Logic and evolution: doubting Darwin (Introduction)

by David Turell @, Wednesday, May 15, 2019, 04:54 (10 days ago) @ David Turell
edited by David Turell, Wednesday, May 15, 2019, 05:09

David Gelernter leaves Darwin:


There’s no reason to doubt that Darwin successfully explained the small adjustments by which an organism adapts to local circumstances: changes to fur density or wing style or beak shape. Yet there are many reasons to doubt whether he can answer the hard questions and explain the big picture—not the fine-tuning of existing species but the emergence of new ones. The origin of species is exactly what Darwin cannot explain.


Darwin’s Doubt is one of the most important books in a generation. Few open-minded people will finish it with their faith in Darwin intact.

Meyer doesn’t only demolish Darwin; he defends a replacement theory, intelligent design (I.D.). Although I can’t accept intelligent design as Meyer presents it, he does show that it is a plain case of the emperor’s new clothes: it says aloud what anyone who ponders biology must think, at some point, while sifting possible answers to hard questions. Intelligent design as Meyer explains it never uses religious arguments, draws religious conclusions, or refers to religion in any way. It does underline an obvious but important truth: Darwin’s mission was exactly to explain the flagrant appearance of design in nature.


Darwin’s theory predicts that new life forms evolve gradually from old ones in a constantly branching, spreading tree of life. Those brave new Cambrian creatures must therefore have had Precambrian predecessors, similar but not quite as fancy and sophisticated. They could not have all blown out suddenly, like a bunch of geysers. Each must have had a closely related predecessor, which must have had its own predecessors: Darwinian evolution is gradual, step-by-step. All those predecessors must have come together, further back, into a series of branches leading down to the (long ago) trunk.

But those predecessors of the Cambrian creatures are missing. Darwin himself was disturbed by their absence from the fossil record. He believed they would turn up eventually.


In fact, the fossil record as a whole lacked the upward-branching structure Darwin predicted.


as Berlinski points out, the fossil record shows the opposite: “representatives of separate phyla appearing first followed by lower-level diversification on those basic themes.” In general, “most species enter the evolutionary order fully formed and then depart unchanged.” The incremental development of new species is largely not there.


The engine that powers Neo-Darwinian evolution is pure chance and lots of time. By filling in the details of cellular life, molecular biology makes it possible to estimate the power of that simple mechanism. But what does generating new forms of life entail? Many biologists agree that generating a new shape of protein is the essence of it. Only if Neo-Darwinian evolution is creative enough to do that is it capable of creating new life-forms and pushing evolution forward.


So, is the simple neo-Darwinian mechanism up to this task? Are random mutation plus natural selection sufficient to create new protein shapes?


We can ask basically the same question in a more manageable way: what are the chances that a random 150-link sequence will create such a protein? Nonsense sequences are essentially random. Mutations are random.


The total count of possible 150-link chains, where each link is chosen separately from 20 amino acids, is 20150. In other words, many. 20^150 roughly equals 10^195, and there are only 10^80 atoms in the universe.


The biologists whose work Meyer discusses are mainly first-rate Establishment scientists.) He estimated that, of all 150-link amino acid sequences, 1 in 1074 will be capable of folding into a stable protein.


In other words: immense is so big, and tiny is so small, that neo-Darwinian evolution is—so far—a dead loss. Try to mutate your way from 150 links of gibberish to a working, useful protein and you are guaranteed to fail. Try it with ten mutations, a thousand, a million—you fail. The odds bury you. It can’t be done.

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