Tuesday, January 10, 2006

Creationist Genome Rearrangements

Following in the footsteps of John Davison, Disco fan and (bad) IDEA club head honcho Casey Luskin has delved into the genome rearrangements discussion. The premise of his argument (from what I can gather seeing as this guy ain't no Dobzhansky) is that humans and other apes do not share a common ancestor because they differ in chromosome number, and that karyotypic change would have been selectively deleterious. There goes the research plan for my postdoc! Anyway, PZ Myers frisks him pretty good, and I added a comment to Myers's post:
Even an argument about duplication would be bogus because of the amount of substantial duplications segregating in populations as Mendelian variants (aka, not mutations in the germline of the previous generation). Luskin doesn't understand how to distill information - yes, there are deleterious rearrangements, but there are also a whole bunch of (nearly) neutral ones. It's just that there has been an ascertainment bias in discovering fussion/fissions, deletions/duplications, and inversion associated with disease. That bias is now fading with population genomic studies of human variation -- there are a lot of structural differences between two "normal" humans.
For an example of the amount of structural variation in the genome, see here. I've also dealt with this when I wrote about a human inversion under selection. And, don't forget that the Robertsonian fusion is probably not responsible for the incompatibility between chimps and humans. Hell, you can take a chunk out of our genome and it still works ok.


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