The discovery of embedded minute diamonds inside zircon rocks in Western Australia has reignited debate over the date of the first appearance of life on Earth.
Image: Location of Jack Hills, Western Australia. Credit: NASA
Experts have determined that the tiny crystals contain a form of carbon usually associated with living things such as plants and bacteria. If they do prove to be descended from living organisms, this would push the date for the birth of life on our planet back some 500 million years, to beyond 4.25 billion years ago. The Earth itself is just 4.6 billion years old, reports the BBC.
“If the light carbon signature is from life, then this is very big indeed,” says Craig O’Neill, a geoscientist at Macquarie University in Sydney. “The trouble is, there are quite a few other mechanisms that can form light carbon signatures.”
However the evidence is unconvincing said Dr Martin Whitehouse of the Swedish Museum of Natural History and one of the authors of the paper to Nature journal.
"We're all a little sceptical," he told BBC News. "When you look at the carbon isotopes, they could be interpreted as biogenic because we know that biologic processes do generate light carbon isotopes. But of course there are other processes that can do that," said Dr Whitehouse. He explained that these processes could include carbon oxides or the arrival from outer space by meteorites.
The rocks were discovered in the remote Jack Hills in Western Australia and experts analysed 22 microdiamond inclusions found inside 18 zircons that ranged in age from 3.05 billion to 4.25 billion years.
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