The dataset excites me more than the fairly vague conclusion that some SNPs possibly linked to traits were selected for (or hitched along to genes which were selected for). Genetic archaeology is just so much more exciting than this.
But I bet there will be a ton more of that too, thanks to the high quality dataset.
> the fairly vague conclusion that some SNPs possibly linked to traits were selected for
Interesting. I find that part of the paper the most exciting. We always knew selection would happen for valuable traits. But seeing demonstrations of it in the timelines we have is pretty important.
This study covers about 10,000 years of recent human evolution in Europe and West Asia.
From the abstract:
>in the past ten millennia, we find that many hundreds of alleles have been affected by strong directional selection. We also document one-standard-deviation changes on the scale of modern variation in combinations of alleles that today predict complex traits. This includes decreases in predicted body fat and schizophrenia, and increases in measures of cognitive performance. These effects were measured in industrialized societies, and it remains unclear how these relate to phenotypes that were adaptive in the past. We estimate selection coefficients at 9.7 million variants, enabling study of how Darwinian forces couple to allelic effects and shape the genetic architecture of complex traits.
The flip side is everything is being degraded by random mutation.
It's like holding a large ball in place on a hill that sees frequent tremors. If the ball is still halfway up the hill it's being held in place, if it's being held in place it's still halfway up the hill. It might be considered a tautology if you're only working with symbols and ignore all the mechanistics.
It's more reproducing than surviving. If the population of some species increases and the number of copies of some allele remains constant we could consider than gene less fit than the other alleles, in the population genetics sense. So it's frequency rather than survival that geneticists look at. But that proves that there are indeed other ways that they could have defined fitness if they wanted to.
Whatever does not survive stops registering in later times; most of the time, what helps survival is retained, and what helps survival is what increases fitness.
As stated, this feels wrong. Specifically, it does not account for traits being appropriate for environment. I like to say it as what was needed for one stage could be the problem for the next stage.
That is, traits that stop registering may no longer be something that helps survival. But that does not mean they were not necessary for survival at an earlier point.
> We finally observed signals of selection for combinations of alleles
that today are associated with three correlated behavioural traits:
scores on intelligence tests (increasing γ = 0.74 ± 0.12), household
income (increasing γ = 1.12 ± 0.12) and years of schooling (increasing
γ = 0.63 ± 0.13). These signals are all highly polygenic, and we have
to drop 449–1,056 loci for the signals to become non-significant
(Extended Data Fig. 10). The signals are largely driven by selection
before approximately 2,000 years )*, after which γ tends towards zero
Presumably pressure in different regions lead to different combinations of those alleles, which I think they are shorthanding a bit, but the fact that those alleles exist makes blank slate theory a kind of rough assumption
> Just because an allele, SNP, or trait swept into or out of West Eurasia during this time doesn’t mean this happened only in West Eurasia. Researchers can use the new computational methods to look for directional selection in other populations worldwide that have enough ancient DNA sequences and construct a clearer picture of what’s unique to different groups and what generalizes across populations.
> Reich expects that future studies will show that shared selective pressures acted on some of the same core traits across diverse human groups, even as those groups split off and migrated to different parts of the world over tens of thousands of years.
There is a graph arguing “intelligence” has been positively selected in west Eurasian population in this paper according to a polygenic score (page 8 fig. 4)
Now I would be quite curious to know how they constructed this polygenic score
To be clear: most people who are keen on making such an argument, or who are identifying racial genetic differences as the primary takeaway of studies like this, are doing so to justify racism, either implicitly or explicitly.
But that's a strawman. Racism is wrong, even if there are minor genetic variances across populations (which... seems obvious?) Variance within a population strongly dominates the weak cross-population effects, and personal history (nutrition, education, etc) strongly dominates that.
And that's setting aside the moral implications of judging someone or changing your behavior towards them even if you have somehow measured them to be "less intelligent," as if that was a single axis of worth.
This interest in IQ has a negative effect on the concept of intelligence, never mind human unity. It attaches exaggerated importance to test scores, jobs, and school. It tends toward snobbery.
And yet you are also likely to argue “weather is not climate”. Differences in population characteristics of all kinds have massive societal implications and we should lean into addressing them.
But I bet there will be a ton more of that too, thanks to the high quality dataset.
Interesting. I find that part of the paper the most exciting. We always knew selection would happen for valuable traits. But seeing demonstrations of it in the timelines we have is pretty important.
This study covers about 10,000 years of recent human evolution in Europe and West Asia.
From the abstract:
>in the past ten millennia, we find that many hundreds of alleles have been affected by strong directional selection. We also document one-standard-deviation changes on the scale of modern variation in combinations of alleles that today predict complex traits. This includes decreases in predicted body fat and schizophrenia, and increases in measures of cognitive performance. These effects were measured in industrialized societies, and it remains unclear how these relate to phenotypes that were adaptive in the past. We estimate selection coefficients at 9.7 million variants, enabling study of how Darwinian forces couple to allelic effects and shape the genetic architecture of complex traits.
It's like holding a large ball in place on a hill that sees frequent tremors. If the ball is still halfway up the hill it's being held in place, if it's being held in place it's still halfway up the hill. It might be considered a tautology if you're only working with symbols and ignore all the mechanistics.
https://en.wikipedia.org/wiki/Fitness_(biology)
That is, traits that stop registering may no longer be something that helps survival. But that does not mean they were not necessary for survival at an earlier point.
Different evolutionary paths between races/regions, with impact on mental health and cognitive performance.
What you think the implications are of that for your present day lived experience, that might be a different conversation.
> We finally observed signals of selection for combinations of alleles that today are associated with three correlated behavioural traits: scores on intelligence tests (increasing γ = 0.74 ± 0.12), household income (increasing γ = 1.12 ± 0.12) and years of schooling (increasing γ = 0.63 ± 0.13). These signals are all highly polygenic, and we have to drop 449–1,056 loci for the signals to become non-significant (Extended Data Fig. 10). The signals are largely driven by selection before approximately 2,000 years )*, after which γ tends towards zero
Presumably pressure in different regions lead to different combinations of those alleles, which I think they are shorthanding a bit, but the fact that those alleles exist makes blank slate theory a kind of rough assumption
If anything they seem to support homogenization of intellectual capacity/mental health in Eurasia since 2kya.
The methodology, if it holds up, seems to hold a lot of promise for answering questions like this in the future.
> Just because an allele, SNP, or trait swept into or out of West Eurasia during this time doesn’t mean this happened only in West Eurasia. Researchers can use the new computational methods to look for directional selection in other populations worldwide that have enough ancient DNA sequences and construct a clearer picture of what’s unique to different groups and what generalizes across populations.
> Reich expects that future studies will show that shared selective pressures acted on some of the same core traits across diverse human groups, even as those groups split off and migrated to different parts of the world over tens of thousands of years.
https://hms.harvard.edu/news/massive-ancient-dna-study-revea...
Now I would be quite curious to know how they constructed this polygenic score
But that's a strawman. Racism is wrong, even if there are minor genetic variances across populations (which... seems obvious?) Variance within a population strongly dominates the weak cross-population effects, and personal history (nutrition, education, etc) strongly dominates that.
And that's setting aside the moral implications of judging someone or changing your behavior towards them even if you have somehow measured them to be "less intelligent," as if that was a single axis of worth.
Because, apparently, this needs to be said.
If you’re talking about trying to improve the genetics of populations at scale… yikes.