
Cultural differences may leave their mark on DNA - upen
http://sciencebulletin.org/archives/9060.html
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toufka
I'll quote myself from a previous comment regarding epigenetics.

Epigenetics. It's the make-file for your genetic source code. Certain
conditions can cause certain parts of your genetic code to be uncommented or
commented-out. There are actually a number of different kinds of comments
(histone modifications [1]) - each set of marks particular to a different
compiler, in different contexts. And these comments/marks are copied with some
fidelity to daughter-cells/children along with a high-fidelty copy of the
underlying genetic code itself.

So the genes themselves are not being heritably altered, rather the recipe for
which gene is where, when can be subtly changed. But again, the same
mechanisms that permit the change in expression of those genes during a
lifetime can be subsequently changed in the next just as easily.

In this way you can store the code for some trait or capability over many
generations without having it always be running. It can manifest itself in
individual organisms as having very different phenotypes even with the same
underlying code.

[1]
[https://en.wikipedia.org/wiki/Histone_code](https://en.wikipedia.org/wiki/Histone_code)

~~~
marxidad
What muscles do you have to flex that will eventually lead to methylation of
histones?

~~~
toufka
LOTS of things affect epigenetics. It currently appears to be a messy,
relatively non-deterministic process with lots of different pathways crossing
wires with lots of other different pathways.

A snapshot of my mental model of epigenetics (warning: epigenetics/histone
modifications are not my particular field of study): "The methylator slides
along DNA to methylate histone tails at location 32 of histone 2 while in
simultaneous competition the demethylator demethylates methyl groups of
histone 1 at locations 4, 12 and 18 under most conditions, or location 32 of
histone 2 IFF it is within three histones of an acetylated histone which
itself has its acetylation competing with a deacetylator - constantly. And if
a certain set of marks occur appropriately in combination, a set of
neighboring histones wrap up and hide themselves and their DNA - preventing
its hidden DNA from being used in that cell until some other mechanism can
unwrap that section. Oh, and (most of) those marks are copied to
children/daughter cells right along with the copying of DNA."

Because it's so fickle, non-deterministic, and tangled (unlike it's DNA
counterpart) it's actually pretty hard to study and is currently (like this
afternoon, down your street) a topic of a significant amount of cutting edge
research. As the wikipedia article above shows, the 'Histone Code' is still a
work in progress, and it now appears unlikely that there is a 1:1 relationship
between this chemical mark and that effect, very much unlike the very nice
deterministic relationship we found between DNA->RNA->Protein.

One common change I've read about that bubbles up to normal life is the
capability of nicotine to affect histone acetylation. It seems to rapidly
alter histone modifications so as to make other habits/actions more addictive
[1] (precisely in a way that we now know THC does _not_ \- the original
'gateway drug' mis-extrapolation).

[1] [https://www.nih.gov/news-events/nih-research-matters/why-
nic...](https://www.nih.gov/news-events/nih-research-matters/why-nicotine-
gateway-drug)

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mcjon77
One thing that I don't hear talked about in many of these discussions about
the genetic components of race is how the mixed racial ancestry of many
"black" people in Europe and the Americas impacts these studies.

MANY blacks in the Americas and Europe have significant European DNA. For
example, even though my family identifies as black, my mother and her siblings
are almost 50℅ European according to DNA tests.

How does this factor in when making medical decisions based on assumptions
regarding race?

~~~
LordKano
As I remember it, something like 80% of people who we identify as African
Americans(or black) have significant amounts of European ancestry.

Outside of Africa, that's probably to be expected.

I too am "black", with two "black" parents but my mother had red hair and
green eyes. My son has blonde hair and blue eyes.

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kenjackson
_" Scientists and clinicians have increasingly tried to move away from
simplistic racial and ethnic categories in disease research, the authors say,
and – with the rise of precision medicine – in clinical diagnosis and
treatment as well. Studies by the Burchard group and others have found that
using genetic ancestry rather than ethnic self-identification significantly
improves diagnostic accuracy for certain diseases.

But the new data showing that a large fraction of epigenetic signatures of
ethnicity reflect something other than ancestry suggests that abandoning the
idea of race and ethnicity altogether could sacrifice a lot of valuable
information about the drivers of differences in health and disease between
different communities."_

The study shows that abandoning the idea of ethnicity could sacrifice
information, but it still seems to indicate that genetic ancestry is more
useful than race. Why does the article seem to conflate the two?

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kingkawn
if culture impacts DNA then the concept of DNA being subject to mutation as
the primary driving factor is at last beginning to crumble.

Also if culture impacts genetics then the idea there are races is clearly not
the case, but rather loosely organized behavioral groups that can change in
whatever direction their common culture takes them next.

All of the conclusions being drawn about the implications of this for your
hobby-grudges about politics are beyond inane

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pc2g4d
In my understanding, the article was saying that who your ancestors are has
less of an impact on DNA methylation (epigenetic markers) than where you grew
up. It's not about race, it's about ethnicity---the cultural identity of the
individuals, the environment they lived in. It's not about DNA, it's about how
DNA is actually manifested, as represented by methylation markers.

~~~
fvdessen
The articles states that at least 76% of the observed differences in the
population come from their raw DNA. Epigenetics may thus affect up to 24% of
the observed differences. So DNA is still the predominant factor.

~~~
medymed
Don't think so, they didn't look at raw dna sequences. They appear to just
look at ethnicities, within which there is a _lot_ of genetic variation.

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tristor
Looks like the TL;DR conclusion is that "race" is not just a social construct,
but actually has genetic markers which are expressed beyond ethnic heritage.
As the authors conclude, this could be extremely important in tailoring
medical treatments for people for differences in their genetic makeup based on
their race. In other words harder sciences are proving that social sciences
obsession with identity politics has hindered medical advancements once again.

