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| Space on Dec 28, 2009

Paul Davies studies possibilities of life beyond Earth

Davies talks about a realm of microbes he calls the ‘shadow biosphere’ – and how these microbes could hold clues to alien life.

Paul Davies: I don’t think anybody expects to go to Mars and find cats and dogs walking around, but I think there’s a good chance that there’s microbial life in the deep subsurface. And so, the same thing here on Earth.

That’s astrobiologist Paul Davies of Arizona State University. Davies studies the possibilities of life beyond Earth. He said that scientists are now studying below the seafloor near deep-sea volcanic vents, and at Earth’s icy poles, for microbes that might be analogs of extraterrestrial life.

Paul Davies: Most life on Earth is microbial. Most microbes haven’t been characterized, let alone their genes sequenced. So it’s entirely possible that in that microbial realm there’s what we like to call a ‘shadow biosphere.’ It doesn’t mean that it’s sort of shadowy in the mystical sense, it just means that we don’t yet know what it is. We could be dealing just with ordinary-looking microbes, but with their innards completely different.

In other words, microbes with bizarre biochemistries live in a kind of ‘shadow’ of the ordinary life we’re used to. What’s more, said Davies, these microbes suggest life might have emerged not just once, but many times throughout Earth’s history.

Paul Davies: Life may have started 58 times on Earth, and we could have 27 ‘shadow biospheres’ descended from those different geneses, but only one of these achieved multicellular life. And we’re the product of that.