Life began on Earth when meteorites bombarded ‘warm little ponds’ on the Earth’s surface rather than in the sea as previously thought, according to new research.
The origin of life is one of the biggest unsolved questions in science.
In recent years experts have favoured the idea that the miracle of life first took place in bubbling volcanic vents deep in the sea.
But the latest research now lends support to a theory of Charles Darwin, who in 1871 attempted to explain how the first life form may have emerged.
In a letter to a fellow scientist, Darwin suggested life began in ‘some warm little pond with all sorts of ammonia and phosphoric salts, light, heat, electricity etcetera present’.
But only now has its plausibility been proven through evidence-based calculations carried out by scientists at McMaster University in Canada and the Max Planck Institute in Germany.
Co-author Dr Thomas Henning said: ‘In order to understand the origin of life, we need to understand Earth as it was billions of years ago.
‘As our study shows, astronomy provides a vital part of the answer.
‘The details of how our solar system formed have direct consequences for the origin of life on Earth.’
And it is now thought life on Earth began between 4.5 and 3.7 billion years ago when small meteorites – under eight inches wide – hit the planet.
These rocks contained ammonia and hydrogen cyanide, chemicals necessary to make a molecule called RNA.
Their calculations suggest that the RNA molecules were formed during the wet phase.
As the ponds dried out, concentrating the ‘broth’, the molecules formed long chains.
These long chains got even longer in further ‘wet and dry’ cycles.
In some cases, favourable conditions saw some of those RNA chains fold over and spontaneously replicate themselves.
These molecules constituted the first genetic code for life on the planet.
Professor Ralph Pudritz, a lead author of the study, said: ‘Because there are so many inputs from so many different fields, it’s kind of amazing that it all hangs together.
‘Each step led very naturally to the next – to have them all lead to a clear picture in the end is saying there’s something right about this.’
The leading rival theory holds that life began in volcanic vents in ocean floors, where the elements of life came together in blasts of heated water.
But the authors of the new paper say such conditions were unlikely to generate life, since the bonding required to form RNA needs both wet and dry cycles.
Professor Pudritz said: ‘We’re thrilled that we can put together a theoretical paper that combines all these threads, makes clear predictions and offers clear ideas that we can take to the laboratory.’
The authors plan to test their theory that they can create artificial life in the laboratory next year.
The authors stress that any life formed would not be ‘life as we know it’ – but a forerunner to even the simplest one-cell creature that exists today.