"In 1833, Charles Darwin was astonished by an animal he met in the Falkland Islands: handsome, social, and oddly crow-like falcons that were "tame and inquisitive . . . quarrelsome and passionate," and so insatiably curious that they stole hats, compasses, and other valuables from the crew of the Beagle. Darwin wondered why these birds were confined to remote islands at the tip of South America, sensing a larger story, but he set this mystery aside...