Elements Covers

Posts by Hussein Kaddour

Incubating Life: Prebiotic Sources of Organics for the Origin of Life

The onset of life on Earth was preceded by prebiotic chemistry in which complex organic molecules were formed from simpler ones in the presence of energy sources. These prebiotic organics were either synthesized on Earth itself (endogenously) or synthesized extraterrestrially (exogenously) and then delivered to Earth. Organics have been detected in space and have been successfully synthesized under experimental conditions simulating both extraterrestrial environments and early Earth environments. Homochirality and enantiomeric enrichment of organic molecules, which were once considered to be biosignatures, can, in fact, be achieved abiotically. It is important to determine conditions that allow the formation of prebiotic organics and those that preserve them against degradation.

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The Transition from Geochemistry to Biogeochemistry

Paradigm-changing discoveries about stellar and planetary evolution, the survival of organic molecules and microorganisms under extreme conditions, and geochemical environments on early Earth and other planets are sparking a synergistic dialogue between geoscientists, chemists, and biologists to understand how life originated. To achieve this goal, we must (i) explain the non enzymatic synthesis of biologically relevant organic molecules under geologically plausible conditions; (ii) overcome the rigid conceptual dichotomy of the “RNA world” versus the “metabolism-first” hypotheses; and (iii) develop high-throughput analytical systems to sample the myriad possible combinations of environmental conditions to find those that could initiate life. This issue of Elements highlight the roles of minerals and geochemical environments in the emergence of protocells, the cell-like entities that might have preceded the Last Universal Common Ancestor.

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