Michael Marshall writes:

Here’s a story you might have read before in a popular science book or seen in a documentary. It’s the one about early Earth as a lifeless, volcanic hellscape.

When our planet was newly formed, the story goes, the surface was a barren wasteland of sharp rocks, strewn with lava flows from erupting volcanoes. The air was an unbreathable fume of gases. There was little or no liquid water. Just as things were starting to settle down, a barrage of meteorites tens of kilometres across came pummelling down from space, obliterating entire landscapes and sending vast plumes of debris high into the sky. This barren world persisted for hundreds of millions of years. Finally, the environment settled down enough that oceans could form, and the conditions were finally right for microscopic life to emerge.

That’s the story palaeontologists and geologists told for many decades. But a raft of evidence suggests it is completely wrong.

The young Earth was not hellish, or at least not for long (in geological terms). And, crucially, life formed quickly after the planet solidified – perhaps astonishingly quickly. It may be that the first life emerged within just millions of years of the planet’s origin.

With hindsight, it is strange that the idea of hellscape Earth ever became as established as it did. There was never any direct evidence of such lethal conditions. However, that lack of evidence may be the explanation. Humans are very prone to theorise wildly when there’s no evidence, and then to become extremely attached to their speculations. That same tendency – becoming over-attached to ideas that have only tenuous support – has also bedevilled research into the origins of life. Every journalist who has written about the origins of life has a few horror stories about bad-tempered researchers unwilling to tolerate dissent from their treasured ideas.

Now that the idea of hellscape Earth has so comprehensively collapsed, we need to discard some lingering preconceptions about how life began, and embrace a more open-minded approach to this most challenging of problems. Whereas many researchers once assumed it took a chance event within a very long timescale for Earth’s biosphere to emerge, that increasingly looks untenable. Life happened fast – and any theory that seeks to explain its origins now needs to explain why. [Continue reading…]