[Continued from part #1.
Graphic: Baleen Jaw Cross Section.
The origin of baleen in whales was among the examples of "The Incompetency of Natural Selection to Account for the Incipient Stages of Useful Structures" that one of Darwin's strongest contemporary critics, St. George Jackson Mivart "gathered, and illustrated `with admirable art and force":
"Mivart gathered, and illustrated `with admirable art and force' (Darwin's words), all objections to the theory of natural selection-`a formidable array' (Darwin's words again). Yet one particular theme, urged with special attention by Mivart, stood out as the centerpiece of his criticism. This argument continues to rank as the primary stumbling block among thoughtful and friendly scrutinizers of Darwinism today. No other criticism seems so troubling, so obviously and evidently `right' (against a Darwinian claim that seems intuitively paradoxical and improbable). Mivart awarded this argument a separate chapter in his book right after the introduction. He also gave it a name, remembered ever since. He called his objection `The Incompetency of Natural Selection to Account for the Incipient Stages of Useful Structures.' If this phrase sounds like a mouthful, consider the easy translation: We can readily understand how complex and fully developed structures work and how their maintenance and preservation may rely upon natural selection-a wing, an eye, the resemblance of a bittern to a branch or of an insect to a stick or dead leaf. But how do you get from nothing to such an elaborate something if evolution must proceed through a long sequence of intermediate stages, each favored by natural selection? You can't fly with 2 percent of a wing or gain much protection from an iota's similarity with a potentially concealing piece of vegetation. How, in other words, can natural selection explain the incipient stages of structures that can only be used in much more elaborated form?" (Gould, S.J., "Not Necessarily a Wing," in "Bully for Brontosaurus: Further Reflections in Natural History," [1991], Penguin: London, 1992, reprint, pp.140-141)
Mivart conceeded that once baleen had attained a sufficient size that it would be useful to a whale, then natural selection could preserve and augment it, but how could natural selection favour "the beginning of such useful development?" (my emphasis):
"The development of whalebone (baleen) in the mouth of the whale is another difficulty. A whale's mouth is furnished with very numerous horny plates, which hang down from the palate along each side of the mouth. They thus form two longitudinal series, each plate of which is placed transversely to the long axis of the body, and all are very close together. On depressing the lower lip the free outer edges of these plates come into view. Their inner edges are furnished with numerous coarse hair-like processes, consisting of some of the constituent fibres of the horny plates-which, as it were, fray out, and the month is thus lined, except below, by a network of countless fibres formed by the inner edges of the two series of plates. This network acts as a sort of sieve. When the whale feeds it takes into its mouth a great gulp of water, which it drives out again through the intervals of the horny plates of baleen, the fluid thus traversing the sieve of horny fibres, which retains the minute creatures on which these marine monsters subsist. Now it is obvious, that if this baleen had once attained such a size and development as to be at all useful, then its preservation and augmentation within serviceable limits would be promoted by `Natural Selection' alone. But how to obtain the beginning of such useful development?" (Mivart, St.G.J., "On the Genesis of Species," Macmillan & Co: London, Second edition, 1871, pp.45-46. My emphasis)
Darwin's response to Mivart's criticism, in the 1872 sixth and final edition of his Origin of Species was that "the early progenitors of the whales with baleen have possessed a mouth constructed something like the lamellated beak of a duck":
"With respect to the baleen, Mr. Mivart remarks that if it `had once attained such a size and development as to be at all useful, then its preservation and augmentation within serviceable limits would be promoted by natural selection alone. But how to obtain the beginning of such useful development?' In answer, it may be asked, why should not the early progenitors of the whales with baleen have possessed a mouth constructed something like the lamellated beak of a duck? Ducks, like whales, subsist by sifting the mud and water; and the family has sometimes been called Criblatores, or sifters. I hope that I may not be misconstrued into saying that the progenitors of whales did actually possess mouths lamellated like the beak of a duck. I wish only to show that this is not incredible, and that the immense plates of baleen in the Greenland whale might have been developed from such lamellæ by finely graduated steps, each of service to its possessor." (Darwin, C.R., "The Origin of Species By Means of Natural Selection," Sixth Edition, 1872, Senate: London, 1994, p.183)
Then after about two pages of examples of variations between the beaks of ducks and geese, Darwin cited an actual whale example of Hyperoodon bidens (pygmy sperm whale) which he claimed is "destitute of true teeth in an efficient condition" and its "palate is roughened ... with small, unequal, hard points of horn":
