Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

The historically oldest hypotheses are probably those viewing sexual reproduction as a mechanism enhancing the evolutionary potential of the species.These include concepts of sexual reproduction as a source of variability of organisms or a mechanism of maintenance of polymorphism in the population, diploidy of organisms or the existence of species as distict entities or permitting simultaneous selection in favour of several mutations, or enabling advantageous mutations to get rid of neighbouring disadvantageous mutations.All these hypotheses have the drawback that they assume that sexual reproduction is a product of group or interspecies selection.Generally, it is assumed that particularly the effectiveness of group selection is less than the effectiveness of individual selection.It is thus doubtful whether they could lead to such a complicated adaptive trait as sexual reproduction.In addition, traits emerging through the action of group selection are not usually evolutionarily stable, and mutants can easily predominate in the population, which lose traits that are advantageous from the viewpoint of the population or species.