The Real Barrier to Unguided Human Evolution

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Comparing DNA sequences and estimating by how many nucleotides we differ from chimps doesn't tell us much about what makes us human. Many of those nucleotide differences have no effect, because they are the product of neutral mutation and genetic drift. While these neutral mutations may affect the over-all mutation count, they don't answer how many mutations are required for the transition from chimp-like to human.

This problem is analogous to one we examined concerning protein evolution last year in the journal BIO-Complexity (Gauger and Axe 2011). Converting one protein to another's function can be viewed as a version, in miniature, of converting one species to another. But it is much easier to convert proteins than species.

We began by identifying two proteins that are close together in structure, but that have distinct functions. We examined what the minimal number of mutations to convert one protein to the other were. If all the places where they differed had to be changed, that would mean we would have to switch 70% of one protein to achieve conversion to the other's function. It's unlikely that all those mutations are required, however, since many if not most of those changes are due to neutral mutation and drift, just like in the chimp-like to human case.

So to estimate the minimal number of mutations required for conversion to a new function, we identified and tested the most likely amino acid candidates using structural and sequence comparisons, one by one and in combination. We ended up changing nearly the entire active site to look like the target protein, but failed to achieve conversion.

Based on the number of groups we changed, we made a minimum estimate that seven specific mutations would be required for a functional shift to be observed. To get seven coordinated mutations takes far too long, even for bacteria, with their high mutation rate and large population sizes. 10^27 years is our estimate, based on Doug Axe's population genetics model, also published in BIO-Complexity.

Personally, I think the chimp-like to human conversion would have to have taken many more years than any protein conversion, 

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Science and Human Origins: An Important New Book by Ann Gauger, Douglas Axe and Casey Luskin

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Lurking behind the evolution debate is a question that is smaller than evolution as a whole, having encompassed only an exceedingly brief span of time in the more than 3-billion-year history of life. Yet in emotional terms, for Darwinists and Darwin doubters alike, this question -- the mystery of human origins -- drives the controversy around Darwinian theory as does no other point of contention.

Intensely personal in a way the bacterial flagellum never will be, it is the subject of an important new book just published by Discovery Institute Press. You will hear a lot about it from us in coming days, including from the book's scientist authors, Ann Gauger, Douglas Axe and Casey Luskin.

Science and Human Origins is a book about science yet its importance lies no less in anthropology. Not anthropology the social-science field, but the ageless enigma of what a man is. Are you a clever animal, or something incomparably other? In his Introduction, John West cites G.K. Chesterton who wrote that, "Man is not merely an evolution but rather a revolution." That frames the subject concisely.

If the book's message can be crystalized in brief, it is that the scientific mystery of man's origins remains very much a mystery. Aggressive advocates of scientism -- and some equally aggressive theistic evolutionists who claim to disavow scientism -- insist that evolutionary biology has got us all figured out. But this is a huge bluff. The highlights of Science and Human Origins include:

  • Dr. Gauger and Dr. Axe lay out the sobering evidence showing how far beyond Darwinian evolution's power the task of building a human being actually lies.
  • Ann Gauger and Casey Luskin interrogate the fossil and genetic evidence on offer that claims to trace a smooth evolutionary path from earlier primates many million years ago to Koko and Bonzo on one hand and to Bach, Beethoven and Brahms on the other.
  • Finally Dr. Gauger considers a controversy swirling in the religious and evolutionary communities: whether the origin of the first human beings could potentially go back to a single pair, or whether a "bottleneck" of 10,000 or more individuals seems required by population genetics.

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