This is true but as you suggest the existence of somatic hypermutation in immune cells no more shows a role for guided mutation causing evolution than the epigenetic changes which lead to lineage differentiation in development show a role for Lamarckian mechanisms in evolution.
Your absolutely right about that.
It is also important to bear in mind that while somatic hypermutation is restricted to specific regions the actual mutations and rearrangements themselves are still essentially random, especially with regard to the immunological challenges they are going to face. Somatic hypermutation is not targeted in such a way as to respond to a specific immunological challenge, it depends on the generation of vast amounts of random variation followed by selection to find suitable antibodies.
It's non-random in three ways:
- The mutations are local (which you mentioned).
- The mutations are limited to certain nucleotides more than others; as the name of the enzyme suggests - cytodine deaminase.
- The mutations occur in specific (WRCY) motifs.
It is definitely worth noting though that where such a guided mechanism exists it has been identified and characterised, unlike the cryptic mechanisms of guidance so many ID supporters postulate.
Deliberately cryptic...
As opposed to the kind of cryptic ideas that scientists form, e.g. "dark matter".
Edited by kalimero, : Apparently there is no underlining in this forum, LOL.
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