From Charles Darwin's Concept of Natural Selection. Survival of the fittest. In this struggle for existence as we have seen few survive: majority dies out. This is explained as being due to the fact those few which survive have necessary advantageous varitaion which though small have been high survival valus to the individual concerned, i.e., such of them as are fit to survive have survived and such of them as are unfit for survival have perished. This idea of the "The survival of the fittest" is the core of the theory of Natural Selection.