  Without contributing, defectors take more benefit from social resources than
cooperators which is the reflection of a specific character of individuals.
However, natural physical mechanisms of our society promote cooperation. Thus,
in the long run, the evolution about genetic variation is something more than
the social evolution about fitness. The loci of evolutionary paths of the
cooperation and the defection are correlated, but not a full complement of each
other. Yet, the only single specific mechanism which is operated by some rules
explains the enhancement of cooperation where the independent analysis of
defect evolutionary mechanism is ignored. Moreover, the execution of a
particular evolutionary rule through algorithm method over the long time
encounters highly sensitive influence of the model parameters. Theoretically,
biodiversity of two types relatively persists rarely. Here I describe the
evolutionary outcome in the demographic fluctuation. Using both analytical
procedure and algorithm method the article concludes that the intratype fitness
of individual species is the key factor for not only surviving, but thriving.
In consideration of the random drift, the experimental outcomes show that
dominant enhancement of cooperation over defection is qualitatively independent
of environmental scenario. Collectively, the set of the rules becomes an
evolutionary principle to cooperation enhancement.
