Saturday, March 21, 2009

Answers in Genesis Botches Evolution Again

Answers in Genesis is promoting the new Natural Selection exhibit at the Creation Museum and manages to completely get it wrong. They write:
Commonly cited as “evolution in action,” antibiotic resistance in bacteria provides a case study that we can use to illustrate four problems with equating natural selection and evolution. First, natural selection decreases genetic diversity, but evolution would require an increase in genetic information. Using the “super bacteria” example, a mutation in the antibiotic-resistant bacteria changes the protein that is the target of the antibiotics. The mutation results in a loss of genetic information—the mutated bacteria can no longer produce the normal protein. Such a decrease in genetic information would hinder evolution, not drive it.
Natural Selection acts on variation present in a species. The idea that mutations result in a loss of genetic information is absolutely backwards. Mutations increase genetic variability—whether for good or ill. Selection acts on that variability. If the mutation confers an advantage, it is positively selected. If not, it is negatively selected. All of this is driven by the environment. Further, the writer assumes that all mutations are bad. That simply isn't so. Most mutations are, in fact, neutral in terms of selection. The fact that we cannot produce our own vitamin C due to a mutation that we share with the higher apes does not have an impact on our fecundity; we continue to reproduce just fine. We have seen other examples where mutations have actually benefited. A mutation in the T-cell receptor in humans results in the HIV virus not recognizing it for what it is. The people with that mutation, whether exposed to the virus or not, never get AIDS. Examples such as these abound. Onward. They continue:
Secondly, natural selection is non-directional, and evolution requires directional change. In other words, we have never seen natural selection bring about a change that would transform fish into land-dwellers or reptiles into birds. Back to our bacteria example, the “super bacteria,” for all the hype they have generated, are still single-celled bacteria. They are no closer to being multi-cellular animals than the non-mutated bacteria.
Selection most certainly is directional. There is either positive selection for a trait or negative selection. At the tail end of the Devonian, there was selection for fishapods that could breathe both in water and out of it, and the fossil record records this transition from fish to land animals. There was positive, directional selection from the last of the small sauropods (including those that could not fly and yet had feathers for insulation) to the earliest birds. This is also recorded in the fossil record. That AIG and the ICR fail to recognize the transitional fossils for what they are does not change the fact that these fossils are exactly what is predicted from evolutionary theory.

The writer of this piece fails to understand that natural selection is only one aspect of evolution. Mutation is the driving force of new variation but population variation occurs in other ways as well. Gene flow between populations will change the genetic make-up of these populations, submerging bad traits. Genetic drift, where a small population is cut off from the main population tends to force traits that would not normally express themselves to do so. It also tends to allow traits to "fix" themselves in the population. Multitudinous studies have shown that evolution occurs faster in these populations than in larger ones. Natural selection acts on these main forces and concepts such as adaptive radiation and founder effect are direct outgrowths of how evolution works in populations. If someone at AIG would pick a basic biology book and read it, these misunderstandings would be cleared up in an instant. Sadly, there is little chance of that happening.

6 comments:

  1. Mutation is the driving force of new variation but population variation occurs in other ways as well.

    On a global scale, wouldn't mutation have to be the sole source for new variation? Gene flow might bring new variation into population X from population Y, but the reason population Y has that variation is mutation, no?

    If someone at AIG would pick a basic biology book and read it, these misunderstandings would be cleared up in an instant. Sadly, there is little chance of that happening.

    Ha! You hopeless optimist!

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  2. I figured they would botch evolution. I thought Natural Selection would be kind of easy for anyone. I used to go to AIG for news on Christianity and science. But it's also because of them I found out about Christians that accepted evolution.

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  3. Well, Angel, you can be sure that finding out about other Christians that accept evolution on their site was NOT what they had in mind.

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  4. AMW, you also get variation by things like crossing-over where whole sections of DNA get exchanged between chromosomes. This has the net effect of producing more phenotypic variation. That is the key—not so much that there is genotypic variability but that it gets expressed as phenotypic variability. As far as the AIG picking up a book on biology, I sort of answered my own question. Oh well. One can only hope.

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  5. you also get variation by things like crossing-over where whole sections of DNA get exchanged between chromosomes

    Does that include meiosis?

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  6. Crossing-over actually happens during meiosis, which introduces its own set of variability that selection can act upon.

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