A CALCULATION OF THE PROBABILITY OF ASSEMBLING THE FIRST PROTOCELL: IMPLICATIONS FOR EARLY EARTH’S SURFACE CHEMISTRY AND POSSIBLE CATASTROPHIC DISRUPTIONS OF EARLY LIFE ON EARTH

The conditions under which life emerged, and the probability of this happening, depend strongly on the geochemical state of Earth’s early surface. The emergence of life as we know it involves complex interactions of critical biochemical molecules. These result in self-sustaining production of enzymes and the polynucleic acids necessary to produce them and record the information for doing so reliably. This appears to require the simultaneous assembly of a minimal collection of molecules into a coherent package at least partly isolated from the larger environment. As a bare minimum perhaps a dozen transfer RNA (tRNA) molecules are necessary for translation of genetic code into primitive proteinoids, and these must be present simultaneously and enclosed in some kind of membrane to constitute what might be the most primitive organism. Calculations of the probability of this happening in a “primordial soup” containing monomers, polymers, and lipid-membraned particles support the idea that such a primitive organism is actually quite probable, provided that the early surface conditions were conducive to producing the biochemicals in significant quantities. That life does exist, and arose rather early in Earth’s history, suggests not only that these calculations are reasonable, but that they support the idea of an organic-compound-rich primitive atmosphere and ocean. The facility with which life may have originated also implies that recovery from early impact-induced catastrophes was similarly facile.