Many of us, scientists included, harbor contradictory intuitions about Mother Nature. We can see that ecosystems often have an inherent ability to self-stabilize, and we know we wouldn’t be here if the planet hadn’t maintained conditions suitable for life for almost 4 billion years. One reaction is to claim that some Earth-wide equilibrium, though fragile, does exist, and reflects the fact that species have evolved to cooperate with one another. Another is to say that the first response is nonsense: organisms are ‘selfish’, and evolution isn’t cooperative but rather a brutish Darwinian competition that selects individual organisms based on their ability to survive and reproduce. The primordial balancing act performed by our biosphere, if it exists at all, is more or less a lucky accident.