There is a puzzle in nature. This is one example, but there are many more like it.
- Between these species pairs, Humans-Chimps have more functional differences than Mice-Rats.
- Between these species pairs, Humans-Chimps have about 5x-10x fewer genome differences than Mice-Rats.
Why is that functional differences do not predict genomic differences? Neutral theory (or variant) gives the answer. Most those differences are neutral, and are just a record of shared history (common descent). It turns out that only a tiny tiny proportion of the observed genetics differences are needed to cause the large functional differences between closely related species.
We can estimate the ratio of selected to non-selected genetic changes. It is something like 1:1000. That ratio, which shows most mutations are neutral, is what makes it clear that:
- God need not intervene much to have a large effect on phenotype.
- Rare interventions will be lost in a sea of neutral and selected mutations.
Biology need not have been this way. It certainly is not intuitive, and took a lot of effort from Kimura to figure out and make his case. However, given these two findings of biology, we just don’t expect that if God is intervening for the purpose of directing evolution that we would expect to detect a signal for His direction.
If we did detect his involvement, it would be because he somehow wanted to be revealed this way. It would take intentional effort, independent of functional goals, to make it clear in our genomes that He was tinkering.
If biology worked differently, we might end up with a different answer. Biology, however, is what it is.
I do take that back somewhat. Understanding it already, I’m not surprised. However, population genetics is very non-intuitive and surprising. You are clearly an expert here, but that is the fun of this. It is deep enough that it can still surprise the experts. So maybe you do you have reason to be surprised.