This is Latin for "don't let the bastards grind you down". Would you tend to agree that by calling us "bastards" Mr. LLLICHY is behaving in a gratuitously name-calling and unChristian manner?
Mechanisms exist within cells that correct various mutations. This can be demonstrated by a stretch of DNA associated with Vitamin C and used as an argument for the common descent of humans and other primates. The peculiar thing about this DNA stretch is that there are regions within it that have absolutely no mutations amongst animals that have been separated by over 50 million years(or 100 million both way years). That range of time is nearly 10 percent of the time since "complex" animals first appeared on the earth. This indicates that whatever causes the fidelity of those regions is a reliable process. The point being there is a reliable process that limits change.
Note that this is an enormous red herring. Sure, cells have mechanisms to "limit change". But so bloody what? Enough change still occurs anyway to drive evolution, since no repair-and-maintenance process is ever 100% accurate.
Mr. LLLICHY's word choices are misleading, especially "peculiar" and "absolutely".
There's nothing at all "peculiar" about the actual amount of changes in the primate/human vitamin-C synthesis psuedogene (more technically, the L-gulono-gamma-lactone oxidase gene, or GLO). The amount of mutations it has accumulated are quite consistent with evolutionary theory, both in the number of mutations and in its implications for common descent.
And to say that there have been "absolutely" no changes in "regions" of it gives the impression that on the whole the pseudogene has remained mostly and suprisingly pristine. On the contrary, at least 20% of its basepairs have mutated (including point mutations, insertions, and deletions), resulting in 30% of its coded amino acids to vary, which is a *very* significant accumulation of mutation. And I say "at least" because the 20%/30% is only a tally of the regions which could be directly compared -- Exon VIII is either entirely gone from the human genome due to a deletion event, or has changed so significantly that it can not be recognized any more compared to the non-primate Exon VIII, and Exon XI was too short to positively identify (it is either gone as well or the tentatively identified human XI is 32% changed in basepairs but was not included in the above tally).
...But that's hardly the impression a casual reader of the above post would come away with, is it? How misleading would an autopsy report be of a victim of a machine-gun killing who had bullet holes ripped through 20% of his body if the coronor had written nothing more than, "The peculiar thing about this body is that there are portions of it that have absolutely no damage" without acknowledging the actual extent of the damage, and concluded "The point being there is a reliable process that limits bullet damage"? Would the coronor be declared incompetent, dishonest, or both?
A few more observations:
[...]over 50 million years(or 100 million both way years).
The implication seems to be that there should be 50 million years worth of mutations on both lineages after the split. The problem is that "both ways" are not symmetric in this case. While it's true that the primate lineage was free to accumulate mutations at the mutation-occurence-and-neutral-fixation rate, the same is not true of the non-primate lineage. In that lineage, the fact that the vitamin-C synthesis gene was still functional would cause an additional process to come into play to weed out mutations in the gene, and that process is natural selection. This would cause the non-primate GLO gene to be highly conserved compared to the primate pseudogene.
Interestingly, if common descent and evolution are true, the primate lineage(s) would be free to mutate at the neutral fixation rate away from the non-primate lineages *and* each other, resulting in large divergences, while the non-primate lineages would be less free to accumulate mutations (but some would still occur), and would thus differ much less from each other. And voila, this is exactly the characteristic pattern which is seen in the DNA of the various species. Chalk up another successful prediction and confirmation for evolution.
That range of time is nearly 10 percent of the time since "complex" animals first appeared on the earth.
Note that this is enough time for fully 90% (1-0.8^10) of an entire genome to mutate to something else through neutral mutation fixation *alone* in a *single* lineage. Multiply that times the total number of lineages on the planet (billions, at least), *and* take into account the fact that beneficial mutations fixate far more quickly and reliably than neutral ones, *and* mutation introduction rate is far higher than fixation rate, and it's quite clear that rather than showing that DNA is too much protected from change to allow evolution, as the post seemed imply, in fact there is an enormous amount of mutation grist for evolution's mill.
Cloning and chromosomal mapping of the human nonfunctional gene for L- gulono-gamma-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in manHere is the abstract, and here is the complete paper.
M Nishikimi, R Fukuyama, S Minoshima, N Shimizu and K Yagi, Institute of Applied Biochemistry, Yagi Memorial Park, Gifu, Japan.
I can see where the mechanism mentioned limits--as in "somewhat suppresses"--the rate of mutation. I don't see where it would over vast amounts of time completely cap the total number of mutations which do get through. The latter sort of limit was what Patrick was asking Ditto about. Without such a cap, once two populations have speciated, mutational differences just keep on accumulating. Everything we know about mutational clocks says that this idea works.