On the Origin of Species integrated with a model of variation. This modern evolutionary synthesis had been dubbed Neo Darwinian Evolution because it encompasses Charles Darwin's theories of evolution with Gregor Mendel's theories of genetic inheritance. Chapter VI begins by saying the next three chapters will address possible objections to the theory, the first being that often no intermediate forms between closely related species are found, though the theory implies such forms must have existed. As Darwin noted, "Firstly, why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in
On the Origin of Species only the last chapter still to write. In September the main title still included ""An essay on the origin of species and varieties"", but Darwin now proposed dropping "varieties". With Murray's persuasion, the title was eventually agreed as "On the Origin of Species", with the title page adding "by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life". In this extended title (and elsewhere in the book) Darwin used the biological term ""races"" interchangeably with ""varieties"", meaning varieties within a species. He used the term broadly, and as well as discussions of "the several