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The 2,000 Year Selection of the British
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Screenshot 2016-05-07 22.23.55

Phenotype selected for

Selection is one of the major parameters which population geneticists investigate. The easiest way to investigate selection is to have omniscience as to the change in allele frequencies over time. If you are a Drosophila geneticist this is feasible, as you control the reproduction of your model organism in the lab. It is obviously much more difficult in natural populations (one reason that I think ecological genetics went into decline for a while is that it is just very hard). And in long-lived species like humans it is really not feasible to “track” change in allele frequencies in real time, as that would take centuries in the least.

So researchers have to make recourse to inferences from patterns of variation in the genome for species like humans, as it allows us to look back into the deep past. The inheritance pattern of Mendelian genetics is such that transmission of variants across the generations can be modeled, and processes such as rapid population growth or positive selection leaves footprints in the genome long after they’ve done their job. So you can test for selection, or population expansion, or bottlenecks, just by looking at patterns that you’d expect being left in their wake. The PSMC method famously infers demographic history of populations by examining variation within a single whole genome!

principlespopulationgenetics In regards to selection, which population geneticists are interested in because it is one of the preconditions for the evolutionary process of adaptation, there are many methods of inference from genetic and genomic data. Tajima’s D is an older method which compares different types of diversity across the genome, and popular for those looking more at inter-specific differences. More recently haplotype based tests look for long segments of variants within the genome. EHH and iHS are probably two of the more popular versions of this. Haplotype based methods really didn’t become popular until the middle 2000s because they require a certain density of data which is really “post-genomic” era. Then you have the methods which look for frequency differences between populations, and compare them to the expectation based on patterns across the whole genome (e.g., PBS). Again, these require genome-wide data. More generally the popularity of site frequency based techniques rely on enough data to actually produce a site frequency.

And just as these methods have needs in terms of the raw data necessary to produce viable statistics, they also exhibit different strengths and weaknesses. The haplotype based methods are good at detecting “hard sweeps,” that is, strong positive selection on a novel mutation emerging against the ancestral background. EHH picks up completed sweeps across populations. In contrast, iHS is better at obtaining traction at incomplete sweeps. Though they have good power to detect events on a human microevolutionary scale, think on the order of 10,000 years, they get fuzzy as one approaches the present. Specifically, when iHS detects older incomplete sweeps it may not tell you if the sweep is still occurring, but it probably is. Additionally, they’re not particularly good at picking up “soft sweeps,” where alleles long segregating within the population are driven up in frequency by selection, or polygenic selection where the impact of the coefficient is distributed across the genome.

intropopulationgenetics Finally, there have been attempts to detect selection using ancient DNA. This a technique which takes a step toward omniscience; rather than inferring from extant variation one can track allele frequency change in “real time” through the record of the DNA. The problem of course is that sample sizes are finite and data quality is often hit and miss.

This is why the preprint Detection of human adaptation during the past 2,000 years, out of Jonathan Pritchard’s lab, has me so excited. Using the whole genome sequence data that has come online over the past few years at large sample sizes they manage to infer selection events over the past 2,000 years among the British! Here’s the abstract:

Detection of recent natural selection is a challenging problem in population genetics, as standard methods generally integrate over long timescales. Here we introduce the Singleton Density Score (SDS), a powerful measure to infer very recent changes in allele frequencies from contemporary genome sequences. When applied to data from the UK10K Project, SDS reflects allele frequency changes in the ancestors of modern Britons during the past 2,000 years. We see strong signals of selection at lactase and HLA, and in favor of blond hair and blue eyes. Turning to signals of polygenic adaptation we find, remarkably, that recent selection for increased height has driven allele frequency shifts across most of the genome. Moreover, we report suggestive new evidence for polygenic shifts affecting many other complex traits. Our results suggest that polygenic adaptation has played a pervasive role in shaping genotypic and phenotypic variation in modern humans.

Screenshot 2016-05-08 00.35.44 The basic logic is not difficult to grasp. Derived alleles (the novel ones which mutated recently) subject to selection tend to alter their local genomic region in predictable ways. In particular, derived alleles subject to positive selection will exhibit shallower genealogies than ancestral neutral variants. Conventional neutral processes result in the birth of mutations and extinction of ancestral variants at regular intervals as modeled by the coalescent process. Some alleles will increase in frequency rapidly, and some more slowly, but it will be a random affair. In the figure above the dark branches are ancestral and red derived. The right panel shows that the coalescence of ancestral and derived are regular and approximately the same for a neutral context (i.e., selection is not targeting the derived variant). In contrast, in the left panel you see that the derived variants have a much shallower coalescence, presumably because of rapid expansion in the population of alleles in the recent past back to a common ancestor.

