Wild Boy of Hamelin
or Man of Nature, found in the forest of Hertswold, Hanover. He walked on all fours, climbed trees like a monkey, fed on grass and leaves, and could never be taught to articulate a single word. Dr. Arbuthnot and Lord Monboddo sanctioned the notion that this poor boy was really an unsophisticated specimen of the genus homo; but Blumenbach showed most conclusively that he was born dumb, of weak intellect, and was driven from his home by a stepmother. He was discovered in 1725, was called Peter the Wild Boy, and died at Broadway Farm, near Berkhampstead, in 1785, at the supposed age of seventy-three.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894