Scientists Discover 'Hidden' Code in DNA Evolves More Rapidly Than Genetic Code

http://www.sciencedaily.com/releases/2011/09/110916152401.htm

The researchers discovered that as many as a few thousand methylation sites on the plants' DNA were altered each generation. Although this represents a small proportion of the potentially six million methylation sites estimated to exist on Arabidopsis DNA, it dwarfs the rate of spontaneous change seen at the DNA sequence level by about five orders of magnitude.
This suggests that the epigenetic code of plants -- and other organisms, by extension -- is far more fluid than their genetic code.