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Another argument on the Haldane's Dilemma question, from Are the Odds Against the Origin of Life Too Great to Accept?

But in the same Wistar symposium publication, C. H. Waddington (in his "Summary Discussion") hits the nail so square on the head that I will quote his remarks at great length:

The point was made that to account for some evolutionary changes in hemoglobin, one requires about 120 amino acid substitutions...as individual events, as though it is necessary to get one of them done and spread throughout the whole population before you could start processing the next one...[and] if you add up the time for all those sequential steps, it amounts to quite a long time. But the point the biologists want to make is that that isn't really what is going on at all. We don't need 120 changes one after the other. We know perfectly well of 12 changes which exist in the human population at the present time. There are probably many more which we haven't detected, because they have such slight physiological effects...[so] there [may be] 20 different amino acid sequences in human hemoglobins in the world population at present, all being processed simultaneously...Calculations about the length of time of evolutionary steps have to take into account the fact that we are dealing with gene pools, with a great deal of genetic variability, present simultaneously. To deal with them as sequential steps is going to give you estimates that are wildly out." (pp. 95-6)