By Michael Marshall
Life may have begun on our planet hundreds of millions of years earlier than thought, according to two studies published this week. But both papers are already proving controversial.
Ben Pearce of McMaster University in Hamilton, Ontario, Canada, and colleagues simulated conditions on early Earth to find out how readily the key molecules of life could have formed. They focused on “warm little ponds” on land, which are one of the suspected sites of the origin of life – the other being deep-sea vents.
Pearce tackled the formation of RNA, a close cousin of DNA that is widely thought to have been the basis for the first life. Many of the building blocks of RNA are found in asteroids and meteoroids, so Pearce calculated how much could have been delivered to Earth by impacting rocks – of which there were plenty during Earth’s first billion years – and then how much could have accumulated in ponds, given the molecules’ fragility and tendency to leech away.
He concluded that RNA could have formed within a handful of years of major impacts, implying that life could have formed very early in Earth’s history.
There are two problems with this argument, says John Sutherland of the MRC Laboratory of Molecular Biology in Cambridge, UK.
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