Scientists discover 'hidden' code in DNA evolves more rapidly than genetic code
sciencedaily.com
sciencedaily.com
Second, it is questionable to what extent the term "evolution" can apply to DNA methylation, since these changes are usually lost within a few generations.
Third, epigenetics are relatively inconsequential for animals, for which the Weismann barrier is hardly ever penetrated: http://en.wikipedia.org/wiki/Weismann_barrier
The human genome is composed of roughly 20K protein-coding genes, not enough at all to code for all the complexities in our body (if there was a gene for every bifurcation in our capillaries, we'd run out of genes pretty fast; in addition to the fact that there is no single gene for specific human behaviors, i.e. "aggression").
Epigenetics, in its simplest form as DNA methylation, provides a powerful solution to many of the issues of "there aren't enough genes", and explains a lot of the chaos-elements / environmental impacts on heritability of traits.
DNA methylation, by consequence of wrapping the DNA in chromatin, controls access to which genes get turned off/on by transcription factors (TF). TFs in turn are often influenced by environment, especially neonatal. If you do the permutations of which genes are on/off, b/c a TF can/can't access the DNA, b/c the chromatin is on/off = a whole new set of permutations that entail a new information code.
A good example of the impact of epigenetics is obesity. Children's propensity to obesity often has a lot due to with epigenetic influences during neonatal development. For instance, if a mother is pregnant during a famine and thus doesn't eat much, the fetus' digestive system will adapt to starving conditions through epigenetic changes in chromatin that bind the relevant genes, thus developing a "thrifty metabolism" (digests food slowly). This trait then stays through generations, and when such people move to the West, their metabolisms incline them towards obesity as their body still digests food slowly thinking they were born into starving conditions.
So long story shot, epigenetics aren't "evolutionary" in the original sense, but they are redefining how traits/behaviors (too complex to be explained by genes) are inherited/developed.
I think it'd be fair to characterise this as an early hypothesis?
The most widely cited example in humans is "Dutch Hunger Winter"
All epigenetics does is determine which genes are turned on at which particular times and at what levels, i.e. it is simply another mechanism relating to the regulation of the protein-coding genes (which itself has been well-understood for decades).
'Epigenetics' is simply a fashionable term that plays well on grant applications. It's not unimportant, but neither is it revolutionary.
But what I find most fascinating about epigenetics is its ability to explain environmental vs biological effects on our traits/behavior, not intrinsically described by our genes. As the DNA-methylation described in epigenetics determines which genes are on/off, it is external stimuli that often affect the methylation of epigenetics in the first place. (a Nature brief on the topic in mice: http://njc.rockefeller.edu/PDF_BN08/topic%202-FrancisEpigene...) It's a fascinating way of understanding how our environment affects us on a biological level.
On a side note: I am a biochem student w/ an interest in programming.. HN has been really helped me to learn _what_ to learn about computer science. I love when I see good discussion of biology here, but I wish there was a similar online community for molecular biology / genetics. Anyone have any suggestions?
Cross-advertisements could get seed users, for bootstrapping the new X variants. (Starting with the present Hacker News, then going to CellHacker News, etc.)
I guess lots of the code is already there.
I think DNA methylation is just one type of epigenetics -- literally above the genes -- it can refer to any information encoded on top of nucleic acid base pairs.
http://en.wikipedia.org/wiki/Epigenetics
Would you say that cultural does not "evolve" because the changes are usually lost within a few generations? Is "evolution" a trademark of classical genetic evolution scholars?
Also, at least according to NOVA on PBS in 2007, methylation epigenetics (which vary from cell to cell in the body) can be modified during one's life and influence inheritance. The NOVA program also claims methylation epigenetics accounts for the difference in phenotypes in identical twins. [edit: grammar]
http://www.pbs.org/wgbh/nova/genes/
It might be possible to analyze cultural change, to some extent, on these lines, provided the units of selection are well picked. (Dawkins made a brave attempt with "memes", but the only credible uses of that theory that I've seen involved peripheral phenomena, like earworms and various other inconsequential fads.) Methylation doesn't seem to fit that bill.