Monday, February 11, 2013

Nature and Nurture: The Epigenetic Monkey Wrench

For those of you with a little science background, do you remember the Lamarckian theory of how traits developed?  It was like this: a giraffe finds itself doing well in a habitat where the best and most plentiful food for it is in trees, specifically the leaves.  So, the giraffe stretches for the leaves and can reach a few.  The continued neck stretching has tends to develop a bit longer neck which is then passed on to his kids.  Likewise, these kids stretch for higher leaves and eventually, a few years down the line, we have the modern giraffe with the long neck.


This is called soft inheritance.  It means that if I read a lot, I will pass along more reading/comprehension ability to my child.  If I spend time in the gym developing biceps, I will pass along a tendency for my child to have stronger biceps.  Kind of like Darwin, except that the changes are not coded in a hard way and then, over time, weeded out by nature, but rather acquired through life experience.

According to Darwin, the taller giraffes were more able to get leaves and thus more able to live.  They were more fit for their environment.  That, in turn, meant that they were more able to reproduce other giraffes kind of like them and over generations the giraffe gets taller.  We all know that Darwin won that argument, right?

Well, yes.  But it is more complicated.  In the past 40 years another factor has come to light, only really studied for the past 20.  Superficially it seems like Lamarckism.  What it is more accurately described as is life experience turning certain genes on and off and these new switches often passing to offspring.  And, it is a theory with very rigorous proofs and observations behind it, quite as solid scientifically as what Darwin brought us.

For example, the Nova episode below shows lab rats raised by “licking” mothers, mothers who lick the babies and give them attention, lab rats that grow up to be cuddly and sociable.   Non-licking moms raise anti-social rats.  It can be shown that these tendencies are created by the experience by swapping litters at birth.  The non-licking moms raising offspring of licking moms raise unsociable little characters.  The licking moms getting the offspring of the non-lickers, raise sociable pups.

This is the real zinger.  They discovered what the switches were, and seeing precisely what they were, they gave non-social rats one single shot from a hypodermic designed specifically to erase these switches and … voila, the rats became sociable!  After one shot!  AND THE CHANGE WAS PERMANENT!


That is only one of the things shown through epigenetics.  The Nova show also shows how the diet of your grandparents can skip health effects on your parents and affect YOU.  Chew on that for a bit.

That is why I said that the “Nature vs. Nurture” idea was more complex than most people think.  I leave you to enjoy your own research of epigenetics.

For further study (the first in the list from Nova is my favorite):



  1. That's frightening, because my grandparents lived during the depression, and didn't have that great of a diet....

  2. @Delirious

    Well, that is most of us, I must say. It seems more connected with famine and with the stage of life at which the famine happened. That is only as far as I'm aware of it, but that hardly means that is the limit of the influence.

    Still, I'd hate to spend my time worrying about that just to walk out in the front yard and be struck by a meteor! LOL

  3. My paternal grandfather was born during the potato famine in Ireland. His children were as tall as giraffes, perhaps because they had to reach further for food, My brothers are tall, but none of them could match their uncles in height. Were we too well fed?

    I remember watching a programme when I was pregnant about young babies - those who were talked to all the time were alert, while those met with silence, drifted off to sleep and were slower to learn. Once Elly arrived I talked quietly, non stop to her. One day in the hospital, a lady diagonally across the ward, asked me to stop talking because her son stopped breast feeding every time he heard my voice. So it worked!!

  4. @Grannymar

    The connection with grandparents food intake is more complex than we are allowing for in this discussion. It affects things like diabetes if I remember correctly. Or ... maybe it affects the memory. :)

    Anyway, the effects are very specific, have to do with the specific timing of the famine in the grandparent's life, etc. But, it is one of a myriad of effects that are observable, explainable and reproducable. It is an exciting new science branch and our separated twins definitely come into play in the Nova piece, a program and episode that I think is marvelous.

  5. Your example seems to have given heavier weight to the nurture side of the equation Fos - now about that shot - can I have the "makes you skinnier" shot? (skinier - not skinbny as I kinda enjoy being big:-))

    My own experience does support this though - perhaps a topic for discussion at another date.

  6. @shackman

    You want the skinnier shot and I want the smarter shot. We work this right and we could get rich opening a new bar!

    This definitely puts a new wrinkle in the equation. The problem is that we still have to determine a lot of the complexity that equates to nurturance. Is it always as clearcut as it was with the mice? What is the effect of something like Marine Bootcamp?

    What they are just finding right now is that lab mice don't map to humans as closely as they thought in many areas, so I think this will be unfolding for quite a few years. Still, I think you would enjoy the Nova piece, because it really does add some interesting twists to the nurturance side of the equation.

  7. Hmm, used to be a shot and beer. Now it's a shot and a shot, great name for a pub.
    There is no end to the nature vs. nurture discussion. Still, at 5'1" I wouldn't mind if I could inherent some the giraffe's genes.
    Blessings ~ Maxi

    1. Ah yes Maxi - thge old Double Shot - great song from way back when - LOL


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