This influential, yet controversial idea requires that the mixture of species on Earth at any moment acts as a collective organism that continuously (yet unwittingly) tunes Earth's atmospheric composition and climate to promote the presence of life. . . But I'd bet there are some dead Martians and Venusians who advanced the same theory about their own planets a billion years ago.
How I loathe the servitude people try to hold up to me as being so valuable. I pity the man who is condemned to it, who cannot generally escape it, but it is not the burden of his labor that disposes me in his favor, it is - it can only be - the vigor of his protest against it.