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Comment by ImaCake | Hacker News Reader

Yes, ppl in the same country have more similar genomes. But modern population genetics has found that 1. There is more similarity than difference between any 2 humans on earth (there are africans and europeans who share more dna than with others of their own ancestry. And, 2. People move around, a lot! We knew this already but there are a huge number of undocumented migrations that are being revealed by these studies. Turns out 20th century multiculturalism is just an acceleration of what we already did.

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Man, it’s kinda scary hearing the “more similarity between any two humans” line here on HN. That one’s up there with the “we only use 10% of our brains” line, for me. My understanding is that’s a pretty well documented misconception about genetic diversity which doesn’t really apply here.

> there are africans and europeans who share more dna [with each other] than with others of their own ancestry

No, there aren't. That's not a thing.

Note that your statements don't seem to contradict the idea of strong correlations based on ancestry that are visually inferrable

> But modern population genetics has found that 1. There is more similarity than difference between any 2 humans on earth

It's not even that modern. A human shares over 98% of the DNA of a pig, and about 50% of the DNA of a tree. Anything much closer to us than a tree has "more similarity than difference" to humans on a genetic level.

https://thednatests.com/how-much-dna-do-humans-share-with-ot...

> A human shares over 98% of the DNA of a pig

"The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which." - Orwell

> there are africans and europeans who share more dna than with others of their own ancestry

You're probably referring to the "greater variation within than between races" argument. But it's only true when looking at single genes, not collections of genes - that is how genetic tests can accurately determine race. And most traits are polygenic, so it does not even make sense to compare using only individual genes.

That's the reason Asian couples don't spontaneously give birth to European-looking children, and vice versa. And genes not expressed in superficial appearance were exposed to selection pressure just as much.

Whenever you see a theory so obviously contradict the evidence of your eyes, you should be at least skeptical of it (though not dismissive - e.g. quantum mechanics are true, however counterintuitive)

You're talking about averages. The idea that "genetic tests can accurately determine race" kind of falls apart when you apply it to an individual with mixed ancestry. You can probably detect and quantity the extent of the mix (which is why 23andme or ancestry can make money), but labelling a bunch of averages as "race" and arguing that there is an innate and immovable property of biology seems like there's something you're missing in drawing these correlations. You can start at a conclusion and show all sorts of correlations given enough data, but it doesn't give validity of how this is somehow the right way to look at it.

And that's not even getting into how you're giving off creepy eugenicist vibes.

Yes you are right about the greater variation being localised. But I thought it was localised at the level of linkage disequlibrium blocks which can encompass many thousands of genes at their largest.

Regardless the genetic distance between any two people remains tiny compared to the distance between even closely related species or sub-species elsewhere.

That's a roundabout expression of the narrative.

Lewontin came to that conclusion by examining exclusively blood type alleles, which was kind of asinine because they have no apparent geographic distribution pattern at all. Other genetic markers tell a much clearer story, as the principal component analysis shows. It couldn't really be any more obvious - the PCA makes a map. You can literally see each of the continents represented in a projection of genetic data.

Something like 30-50% of all human genetic variants are shared across continents. It's hardly asinine to say that a significant proportion of genetic variation is shared with everyone. Depending where you are talking about, ~20% of variation is unique to a given continent.

I don't think PCA plots really tell us much beyond there being distinct genetic clusters? One could do a PCA only on people with european ancestry, or people living in a small town, and there would be plenty of interesting structure to look at.

https://www.nature.com/articles/nature15393

  "One could do a PCA only on people with european ancestry, or people living in a small town"

That would be extremely interesting. Maybe a way to do polygenic risk scores for traits like IQ.

If the difference was 70 or 80% would they even be the same species?

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