Malthusian Relativityι**=7/3ψ
Life history evolution - traits & transitions

Interacting individuals and reproducing units

Males evolve as interacting individuals that use energy in interactive competitive at the cost of self-replication

There is no doubt that the individuals of many natural populations organise themselves into reproducing units with a single reproducing female and one, or several, non-replicating individuals; let them be males or offspring workers. It is also evident that the deduced structuring exists; with no interacting individuals in self-replicating cells, with the widespread reproducing units in multicellular animals containing a single male and maybe a few offspring workers, and with the eusocial colony being a special case where the sexual pair is associated with a plenitude of offspring workers.

It is less straightforward to prove that these units evolve by selection by density dependent competitive interactions. But, from a theoretical point of view we note that non-replicating individuals like males and offspring workers necessarily must gain fitness by other means than replication, because there is strong replication-selection against the allocation of energy to individuals that do not directly replicate. Hence, if these individuals are to be maintained by natural selection, they must gain fitness to the reproducing unit from some sort of behaviour that will outweigh their energetic costs. This is possible through interactive competition, with selection by density dependent competitive interactions being the only hypothesis that predicts the evolutionary structuring from the asexual self-replicator to the eusocial colony from first principles of self-replication.

In favour of the interaction hypothesis for the evolution of males and off-spring workers, we note that these individuals may compete for the reproducing female in mobile organisms by defending limited resources. This is impossible in sessile organisms where individuals compete by size and position in a flow of resources. Sessile organisms cannot generally co-operate in interactive competition, and the optimal interacting unit is therefore the individual organism allowing no room for pure interacting individuals to evolve. It is therefore not surprising that males and off-spring workers are found only in mobile organisms.