There's Growing Evidence Life on Earth Started With More Than Just RNA 

18 JULY 2022 

How life originated on Earth continues to fascinate scientists, but it's not easy peering back billions of years into the past. Now, evidence is growing for a relatively new hypothesis of how life began: with a very precise mix of RNA and DNA.

RNA and DNA both determine the genetic make-up of all biological life, with DNA acting as a genetic blueprint and RNA as a blueprint reader or decoder. For a long time, it was thought that RNA developed on Earth first, with DNA evolving afterwards – but mounting evidence suggests they may have emerged at the same time and both been involved in kickstarting life on the planet.

A 2021 study backed up this idea by explaining how the simple compound diamidophosphate(DAP) – which may have predated life on Earth – can knit together DNA building blocks called deoxynucleosides into basic DNA strands. 

"This finding is an important step toward the development of a detailed chemical model of how the first life forms originated on Earth," said chemist Ramanarayanan Krishnamurthy form Scripps Research in California back in January 2021.

The findings add credence to the idea that both DNA and RNA developed together from the same sort of chemical reactions at the beginning of life on our planet, and that the first self-replicating molecules could have been mixes of both these nucleic acids – not just RNA, as suggested in the more established 'RNA world' hypothesis.