Epigenetics

I found out about epigentics while browsing this video.

http://fora.tv/2010/03/18/The_Genius_in_All_of_Us_David_Shenk#chapter_13

I've read up more on it, and it's quite interesting.  I'm not going to go into the details here.  There's a pretty good article on wikipedia http://en.wikipedia.org/wiki/Epigenetics .

When I took high school biology, we covered genes and reproduction.  Basically we are all carry a set of genes.  When we mate, our offspring get the genes of the mother and the father.  And sometimes there is also a random mutation; a mistake in copying the genes.  Through random mutations, over billions of years, you get evolution as the random mutations give rise to 'better' versions of the species who in turn get to reproduce more.  So good genes get passed on.   Bad genes die over time.

I was never really comfortable with that being the only mechanism at play here.  The easy one is skin color.  Supposedly the more your 'race' was exposed to sun, the darker your skin as ur prevents sunburns.  But in areas without enough sun, you need lighter skin to absorb enough vitamin D.  I'm a 'brown' person.  If I were to go to Sweden.  And I stayed there for generation upon generation.  Only mating with other 'brown' people.  In a billion years, would we still be as 'brown'?  Would there be no mechanism for the human genome to adapt to this situation?  

So epigenetics brings an interesting feedback mechanism here.  Basically you have to separate the gene from the gene expression.  Imagine each gene has an on/off switch.  Epigenetics is the ability to turn on/off the various genes.  The actions/enviroment can alter then gene expression of your offspring.  So if I moved to Sweden, I would be exposed to less vitamin D.  My body would detect this.  This would be passed on via epigenetics.  So the expression of my off spring's gene would take this lack of vitamin D into account and try to lessen the skin tone.

Now it's not as simple as this.  But you get the idea.  Epigenetics is limited as it can only impact the genes you currently have.

What does this mean for individuals.  Well that you can actually impact the gene expression of your kids.
Let's imagine you have history of being fat.  Your parents were fat.  You're fat.
Does that doom your child to being fat?

Not necessarily.  Suppose you work out hard and try and stay in good shape.  Then the epigenetics will take that into account and try and prime your child to handle that workload and perhaps increase their metabolisms... and they might end up not being so predispoed to being fat.


Ditto for intelligence, allergies, manual ability...


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