In Darwin’s “Recapitulation and Conclusion” he does a very thorough job at revisiting his arguments for evolution through natural selection and there is much to take away regarding the arguments for and against this theory in this section even if you hadn’t read the earlier chapters. One of the arguments to prove natural selection was what Darwin calls the “Struggle for Existence” involving the forces of climate change and its effects on species as well as their geographic location. Further he discusses the struggle of competition between species and these natural forces are what interact with species variation, eventually resulting in descent with modification caused by natural selection. To strengthen these arguments, he often has the reader consider contemporary domestication processes as an analogy to the forces of nature have on the evolution of species. Specifically, Darwin states that man has for a rather long time “…unintentionally exposes organic beings to new conditions of life, and then nature acts on organization, and causes variability” (p. 488). The variations then are explained to be either specifically selected for or unconsciously preserved when most beneficial to man.
For me the most convincing argument he provides is that of the great length in time which has occurred on earth and the on-going forces of nature will inevitably cause species to migrate, die, or have selected variation. As Darwin defends his theory with the idea of an imperfect geological record resulting in the loss of intermediate fossil species, he also is defending the powerful idea of uniformitarianism and that contemporary observation provided by many people such as natural historians can give great insight to the forces which literally break up and change the world around us every day. If breaking waves can eventually topple down a coastal cliff or rising sea levels drown island civilizations couldn’t these same natural forces cause change in the flora and fauna which survives off of these environments’ productivity?