New study narrows timeline for RNA World, the pre-DNA era of life's origins

Researchers have pinpointed 4.33 billion years ago as the optimal window for the RNA World, a hypothesized phase when RNA served as the primary replicating molecule before DNA and LUCA emerged. The study, published in Nature Communications, uses modeling to narrow the onset range to between 4.4 and 4.26 billion years ago, consistent with earlier estimates but with greater precision. This period followed the end of heavy asteroid bombardment, making conditions suitable for RNA-based life to take hold.

The study's computer model simulated how asteroid and comet impacts between 4.5 and 3.5 billion years ago altered conditions in Earth's crust, allowing researchers to assess when the planet became hospitable to RNA-based replication. The refined window of 4.4 to 4.26 billion years ago narrows prior estimates that ranged as broadly as 4.45 to 3.9 billion years ago, offering sharper constraints on this pivotal pre-DNA phase.

RNA, a single-stranded molecule structurally akin to DNA, is thought to have carried genetic information by self-copying before giving way to DNA in staged transitions called the U-DNA and T-DNA worlds. This progression ultimately led to LUCA, the common ancestor of all contemporary life. The findings reinforce the RNA World as a leading hypothesis among several proposed origin-of-life scenarios.