(2017-10-16, 07:10 PM)Michael Larkin Wrote: There would be many new proteins required to make a new organ, e.g. one for the whale's echo location system, and if one estimates each protein would be a minimum of 300 amino acids, then there would be 20^300 possible combinations for each one (because there are 20 different amino acids, any one of which could be in any position).
Okay, because of the redundancy of the genetic code, in some cases different combinations of the 64 nucleotide triplets can specify the same amino acid. So the number of combinations might come down a bit. Let's be extremely generous and say there are effectively 20^100 combinations of triplets for the one protein. We're still talking gargantuan numbers and there's only so much time available to produce even one specific protein.
Even if we assume 1 mutation per second per individual in a stable population of a billion, that's only 31,563,000,000,000,000 (around 3*10^16) mutations per year for the whole population. For the hell of it, let's multiply that by 100,000,000 years: (3*10^16)*(10^8) = 3*10^24, which is still a tiny fraction of the 20^100 combinations for a single 300-amino-acid protein. Even using 4*10^9 (the putative age of the earth) as a multiplier, we would have (3*10^16)*(4*10^9) = 1.2*10^25, still a small fraction of 20^100.
When one bears in mind that many proteins would be required for a new organ or structure, one can get a feeling for just how hopeless the task is, because proteins often work in symphony with other proteins and getting the right protein in one case might not work if another protein isn't exactly the right one.
Hope my maths is correct, by the way!
I probably don't understand enough about proteins to follow the argument. But does the composition of the protein really have to be specified to that extent for it to do the job?