Nature's Dis-Continuum: Why Structural Explanations Win Hands Down
Editor's note: In his new book Evolution: Still a Theory in Crisis, Michael Denton not only updates the argument from his groundbreaking Evolution: A Theory in Crisis (1985) but also presents a powerful new critique of Darwinian evolution. This article is one in a series in which Dr. Denton summarizes some of the most important points of the new book. For the full story, get your copy of Evolution: Still a Theory in Crisis. For a limited time, you'll enjoy a 30 percent discount at CreateSpace by using the discount code QBDHMYJH.
There is no evidence to support the Darwinian claim that the biological world is a functional continuum where it is possible to move from the base of the trunk to all the most peripheral branches in tiny incremental adaptive steps.
On the contrary, all of the evidence as reviewed in the first six chapters of Evolution: Still a Theory in Crisis implies that nature is a discontinuum. The tree is a discontinuous system of distinct Types characterized by sudden and saltational transitions and sudden origins of taxa-defining novelties and homologs, exactly as I claimed in Evolution thirty years ago. The claim has weathered well!
The grand river of life that has flowed on earth over the past four billion years has not meandered slowly and steadily across some flat and featureless landscape, but tumbled constantly through a rugged landscape over endless cataracts and rapids. No matter how unfashionable, no matter how at odds with current thinking in evolutionary biology, there is no empirical evidence for believing that organic nature is any less discontinuous than the inorganic realm. There is not the slightest reason for believing that the major homologs were achieved gradually via functional continuums. It is only the a priori demands of Darwinian causation that have imposed continuity on a basically discontinuous reality.
No matter how "unacceptable," the notion that the organic world consists of a finite set of distinct Types, which have been successively actualized during the evolutionary history of life on earth, satisfies the facts far better that its Darwinian rival.
Firstly, the absence of transitional sequences leading from antecedent structures to the each of the thousands of Type-defining homologs actualized during phylogeny is far more consonant with typology than Darwinism. The Darwinian claim that all the homologs were gradually achieved over millions of generations by incremental functionalism -- the genetic code, human language, the flower, the feather, the diaphragm, etc. -- is a phantasm. The near-universal absence of intermediates leading from antecedent structures to the homologs speaks volumes.
Secondly, on any Darwinian account, one must assume that previously plastic forms, "the homologs in the making," became fixed for some absolutely mysterious reason at specific points in phylogeny and thereafter remained invariant. This is a curiously non-adaptive picture, and highly incongruous in the context of a biology wedded to pan-adaptationism and a biological worldview that posits all living forms as part of an ever-mutating continuum.
Thirdly, and perhaps most importantly, in the case of many of the homologous patterns -- and particularly the Bauplans like the tetrapod limb -- there is no evidence that they are basically adaptive forms. Certainly in the vast majority of cases, they have never been shown to serve some functional end. Self-evidently, in accounting for the evolutionary emergence of homologs that serve no specific adaptive function, structural explanations win hands down.
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