“every society selects for something.”
see also: Talking to Economists
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just when you think you’ve got inbreeding and genetics sorted out in your head (almost — well, no, not really), they throw something new at ya.
here’s an article that linton @nobabies.net pointed out to me (thanks, linton!):
“Epigenetics Linked to Inbreeding Depression”
16 September 2011
“Inbreeding depression is the bane of conservation biology. When closely related individuals mate, which can happen when there aren’t too many members of a species left, their offspring are often less fit and less fertile, making the species all the more vulnerable. Both plants and animals can suffer from inbreeding depression, and textbooks typically attribute this phenonmenon to genetics: Recessive genes with harmful effects, whose negative influences are normally masked by a dominant copy of a gene, are more likely to pair up in offspring of more genetically similar parents.
“Or so the theory goes.
“But Philippine Vergeer, an evolutionary ecologist at Radboud University Nijmegen in the Netherlands, suspects that epigenetics — chemical modifications to the DNA that alter gene activity — may also be to blame, at least in plants….
“Vergeer and her Radboud colleagues Niels Wagemaker and Joop Ouborg compared DNA methylation between outbred and inbred S. columbaria — also known as small scabious — derived from the same mother plant. Methylation was 10% higher in inbred plants…. Also, inbred and outbred plants have different parts of their genomes methylated.
“The scientists then decided to look at what happened to plant offspring if they reconfigured the flora’s methylation. Every day for a week, they exposed germinating seeds of inbred and outbred plants to a demethylating agent. The result: ‘Phenotypic differences between outbred and inbred plants are nullified,’ Vergeer reported….”
so, at least in the case of these little plants, inbreeding depression seems to be connected to epigenetics and not genetics. when they reversed the epigenetics in these plants, the inbred plants photosynthesized (which is what the researchers were measuring) just as well as the outbred plants.
there has been some research done showing that epigenetic states are probably regulated (if that’s the right way to put it) by the underlying genetics, so perhaps the inbreeding depression in these plants was still a result of too many “bad genes.” but it’s cool that they could reverse the inbreeding depression by getting rid of the methylation!
there have also been studies, of course, showing that some epigentic states can be inherited across a few or several generations.
previously: the genetics of epigenetics
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tschafer said: “I can see that ‘epigenetics’ is going to be this century’s excuse for socialism, just as ‘environmental determinism’ was last century’s excuse…. If enviornment predominates, well, we need to manipulate the environment to breed the New Socialist Man. If epigenitics is a factor, we must manipulate the environment in order to influence mutable genes.”
sho’nuff, the lefties seem to be lovin’ epigenetics: Why Your DNA Isn’t Your Destiny.
epigenetics is cool, no doubt. along with other things, some epigenetic thingies [<< technical term] seem to be relatively short-term hacks of the genome in order to enable organisms to more quickly "adapt" to the environment. if there's a shortage of food, it might be useful that the next generation or two can metabolize food differently and, perhaps, extract more calories/nutrition than otherwise. (of course, if the environment doesn't remain so detrimental, the next generation or two might wind up obese and/or with high rates of diabetes.) this is a great adaptation to have — it means your lineage won't necessarily disappear immediately if the environment goes somewhat sour on you. gives the lineage a little time to adapt properly before being selected right out of the gene pool.
and that's the part that the happy leftists are missing from their thinking [sic] about epigenetics. epigenetics is obviously some sort of adaptation … so it must be coded for in our genes somewhere. that methylation happens to alter the expression of genes isn’t some miracle, however amazing it may be. it’s coded for:
“Despite the fact that the epigenetic state of the eukaryotic genome has profound effects on ultimate phenotype, little is known about the mechanisms by which these states are established. In mammals, genomewide epigenetic reprogramming occurs during both gametogenesis and early embryonic development (1). For technical reasons, mainly related to the challenges of manipulating such small starting material, it has been difficult to study these events. We have designed a screen to detect genes involved in establishing and maintaining the epigenetic state of the genome in the mouse by screening for mutations that affect variegated gene expression in the adult….
“Using a sensitized screen for modifiers of transgene variegation in the mouse, we have identified a number of mutations that affect epigenetic reprogramming during gametogenesis and early development….
“These mutant lines should provide a valuable resource for those working in the field of epigenetics. The study demonstrates the power of sensitized screens not only for the discovery of novel genes involved in a particular process but also for the elucidation of the biology of that process.”
in other words, there are genes behind epigenetics, and since all individuals are different, there are variations in these genes behind epigenetics. in fact, i’ll bet anyone $1.00 — no, $1.50! — that different frequencies of these genes will be found in different populations.
it might be epigenetics we’re talking about here, but it’s still biology.
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