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Epigenetics and Evolution

  1. Sep 18, 2010 #1
    So I just watched a Nova documentary on epigenetics called "Ghost in your Genes"... I had never heard of epigenetics. Apparently its things being passed down amongst people by means other than our GENES and DNA. Things like smoking being passed down from grandparents to grandchildren and resurfacing as asthma or... if a grandparent goes through a period of starvation he could have grandchildren with diabetes. All kinds of strange things passed down in unexpected ways.

    It reminded me of crows and how they can pass down FEAR of certain things genetically. Perhaps its actually passed down epigenetically. Has anyone seen a Murder of Crows? A Crow is taught to fear a man wearing a certain mask. Later that crow has offspring and the offspring CLEARLY act as if they remember this man in the mask... and to fear him.

    Anyway, watching it also had me thinking about the role epigenetics must play in evolution. I mean only so much of our DNA can explain us. I've heard plants have more complex genetic data than a HUMAN. Humans and monkeys share a near 99% of their respective genomes. It actually makes me think... evolution has always made sense but has always seemed like maybe there's something missing. Evolution seems to move almost too fast to me for some reason. To me, anyway, there IS room in the theory for some directive mutations and mutations caused by the environment... perhaps this epigenetics could explain some of that. I guess that is Lamarcks theory of evolution. I never quite got over his theory. I have always thought there is some sort of truth to it. Maybe epigenetics is it...
    Last edited: Sep 18, 2010
  2. jcsd
  3. Sep 18, 2010 #2
    I don't believe you've interpretative this correct; what you're describing is a matter of genetics and the expression or suppression of certain genes... and the crows... aiya. You need to understand the difference between the genome as a whole, and what is expressed under certain conditions; you do not separate inheritance from from genetics AT ALL. You've completely misunderstood what epigenetics is: inheritance of a given phenotype and/or expression and not some magical "other" factor.

    PLEASE read this: http://en.wikipedia.org/wiki/Epigenetics

    I should add, you must not have really understood the crow experiment, or you're intentionally misrepresenting this. http://news.sciencemag.org/sciencenow/2010/02/is-that-a-caveman-or-dick-cheney.html [Broken]
    Last edited by a moderator: May 4, 2017
  4. Sep 19, 2010 #3
    Epigenetics is another subject much loved by those who wish to obfuscate rather than clarify. It is much confused with Lamarckism and is often employed in spurious arguments in attempts to undermine acceptance of evolutionary theory. But, as ever in these things, it actually quite clear what epigenetics is and what it is not. A much better example of it concerns what happened to the grandchildren of women who suffered starvation while pregnant during the second world war. Again I have difficulties citing my source because this time, it is not even a popular science book, but something posted by someone extremely knowledgeable on a completely different forum. But let me offer you this direct quote from him:

    ‘What seems to happen is that environmental factors can alter the methylation of activation sites on the genes so that the next generation may develop and express the genetic code they have in slightly different ways.’

    The key point is that the undernourishment of the grandmothers obviously caused some alteration in the children that in turn affected the grandchildren, even though their parents were properly nourished at the time of their development. Nonetheless, it is equally clear that these effects are short-term, make no permanent alteration to the genetic code and thus are quite clearly not evolutionary.
  5. Sep 19, 2010 #4
    There is also an effect in whitch the biochemical pathways can be front loaded by the parents for example by drinking alcohol between conception to birth. The biochemical pathways can be self promoteing and thus make the offspring more likely consume alcohol. In this case it can take decades for the offsprings dna to take control. Maybe in your example of the crows the offspring were front loaded to just be more fearful in all cases?
  6. Sep 19, 2010 #5


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