The SDS needs genome-wide data, as well as large sample sizes. In 2016 you have both, at least for some regions of the world and populations. Comparing SDS to haplotype-based methods they find that the biggest differences in selection in the latter are continental-scale; that is, between Europe and Africa. In contrast, SDS tends to zoom in on intra-European variation, because a ~2,000 year time scale is likely to be localized.

Screenshot 2016-05-08 00.46.28They found lots and lots of selection. The signals around LCT and MHC were not entirely surprising. LCT is almost a positive control for a test of selection. It’s pervasive in Europe, but it was only recently selected, and so there are still ancestral variants around (unlike SLC24A5 which went nearly to fixation in a literal sense). MHC has to do with immune response, and that’s always evolving.

Perhaps more interesting is that the authors detect continuous selection on height and pigmentation in their sample. Why height? I’ve been skeptical of some of the genetic arguments in Greg Clark’s A Farewell to Alms (and have told Greg so), but, recent selection for height does seem to align with his idea that the English were particularly wealth and healthy over the past ~2,000 years. And, it also seems to support the suggestion of elite over-production, as presumably tall men would be more well represented among elites for both nutritional and genetic reasons.

410uvoV1qDL._SY344_BO1,204,203,200_ The results for pigmentation are intriguing. Some of the older signals don’t show up (e.g., SLC24A5 and SLC45A2). They’re either fixed, or near fixed, so where are the old haplotypes going to be to compare to? But intriguingly the selection around KITLG and OCA-HERC2 still seems to be occurring! Though the authors associate them with hair and eye color, the extreme tissue specific expression does not mean they have no effect on skin color. In the supplements they note that “In all 14 cases the derived allele is associated with either lighter pigmentation (i.e., lighter hair, skin, or eyes) or increased freckling.” Additionally, they state in the main text that “We speculate that recent selection in favor of blond hair and blue eyes may reflect sexual selection for these phenotypes in the ancestors of the British, as opposed to the longer-term trend toward lighter skin pigmentation in non-Africans, generally thought to have been driven by the need for Vitamin D production.”

At this point reader Sean will probably have a meltdown, and have to go to his natural reflex to core-dump everything on sexual selection he has taken in from Peter Frost for the 1000th time. If he doesn’t control his overwhelming sexually selected urge to repeat himself like a robot I’m going to ban him, as I don’t really want to re-read the same comment again. That being said, I don’t really know how seriously the authors take the idea that pigmentation is sexually selected….

41czavSUnNL._SY344_BO1,204,203,200_ I find Geoffrey Miller’s The Mating Mind interesting, but I’m mildly skeptical of the importance of sexual selection in recent human history (as opposed to earlier periods when broad human behaviors became fixed in our lineage). Often sexual selection crops up as a deus ex machina in these sorts of papers (I also don’t see enough variation in reproductive skew to make sexual selection plausible). The reason is simple. Geneticists are good at detecting selection occurring, but far less clear how and why selection is occurring. In this way LCT is an exception.

With all that said, this is an incredible paper. Because of the large genomic data sets in the United Kingdom the preprint focused on the British. But this is the sort of analysis going to expand to all populations in the near future. Genomics will be ubiquitous, as will the tools to make inferences about population history and dynamics.

 
• Category: Science • Tags: Genomics 
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  1. Quite a thing.

    I must admit I wasn’t expecting this as I’d been assuming most of the things they mention were selected for in the more distant past and just glided since then. Recalibrating.

  2. Decent of you to give a shout out to Sean. That indicates what some of us have suspected all along, deep down you are not really an ole meanie.

  3. A familiar problem in our world of loss-of-function deleterious mutations with typically older-adult ages of onset mitigating purifying selection (a.k.a. cancer predisposition genes). Very interesting, Razib.

    When one relies on coalescence-modeling, wouldn’t preexisting population structures associated with differential reproduction success muddy the waters? Privileged classes, or reproductively successful cultural and religious groups, often arise from genetically distinct subpopulations (the extreme version of this would be thoroughly endogamous castes of India?). I’m sure that in Old England, gentry and merchants and successful religious minorities would have overlaid with the population structure patterns. Could the coalescence patterns in these subpopulations appear to be more shallow simply because they proliferated faster than average?

    • Replies: @Rick
    "Could the coalescence patterns in these subpopulations appear to be more shallow simply because they proliferated faster than average?"

    If they did, it would be low level and randomly all across the genome. The exception is if there was selection on certain positions in the genome. This is exacly the signal that is being picked up.
  4. Rick says:
    @Dmitry Pruss
    A familiar problem in our world of loss-of-function deleterious mutations with typically older-adult ages of onset mitigating purifying selection (a.k.a. cancer predisposition genes). Very interesting, Razib.

