In 1928, naturalist Henry Beston famously wrote that our fellow animals are “gifted with the extension of the senses we have lost or never attained, living by voices we shall never hear. They are not brethren, they are not underlings,” he added. ”They are other nations .” Beston employed this turn of phrase to make a fundamental point: humankind is not the standard by which other species should be judged.  That worldview would have come as a surprise to the leading thinkers from the Age of Discovery. Even as Columbus was sailing the ocean blue, many of the world's top scientists and writers were still extolling the virtues of an ancient ranking system known as the Great Chain of Being . On the top rung of that hierarchy was, of course, God. Below Him were angels, followed by all of humankind, from kings and queens to commoners and thieves. Who could possibly be lower than the lowly thieves? This, the Great Chain said, was the domain inhabited by nonhuman animals.…