Origin Ch.15: Polemic

This post is part of a series on The Origin Of Species.  It was originally posted on the old blog in feb 2009, during the Darwin 200 celebrations.

There are those who declare Darwin’s literary brilliance, and those who proudly announce that The Origin is beyond their wit and attention span. Occasionally, the truth may be found between extremes: reading The Origin has been frequently fascinating, occasionally a joy, and not infrequently tedious. Chapter 15, however, is nothing but a delight.

Darwin recapitulates his “one long argument”, putting together a brilliant persuasive case. He starts with the objections to common descent and natural selection, admitting that he has “felt these difficulties far too heavily over many years”, before reminding us where the objections fail. Throughout the book, Darwin has made few references to the alternative ideas on the origin of species that had been proposed during his time, but in chapter 15, he openly mocks them: “how inexplicable on the theory of special creation is X, Y, and Z;” “do they really believe that at certain innumerable periods in the earth’s history certain elemental atoms have been commanded suddenly to flash into living tissues?;” “mammals: were they created bearing the false marks of nourishment from the mother’s womb?”

Meanwhile, he constantly reminds us of the power of evolution: “how simply explained X, Y, and Z are on the theory of common descent;” “innumerable other facts at once explain themselves;” “we may cease marveling, and understand on this view…”. He reminds us of some of the many otherwise inexplicable quirks of biology that he can shed light on: his “specific characters”; the honey-bee’s comb; the neuter insects and their social structure; the geographic distribution of species; the structure of different genera; the homologous bone structures of the human hand, bat wing, and porpoise fin; the identical number of vertebrae in elephant and giraffe necks; the branchial slits of mammalian embryos. “It can hardly be supposed that a false theory would explain in so satisfactory a manner as does the theory of natural selection, the several large classes of facts above specified.”

This is the sixth edition of The Origin, and by now Darwin can allow himself a moment to bask in some glory. By the time he got to the sixth, “almost every naturalist now accepts the great principle of evolution,” with only a few old dissenters stuck in their ways. And, knowing how powerful the theory is in explaining the items on his list of quirks, he knows that it will revolutionise biology — “a grand and almost untrodden field will open up” — and even notes how it applies to neighbouring fields like psychology. “Much light will be thrown on the origin of man and his history.” And, in the knowledge that he has made a contribution to science as great as that of Newton, he goes out with the famous bang.

“There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

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