The Tangled Tree: A Radical New History of Life

by David Quammen

“The kingdoms are man’s classification,” he added, and their meaning derives only from the fact that we humans choose to recognize them, purely for our convenience in organizing biological knowledge. This is similar to what he had said about plant communities: that the communities, as distinct from individual plants or populations of this species or that, have a “low degree of reality” in the tangible world. Plant communities are how we think about plant diversity, which tends to get arranged so that plants with similar needs share similar habitats. Kingdoms of life are how we think about life’s diversity, so that we don’t get nosebleeds and despair of the whole enterprise of biology. It’s worth noting too that Robert Whittaker, like Herbert Copeland, was a professor as well as a scientist. He understood that teaching biological information, along with organizing and retrieving it, required putting its bounteous variousness into handy categories.