    When one relies on coalescence-modeling, wouldn't preexisting population structures associated with differential reproduction success muddy the waters? Privileged classes, or reproductively successful cultural and religious groups, often arise from genetically distinct subpopulations (the extreme version of this would be thoroughly endogamous castes of India?). I'm sure that in Old England, gentry and merchants and successful religious minorities would have overlaid with the population structure patterns. Could the coalescence patterns in these subpopulations appear to be more shallow simply because they proliferated faster than average?

    “Could the coalescence patterns in these subpopulations appear to be more shallow simply because they proliferated faster than average?”

    If they did, it would be low level and randomly all across the genome. The exception is if there was selection on certain positions in the genome. This is exacly the signal that is being picked up.

    • Replies: @Dmitry Pruss
    Probably not randomly across the genome because in many loci, purifying selection is always present to weed out some new variation.

    Speaking of which ... what do they have to say about functional significance of the recently acquired variation in the selected loci? Exonic / intronic, neutral / missense / truncating? Surely understanding what exactly the observed variants did to the genes function would elucidate the selection pressures?

  5. they really went all out on correcting for pop substructures. also, i have looked at lots of british data for ftDNA. there’s some as you might expect from anglo-saxons…but it’s very minor.

    • Replies: @Bhroham
    So do you mean that this selection is largely not due to sexually successful Germanic invaders, but dynamics internal to the population?
  6. @Razib Khan
    they really went all out on correcting for pop substructures. also, i have looked at lots of british data for ftDNA. there's some as you might expect from anglo-saxons...but it's very minor.

    So do you mean that this selection is largely not due to sexually successful Germanic invaders, but dynamics internal to the population?

    • Replies: @Razib Khan
    yes. read the supplements. they checked for structure every which way. additionally, PoBI makes clear that germanic ancestry tails off very fast away from east anglia. they would be able to tell if SDS correlated positively with germanic ancestry....
  7. @Rick
    "Could the coalescence patterns in these subpopulations appear to be more shallow simply because they proliferated faster than average?"

    If they did, it would be low level and randomly all across the genome. The exception is if there was selection on certain positions in the genome. This is exacly the signal that is being picked up.

    Probably not randomly across the genome because in many loci, purifying selection is always present to weed out some new variation.

    Speaking of which … what do they have to say about functional significance of the recently acquired variation in the selected loci? Exonic / intronic, neutral / missense / truncating? Surely understanding what exactly the observed variants did to the genes function would elucidate the selection pressures?

  8. @Bhroham
    So do you mean that this selection is largely not due to sexually successful Germanic invaders, but dynamics internal to the population?

    yes. read the supplements. they checked for structure every which way. additionally, PoBI makes clear that germanic ancestry tails off very fast away from east anglia. they would be able to tell if SDS correlated positively with germanic ancestry….

  9. Sean says:

    Yes geneticists can’t tell us why something was selected, but by the same token they cannot tell if a gene has been selected for cultural, (biologically speaking purely arbitrary) reasons.

    The Civilization of the Goddess articulated what Gimbutas saw as the differences between the Old European system, which she considered goddess- and woman-centered (gynocentric), and the Bronze Age Indo-European patriarchal (“androcratic”) culture which supplanted it. According to her interpretations, gynocentric (or matristic) societies were peaceful, honored women, and espoused economic equality. https://en.wikipedia.org/wiki/Marija_Gimbutas#Late_archaeology

    Maybe back then no one thought aspects of visible phenotype significant.

    Humans can tell if someone is blond, just as easily as they can tell the difference between Harpo Marx and Forrest Tucker, so at first blush it seems feasible for non-cryptic traits to be the subject of preference, and such selection could be entirely due to cultural change, quite old cultural charge. The Indo Europeans in their conquests seemed to have killed men and used the nubile women as sex slaves (who could be tortured and sacrificed on their masters death). That might have been the origin of a patriarchal society in which phenotypes came to have significance they lacked before.

    Being short is not an appreciable disadvantage for a woman, in fact:-

    This study used data from Britain’s National Child Development Study to examine the life histories of a nationally representative group of women. Height was weakly but significantly related to reproductive success. The relationship was U-shaped, with deficits at the extremes of height. This pattern was largely due to poor health among extremely tall and extremely short women. However, the maximum reproductive success was found below the mean height for women. Thus, selection appears to be sexually disruptive in this population, favouring tall men and short women. Over evolutionary time, such a situation tends to maintain sexual dimorphism. http://www.ncbi.nlm.nih.gov/pubmed/12350254

    When the Anglo Saxon invaders of England (big men with skulls as thick as a Cromagnon’s) arrived I suppose the native men, in the words of Duke Nukem, got it “Right in the jewels” and were left lamenting “Damn it, why do they always take the hot ones?”.

