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Are mutation rates too much for complex creatures?

Hey, basically I need help. I’ve been encountered with more than a few creationists arguments that I don’t really see addressed very well.

Basically this guy, Sean D. Pitman, MD, has this site that seems pretty comprehensive. One of his major arguments (although elaborated on many creationist sites) is that mutation rates of beneficial mutations are too low, and deleterious mutations too high, in complex creatures. Basically, that it is impossible for it to happen…

Please tell me this isn’t some sort of valid problem for evolution by natural selection, or evolution in general.

http://www.detectingdesign.com/dnamutationrates.html

Posted: December 22nd 2011

Eric_PK

I didn’t see any summary in what he was asserting, so it’s a bit hard to respond without spending more time than it’s worth.

I think he has a weird view of mutations, however.

There are clearly very bad mutations that lead directly to death, either very early after conception, or early as infants. You also see that in sexual reproduction; you get an unfortunate mix of genes from the parents and it is fatal.

But other mutations span the gamut from pretty bad to good – and, of course, some mutations are bad in some environments, good in others (sickle cell is a classic case of this).

So I think the sort of view he has is overly simplistic.

Posted: January 5th 2012

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logicel

Sexual reproduction allows complexity to evolve by blunting the edge of negative effects of mutations while upping the rate of evolution.

From The Journal of Evolutionary Philosophy:

A larger population has a higher chance of producing a beneficial mutation, but for asexually reproducing organisms, a considerable amount of time may need to pass before the mutant population grows large enough to have any chance of producing a second beneficial mutation.

Sexual reproduction removes this speed limit by allowing beneficial mutations to spread back into an existing population to be combined with other beneficial mutations, and this greatly magnifies the rate of evolution.

Posted: January 5th 2012

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brian thomson www

While I’m no geneticist, a quick read of that page makes me wonder how anything on it could be taken as supporting a “design” hypothesis. It’s a “literature review”, describing studies undertaken by others, not studies by the author.

The first part is about mutation rates, describing flaws with various computer simulations, which is hardly shocking in itself. For example, it talks about how replication errors are not the only source of mutations, as was assumed.

The second half is not really about “flaws” at all, and doesn’t appear (to me) to raise any concerns about natural selection in general – it’s speculation about possible problems with DNA deterioration. It does mention something I was expecting to see in the first part: the role of genetic recombination in the generation of complexity, working alongside mutation.

In other words: if mutation rates alone apparently don’t explain all the complexity we see, there are many reasons why that could be: flawed assumption in studies, such as the assumption of a constant linear mutation rate; extrapolation from non-mammals in to mammals; leaving out genetic recombination.

A working geneticist might be better able to see whether there are any serious issues raised there, because I can’t see any. I’m not a geneticist, but then neither is Dr. Pitman: his published literature is in Pathology.

Posted: January 5th 2012

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