General Characteristics of the Origin-of-Life Medium

Abstract

According to author’s approach, the three well-known required conditions for the origin of life (availability of aqueous environs, organic compounds, and an energy source) should be added with the fourth one: multilevel fluctuations of the parameters. Due to this addition, fluctuating hydrothermal medium possessing all the four conditions seems much more appropriate for the origin of life than a quiet ocean. In this context, the origin-of-life medium is subdivided into the following: (a) medium for chemical prebiotic evolution, where organic matter complicates up to the formation of prebiotic macromolecules and microsystems; (b) medium for the transition to life, where prebiotic microsystems transform into initial life-forms through thermodynamic inversion. Fluctuations of main parameters in hydrothermal systems were studied by means of two approaches: theoretical calculations and direct monitoring in situ. In accordance with the elaborated model “fluid–rock interaction,” changeability of fluid composition under different conditions of temperature, pressure, gas chemistry, and water–rock ratio was theoretically estimated. Data on direct measurements of pressure, temperature, and hydrochemistry in hydrothermal systems of Kamchatka and Slovenia were used to characterize multilevel fluctuations (amplitudes, periods, and frequencies). The offered “two-level” model of the origin-of-life medium based on terrestrial geology has been applied to extraterrestrial rocky planets and smaller bodies.