For decades, an origin-of-life story starring RNA has prevailed. New research may be shaking that theory’s hold on our understanding of life’s beginnings.
A popular theory holds that life emerged from a rich chemical soup in which RNA was the original self-replicator. But a combination of peptides and RNA might have been more effective.
Novikov Aleksey Four billion years ago, the first molecular precursors to life emerged, swirling about in Earth’s primordial soup of chemicals. Although the identity of these molecules remains a subject of fractious debate, scientists agree that the molecules would have had to perform two major functions: storing information and catalyzing chemical reactions. The modern cell assigns these responsibilities to its DNA and its proteins, respectively — but according to the narrative that dominates origin-of-life research and biology-textbook descriptions today, RNA was the first to play that role, paving the way for DNA and proteins to take over later.
This hypothesis, proposed in the 1960s and dubbed the “RNA world” two decades later, is usually viewed as the most likely explanation for how life got its start. Alternative “worlds” abound, but they’re often seen as fallback theories, flights of fancy or whimsical thought experiments.
The RNA world doesn’t tell you anything about genetics.
That’s mainly because, theorizing aside, the RNA world is fortified by much more experimental evidence than any of its competitors have accumulated. Last month, Quanta Magazine reported on an alternative theory suggesting that protein-like molecules, rather than RNA, may have been the planet’s first self-replicators. But its findings were purely computational; the researchers have only just begun experiments to seek support for their claims.
Now, a pair of researchers has put forth another theory — this time involving the coevolution of RNA and peptides — that