Self-organising natural selection from replicating molecules to multicellular sexually reproducing organisms

Lars Witting

During their evolution from molecular replicators over unicellular prokaryotes and eukaryotes to multicellular sexually reproducing organisms, biological lifeforms increased in size with heritable codes increasingly embedded in more organised slower replicating units. This evolutionary unfolding is traditionally seen as a remarkable unpredictable coincidence of a directionless natural selection following long sequences of improbable diversifying events. I describe how this contingent paradigm of unpredictable evolution was consolidated somewhat counterintuitively by the life history theory of the population genetic synthesis that was developed to explain life history evolution.

The prediction of unpredictable evolution follows from an applied selection increase in average fitness towards contingently defined fitness peaks; a selection that is structurally insufficient to explain the Darwinian hypothesis that the life histories of species are naturally selected from the life history of their common ancestor. This major evolutionary paradox, where the life histories of the attracting fitness peaks follow from unknown contingencies instead of the identified natural selection itself, is solved in the scientific literature by integrating intra-specific interactive competition into the demographic selection of life histories.

This provides a population ecological synthesis that includes and expands beyond the traditional theory, generating a deterministic natural selection force that self-organises from mass, energy, and replication at the origin of replicating molecules. This selects---not an increase in average fitness but---a self-organising net energy driven change in relative fitness and natural selection itself, a selection change that is necessary and sufficient to select the evolutionary succession of the major lifeforms from a common ancestor.

I review how this selection of net energy for replication generates population growth that generates a density-frequency-dependent interactive competition that reallocation-selects the increase in replication-energy into larger, more cooperatively organised slower replicating units. This predicts an essentially inevitable evolution of the major lifeforms, including large multicellular organisms with inter-specific body mass allometries and sexual reproduction by a diploid genome with fair meiosis.