Maya De Almeida Araujo/Plainpicture
By Colin Barras
AT THE bottom of the Mediterranean Sea, just south of Greece, there is a lake. Complete with a delicate shoreline and an inviting deep blue surface, the L’Atalante basin looks almost like a lake on land. But this is an inhospitable place. Its waters are about as salty as water can be and never mix with the layers above – making it completely devoid of oxygen.
It was a shock, then, when biologist Roberto Danovaro scooped up samples from the bottom of this briny pool and found a thriving community of microscopic animals living there. The discovery went against everything we thought we knew about animal __life and its reliance on oxygen.
Some biologists still think Danovaro must have made a mistake. Yet his is just the most exotic in a series of discoveries that are chipping away at our long-held beliefs about the importance of oxygen to complex life. We thought anything beyond the simplest cell couldn’t do without it. But now we’re finding that some animals can carry on more or less happily with the merest whiff of the stuff.
It’s a finding primed to upset our tidy story of why complex __life evolved on Earth. Nick Butterfield, a palaeontologist at the University of Cambridge, puts it bluntly: “Atmospheric oxygen has nothing to do with it.” He reckons there is a much simpler explanation – one that’s been staring us in the face.
For the first 80 per cent of our planet’s history there was barely any oxygen, and no complex life either. That has always seemed perfectly logical. Organisms that use oxygen to respire can
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