On 8/13/2013 12:00 PM, Chris de Morsella wrote:
John >> Epigenetic changes do not change the sequence of bases in DNA, and more important I see no evidence that the body has learned any lessons. I see no evidence that epigenetic changes are more likely to happen in the direction of greater adaptability rather than the reverse. All I see is the environment causing random changes in hereditary factors that, like all changes, are more likely to be harmful than helpful. Sure, but then neither do random mutations to an organisms DNA, imply that the body has learned anything either. The introduction of some random change is either harmful, beneficial or of little or no consequence to the individual, whether this phenotypical change is the result of inhibiting or promoting the expression of some underlying DNA or how that DNA get's transcribed, or is the result of an actual change in the individuals sequence of DNA. What you say about epigenetic changes: "environment causing random changes in hereditary factors" applies as much to the classical hereditary mechanism of DNA changes. Evolution only happens after multiple generations of selective pressure have either, presumably weeded out harmful maladaptations and promoted beneficial ones. There is nothing qualitatively different in random DNA mutation or random methylation and so forth. They are both instances of mutations in an organisms hereditary mechanisms. Why make one a first class citizen and the other an interloper? Naturally I am not arguing that epigenetic re-wiring is as permanent or important as classic genetic based heredity; it certainly seems more reversible for example.


But isn't that the problem with epigenetic 'evolution'. Evolution requires faithful reproduction sufficient at least to create a local breeding population. My understanding of epigenetics is that it is hit-or-miss after only a couple of generations.

Brent

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