
Memories of positive associations get written onto DNA - LiveTheDream
http://arstechnica.com/science/2013/08/memories-of-positive-associations-get-written-onto-dna/
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JunkDNA
This is fascinating but unsurprising given all the things that have come out
lately with regard to epigenetics. If your mental model of DNA involves some
image of a pristine blueprint that is followed with clockwork-like precision
in the exact same way by every cell in your body, your model needed updating
quite some time ago.

I feel that many researchers, even geneticists who should know better, still
have not internalized the idea that epigenetics is pretty good evidence that
somatic DNA is a read/write medium. This leads to sloppy thinking about
genetic causes of disease as well as continued persistence of the idea that if
we can just collect enough sequences, all genetic causes of disease might be
found.

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mathattack
By this argument, culture can be imprinted into DNA too, no?

This also implies that it would be much tougher to do a Jurassic Park
recreation, because the environment is different. You can't just start from
scratch with the DNA.

Or am I misinterpreting?

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3am
You are misinterpreting. As others have noted, this is DNA in the nuclei of
nerve cells, not gametes. It is not heritable.

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voidlogic
This, thank you. People often forget about this when they are thinking about
environmental elements modifying DNA.

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Flenser
Although the primary structure of DNA remains unaltered it is still possible
for the environment to alter the traits of offspring:
[http://en.wikipedia.org/wiki/Transgenerational_epigenetics](http://en.wikipedia.org/wiki/Transgenerational_epigenetics)

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samatman
Methylation can happen in gametes also, making some epigenetic changes
heritable. The precise mechanisms of methylation are under intense study, but
not well understood; it doesn't appear to be a random process in general.

This points to an almost-paradox in biology, which I call Lamarck's Lemma:
There may be evolutionary advantage to being able to pass on acquired traits
to one's offspring, and no known physical law that prevents it. Why,
therefore, would biology not develop at least some Lamarckian mechanisms,
since they could offer fitness in the Darwinian sense?

Answer: there appears to be exactly that. It's an exciting time for genetics.

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nollidge
I don't see why it's a paradox. Lots of things would offer fitness - why can't
all animals talk? Why can't plants move? Surely these things would offer
greater Darwinian fitness.

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samatman
I did want to address one other total misconception here: Darwinian fitness is
a result, not an effect. There is _no_ adaptation, at all, which predictably
increases fitness. Evolution is not a direction.

"Surely these things would offer greater Darwinian fitness" is as basic a
mistake as "Surely we can figure out whether this program will halt without
running it".

EDIT: In fact, as I think about it, there is a deep connection between the
thought "Knowing the genes of this organism, we may predict its fitness" and
"Knowing the instructions of this program, we may predict its halting". I'd
love to see a paper on that.

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rflrob
That doesn't seem rit to me. There's lots of adaptations that could probably
increase fitness of offspring as a function of the parent's environment. In
the same way, you can look at some programs and predict whether they halt,
just not all programs, and potentially not even all "interesting" programs,
for some definition of interesting.

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XorNot
You contradict your own point though: yes, we can predict - but we can't
_know_ that a program - an arbitrary program - will halt.

Evolution is much the same, but most people are worse at it because they make
the mistake of prioritizing human-values as evolutionary advantages for all
species.

For example, cows get slaughtered by the billion by humans. But they're an
evolutionary success story from a Darwinian perspective: by being easy to
domesticate by early tribes and delicious, they've proliferated far beyond
anything which would've happened un-aided by humans.

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dllthomas
For any arbitrary program, we _may_ be able to _know_ that it will halt.

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HCIdivision17
For any very simple arbitrary program, perhaps. But certainly not in general.
That's sort of the point of the Halting Problem: you can't know because it is
undecidable.

Of course, there are simple and trivial programs that can be specifically
analyzed, but we're definitely not to that level on any of the stuff under
discussion here. The analogy really is pretty apt.

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dllthomas
The halting problem is undecidable much like logic is incomplete. There will
always be true statements we can't prove, and there will always be programs
that might or might not halt. That doesn't mean that we can't prove lots of
interesting things, it just means we can't promise to prove it when handed a
program. We can try, and sometimes we'll succeed.

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XorNot
The thing is a very simple program can be argued to be have been executed by
the person's reading it. You know it halts because you look at the code, step
through it mentally and - hey, it halts.

But that's the nature of the problem: you know it halts because just executed
it till it halts.

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dllthomas
Yes, running them until they halt is one way of determining that a program
halts on a given input. However, we can prove things do or don't halt without
that. Consider running, on an idealized machine (so no overflows),

    
    
        while(i>0) { i * 2; }
    

I think you would agree that this clearly never halts for any i > 0, and I
think it also clear that we did not determine that by running it until it did
not halt (because there is no such point).

Turing proved that _for some programs_ there is nothing we can do but run them
and see. That doesn't mean that's all we can ever do.

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rflrob
I'd need to read the paper, but the write up seems to ignore the possibility
that methylation is required to express the genes necessary to form memories,
and not that the methylation itself is, in any meaningful sense, the memory
itself (as in "memories [...] get written onto DNA).

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karpathy
This was my first reaction as well. Blocking methylation is a drastically
global operation for a cell as methylation is involved in so much of the
epigenetic regulation. Turning it off probably disabled much of the normal
functioning of those cells and could have had all kinds of downstream effects.

It doesn't seem fair to jump to the conclusion that the memory is actually
encoded in the methylation pattern somehow. Based on a skim of the paper, the
researchers don't seem to claim this either.

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XorNot
I'm hoping this turns out to be incorrect - a false lead. It would really suck
if in order to download mindstates, we needed to get inside the chemistry of
neuronal cells.

We can conceivably find an imaging technique that would let us 3D snapshot a
brain and all it's connections. But its a big step from that big step down to
getting nanoscopic views of the chemistry in every cell.

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gizmo686
If you want to download a mindstate, you will almost have to deal with details
at a molecular level. I am not familiar with the details of how the brain
works, but consider that their is likely a huge evolutionary advantage to
storing data more densely.

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bencollier49
Dodgy newspaper pop-sci interpretation involving past lives in 3..2..1..

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pnathan
While snarky, you're right. Also see the 1910-1940 idea of "Racial Memory".
One of the more popular and weird ideas to come out of Lamarkian concepts.

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ust
There was an interesting article in the Discover magazine about epigenetic
changes: [http://discovermagazine.com/2013/may/13-grandmas-
experiences...](http://discovermagazine.com/2013/may/13-grandmas-experiences-
leave-epigenetic-mark-on-your-genes)

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awda
Interesting that they could also block memory formation in addiction centers.
I wonder if there is a preventative treatment possible in that direction, by
blocking addiction before it happens? It's a nice dream, anyway.

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contingencies
Err, err, centralized government bureaucracy imposing own will-of-committee
between world and consciousness to inflict totalitarian conformance to pre-
approved homogeneity ... not good, even if: drugs/childporn/terrorism/etc.

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awda
What makes you think this is pushed by the government? I'm envisioning opt-in.

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nsxwolf
So... the premise of Alien 4 might not be as ridiculous as it seemed at the
time? :O

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nateabele
The takeaway: ASSASSIN'S CREED WAS RIGHT!!oen1

:-D

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StandardFuture
I really like the potential implications of this to future A.I. research. ;)

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xzrrwe
Genetic memory.

