From “Epigenetic Changes Often Don’t Last, Probably Have Limited Effects On Long-Term Evolution, Research Finds” (ScienceDaily, Sep. 20, 2011), we learn,
The first comprehensive inventory of epigenetic changes over several generations shows that these often do not last and therefore probably have limited effects on long-term evolution, according to scientists in Germany.
Using Arabidopsis, the workhorse of modern plant genetics, the researchers determined how often and where in the genome epigenetic modifications occur — and how often they disappear again. They found that epigenetic changes are many orders of magnitude more frequent than conventional DNA mutations, but also often short lived. They are therefore probably much less important for long-term evolution than previously thought.
Of course, if the epigenetic changes are many orders of magnitude more frequent, a small minority of them might be just as significant as genetic mutations. Or more. An obvious conclusion the researchers appear to back away from:
What makes epigenetics interesting for human health is the fact that some epigenetic changes can be triggered by external factors. There is evidence that nutrition or the bond between children and their parents can leave traces in the genome that can be passed on to the next generation. The limited stability of DNA methylation implies, however, that such differences do not necessarily last forever, which is probably not a bad idea because a famine might not last forever. It also means that altered DNA methylation often cannot become subject to natural selection.
It’s a good thing someone is letting the air out of the epigenetics balloon; it was in danger of becoming pop science, now maybe it’ll remain real science. It’ll be interesting to come back a decade later and see what’s turned up
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