    Though the authors associate them with hair and eye color, the extreme tissue specific expression does not mean they have no effect on skin color. In the supplements they note that “In all 14 cases the derived allele is associated with either lighter pigmentation (i.e., lighter hair, skin, or eyes) or increased freckling.”

    There are apparently nonsynonymous OCA2 variants important in human eye color and while some affect skin colour as well, my reading at aforementioned abstract link is recent evidence suggests some that just produce novel eye colours like grey and green.

    • Replies: @Razib Khan
    my reading at aforementioned abstract link is recent evidence suggests some that just produce novel eye colours like grey and green.


    markers aren't always functional. that being said, i'm 95% sure all oca2/herc2 functional variants have an impact on skin color. if the study doesn't detect it then it's due to lack of statistical power etc. there's no plausibility to me that tissue specific expression (or lack of) is going to be so specific.

    though i matters. my son is darker of skin than his sister, but lighter of hair. he is a het. at KITLG, as are 15% of northern europeans....
  10. OK, so of course they don’t make claims about the significance of new variation in the loci. Although as I said, one might have obtained additional evidence for selection from it. But they just look at the density of new variation near the SNPs to gauge which SNP alleles had substantially different frequencies in the recent past vs. today. (“Recent” being tens generations).

    Some SNP alleles may have increased in frequency due to selection, and others, due to randomly higher frequency of these alleles in a subpopulation which exhibited higher population growth in this timeframe?

    • Replies: @Razib Khan
    Some SNP alleles may have increased in frequency due to selection, and others, due to randomly higher frequency of these alleles in a subpopulation which exhibited higher population growth in this timeframe?

    the time frame is pretty short. aside from anglo-saxons there's not feasible structure that i can think of.
  11. @Dmitry Pruss
    OK, so of course they don't make claims about the significance of new variation in the loci. Although as I said, one might have obtained additional evidence for selection from it. But they just look at the density of new variation near the SNPs to gauge which SNP alleles had substantially different frequencies in the recent past vs. today. ("Recent" being tens generations).

    Some SNP alleles may have increased in frequency due to selection, and others, due to randomly higher frequency of these alleles in a subpopulation which exhibited higher population growth in this timeframe?

    Some SNP alleles may have increased in frequency due to selection, and others, due to randomly higher frequency of these alleles in a subpopulation which exhibited higher population growth in this timeframe?

    the time frame is pretty short. aside from anglo-saxons there’s not feasible structure that i can think of.

    • Replies: @Dmitry Pruss
    With population structure controlling, didn't they just try to exclude descendants of the South Asians and like? I understand that they marked a subset of singletons "possibly migration-related" if they were presented in non-European datasets, and excluded the top decile of the British subjects as ranked by tally of these "migration singletons"? It didn't look to me like they were trying to sort out any intra-European influxes. Among those Danes, Irish, Normans, Sephardi Jews all might have contributed to he disproportionately growing subpopulations within the last two millennia?

    This said, I also noticed in the supplemental materials that all of their pigmentation loci with the evidence of increasing derived allele frequency were acting in the same direction (lighter colors / increased freckles). Which does look like a good proxy for functional characterization of the variants. Essentially, we don't simply see shifts in allele frequencies in the same set of traits, but also shifts all in the same direction. It's a lot harder to explain by population heterogeneity considerations...

  12. @Sean
    Yes geneticists can't tell us why something was selected, but by the same token they cannot tell if a gene has been selected for cultural, (biologically speaking purely arbitrary) reasons.

    The Civilization of the Goddess articulated what Gimbutas saw as the differences between the Old European system, which she considered goddess- and woman-centered (gynocentric), and the Bronze Age Indo-European patriarchal ("androcratic") culture which supplanted it. According to her interpretations, gynocentric (or matristic) societies were peaceful, honored women, and espoused economic equality. https://en.wikipedia.org/wiki/Marija_Gimbutas#Late_archaeology
     
    Maybe back then no one thought aspects of visible phenotype significant.

    Humans can tell if someone is blond, just as easily as they can tell the difference between Harpo Marx and Forrest Tucker, so at first blush it seems feasible for non-cryptic traits to be the subject of preference, and such selection could be entirely due to cultural change, quite old cultural charge. The Indo Europeans in their conquests seemed to have killed men and used the nubile women as sex slaves (who could be tortured and sacrificed on their masters death). That might have been the origin of a patriarchal society in which phenotypes came to have significance they lacked before.

