Microfossils in 3.4-billion-year-old Australian sandstone. Photo by David Wacey.
Life on Earth began earlier than anyone has imagined possible. That’s the conclusion of scientists studying a 3.4-billion-year-old fossil discovered in Western Australia.
Until roughly 3.8 billion years ago, the planet was a world of molten rock and boiling oceans, constantly bombarded by asteroids. Tides were huge because the moon was orbiting so close to Earth, and the atmosphere was a noxious cocktail of greenhouse gases like methane since there were no plants yet to produce oxygen.
It can’t be said with 100 percent certainty that the fossils in the rocks that scientists have been studying come from living organisms, but it’s at least a very strong likelihood. And it means that life began amazingly quickly – just as soon as the period known as the Late Heavy Bombardment came to an end.