A study of five far-flung human populations gives clues to adaptations to environmental pressures.
The results revealed a strong link between population-specific DNA methylation, mRNA levels, and genotypes. However, the CpG sites where methylation occurred that had the highest degree of population specificity were more strongly associated with a local variation in a single nucleotide (SNP) compared with the association of mRNA levels with local SNPs. Population-specific DNA methylation patterns are therefore explained better by local genetic variants than population-specific expression levels, the team says.
Because the DNA methylation variation appears to be under genetic control, it could greatly affect human adaptability. Fraser notes, however, that the consequences of methylation still aren’t clear. “It is likely that most of the variation we measured is not having any important impact, so the challenge is to figure out which genomic regions are important and how their DNA methylation impacts human traits,” he says.More.
The fact that the subject is under discussion at all shows how much has changed in the last decade or so.
Note: The study authors say that “DNA methylation—changes to the activity of a DNA segment without changing the sequence—may be a rich source of raw material for natural selection.” But they have subtly redefined natural selection, as many researchers are now doing.
Natural selection used to be Darwinism, plain and simple (natural selection acting on random mutation). But epigenetic mutations are not random; they occur in response to the environment during the lifetime of the individual and are passed on. If all that natural selection means is that the best aapted are more likely to survive than the worst-adapted, it is a self-evident truism.
Darwin’s faithful have always been after bigger fish: Pretend that natural selection alone is a source of massive amounts of information in very short periods. Magic.
See also: Can we test for information, as the basis of the universe, as opposed to matter or energy?
Epigenetics may explain how Darwin’s finches respond to environment
Researchers: DNA replication problems can cause epigenetic changes
Hot weather story: When epigenetics becomes politics…
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Epigenetic change: Lamarck, wake up, you’re wanted in the conference room!