Why life on Earth could have emerged from a puddle

The beginnings of life on Earth may previously have been explained in terms of a dramatic crash of lightning or a collision with a comet. But a new study proposes another origin altogether: the humble puddle.

Small pools of water, rather than anything more grand, might have been the place where life on Earth began, according to the new research.

Scientists from the NSF/Nasa Center for Chemical Evolution showed in a simple laboratory reaction that they could produce missing links towards RNA – one of the 'building blocks of life' – using water.

The research could show that the chemistry that started life wasn’t a rare thing that began in the chaos of the early universe. Instead, it might have been more abundant than previously thought.

Whether or not the researchers find that the ingredients for life would have been more easily brought about than expected, they will have an impact for our understanding of how probable it is that life could have formed and exists elsewhere in the universe.

To conduct the research, the scientists looked at a pair of chemical ancestors of the compounds that go together to make RNA, a close relative of DNA. RNA is very similar to DNA and scientists think that DNA-based life would have been preceded by life forms that made heavy use of RNA, which itself may have been preceded by another proto-RNA.

Using those two chemicals, the scientists were able to form what appears to be the building blocks of life – "proto-nucleotides” that look a lot like those found in RNA, and so are likely to be their ancestors. They found that some of those reactions were especially surprising, because they happened even more quickly and tellingly than had been expected.

The two ingredients used would have been abundant on the early Earth, and would have been “well suited for primitive information coding”, according to Nicholas Hud, who led the research project. That means that they would both be available and able to form the building blocks of life.

But scientists want to be sure about how those parts may have come together before claiming for sure that they have discovered the truth about the ancestors of the all-important RNA and DNA. But they are excited about the possibility of getting closer to understanding what the very earliest parts of life might have looked like.

"We're getting close to molecules that look the way life may have looked in early stages," Ram Krishnamurthy, who worked with Professor Hud on the study, said.