In this last chapter, Charles Darwin mentions some reasons why he considers the natural selection as something available to understand and, somehow, explain the species in the planet, although it cannot be found a definite prove for it. However, he considers some arguments in favor of this theory. He explains that the Glacial period has a tremendous impact “on the distribution both of the same and of representative species throughout the world.” (Darwin, 485). Another issue he comments is the absence of fossiliferous formations in the Silurian strata, as geology shows how elements have changed throughout the time, so following his theory, these have changed slowly and are closely related. Domestication is also seen as a way of modifying the selection of the animals due to its variability, so this system “fails to reproduce offspring exactly like the parent form.” (Darwin 488). As a curiosity, we can also highlight the importance of the increasing in size and diverging in large groups of species and the use of it as a prove against the theory of creation: “this grand fact of the grouping of all organic beings seems to me utterly inexplicable on the theory of creation.” (Darwin, 492).
Personally speaking this last concept (domestication) is very important its high grade in variability: “variability is governed by many complex laws, –by correlation of growth, by use and disuse, and by the direct action of the physical conditions of life.” (Darwin, 488). Then, human beings, whether methodologically or not, change animals and plants “behavior” for their own benefits. This reminds me to Harari chapter about the Agricultural Revolution, when Sapiens started to use animals as tools. Consequently, they changed how animals and plants acted and man “can largely influence the character of a breed by selecting individual differences […].” (Darwin, 488).