    Being short is not an appreciable disadvantage for a woman, in fact:-

    This study used data from Britain's National Child Development Study to examine the life histories of a nationally representative group of women. Height was weakly but significantly related to reproductive success. The relationship was U-shaped, with deficits at the extremes of height. This pattern was largely due to poor health among extremely tall and extremely short women. However, the maximum reproductive success was found below the mean height for women. Thus, selection appears to be sexually disruptive in this population, favouring tall men and short women. Over evolutionary time, such a situation tends to maintain sexual dimorphism. http://www.ncbi.nlm.nih.gov/pubmed/12350254
     
    When the Anglo Saxon invaders of England (big men with skulls as thick as a Cromagnon's) arrived I suppose the native men, in the words of Duke Nukem, got it "Right in the jewels" and were left lamenting "Damn it, why do they always take the hot ones?".

    Though the authors associate them with hair and eye color, the extreme tissue specific expression does not mean they have no effect on skin color. In the supplements they note that “In all 14 cases the derived allele is associated with either lighter pigmentation (i.e., lighter hair, skin, or eyes) or increased freckling.”
     
    There are apparently nonsynonymous OCA2 variants important in human eye color and while some affect skin colour as well, my reading at aforementioned abstract link is recent evidence suggests some that just produce novel eye colours like grey and green.

    my reading at aforementioned abstract link is recent evidence suggests some that just produce novel eye colours like grey and green.

    markers aren’t always functional. that being said, i’m 95% sure all oca2/herc2 functional variants have an impact on skin color. if the study doesn’t detect it then it’s due to lack of statistical power etc. there’s no plausibility to me that tissue specific expression (or lack of) is going to be so specific.

    though i matters. my son is darker of skin than his sister, but lighter of hair. he is a het. at KITLG, as are 15% of northern europeans….

  13. Ireland and The United Kingdom are unique in that even among ethnic Indigeneous Irish and Brits who have black hair or dark brown hair, the majority of them still have blue eyes.

    Which is the opposite of the Mediterranean where the majority of people with black hair and dark brown hair have brown eyes, followed by hazel eyes, and than blue eyes come in 3rd place.

    But in Ireland and The U.K the brunettes are just as equally blue eyed as the blondes and the gingers.

  14. Sean says:

    I’m 95% sure all oca2/herc2 functional variants have an impact on skin color.

    Plausible that if you look close enough there is functional effect on skin, but then I think it depends if those variants got off the ground in a time and place where they conferred some advantage and there was none of the other variants around (aren’t some the two east Asian lightening variants suspected to have originated from different regions?).

    On the other hand in a European population where the other variants already existed, what would the advantage be of a weak tweak in skin colour? In that case the SNP’s advantage if more likely to have lay with the effect on eye colour. I would note the 14,000-year-old Villabruna, Italy, cluster had a male with blue eyes. http://www.bbc.co.uk/news/science-environment-36150502

    If there were separate SNPs on the ground floor of isolated population across Europe, and they all came together later, then you are right.

    • Replies: @Razib Khan
    i have no idea what you are trying to say.

    though thanks for being concise about it.

  15. @Sean

    I’m 95% sure all oca2/herc2 functional variants have an impact on skin color.
     
    Plausible that if you look close enough there is functional effect on skin, but then I think it depends if those variants got off the ground in a time and place where they conferred some advantage and there was none of the other variants around (aren't some the two east Asian lightening variants suspected to have originated from different regions?).

    On the other hand in a European population where the other variants already existed, what would the advantage be of a weak tweak in skin colour? In that case the SNP's advantage if more likely to have lay with the effect on eye colour. I would note the 14,000-year-old Villabruna, Italy, cluster had a male with blue eyes. http://www.bbc.co.uk/news/science-environment-36150502

    If there were separate SNPs on the ground floor of isolated population across Europe, and they all came together later, then you are right.

    i have no idea what you are trying to say.

    though thanks for being concise about it.

  16. @Razib Khan
    Some SNP alleles may have increased in frequency due to selection, and others, due to randomly higher frequency of these alleles in a subpopulation which exhibited higher population growth in this timeframe?

    the time frame is pretty short. aside from anglo-saxons there's not feasible structure that i can think of.

    With population structure controlling, didn’t they just try to exclude descendants of the South Asians and like? I understand that they marked a subset of singletons “possibly migration-related” if they were presented in non-European datasets, and excluded the top decile of the British subjects as ranked by tally of these “migration singletons”? It didn’t look to me like they were trying to sort out any intra-European influxes. Among those Danes, Irish, Normans, Sephardi Jews all might have contributed to he disproportionately growing subpopulations within the last two millennia?

