R
ricmat
Guest
I’ve heard that junk DNA is turning out to be not junk. It seems strange that non-functional DNA would be propagated.That may well be correct in the case of encyclopedias, but it is not correct in the case of genomes. In the human genome about 5% of our DNA codes for proteins while a further 5% codes for switches to turn genes off an on but not for actual proteins. The rest has no apparent function. Mutations in that 90% have no effect on us.
Well, thanks for actually doing the math. But don’t you need to take the whole encyclopedia into account? While pi is getting improved, everything else is deteriorating. Oops…there goes a kidney. Oops…the hemoglobin doesn’t work anymore. Oops…etc. [excuse me for going back to biology for a minute].So to the calculation. Taking the string “pi = 3.14159” and restricting ourselves to single character changes.
1 Deletions. With 12 characters there are 12 possible single character deletions. Two of these are neutral “pi= 3.14159” and “pi =3.14159”, the other ten are deleterious.
2 Insertions. Assume an alphabet of 26 letters, space and eleven punctuation marks for a total of 38 characters. A few insertions are neutral: " pi = 3.14159", “pi == 3.14159” and so forth, but the great majority are deleterious. Two insertion mutations are slightly beneficial: “pi = 3.141591” and “pi = 3.141593” while one single insertion mutation is very beneficial: “pi = 3.141592”.
If we assume that there are ten neutral insertions then we can just match them with the ten deleterious deletions and just calculate the total number of possible insertions. There are 13 possible places for an insertion and at each position there are 38 possible characters to insert. The total number is 3813 insertions = 3.44 x 1020 insertions. If we assume a population of 600,000,000 encyclopedias (one for every ten people) then using my figure above of 5,000 changes per million we have 600 x 5,000 = 3 x 106 changes per generation. We would expect on average to see the first beneficial mutant after about 3.44 x 1020 / 3 x (3 x 106) = 3.83 x 1013 generations.
By the time the trivial improvement in pi comes about (say very optimistically after 1013 generations, it is either in conjunction with other detrimental changes, or is on a base which includes 1013 generations worth of detrimental changes.
Now (per a previous question I asked) if DNA has “copy error protection” then it is not biased to create [many mutations / very few improvements], but rather “no changes at all”. It is difficult to see how this can be part of an evolutionary scheme from simple to complex life.
I appreciate your willingness to discuss all this, but my personal incredulity remains