The Shadow Biosphere

Paul Davies urges us to look for “alien” life here on Earth, arguing that if we find a “second genesis” on our own planet, it would increase the likelihood that there’s life elsewhere in the universe:

No planet is more Earth-like than Earth itself, so if the path to life is easy, then life should have started up many times over right here.
Searching for alternative life on Earth might seem misconceived, because there is excellent evidence that every kind of life so far studied evolved from a common ancestor that lived billions of years ago. Yet most of the life that exists on Earth has never been properly classified. The vast majority of species are microbes, invisible to the naked eye, and scientists have analyzed only a tiny fraction of them. For all we know, there could be microbes with other ancestral origins living literally under our noses—or even inside our noses—constituting a sort of shadow biosphere, containing life, but not as we know it.

Category: Observations

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