Multicellular animals are selected from protozoa by a fully developed population dynamic feed-back
When the exponent of the maximal resource bias from interactive competition is evolving beyond unity [ ψι* > 1 ], there is selection for a mass that evolves beyond the threshold where the metabolic pathways are fully developed. Mass specific metabolism is then functionally independent of mass, and mass is selected entirely by the intra-specific competitive interactions between individuals.
This marks a transition where the interference in the population is determined by the selection attractor on mass. With stable net energy, the resource bias exponent is selected to unity, and this defines mass invariant interference competition [ ψι** = 1 , => ι** = 1 / ψ, Fig. 1 right ]. The positive selection of mass from the resource bias of interference is then outbalancing the negative selection of the quality-quantity trade-off.
With a mass that evolves beyond the minimum that is required by the mass specific metabolism of the organism, there is no longer active selection for a single celled self-replicator. A multicellular animal is instead expected by the selection of a multitude of metabolic cells that specialise and cooperate to enhance the behavioural and physiological functionality of the individual.
With a resource bias exponent from interactive competition that is selected to unity by the selection attractor on mass, there is interactive selection for a reproducing unit where a male and female individual are using sexual reproduction to share the genome in the offspring equally among them (Witting, 1997, 2002).
The resource bias implies also that energy that could be used to maintain the tissue of the individual to obtain potential immortality, is predicted to be invested better in interactive competition (Witting, 1997). This is generating the expected evolution of a senescing soma.
With a resource bias of interference that is selected as an invariant attractor, the potential for population dynamic growth is selected to be invariant on the time-scale of the organism [ λ = p R = w0 ]. This implies a lifetime reproduction [ R = 1/p ] that is selected as the inverse of the probability to survive to reproduce (p).
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