Methylation and memory:
The mechanism whereby a population declines if mating is random enough and the population so large that the average couple is insufficiently kin manifests itself too slowly to be due to the evolution of DNA. DNA is just too stable to suffice as an explanation. Similarly the effect works itself out over five to ten generations, depending on the local strategy of recruitment, so again genes cannot be at the heart of it. It must be epigenetic. A couple of things that can increase methylation are vitamin B12 and folic acid in the diet. As it turns out, folic acid can be damaging (in a malnourished person) if given without B12. So they are generally given together.
But folate deficiency is related to certain catastrophic malformations of an embryo or fetus, so five or ten years ago the government required that bread be fortified with vitamins to reduce the incidence of the malformations.
One must wonder, as has been pointed out years ago, what other effects might be going on without our having detected them. One must wait a bit longer to see whether fertility will change.
On the other hand, it has now been shown in mice (DNA Methylation Controls Memory NATURE vol. 487 no. 7405 July 5, 2012 page 9 reviewing Nature Neurosci.http://dx.doi.org/10.1038/nn.3151(2012)) that methylation is good for the memory. Mice in their dotage that have lost long term memory can be restored with the right methylating diet. Well that’s a lucky good thing isn’t it? I mean since the government is doing it to us anyway, it’s better than the reverse making us more stupid. Of course the government or somebody is doing a pretty good job of that by other means, most obviously by changing words without changing meanings (sea star for starfish and tsunami for tidal wave) and changing meanings without changing words (evolution with its multiple incarnations I mentioned earlier, and I missed one I think, and politically “liberal” and “conservative.”)
Gosh. Maybe we’ll get so smart we’ll actually notice the demographic elephant in the living room.
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