Other problems for Human Evolution, Nachman’s U-Paradox
|December 29, 2006||Posted by scordova under Intelligent Design|
Cornell geneticist John Sanford pointed out many problems confronting the theory of Darwinian evolution, particularly human evolution. (See: Genetic Entropy ) Many of his arguments were subtle. Among them was his discussion of a somewhat obscure paper: Estimate of the Mutation Rate per Nucleotide in Humans by Nachman.
The high deleterious mutation rate in humans presents a paradox.
What Nachman’s paper discusses is the idea of purifying selection (getting rid of bad mutations). If a population on average is receiving 3 deleterious mutations per individual, each female would have to be making 40 offspring to provide sufficent population resources to purge the bad mutations out of the population. But only 3 deleterious mutations per individual might be extremely optimistic. What if we’re dealing with more?
How much time and population resources would be needed to maintain the population if each individual is adding 100 deleterious mutations per generation (even 100 might be optimistic)? But the problem is worsened by the fact this is just to maintain the status quo, much less evolve the population. This problem is the U-Paradox.
To evolve the population, one needs to add new mutations and either fix some mutations and remove (purify away) others. Haldane’s dilemma deals with the difficulty of fixation. Nachman U-Paradox problem deals with the difficulty of purification. Even if the mutations were neutral, Nachman’s paper still poses the problem of how to purify away neutral mutations such that the genomes between each member of the species remains relatively similar (humans are about 99.5% similar to each other).
Recall that for innovation to happen mutations need to be added. Thus, there is the associated cost of getting rid of unwanted innovations. I would argue that calculations should include purifying away even many neutral mutations because of the high degree of mono-morphism between each member of the species (i.e., humans are about 99.5% similar to each other).
Sanford vigorously objected to the hand-waving in Nachman’s paper and Nachman’s appeals to “synergistic epistasis” to kluge away the problems. “Synergistic epistasis” was essentially a phrase to cover up a serious problem [for example, the Darwinists concocted “abiogenesis” and compartmentalized away a major problem for their theory]. There may be isolated examples of “Synergistic epistasis”, but as a generalized principle and cure-all for the U-paradox, Sanford is highly skeptical.
Nachman pulled the number 3 out of the air simply based on the fact he didn’t think human females would be making more than 40 offspring on average (that would mean some girls need to have 70 kids to make up for the under-producers that have only 10 kids).
The average number of such mutations is designated by the symbol, “U”. For 3 deleterious mutations, U=3. What if U=100 (a more realistic, but still optimistic number)? How hard will the females have to work at making kids?
Consider then that we humans have a 180,000,000 base pair difference from chimps, about 6% difference (see: Humans only 94% similar to chimps, not 98.5%). Does one get the sense a problem is lurking somewhere?
Let’s assume (very generously) that for every 3 desirable mutations fixed we need to purify out 3 unwanted mutations. For the chimp human divergence we would be dealing with 90,000,000 nucleotides (180,000,000 / 2 ). 90,000,000 /3 = 30,000,000 generations or about 600,000,000 years. What if U=100? Recall, U=3 was just pulled out of the air! U=100 has some experimental verification, and it may actually be far worse.
I’ve glossed over a multitude of issues, and I’m sure the Darwinists will be angrily objecting. I can already anticipate all the misrepresentations and distortions the Darwinists in the blogsphere will offer (their usual modus operandi). Well, I’ll counter that they need seriously work the numbers and make a convincing case. Right now, human evolution from accepted evolutionary principles is speculation at best. If a fine geneticist like John Sanford finds the numbers objectionable, then it will at least give me pause.
I’m not saying the issues have been conclusively resolved one way or another, but I post this to suggest, the issue of human evolution via any sort of accepted mechanism is far from settled. The Darwinists to their credit are very clever. When confronted with a insurmountable problem, label the problem as being fixed by a yet undefined mechanism. In this case, the kluge is “synergistic epistasis”.