    This said, I also noticed in the supplemental materials that all of their pigmentation loci with the evidence of increasing derived allele frequency were acting in the same direction (lighter colors / increased freckles). Which does look like a good proxy for functional characterization of the variants. Essentially, we don’t simply see shifts in allele frequencies in the same set of traits, but also shifts all in the same direction. It’s a lot harder to explain by population heterogeneity considerations…

    • Replies: @Razib Khan
    It didn’t look to me like they were trying to sort out any intra-European influxes.

    it seems pretty clear to me that they did do so in the supplements.
  17. @Dmitry Pruss
    With population structure controlling, didn't they just try to exclude descendants of the South Asians and like? I understand that they marked a subset of singletons "possibly migration-related" if they were presented in non-European datasets, and excluded the top decile of the British subjects as ranked by tally of these "migration singletons"? It didn't look to me like they were trying to sort out any intra-European influxes. Among those Danes, Irish, Normans, Sephardi Jews all might have contributed to he disproportionately growing subpopulations within the last two millennia?

    This said, I also noticed in the supplemental materials that all of their pigmentation loci with the evidence of increasing derived allele frequency were acting in the same direction (lighter colors / increased freckles). Which does look like a good proxy for functional characterization of the variants. Essentially, we don't simply see shifts in allele frequencies in the same set of traits, but also shifts all in the same direction. It's a lot harder to explain by population heterogeneity considerations...

    It didn’t look to me like they were trying to sort out any intra-European influxes.

    it seems pretty clear to me that they did do so in the supplements.

  18. RK says:

    Some of the most interesting signals we see here are for increased first age at menarche, increased infant head circumference and increased hip width in women, which is expected due to corresponding requirements for a wider birth canal. This gives some evidence that agricultural-commercial civilisation pushed directionally on human life history strategy, in Britain at least, with a more K-selected phenotype being favoured, and later reproduction and more costly offspring. If we also include height, the complex signal seems to point towards more investment in growth and maintenance at early ages at the expense of reproduction.

    It would be great if this study were repeated across Europe. We could check if signals for K-selection are especially strong within the Hajnal Line, where late reproduction was culturally favoured.

    • Replies: @Rick
    I thought that actual first age at menarche has been decreasing for over 100 years.
    , @RaceRealist88

    increased first age at menarche, increased infant head circumference and increased hip width in women, which is expected due to corresponding requirements for a wider birth canal.
     
    Weird! This lines up with what Rushton says. Black girls have earlier menarche, due to leptin.

    http://notpoliticallycorrect.me/2016/04/02/the-role-of-leptin-and-sexual-maturity-in-black-girls/
  19. Who is the blonde? Rosamund Pike?

    I used Jason Statham’s fiance Rosie Huntington-Whitely to illustrate.

    • Replies: @Jefferson
    "Who is the blonde? Rosamund Pike?"

    There is a film called Johnny English where Rosamund Pike falls in love with Mr. Bean. Hollywood has a history of making films where the non handsome man gets the beautiful woman.

  20. @RK
    Some of the most interesting signals we see here are for increased first age at menarche, increased infant head circumference and increased hip width in women, which is expected due to corresponding requirements for a wider birth canal. This gives some evidence that agricultural-commercial civilisation pushed directionally on human life history strategy, in Britain at least, with a more K-selected phenotype being favoured, and later reproduction and more costly offspring. If we also include height, the complex signal seems to point towards more investment in growth and maintenance at early ages at the expense of reproduction.

    It would be great if this study were repeated across Europe. We could check if signals for K-selection are especially strong within the Hajnal Line, where late reproduction was culturally favoured.

    I thought that actual first age at menarche has been decreasing for over 100 years.

    • Replies: @notanon
    That would be interesting to see - if it had been gradually increasing until say the industrial revolution.
    , @Art
    I thought that actual first age at menarche has been decreasing for over 100 years.

    Why is this happening - why are our girls coming of age sooner - is the species in danger - are our genetics telling us something?

    Do we need to reproduce sooner - if so why? What selection process is at work?
  21. [By mistake I posted this on another thread at Unz. I meant to post it here.]

    In the fullness of time, truth will out, even very embarrassing truth.

    One thing that this result is making obvious is that the truth of ongoing, and significant, selection in human groups is going to be verified from many angles, not just one. The most direct approach of course is to find the set of alleles that lie behind, say, IQ, and show that they are differentially distributed across human groups. Another way is now to show that in certain groups certain areas of the genome connected with IQ show signs of recent selection. I have little doubt that there will other methods to come to the same sort of conclusions.