"The Hyperoodon bidens is destitute of true teeth in an efficient condition, but its palate is roughened, according to Lacèpede, with small, unequal, hard points of horn. There is, therefore, nothing improbable in supposing that some early cetacean form was provided with similar points of horn on the palate, but rather more regularly placed, and which, like the knobs on the beak of the goose, aided it in seizing or tearing its food. If so, it will hardly be denied that the points might have been converted through variation and natural selection into lamellæ as well-developed as those of the Egyptian goose, in which case they would have been used both for seizing objects and for sifting the water; then into lamellæ like those of the domestic duck; and so onwards, until they became as well constructed as those of the shoveller, in which case they would have served exclusively as a sifting apparatus. From this stage, in which the lamellæ would be two-thirds of the length of the plates of baleen in the Balænoptera rostrata, gradations, which may be observed in still-existing Cetaceans, lead us onwards to the enormous plates of baleen in the Greenland whale. Nor is there the least reason to doubt that each step in this scale might have been as serviceable to certain ancient Cetaceans, with the functions of the parts slowly changing during the progress of development, as are the gradations in the beaks of the different existing members of the duck family." (Darwin, Ibid., pp.185-186)
which 1) in typical "slippery" Darwin style "which is not to be reconciled with even average intellectual integrity" (Darlington, C.D., "Darwin's Place in History," Basil Blackwell: Oxford UK, 1959, p.60), Darwin rhetorically begged the question at issue by asserting, "it will hardly be denied that the points might have been converted through variation and natural selection into lamellæ as well-developed as those of the Egyptian goose" (my emphasis); and 2) presumably hoped that no reader would notice that his chosen example of Hyperoodon bidens had not developed baleen!
The bottom line is this fossil shows that Darwin was wrong in his claim that "the early progenitors of the whales with baleen ... possessed a mouth constructed something like the lamellated beak of a duck." It shows that in fact "the early progenitors of the whales with baleen ... possessed a mouth" with "a large set of teeth with no evidence of the comb-like fringes used by other baleen whales to filter their food from seawater" (New Scientist).
Moreover, since natural selection did not provide this baleen whale with baleen, then something other than natural selection must be the true explanation of why one lineage of baleen whales developed baleen and another lineage didn't.
That something other was, as some of Darwin's contemporary critics pointed out, whatever caused "variation" (i.e. mutation) in the first place. As one of those critics, Samuel Butler put it, "The `Origin of Variation,' whatever it is, is the only true 'Origin of Species'":
"If in one respect natural selection may be criticized for trying to explain too much; in another it may be thought to explain too little. Even at the time of its publication, a common charge brought against the Origin was its failure to establish a vera causa [true cause] for evolution. As Samuel Butler later put it: `The "Origin of Variation," whatever it is, is the only true "'Origin of Species."' [Butler, S., "Life and Habit," London, 1878, p.263]. Natural selection, critics complained, might account for the persistence of some variations and the disappearance of others, but it did not account for the origin of the variations themselves. And only an explanation of the origin of the variations would constitute a vera causa. One critic compared Darwin unfavorably, in this respect, with his predecessors, Lamarck and the author of the Vestiges, who, however benighted, at least had the forthrightness to propose specific explanations for the origin of the variations. And even in his own camp Asa Gray and others confessed themselves troubled by this inadequacy in the theory." (Himmelfarb, G., "Darwin and the Darwinian Revolution," [1959], Elephant Paperbacks: Chicago IL, 1996, reprint, pp.321-322. My parenthesis)
That is, as Butler also pointed out, Darwin's theory of natural selection was "an Origin of the Species with the `Origin' cut out" because it only stated that "those traits which are favourable will be selected," but did not explain the origin of those favourable traits:
"In suggesting an explanation for adaptation, the theory of natural selection provides at most a partial explanation for evolution. It is not enough to say that those traits which are favourable will be selected. We have also to explain how they arise, that is, to account for the set of alternatives from which the selection is made. Otherwise we have, in Samuel Butler's (1911) words, 'an Origin of the Species with the "Origin" cut out' [Butler, S., "Evolution Old and New," A.C. Fifield: London, 1911]." (Saunders, P.T., "Development and Evolution," in Ho, M-W. & Saunders, P.T., eds., "Beyond Neo-Darwinism: An Introduction to the New Evolutionary Paradigm," Academic Press: London, 1984, p.243).
That is, Darwin's theory (including its modern Neo-Darwinian "footnotes"):
"This book is written in the conviction that our own existence once presented the greatest of all mysteries, but that it is a mystery no longer because it is solved. Darwin and Wallace solved it, though we shall continue to add footnotes to their solution for a while yet." (Dawkins, R., "The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe Without Design," W.W Norton & Co: New York NY, 1986, p.xiii)
does not explain the origin of the "variations" (i.e. mutations) which caused the favourable traits to arise in the first place.
To be continued in part #3.
Stephen E. Jones, BSc (Biol).
`Evolution Quotes Book'
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