Scientists find new clues about the origins of life

One of the biggest questions in Biology has always dealt with the possible origins of life. For several decades, one hypothesis has been that RNA molecules – which are vital for cell functions – existed on ancient Earth, possibly together with proteins and other organic molecules, and that around four billion years ago, they started to self-replicate and develop from a simple single molecule into a diversity of complex molecules. This step-by-step change eventually led to the emergence of life as we know it, consisting of a wondrous array of plants, animals, and everything in-between.

While there has been much theoretical discussion about this subject, until recently scientists have not been able to physically create such RNA replication systems. However, a new study led by the University of Tokyo has now managed to build an RNA molecule that replicates, diversifies, and develops in complexity, following Darwinian evolution, which is characterized by a self-perpetuating process of incessant change based on mutations and natural selection, enabling different characteristics to emerge, and the ones that were adapted to the environment to survive.

“We found that the single RNA species evolved into a complex replication system: a replicator network comprising five types of RNAs with diverse interactions, supporting the plausibility of a long-envisioned evolutionary transition scenario,” said study lead author Ryo Mizuuchi, an assistant professor of Evolutionary Biology at the University of Tokyo.

“Honestly, we initially doubted that such diverse RNAs could evolve and coexist,” he added. “In Evolutionary Biology, the ‘competitive exclusion principle’ states that more than one species cannot coexist if they are competing for the same resources. This means that the molecules must establish a way to use different resources one after another for sustained diversification. They are just molecules, so we wondered if it were possible for nonliving chemical species to spontaneously develop such innovation.”

The simplicity of Mizuuchi’s molecular replication system, compared to biological organisms, will allow scientists to examine evolutionary phenomena with unprecedented resolution. While there are still many questions left to answer about the origins of life, this study has provided empirically-based insights into a possible evolutionary route that a primitive RNA molecule may have taken on ancient Earth.

“The results could be a clue to solving the ultimate question that human beings have been asking for thousands of years – what are the origins of life?” Professor Mizuuchi concluded.

The study is published in the journal Nature Communications.

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By Andrei Ionescu, Earth.com Staff Writer