A large amount of change in our cultivated plants, thus slowly and unconsciously accumulated, explains, as I believe, the well-known fact, that in a vast number of cases we cannot recognise, and therefore do not know, the wild parent-stocks of the plants which have been longest cultivated in our flower and kitchen gardens. If it has taken centuries or thousands of years to improve or modify most of our plants up to their present standard of usefulness to man, we can understand how it is that neither Australia, the Cape of Good Hope, nor any other region inhabited by quite uncivilised man, has afforded us a single plant worth culture. It is not that these countries, so rich in species, do not by a strange chance possess the aboriginal stocks of any useful plants, but that the native plants have not been improved by continued selection up to a standard of perfection comparable with that given to the plants in countries anciently civilised.
In the first part of Darwin’s famous book it should be noted that Darwin understood selection in light of animal and plant breeders. And in the section above it is clear that Darwin thought that intelligent beings were the chief agents the selection of genetic traits. It is also worth noting that Darwin thought that purpose or intentionality, even if “slowly and unconsciously accumulated”, was a central part of his theory of natural selection.
So when modern proponents of Darwin’s theory like Richard Dawkins advocate Natural Selection as the alternative to blind chance on one hand and design on the other, it seems fair to question what real reason we have to conclude that the selecting is not done according to a definite design and by intelligent agent(s).
Darwin apparently thought so.