An article on DNA methylation, which researchers have demonstrated to have the basis for a biomarker of aging; some of the patterns that tend to occur in the way in which these epigenetic decorations to DNA occur correlate well with biological age. This author is optimistic that manipulating DNA methylation can slow aging, which is something of a programmed aging point of view - that epigenetic changes are a root cause of aging and give rise to the damage of aging we can observe, rather than vice versa. It doesn't seem to me that the evidence rises to support that view and course of action over trying to repair the underlying damage of aging. If damage is the root cause, then when it is reverted the DNA methylation changes should also be restored to youthful levels.
How does the body know how old it is? Our metabolisms change as we get older, even though our DNA doesn't change. Different genes are activated at different times of life, and the timing of gene expression is what controls growth, development, sexual maturity, and perhaps aging as well. The body keeps accurate track of how old it is, though there has been no scientific agreement about where the clocks are, or how they work. Recently, some biologists have suggested that one such biological clock might reside in the epigenetic state of the DNA. If this is true, epigenetics will become an attractive, though challenging, target for anti-aging research.
If we knew where the body kept its "clock", then perhaps we could target the clock itself with biochemical interventions. We would not just be able to slow the progress of aging, but reset the clock to an earlier age.
DNA is decorated with methyl groups, small molecular add-ons that act like "Do Not Disturb" signs for the underlying gene. A gene that is decorated with methyl groups is passed over, and not expressed. Patterns of methylation are programmed into the genome at birth, and they are known to change over a lifetime. The new idea is that these changes can constitute a reference, like a clock face that informs the cell about the body's stage of life, so that it can appropriately adjust its gene expression, and thence its entire metabolism.
If we're really lucky, it will turn out that humans, like flies, respond well to a dumb, across-the-board increase in methylation. [The] methyl transferase system in humans is more complicated, but it will still be far easier to engineer a general increase in methylation than to copy youthful methylation patterns in detail. This question could be posed in research project that we know how to do now.