    There will come a time, likely within 5 years from what I’ve been hearing, in which it will be as discreditable for a geneticist or evolutionary biologist to dispute these conclusions as it became for physicists early in the 20th century to dispute the theory of relativity.

    Which brings to mind the disgraceful letter sent to the NY Times by a number of geneticists and evolutionary biologists denouncing Nicholas Wade:

    http://www.nytimes.com/2014/08/10/books/review/letters-a-troublesome-inheritance.html?_r=0

    How will the signatories of this letter look come this new paradigm? Very much like those dogmatic physicists who rejected relativity. It may be that the single thing they are best remembered for is this disgraceful act of ignorance and suppression: they will be laughingstocks for the ages, a lesson taught to children to warn them of the dangers of ideology and dogmatism.

    It really is time for them to get on the other side of this before their reputation and legacies are beyond repair.

  22. It seems to me that this study has the potential to both prove the basic thrust of HBD, but disprove some of the most common interpretations of it.

    The reason I say this is because it shows that in just one nation, over a period of 2,000 years, there was significant selection for a number of physical traits. This also presumably means that selection could take place over the same period of time for traits influencing cognition or personality. But again, this just one nation – not “Europe” as a whole. Of course significant portions of Europe could have been engaged in roughly parallel selection. But for the most part (and increasingly as time passed) if a trait was selected for across two populations, it wouldn’t be because an allele native to one introgressed into the other. It would be because two populations with broadly similar genetic distributions experienced similar selection pressures, be it from similar cultures or shared environmental changes.

    The main point is within recent times the base unit of “natural selection” for a human population isn’t going to be the continent as a whole – it’s going to be the local population group – which is often defined by whatever ethno-religious group you are considering (although caste can also play a role where the caste system is strong). This is one reason why I’ve always been somewhat suspect of the global IQ maps which show the greatest variation on IQ being on continental/subcontinental basis. Human height, after all, is overall greater in higher latitudes, but shows considerable variation within all continents, even though it appears to be governed by at least an order of magnitude less genes. If populations in close proximity can have selection push them in opposite directions regarding height, the same can clearly happen regarding intelligence, or any number of personality traits, over a period of centuries to millennia.

    • Replies: @candid_observer
    One of the things your account doesn't address is the pressure on selection due to conquest and replacement of populations -- an obviously very common feature across known populations.

    One would ordinarily expect that such patterns of conquest and replacement have a stabilizing effect across large regions -- perhaps even continents. Very likely, there are traits such that, if neighboring populations differ on them by more than a certain amount, then one population will conquer and replace the other. Even if the population that's mostly on the losing end of these conquests manages to hide or move away and survive, there will likely be a strong selection for the traits in question in the remaining population. Likely, IQ is such a trait, though exactly which way it works is open to question. On the one hand, higher IQ would suggest better technology and organizational ability for warriors. On the other hand, higher IQ might create more wealth and sedentary behavior, subjecting the population to predatory behavior from more aggressive outsiders.

    Thinking of human populations as simply evolving separately as groups probably is the wrong model.

  23. @Rick
    I thought that actual first age at menarche has been decreasing for over 100 years.

    That would be interesting to see – if it had been gradually increasing until say the industrial revolution.

  24. @Karl Zimmerman
    It seems to me that this study has the potential to both prove the basic thrust of HBD, but disprove some of the most common interpretations of it.

    The reason I say this is because it shows that in just one nation, over a period of 2,000 years, there was significant selection for a number of physical traits. This also presumably means that selection could take place over the same period of time for traits influencing cognition or personality. But again, this just one nation - not "Europe" as a whole. Of course significant portions of Europe could have been engaged in roughly parallel selection. But for the most part (and increasingly as time passed) if a trait was selected for across two populations, it wouldn't be because an allele native to one introgressed into the other. It would be because two populations with broadly similar genetic distributions experienced similar selection pressures, be it from similar cultures or shared environmental changes.

    The main point is within recent times the base unit of "natural selection" for a human population isn't going to be the continent as a whole - it's going to be the local population group - which is often defined by whatever ethno-religious group you are considering (although caste can also play a role where the caste system is strong). This is one reason why I've always been somewhat suspect of the global IQ maps which show the greatest variation on IQ being on continental/subcontinental basis. Human height, after all, is overall greater in higher latitudes, but shows considerable variation within all continents, even though it appears to be governed by at least an order of magnitude less genes. If populations in close proximity can have selection push them in opposite directions regarding height, the same can clearly happen regarding intelligence, or any number of personality traits, over a period of centuries to millennia.

