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Figure 1 The transition from chance/anthropic selection to biological evolution in the history of life. The grey area and dotted lines illustrate the uncertainty in the identification of the threshold of biological evolution, i.e., the level of complexity at which the transition occurred. The broken red line denotes the boundary between the levels of complexity that, in principle, might be attainable in a finite universe consisting of a single O-region from the higher levels of complexity the spontaneous emergence of which would require an infinite model such as the MWO (see Appendix).

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Figure 2 The upper bound for the putative breakthrough system: a primitive, RNA-based coupled system of replication-translation. LSU, large ribosomal subunit; SSU, small ribosomal subunit.
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Figure 3 The narrowing of the range of possible histories and the increased likelihood of the emergence of high complexity brought about by the transition from chance to biological evolution. The thick read arrow shows the history that leads to the breakthrough system.
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