Via EurekAlert comes this news release on research into error checking during DNA polymerization. I'm not judging the science; I'm judging the reporting, which includes the following statement:
Everyone knows mutations - genetic mistakes in DNA, the material of heredity - are bad: The more mutations in the cell's DNA, the higher the risk of cancer developing.
In case the syntax in the title is unfamiliar to you, lemme spell it out for you: MUTATIONS ARE NOT NECESSARILY BAD. Sure, genetic mutations are responsible for diseases such as cancers, but they are also the raw material upon with all other evolutionary forces act. Without mutation, we wouldn't have evolution. Although natural selection is a fairly important force, evolution can proceed without it. Natural selection, on the other hand, needs heritable variation in order to increase the frequency of alleles that confer the highest fitness in their carriers. That heritable variation comes from mutations.
The entire article is without a single mention of how this research relates to evolutionary biology. I may be biased as an evolutionary biologist, but the first thing I think of when I hear about error prone polymerases is how they are the engine of evolution. Evolution without an imperfect replicator results in a single lineage. It's stasis, which is the antithesis of evolution.
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Also, hello, mutations cause X-men style awesome powers! Nothing bad about that!
To be fair, the bulk of the article is about how some mutations can be beneficial...
I'm curious also why you say evolution can proceed without natural selection. It seems to me that natural selection ensures that good changes get propagated — without natural selection, any beneficial mutations would never really contribute to the gene pool in any meaningful way.
Natural selection is an important evolutionary force, but mutation provides the variation upon which every other evolutionary force acts. Natural selection ensures that beneficial variants increase in frequency, but it depends on mutations.
To answer hch2817 a bit more, evolution at it's core refers to a change in the genetic make up of a population and as rpm notes, mutation is important for evolution. Also evolution can involve non random mating, genetic drift and gene flow between populations, none of which need involve natural selection per say. To complicate the issue, natural selection need not lead to evolution if the phenotypic variation uon which natural selection acts is due soley to the environment.
I was particularly interested in the role of p53 in the error correcting process! Makes sense retrospect.
Maybe I was being too obtuse. I did say that "without natural selection, any beneficial mutations would never really contribute to the gene pool in any meaningful way." To me, this meant that although there would be naturally beneficial mutations in organisms, those good mutations would never really increase in relative frequency throughout the population.
I'm still confused why you say evolution can take place without natural selection. One particular lineage might be able to change/drift without selective pressures, but an entire species...?
Natural selection is mad important. I don't deny that. But it requires mutations. Think of evolution as a car. Mutations are the gasoline, and selection is the engine. The engine won't do jack without the gasoline. The gasoline can be burnt independent of the engine.