The Gaia Hypothesis, suggested by John Lovelock, is a theory that tries to explain how the Earth is actually an organism in itself, and how it has been capable of staying around for billions of years because of the life to which it serves as a habitat. Vis-versa, life is capable of staying on the Earth due to this ecosystem that Earth is in itself. Basically, life and the planet work in collaboration to serve one another for both to stay around.