Actually, Scott Aaronson, something you said in your second to last post made me think of another reason why the axiom “one mutation, one death” may not be true. Actually, it’s just an elaberation of the point I made earlier but I thought I’d flesh it out a bit more.
The idea is that the more physically and mentally complex, and physically larger, a species gets, the more capable is it is of coping with detrimental genes and still surviving to reproduce. When you’re physically bigger, and smarter, there’s more ‘surplus’ resources to draw upon to help in survivial. Example: There is a rare genetic disorder that causes some people to have no finger prints. This mean’s that their manual dexterity is greatly reduced because of lack of friction in the fingers. And while detrimental, this is a historicaly prevelant case that has not gone away just because it’s bad for an individual. You can learn to avoid situations where failure in manual dexterity could be fatal, etc.
I also believe it’s possible for long standing sections of DNA to evolve and become more robust to mutation once they have “proven themselves”. Meaning if a certain series of genes/DNA that serve a benificial function are around long enough, they will become more refined and effective, and especially robust. However this is accomplished specifically, which of course I don’t know, I don’t see why it’s mechanically impossible. Thus, large sections of DNA could essentially be “subtracted” from amount of DNA to be mutated per generation.
Any flaws in this logic?
Eliezer, I see two potential flaws in your argument, let me try and explain:
1.) The copy error rate can’t directly translate mathematically into how often individuals in a species die out due to the copy error rate. We simply can’t know how often a mutation is neutral, good, or detrimental, in part because that depends on the specific genome involved. I imagine some genomes are simply more robust than others. But I believe the prevailing wisdom is that most mutations are neutral, simply because proteins are too physically big to be effected by small changes. Either way, I can’t see how anyone knows enough about this to be confident in coming up with specific mathematically calculated numbers.
2.) One bad mutation does NOT equal one death, as far as I see it. Greater intelligence leads to greater capability to cope with detrimental circumstances. Sickle-Cell-Anemia is detrimental, but people live and reproduce with it, and have for generations. But it’s almost entirely detrimental, especially if your risk of Malaria is low. It’s true, organisms with non-detrimental versions of the genes will gradually take over, but that doesn’t mean the detrimental versions can’t survive on their own and with just a lower population cap.
And not referring to you in saying this Eliezer, but this whole “Most of the DNA is junk” mantra reeks of conventionalist thinking, a classic form of bias, and has always annoyed me when I saw it in science programs and news articles. Current scientific knowledge knows more about proteins than any other aspect of the function of DNA, so it follows that people will focus on this and gloss over the importance of the other functions of DNA. If you know something very concrete about DNA: proteins, that are amazing enough in themselves, it’s very easy to justify the case that the rest is simply junk DNA. I doubt that, I think we just do know what it does yet on a mechanical level.