could inherit traits acquired by their parents. A giraffe that was born with a short neck might gain a longer neck through a lifetime of straining for leaves in tall trees. The offspring of this giraffe would not have to develop the long neck, but rather would be born with it. This mechanism is known as the inheritance of acquired traits.

Problem : How did Lamarck propose species acquired new traits?

Lamarck believed that this occurred through use and disuse. If an animal often used a certain trait or characteristic, that trait would become larger or more pronounced. If the trait went unused, it would no longer develop fully and would become reduced.

Problem : Which part of Lamarck's theory has been disproved by advances made in other fields of biology?

The inheritance of acquired traits has been disproved by advances made in the past century in the field of genetics.