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Mechanism of evolution.

While the fact that biological evolution had taken place was suspected by many scientists, until now no one had suggested a mechanism that would allow it to take place. Why should some catlike creature in the course of generation after generation slowly change, some into lions, some into tigers, and some into pussycats? The first to attempt an answer was Lamarck (see 1801) in his book Zoological Philosophy, published in 1809. Here he suggested that particular animals might use a part of the body steadily, or not use it, and that those parts might develop slightly or degenerate slightly as a result, and that such developed or degenerated parts could be inherited by their young, which, by use or disuse, would continue the process.

Thus some antelopes, by stretching upward to reach leaves, would gradually develop slightly longer necks and legs, which would be inherited by the young, which, also straining, would continue the process so that the giraffe would evolve. Other antelopes, by dint of constantly fleeing from predators, strengthened their leg muscles and became very fleet as the generations progressed. Water birds, by using their feet to push water backward, developed webs, while moles, who didn't need eyes underground, gradually lost them.

This sort of thing is referred to as the inheritance of acquired characteristics. Experiments would show that acquired characteristics were not inherited. Nevertheless, the advancement of a mechanism for evolution, even if a wrong one, heightened interest in the matter.

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Author:Asimov, Isaac
Publication:Asimov's Chronology of Science & Discovery, Updated ed.
Article Type:Reference Source
Date:Jan 1, 1994
Words:244
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