According to the Darwinian Polymer Model (DPM), the path to life started over four billion years ago away from large bodies of standing water. The Earth's surface temperature was the boiling point of water, which was maintained through large-scale water evaporation. Life started on or near the Earth's surface at this temperature within a very large deposit of volcanic material rich in inorganic polyphosphate. 


Time

    The Earth is estimated to be ~ 4.5 billion years old. Early (recognizable) life forms appear in the fossil record ~ 4 billion years ago. Thus, the time window for the DPM is proposed to be from around four and one-half to four billion years ago.

Place

    The DPM proposes the primary energy source for initial life was inorganic polyphosphate. A likely source of high-energy polyphosphate was from deep within the Earth, where it formed under high temperature and pressure. This material was then deposited at the Earth's surface due to volcanic activity. Such a scenario has the advantage that it places a large amount of the first energy source in one place, which would allow for life to arise slowly from a highly abundant starting material.

Temperature

    The DPM proposes that life started at the boiling point of water for several reasons:

    1) A steady temperature was a necessary precursor to sustained evolution. One of the few ways this could be achieved was via constant water evaporation at the Earth's surface.

    2) Constant evaporation would have kept the early polymers concentrated, so that they could preferentially interact with each other.

    3) Constant evaporation would have limited the hydrolysis of inorganic polyphosphate.

NOTE - A clue that early evolution took place at the boiling point of water is the melting temperature of modern nucleic acids, which is near the boiling point (100 C). In the DPM, this is not a coincidence. Put simply: The early polymer types evolved to become RNA-like largely because evolution selected for polymers that replicated by successive rounds of association and dissociation. This was best achieved at or near the polymer melting temperature. Thus, polymers with a melting temperature near 100 C (like nucleic acids) out-competed other polymer types that formed, and became abundant.


Chemical diffusion was limited

    The ideal situation for Darwinian Polymer evolution was to have slower-diffusing polymers remain near their site of synthesis (polyphosphate-rich volcanic material) and be constantly bathed in a solution containing smaller chemicals needed for new synthesis.

    The site of polymer synthesis could have been directly at the Earth's surface. Or, it could have occurred in semi-porous, volcanic material near the Earth's surface. The key feature is that the reactions occurred near the boiling point of water and away from large amounts of standing water. Small amounts of water, especially polymer-bound water, are presumed to have been present much of the time.


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