Regulatory Module Complexity and the Origin of Feathers

• Bergman J.

  Author

The claim that scales can be experimentally converted into feathers, and that this conversion demonstrates the biological plausibility of an unguided transition from reptilian integument to avian plumage, has become a recurring argument in defense of the dinosaur-to-bird hypothesis. In this paper I examine the principal empirical basis for that claim, the study of Wu and colleagues (2018), which identified multiple regulatory modules governing feather morphogenesis and generated intermediate scale-feather morphotypes through directed manipulation of gene expression. I accept the experimental findings and dispute only the evolutionary inference commonly drawn from them. I argue that a careful reading of these results does not support the conclusion that unguided processes can traverse the path from scale to feather. The data instead document a developmentally integrated system that requires the coordinated combination of at least five morpho-regulatory modules, whose experimental reconstruction depended on intelligent intervention and whose intermediate states show no demonstrated selective advantage. I contrast the predictions of a design model with those of a gradualist model and conclude that the observed pattern of developmental integration is at least as well, and I argue better, explained by design. I also delineate the limits of the argument, which is an inference from the current absence of a demonstrated viable pathway rather than a proof of impossibility.

1. Bergman J.

   Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology at Northwest State College in Archbold OH for over 25 years. He has 9 degrees, including 7 graduate (= ‘post-graduate’ in some non-US systems) degrees. Dr Bergman is a graduate of Medical College of Ohio, Wayne State University in Detroit, The University of Toledo, and Bowling Green State University. He has over 800 publications in 12 languages and 20 books and monographs. He has also taught at the Medical College of Ohio where he was a research associate in the department of experimental pathology, and he also taught 6 years at the University of Toledo, and 7 years at Bowling Green State University.

   Among his books is a monograph on peer evaluation published by the College Student Journal Press, a Fastback on the creation-evolution controversy published by Phi Delta Kappa, a book on vestigial organs with Dr George Howe (‘Vestigial Organs’ are Fully Functional), a book on psychology and religious cults, a book on religious discrimination published by Onesimus Press, and a book on mental health published by Claudius Verlag in München. He has also published a college textbook on evaluation (Boston, Houghton Mifflin Co.), and has contributed to dozens of other textbooks. He was also a consultant for over 20 science text books, mostly biology and biochemistry.

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