Charles Darwin, a British naturalist, proposed the theory of biological evolution by natural selection. Retention of characters of no use or vestigial organs could not be explained by Darwin's theory. According to his theory, species keep on evolving or changing with time and almost all organisms share common ancestry with some organism. He also studied that the birds of Galapagos Island (Darwin's finches) developed different beaks as per the availability of the food. This proved adaptive radiation.

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