Burroughs was writing eighteen years after Mowgli and the feral child was Kipling's invention as a popular form: a human infant orphaned in the wild, adopted by animals, taught their law, and then forced to choose between their world and his own. Tarzan keeps the structure and changes the politics, making his hero an English aristocrat whose breeding shows through the jungle. The debt is often noted and Burroughs acknowledged reading Kipling.
