Carta de Michael Behe ao editor do PNAS replicando o artigo de Clemens et al

O PNAS publicou o artigo "The reducible complexity of a mitochondrial molecular machine", de Clements et al, que teria falsificado a tese de complexidade irredutível de Michael Behe através de processos gradualistas darwinanos.

Eu estou dando destaque a esta carta do Behe porque no blog RNAm, o Dr. Roberto Berlinck pediu que eu enviasse o artigo do Casey Luskin para o editor do PNAS. Berlinck sabe que quem deveria fazer isso era o próprio Behe. Foi o que ele fez, e eu tenho o prazer de reproduzir aqui.

Conhecendo a Nomenklatura científica como eu conheço (tive um caso semelhante na Fiocruz quando apontei as improbidades de um artigo e que os pareceristas não tinham lido a literatura mencionada: não tive direito à tréplica como sugeria o Dr. Ricardo Iglesias Rios), eu duvido que esta carta do Behe venha a ser publicada.

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To the editor:

Reducible versus irreducible systems and Darwinian versus non-Darwinian processes

The recent paper by Clements et al (1) illustrates the need for more care to avoid non sequiturs in evolutionary narratives. The authors intend to show that Darwinian processes can account for a reducibly complex molecular machine. Yet, even if successful, that would not show that such processes could account for irreducibly complex machines, which Clements et al (1) cite as the chief difficulty for Darwinism raised by intelligent design proponents like myself. Irreducibly complex molecular systems, such as the bacterial flagellum or intracellular transport system, plainly cannot sustain their primary function if a critical mechanical part is removed. (2-4) Like a mousetrap without a spring, they would be broken. Here the authors first postulate (they do not demonstrate) an amino acid transporter that fortuitously also transports proteins inefficiently. (1) They subsequently attempt to show how the efficiency might be improved. A scenario for increasing the efficiency of a pre-existing, reducible function, however, says little about developing a novel, irreducible function.

Even as evidence for the applicability of Darwinian processes just to reducibly complex molecular machines, the data are greatly overinterpreted. A Darwinian pathway is not merely one that proceeds by “numerous, successive, slight modifications” (1) but, crucially, one where mutations are random with respect to any goal, including the future development of the organism. If some mutations arise non-randomly, the process is simply not Darwinian. Yet the authors say nothing about random mutation. Their chief data are sequence similarities between bacterial and mitochondrial proteins. However, the presumably homologous proteins have different functions, and bind non-homologous proteins. What is the likelihood that, say, a Tim44-like precursor would forsake its complex of bacterial proteins to join a complex of other proteins? Is such an event reasonably likely or prohibitively improbable? Clements et al (1) do not provide even crude estimates, let alone rigorous calculations or experiments, and thus provide no support for a formally Darwinian process. Their only relevant data in this regard is their demonstration that a singly-mutated bacterial TimB can substitute for Tim14 in mitochondrial transport. While that is certainly an interesting result, rescuing a pre-existing, functioning system in the laboratory is not at all the same thing as building a novel system step-by-random-step in nature.

Biologists have long been wary of attempts to fill in our lack of knowledge of the history of life with imaginative reconstructions that go far beyond the evidence. As I have discussed (5), extensive laboratory evolution studies over decades offer little support for the plausibility of such felicitous scenarios as Clements et al (1) propose. The authors may well be overlooking formidable difficulties that nature itself would encounter.

References

1. Clements A, et al. (2009) The reducible complexity of a mitochondrial molecular machine. Proc Natl Acad Sci USA doi/10.1073/pnas.0908264106.

2. Behe, MJ (1996) Darwin's Black Box :The Biochemical Challenge to Evolution (Free Press, New York).

3. Behe MJ (2000) Self-organization and irreducibly complex systems: A reply to Shanks and Joplin. Phil Sci 67:155-162.

4. Behe MJ (2001) Reply to my critics: A response to reviews of Darwin's Black Box: the biochemical challenge to evolution. Biol Phil 16:685-709.

5. Behe, MJ (2007) The Edge of Evolution: the Search for the Limits of Darwinism (Free Press, New York).

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Source/Fonte.