Did life originate from a global chemical reactor?

Abstract

Many decades of experimental and theoretical research on the origin of life have yielded important discoveries regarding the chemical and physical conditions under which organic compounds can be synthesized and polymerized. However, such conditions often seem mutually exclusive, because they are rarely encountered in a single environmental setting. As such, no convincing models explain how living cells formed from abiotic constituents. Here, we propose a new approach that considers the origin of life within the global context of the Hadean Earth. We review previous ideas and synthesize them in four central hypotheses: (i) Multiple microenvironments contributed to the building blocks of life, and these niches were not necessarily inhabitable by the first organisms; (ii) Mineral catalysts were the backbone of prebiotic reaction networks that led to modern metabolism; (iii) Multiple local and global transport processes were essential for linking reactions occurring in separate locations; (iv) Global diversity and local selection of reactants and products provided mechanisms for the generation of most of the diverse building blocks necessary for life. We conclude that no single environmental setting can offer enough chemical and physical diversity for life to originate. Instead, any plausible model for the origin of life must acknowledge the geological complexity and diversity of the Hadean Earth. Future research may therefore benefit from identifying further linkages between organic precursors, minerals, and fluids in various environmental contexts.

Nucleobases bind to and stabilize aggregates of a prebiotic amphiphile, providing a viable mechanism for the emergence of protocells

“…Recent work describes how ribose might have been generated prebiotically (20,21). Under prebiotic conditions, organic matter might have been relatively long-lived, and processes such as adsorption might have concentrated these components (22). We suggest that the binding of bases and sugars to amphiphilic aggregates was one of these processes.…”

At the very beginning of life on Earth: the thiol-rich peptide (TRP) world hypothesis

“…But these surfaces, if existing, were indeed over wet, due to the large amount of water present in the atmosphere and frequent rains. Many captivating scenarios have been proposed since Darwin's little hot pond (Follmann andBrownson, 2009, Damer, 2016): coastal zone (Lathe, 2003), dehydrating/hydrating cycling (Ross and Deamer, 2016), hydrothermal vents (Miller and Bada, 1988), tectonic faults (Schreiber et al, 2012), geothermal fields (Mulkidjanian et al, 2012), ocean abysses (Di Giulio, 2005), surface metabolism (Wächtershäuser, 2006), salt-induced peptide formation (Fitz et al, 2007), a stereochemical era (Fontecilla-Camps, 2014), thermal gradients (Agerschou et al, 2017), the sum of various specific spots (Monard, 2016, Stüeken et al, 2013… To these scenarios, in which life occurred "somewhere", we prefer a scenario in which life came out everywhere or, at least, anywhere in a roughly homogeneous ocean.…”

The Emergence of Bioenergetics: The Formation of a Gluconeogenesis System and Reductive Pentose Phosphate Pathway of CO2 Fixation in Ancient Hydrothermal Systems

“…It has also been suggested that the last common ancestor (LCA) of all extant cell lineages was a chemolithoautotrophic thermophilic anaerobe [10][11][12][13][14] capable of synthesizing organic 'building blocks' from the inorganic carbon. Thus, these microorganisms can serve as a model for studying primordial metabolism.…”