Macrobiont: Cradle for the Origin of Life and Creation of a Biosphere

Abstract

Although the cellular microorganism is the fundamental unit of biology, the origin of life (OoL) itself is unlikely to have occurred in a microscale environment. The macrobiont (MB) is the macro-scale setting where life originated. Guided by the methodologies of Systems Analysis, we focus on subaerial ponds of scale 3 to 300 m diameter. Within such ponds, there can be substantial heterogeneity, on the vertical, horizontal, and temporal scales, which enable multi-pot prebiotic chemical evolution. Pond size-sensitivities for several figures of merit are mathematically formulated, leading to the expectation that the optimum pond size for the OoL is intermediate, but biased toward smaller sizes. Sensitivities include relative access to nutrients, energy sources, and catalysts, as sourced from geological, atmospheric, hydrospheric, and astronomical contributors. Foreshores, especially with mudcracks, are identified as a favorable component for the success of the macrobiont. To bridge the gap between inanimate matter and a planetary-scale biosphere, five stages of evolution within the macrobiont are hypothesized: prebiotic chemistry → molecular replicator → protocell → macrobiont cell → colonizer cell. Comparison of ponds with other macrobionts, including hydrothermal and meteorite settings, allows a conclusion that more than one possible macrobiont locale could enable an OoL.

Catalytic Prebiotic Formation of Glycerol Phosphate Esters and an Estimation of Their Steady State Abundance under Plausible Early Earth Conditions

“…Each of those would alter the steady state GP concentration. This is consistent with the idea suggested by Clark and Kolb [46] who discussed the possibility of various stages from abiotic synthesis to the possible origin of life to have happened in separate ponds or other sites that might be interconnected, and thus various multi-pot processes could potentially be mixed [47][48][49][50]. Hence, the GP produced under hot conditions was transferred to the water bodies with lower temperatures fairly quickly [46,[51][52][53][54] where it could then become incorporated into other prebiotic processes.…”

‘Whole Organism’, Systems Biology, and Top-Down Criteria for Evaluating Scenarios for the Origin of Life

“…The importance of this heterogeneity has been made especially clear with the discovery of molecular condensates, protein delimited compartments that function at many spatial scales within eukaryotic cells [ 45 ], with increasing focus now on prokaryotes [ 46 ]. The importance of spatial heterogeneity has also been noted in the discussion of the prebiotic generation of macromolecule precursors [ 47 , 48 , 49 , 50 ]. These observations lead to the supposition that spatial chemical inhomogeneity was continually present from the earliest phases of life’s development ( Table 1 , criterion 4).…”

Where Did Life Begin? Testing Ideas in Prebiotic Analogue Conditions

“…We have demonstrated that it is possible to test the assumptions of laboratory simulations in prebiotic analogues of hydrothermal fields and hot springs. In the future, laboratory simulations should also take into account what we have learned from ancient hot springs that existed 3.5 billion years ago [ 13 ]. One such example is the Pilbara Craton of Western Australia [ 14 , 15 ], which has preserved both ancient hot spring mineral composition and fossilized stromatolites.…”

“…However, the reactants we used are relatively resistant to oxidation, particularly for short exposures of hours, not years. A last variable to keep in mind is simply the size of the pools as discussed by Clark and Kolb [ 13 ]. For typical field experiments like those in Kamchatka, pools should range from half a liter to several liters in volume.…”