In Darwin’s last chapter in the Origin of Species, he summarizes his arguments about why we should believe in evolution through natural selection, even though he says he can’t prove it. He first writes about the other side of the argument, then goes on to write his arguments. First up is domestication, he claims that shows much variability because the reproductive systems fails to offspring exactly like the parents. He also states that man doesn’t produce variability, he unintentionally exposes organic beings to new conditions of life, which then nature acts upon that. He explains, “having separated sexes there will most cases be a struggle between the males for possession of the females…success will often depend on having special weapons or means of defense; and the slightest advantage will lead to victory.” Natural selection also acts by accumulating many slight, successive, and favorable variations, along with competition. Darwin also states that if species have all been independently created then why do we see species within the same genus differ from one another. he argues that if they were all created independently shouldn’t flowers within the same genus all be the same color.
The argument that I always found strong was the competition and males trying to control females, which drives up the need for evolution, but from what I have read the strongest argument Darwin writes is about about the differences between genus of species. If all species were created individually then why are there such differences between genus’ of species. The fact that there are such small differences between species which are related should be the biggest argument for natural selection. It proves that certain organisms had to change slightly in order to be able to survive, for one reason or another.