Researchers led by John Sutherland at Manchester University have demonstrated the mechanism that led to the first living, breathing creatures – a process attributed by generations of evolutionary theorists, including Charles Darwin, to an unexplained primordial soup.
The team has broken new ground by being able to synthesise two of the four building blocks of RNA, the self-replicating molecule that many scientist believe to be the most likely contender for the original molecule of life. Dr Sutherland believes that he has shown how it was possible to make all the building blocks of RNA from the simple chemicals that existed on Earth at the time.
The breakthrough is reported in the science journal, Nature.
"We've made the building blocks of RNA from what was around on the early Earth and is still around in interstellar space and in the atmosphere of Saturn's moon Titan," Dr Sutherland said.
"We haven't yet made the RNA molecule itself but we've made two of the four sub-units or building blocks. It suggests that making the molecule is possible. The building blocks are strung together and doing that is actually easier than making the building blocks themselves," he said.
DNA encodes the genetic blueprint for life while RNA acts as an intermediary, making protein from DNA. Scientists have long believed RNA molecules were more likely to be the origin of life than DNA but until now could not explain how RNA formed under the sort of conditions that existed four billion years ago.
"The trouble is, the human eye sees the three components of RNA and so the human brain assumes that to make the molecule you should combine those three components. People have found that they can make the sugars and the bases but the key thing they can't do is to join them together," Dr Sutherland said.
"And so for 40 or so years they have worked on the problem and have become so frustrated that they have decided that RNA, although very desirable, is just too complicated and so there must have been a simpler molecule that spawned RNA. We've just changed the order of assembly of the pieces, but it's overcome the dogma that it cannot be done," he said.
Among the early theories of how the first self-replicating molecule came into existence was the "primordial soup", where simple molecules mixed together in a broth that was regularly energised by ultraviolet light and electric storms.
Scientists first proposed that RNA preceded proteins in the 1960s.