... still maintain that there is no especial difficulty in a bear's mouth being enlarged to any degree useful to its changing habits,—no more difficulty than man has found in increasing the crop of the pigeon, by continued selection, until it is literally as big as the whole rest of the body. If this had not been known, how absurd it would have appeared to say that the crop of a bird might be increased till it became ... — More Letters of Charles Darwin - Volume I (of II) • Charles Darwin
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