The Origin of the Feedstock Molecules for Life on the Hadean Earth

TL;DR

The paper explores how essential molecules for life could have formed on the early Earth under a CO2-rich atmosphere.

Contribution

It identifies new feedstock molecules formed under Hadean conditions that could lead to amino acids and nucleosides.

Findings

HNO and formaldehyde in a weakly reducing atmosphere produce oxime and amidoxime molecules.

These molecules are precursors to amino acids and canonical nucleosides.

The findings suggest life's building blocks could form on CO2-dominated rocky planets with volcanic activity.

Abstract

The origin of life in the Hadean eon required the formation of amino acids and nucleosides among the key molecules of life. It is assumed that highly unsaturated carbon and nitrogen containing feedstock molecules, which form in a strongly reducing H2‐atmosphere were the reactive starting materials. The Hadean Earth was, however, surrounded by a CO2‐dominated atmosphere and the question of how under such inert conditions the biomolecules could have formed is unsolved. Here, we report that HNO and formaldehyde, which form robustly in a weakly reducing atmosphere by lightning and UV‐irradiation, react with SO2 to produce oxime, amidoxime, and nitrile‐containing molecules, which react to give precursors to amino acids and all four canonical nucleosides. The small number of feedstock molecules required suggests that the molecules of life can robustly form on all types of rock planets with volcanic activity and a CO2‐dominated atmosphere.

The origin of life in the Hadean eon required the formation of amino acids and nucleosides among the key molecules of life. In an often postulated strongly reducing atmosphere, HCN and its derivatives are robustly formed as plausible starting molecules. But HCN does not form in a Hadean, weakly reducing atmosphere. Instead, aldehydes and NO are produced, which react to produce oxime, amidoxime, and nitrile‐based feedstock molecules as precursors.

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