This is interesting, and a good point, but the existence of harmful natural mutations isn't by itself a refutation. The idea I have (again, perhaps wrongly) is

This is interesting, and a good point, but the existence of harmful natural mutations isn't by itself a refutation. The idea I have (again, perhaps wrongly) is approximately that harmful-to-humans mutations make up a smaller fraction of the space of viable (i.e. allows the organism to survive at all) natural mutations, and a larger fraction of the space of viable transgenic mutations. A secondary point is that this is because the space of viable transgenic mutations is not constrained by the prior state of the genome, the same thing that makes transgenic mutations powerful also makes them risky. So, I am (or I was, anyways) positing _fewer_ dangerous natural mutations, not necessarily zero. I'm certainly less convinced that there's an important difference than I was yesterday, though, but mostly because the _accessible_ space of transgenic behaviors is evidently limited by investigator effort, which does not scale, so even if the _theoretical_ space is larger, it doesn't matter, we're not going to sample it.