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Cultural differences may leave their mark on DNA

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Re: Cultural differences may leave their mark on DNA

#61

Post by fvdessen »

pc2g4d wrote: post #47

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.

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.

Re: Cultural differences may leave their mark on DNA

#62

Post by ChemicalWarfare »

svachalek wrote: post #31
ChemicalWarfare wrote: post #19

Earlier quoted context omitted.

"Race" has 2 meanings. 1. Race as a social construct. It does exist in that capacity - as an extreme example Irish were not considered "white" in America (google for some "hilarious" images from "back in the day"). 2. Race as a biological reality. This is a touchy subject for a variety of reasons. But that doesn't mean that well documented taxonomic differences between human races are "fake". They do exist and are mo…

What I understand of the issue is that genetic differences between populations are real, but they form a continuum whose boundaries are extremely blurry if visible at all from a genetic level. Thus the drawing of boundary lines and the assignment of individuals into those handful of categories is something subject to change from culture to culture. In other words, genetic differences do not make race a "biological re…

Just because there's "color brown" doesn't mean there's no "red" or "green" used to produce it even if (hypothetically) in someone's culture "brown" is considered to be "red-ish" :)

Re: Cultural differences may leave their mark on DNA

#63

Post by toufka »

marxidad wrote: post #59
toufka wrote: post #52

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 ar…

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

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...

Re: Cultural differences may leave their mark on DNA

#64

Post by 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?

Re: Cultural differences may leave their mark on DNA

#66

Post by fvdessen »

openasocket wrote: post #57
fvdessen wrote: post #49

Earlier quoted context omitted.

If you do a clustering analysis on a large sample of DNA data you will get different clusters corresponding to the usual definitions of races or ethnicities, depending on the number of clusters you choose. https://en.wikipedia.org/wiki/Human_genetic_clustering

That wiki page has a pretty substantial "Criticism" section. The Rosenberg et. al. paper even says their paper "should not be taken as evidence of our support of any particular concept of biological race." Their study shows that genetic distance is roughly linear with physical distance, barring obstacles like mountains and oceans. The consensus in the field, based on citations on that wiki page, seems to be that huma…

You can make meaningful and consistent groupings in a continuum . For example you can make a distinction between poor and rich citizens, even tough the income distribution is a continuum. Same goes for the rainbow, the fact that it is continuous doesn't prevent people from being able to differentiate yellow and blue.

But even so the human genome is not continuously distributed, even if the difference is linear with distance, simply due to the fact that humans are not continuously distributed geographically. You can't handwave oceans and mountains away.

The main criticism of clustering is that the hierarchy of clusters that you obtain depend on the distribution of your samples, and that we currently do not have a good uniform sampling of human DNA. In short clustering can tell you reliably if someone is Irish or Italian, but may falsely identify the french as italian if there are not enough samples for french people.

Re: Cultural differences may leave their mark on DNA

#67

Post by medymed »

fvdessen wrote: post #61
pc2g4d wrote: post #47

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.

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.

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.

Re: Cultural differences may leave their mark on DNA

#68

Post by sctb »

known wrote: post #27

"Diversity society will fail" --Putnam; http://www.boston.com/news/globe/ideas/articles/2007/08/05/t...

We asked you to please stop in response to this exact comment just over a month ago. Drive-by posts like this are not what Hacker News is for. We have to ban accounts that refuse to comment civilly and substantively.

Re: Cultural differences may leave their mark on DNA

#69

Post by sctb »

tiatia wrote: post #12

"conclusion is that "race" is not just a social construct" I mean, come on. This is news? What was he thinking were the different crime rates come from?

This is not a great comment for HN because it's no-information flamebait. Those kinds of posts are off-topic here.

https://news.ycombinator.com/newsguidelines.html

Re: Cultural differences may leave their mark on DNA

#70

Post by tristor »

openasocket wrote: post #13
tristor wrote: post #5

Earlier quoted context omitted.

I am not a geneticist, so perhaps I misunderstand, but the conclusion I formed seems to be reinforced by the quotes from the authors in the article. That is, there are specific gene expressions which are relevant in a medical context affected by cultural factors that are genetically transmitted. Genetic transmission at least to me implies that a person receives these things from their parents at birth, regardless of…

Gene expression is partially inherited and partially a product of environment. See https://en.wikipedia.org/wiki/Transgenerational_epigenetic_i... The classic example discussed is a study of children born during a famine. Children born during famine are going to be smaller than normal, but it was found that their children and grandchildren would be born smaller than normal, even though the famine has long since passe…

Thanks for the link. I read that, it seems to support my conclusion of this article as well. "As in, cultural differences can be expressed over time as genetic differences."

It seems like the debate we're having is a rehash of nature vs nurture, where it seems like the new research indicates nurture can affect nature for future generations through gene expression.

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