I have a question about one of @DennisVenema’s blog articles on the Biologos website. Perhaps Dennis or someone else who is also knowledgeable of genetics could answer it?
The article is this one about the evidence for common ancestry for humans and other apes due to nested hierarchies of genetic mutations:
I’m no expert on any of this, but this is the most compelling evidence for common ancestry I’ve ever seen.
But I do have a question about the main argument. Could the nested hierarchy pattern be explained by the degree to which the species that share the mutations also share overall DNA similarity? So, for instance, suppose my Honda and my wife’s Toyota are 95% mechanically similar to each other but only 90% similar to my neighbor’s Kia. Then suppose that we found out that the Honda and Toyota shared six mechanical problems, but of those six only four are shared with the Kia. In this sort of case, a plausible explanation would be that the commonalities in mechanical problems are due to broader commonalities in overall mechanical structure. That is, the four problems shared across all the cars is due to the 90% shared structure, and the two that the Honda and Toyota share are due to the extra 5% similarity in structure that they share that isn’t shared by the Kia.
The point is that for the nested hierarchy pattern to be evidence for common ancestry, we’d need to know that the pattern isn’t explained by the very features that already gave us the hierarchical structure to begin with: the much broader similarities in DNA and phenotypic traits. We’d need to know that the mutations specific to two species on a “branch” of the hierarchy “tree” are not caused by the commonalities in virtue of which they share the same branch.
But maybe there are good reasons to think that genes can’t bring about mutations in other genes, or that common phenotypic traits can’t contribute to common genetic mutations. I’m just too ignorant of genetics to know.
Any thoughts would be much appreciated. Or if this has been addressed this before, even a link would be great! Thanks!
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