Not all planets qualify as organisms – Mercury, Venus, and Mars, for example, are nothing more than rocks in space, as dead as dodos. Earth, however is biologically self-actualised. It possesses a biosphere – a resident population of biological forms – which cooperatively interact to create a global self-regulating system. All of us, from weasels to banana trees, unconsciously participate in the life of the Earth, collectively maintaining air, water, and soil in quantities and compositions to suit ourselves. Earth is a living planet, in other words, because living things are on it, collaborating to produce a favourable climate in the same manner that lungs, liver, heart, and brain cooperate to maintain a functional human being.
There may be a few less admirable parallels, too. “It is far from easy to determine,” wrote Pliny the Elder, “whether she [nature] has proved to man a kind parent or a merciless stepmother.” Gaia, according to her ancient biographers, was no maternal role model: she committed incest and adultery, bore enormous numbers of hideous children, and had her husband, Uranus, castrated. This is Gaia’s dark side: nature, red in tooth and claw. The biosphere cooperates globally, but on the individual level its members go to unpleasant lengths in order to survive. Lions eat zebras; polar bears eat seals, snakes swallow mice; and sharks – though very rarely – even eat us, at least if given half a chance. Chimpanzees commit infanticide, in-crowd chickens peck outsiders to death; female spiders and praying mantises, after a bout of consensual sex, eat their erstwhile mates. To Gaia, it’s all one. Mother Earth happily dispenses flowers and fruit; then with cheerful equanimity, she dices us up for dinner.
Rebecca Rupp, Four Elements: Water, Air, Fire, Earth (Profile Books; 2005) 286.