~~~
hx87
_Biological populations_ certainly do exist, it's just that they don't
correlate well with prevailing concepts of "race". The average western African
is more similar to the average European than to the average southern African.

~~~
erispoe
Populations in Africa are also genetically more diverse than the rest of the
world combined.

~~~
lacampbell
But people are ignorant of Africa in general. When they talk about an African
race they're ignoring Ethiopians or khoisans or pygmies - they mean Bantu
people.

I don't think there's more genetic diversity among Bantus than the rest of the
world combined.

~~~
hx87
> But people are ignorant of Africa in general.

Not population geneticists. Africa in those cases == sub-Saharan African
people, not just Bantu.

------
macawfish
You know what's crazy? My cousin is months away from finishing his PhD in
pharmacy. Over thanksgiving break, he revealed to me that he had never heard
the term "epigenetics". I explained it to him. He works for a drug company
modeling interactions for new animal antibiotics and he'd never heard the term
"epigenetics"

My cousin is a bright, driven guy. There are reasons I distrust the western
medical establishment.

~~~
JamesBarney
The other way to look at it is epigenetics is much more important to pop-
science than real science.

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nickeleres
Ugh, the alt-right supremacists are going to have a field day with mis-
information around this o_o

------
lngnmn
Cultural changes rate are too infinitesimal compared to the time which is
required for any genetic change to get a chance to form and propagate through
a population to attain a stable presence (forming a distinct trait).

The probability that a certain cultural difference induced mutation could be
formed (given that there is no flow of information from a phenotype back to
genotype) is something incalculable.

What might work for a bacteria does not work for humans due to, you see,
fundamental differences in the reproductive system and development.

There are a few main principles from genetics 101 to consider before making
any attempts of "doing science".

    
    
       1. all mutations are *random*
       2. there is no backward flow of information
       3. environment does not alter DNA. random mutations do
       4. propagating of a mutation is an extremely rare event
       5. it takes *many* generations.
    

To understand these principles think _why_ we do not have much mutations of,
say, hemoglobin or glucose pathway enzimes.

There is another fundamental principle: way to many hipsters in what they call
"modern science".

~~~
danharaj
The article talks about gene expression, which is much more fluid. Another
factor that influences gene expression whose effects are just starting to be
measured is poverty.

~~~
lngnmn
Gene expression has nothing to do with altering DNA, leave alone any
propagation of such "changes".

~~~
danharaj
> The study examined DNA methylation—an “annotation” of DNA that alters gene
> expression without changing the genomic sequence itself—in a group of
> diverse Latino children. Methylation is one type of “epigenetic mark” that
> previous research has shown can be either inherited or altered by life
> experience.

What are you even arguing against?

~~~
lngnmn
I am arguing against ignoring the fundamental principle about one-way flow of
information DNA->RNA->protein which makes life sustainable.

Anything which contradicts with this principle is plainly nonsense - a product
of unconstrained imagination.

BTW, any changes which could be propagated through the mother's body, the way
some deceases do, would not get into the DNA. This is another fundamental
principle which contributes to sustainability of life - it is about isolation
and washing out of pathogens.

~~~
toufka
See my comment above. DNA can be commented in/out during an organism's
lifetime. And these comments/silencing capabilities are in fact transferable
to a child with some fidelity. And in that way those changes are heritable and
genetic, if not actually altering the DNA of the child in any way. This
capability is called epigenetics.

You are correct that the code of the DNA itself is not being altered, but
there are other heritable mechanisms that affect the structure, capability and
accessability of that DNA - i.e. gene expression, beyond the code of DNA
itself. This enables capabilities encoded in DNA to be passed down to children
without actually using them - or conversely, to enable certain latent
capabilities under certain environmental conditions.

Life is a bit more nuanced than the dogmatic one-way flow of information we
teach as 'the central dogma'. It gains its complexity by _always_ having an
exception to its own rules somewhere at some point if it physically possible
so, as to hedge against some change in conditions where that exception becomes
more powerful than the existing rule. The exception may be inconsequential and
of little benefit - until such time as it is not.

~~~
lngnmn
With generational time of almost 20 years?

What you are taking about is an ordinary blood-borne sexually transmitted
decease model (or a virus), and it has _nothing to do with genetics_ (gene
expression is a developmental topic), so there will be no "marks on a DNA" in
principle - it does not work that way.

There, however, could be some certain proteins bound to DNA, but it is a not a
genetic but biochemical (pathogenic-like) change. Those proteins could be
treated as markers.

The propagation rate of such proteins is still limited by the generation time,
so any connection to cultural differences is nonsense.

So, it is _not genetic_ , there is _no marks on DNA_ , it is not cultural.
Period.

~~~
macawfish
Even the number of twists in a DNA molecule can impact its interaction with
the environment.

[https://www.quantamagazine.org/20160105-supercoiled-
dna/](https://www.quantamagazine.org/20160105-supercoiled-dna/)

Living DNA exists in complex coils, smothered in a jelly of inter-mediating
molecules. It's quite messy and poorly understood! What _is_ understood is
that inheritance and expression of DNA information are absolutely non-linear.

