Origin of Life’s Building Blocks in Carbon- and Nitrogen-Rich Surface Hydrothermal Vents

Abstract

There are two dominant and contrasting classes of origin of life scenarios: those predicting that life emerged in submarine hydrothermal systems, where chemical disequilibrium can provide an energy source for nascent life; and those predicting that life emerged within subaerial environments, where UV catalysis of reactions may occur to form the building blocks of life. Here, we describe a prebiotically plausible environment that draws on the strengths of both scenarios: surface hydrothermal vents. We show how key feedstock molecules for prebiotic chemistry can be produced in abundance in shallow and surficial hydrothermal systems. We calculate the chemistry of volcanic gases feeding these vents over a range of pressures and basalt C/N/O contents. If ultra-reducing carbon-rich nitrogen-rich gases interact with subsurface water at a volcanic vent they result in 10 − 3 – 1 M concentrations of diacetylene (C4H2), acetylene (C2H2), cyanoacetylene (HC3N), hydrogen cyanide (HCN), bisulfite (likely in the form of salts containing HSO3−), hydrogen sulfide (HS−) and soluble iron in vent water. One key feedstock molecule, cyanamide (CH2N2), is not formed in significant quantities within this scenario, suggesting that it may need to be delivered exogenously, or formed from hydrogen cyanide either via organometallic compounds, or by some as yet-unknown chemical synthesis. Given the likely ubiquity of surface hydrothermal vents on young, hot, terrestrial planets, these results identify a prebiotically plausible local geochemical environment, which is also amenable to future lab-based simulation.

TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

“…blocks can arise another way, either within hydrothermal vents (Rimmer & Shorttle 2019), in surface scenarios without ultraviolet light (Rimmer & Shorttle 2019), or that they may be delivered exogenously (Rimmer & Shorttle 2019). In addition, within the scenario explored by Rimmer et al (2018), the threshold UV flux provides a necessary but not sufficient condition for the origins of life on a rocky planet.…”

Astrochemistry and Astrobiology: Materials Science in Wonderland?

“…The discovery of extremophiles, organisms thriving only at conditions inhospitable for human beings (extremes of temperature, pH, salts, pressure, or a combination of these), and their deep rooting in the 16S phylogenetic tree of life substantially modified our understanding of the physical limits of life and opened new perspectives as to how life originated on our planet [48]. Hydrothermal vents, which host Archaea, the third domain of life after Bacteria and Eukarya, are characterized by temperatures close to the boiling point of water and pH values < 3.0, environmental conditions that are quite close to those found on Earth when life began [49]. From an astrobiological perspective, this hypothesis justifies the study of terrestrial hyperthermophilic microorganisms, and, in particular, the study of the molecular determinants of the extreme stability of the biomolecules of hyperthermophilic Archaea.…”

A dual perspective on the microwave-assisted synthesis of HCN polymers towards the chemical evolution and design of functional materials

“…From the point of view of studies on the origin of life, astrobiology and prebiotic chemistry, microwaveassisted syntheses may simulate hydrothermal environments. Currently, these conditions are interesting because hydrothermal vents, either submarine 19,20 or subaerial 21 , as well as nuclear geyser systems 22 , are suggested as preferential sites for increasing the molecular complexity that led to pristine biochemistry on early Earth. In addition, from a prebiotic perspective, aqueous HCN polymerization may be mainly considered as cyanide polymerization.…”