Then, after pointing out that under domestication two different races, the race-horse and the dray-horse, for instance, might arise by selecting different sorts of variations, Darwin inquires:—
“But how, it may be asked, can any analogous principle apply in nature? I believe it can and does apply most efficiently (though it was a long time before I saw how), from the simple circumstance that the more diversified the descendants from any one species become in structure, constitution, and habits, by so much will they be better enabled to seize on many and widely diversified places in the polity of nature, and so be enabled to increase in numbers.”
Here we touch on one of the fundamental principles of the doctrine of evolution. It is intimated that the new form of animal or plant first appears (without regard to any kind of selection), and then finds that place in nature where it can remain in existence and propagate its kind. Darwin refers here, of course, only to the less extensive variations, the individual or fluctuating kind; but as we shall discuss at greater length in another place, this same process, if extended to other kinds of variation, may give us an explanation of evolution without competition, or selection, or destruction of the individuals of the same kind taking place at all.
CHAPTER V
THE THEORY OF NATURAL SELECTION (Continued)
Objections to the Theory of Natural Selection
Although in the preceding chapter a number of criticisms have been made of the special parts of the theory of natural selection, there still remain to be considered some further objections that have been made since the first publication of the theory. It is a fortunate circumstance from every point of view that Darwin himself was able in the later editions of the “Origin of Species” to reply to those criticisms that he thought of sufficient importance. He says:—
“Long before the reader has arrived at this part of my work, a crowd of difficulties will have occurred to him. Some of them are so serious that to this day I can hardly reflect on them without being in some degree staggered; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to the theory.”
The first difficulty is this: “Why, if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion, instead of the species being, as we see them, well defined?”
The answer that Darwin gives is, that by competition the new form will crowd out its own less-improved parent form, and other less-favored forms. But is this a sufficient or satisfactory answer? If we recall what Darwin has said on the advantage that those forms will have, in which a great number of new variations appear to fit them to the great diversity of natural conditions, and if we recall the gradations that exist in external conditions, I think we shall find that Darwin’s reply fails to give a satisfactory answer to the question.