    One of the things your account doesn’t address is the pressure on selection due to conquest and replacement of populations — an obviously very common feature across known populations.

    One would ordinarily expect that such patterns of conquest and replacement have a stabilizing effect across large regions — perhaps even continents. Very likely, there are traits such that, if neighboring populations differ on them by more than a certain amount, then one population will conquer and replace the other. Even if the population that’s mostly on the losing end of these conquests manages to hide or move away and survive, there will likely be a strong selection for the traits in question in the remaining population. Likely, IQ is such a trait, though exactly which way it works is open to question. On the one hand, higher IQ would suggest better technology and organizational ability for warriors. On the other hand, higher IQ might create more wealth and sedentary behavior, subjecting the population to predatory behavior from more aggressive outsiders.

    Thinking of human populations as simply evolving separately as groups probably is the wrong model.

    • Replies: @Karl Zimmerman
    Obviously in many circumstances conquest and replacement was a hugely important aspect of population genetics - and ultimately affected the selection of traits. But in the case of Britain in particular, it was apparently not hugely important over the common era. As of last year, it's finally been definitively proven the Saxon admixture into the British substrate was relatively minor (on the order of 20%). IIRC the same study concluded there was relatively little sign of a genetic legacy of the Romans, Vikings (outside of the Orkneys) or Normans despite these conquests. The English really are mostly "Celtic" in terms of their ancestry - if not their culture.

    Of course, Britain is just one example in Europe. But my general understanding is the Slavic demographic explosion and resulting migration was probably the last substantive change of the ancestry of Europe until the modern era. To the extent that I have seen papers addressing other elements, they have found either minor levels of admixture (i.e., Arabs and Berbers in Iberia and Sicily) or no detectable admixture at all (Hungarians, who are genetically indistinguishable today from nearby German or Slavic peoples). There were of course individual areas, like Banat, which were depopulated due to war and then resettled by a patchwork of ethnicities, but in general population replacement just doesn't seem like it has been a huge thing in Europe in the modern era - or at least a much more minor element than shifts to neighboring cultures via elite dominance.

    Regardless, in the Neolithic, Bronze Age, and even early Iron Age, I agree with you that conquest and ethnic replacement often played a big role in altering local demographics. But it really does seem like for the most part in post-Roman Europe natural selection has taken place across population clusters. If Germany, France, Britain, and Italy all got smarter, it wasn't because genes spread from any one of them to the others. It was because culture and climate created roughly identical incentives for higher IQ people to produce more offspring who themselves reproduced in turn.

  25. Could the selection for height be related to Bergmann’s rule? https://en.wikipedia.org/wiki/Bergmann%27s_rule

    • Replies: @Hayrick
    Go and ask a Fijian (or a Samoan)
  26. @candid_observer
    One of the things your account doesn't address is the pressure on selection due to conquest and replacement of populations -- an obviously very common feature across known populations.

    One would ordinarily expect that such patterns of conquest and replacement have a stabilizing effect across large regions -- perhaps even continents. Very likely, there are traits such that, if neighboring populations differ on them by more than a certain amount, then one population will conquer and replace the other. Even if the population that's mostly on the losing end of these conquests manages to hide or move away and survive, there will likely be a strong selection for the traits in question in the remaining population. Likely, IQ is such a trait, though exactly which way it works is open to question. On the one hand, higher IQ would suggest better technology and organizational ability for warriors. On the other hand, higher IQ might create more wealth and sedentary behavior, subjecting the population to predatory behavior from more aggressive outsiders.

    Thinking of human populations as simply evolving separately as groups probably is the wrong model.

    Obviously in many circumstances conquest and replacement was a hugely important aspect of population genetics – and ultimately affected the selection of traits. But in the case of Britain in particular, it was apparently not hugely important over the common era. As of last year, it’s finally been definitively proven the Saxon admixture into the British substrate was relatively minor (on the order of 20%). IIRC the same study concluded there was relatively little sign of a genetic legacy of the Romans, Vikings (outside of the Orkneys) or Normans despite these conquests. The English really are mostly “Celtic” in terms of their ancestry – if not their culture.

    Of course, Britain is just one example in Europe. But my general understanding is the Slavic demographic explosion and resulting migration was probably the last substantive change of the ancestry of Europe until the modern era. To the extent that I have seen papers addressing other elements, they have found either minor levels of admixture (i.e., Arabs and Berbers in Iberia and Sicily) or no detectable admixture at all (Hungarians, who are genetically indistinguishable today from nearby German or Slavic peoples). There were of course individual areas, like Banat, which were depopulated due to war and then resettled by a patchwork of ethnicities, but in general population replacement just doesn’t seem like it has been a huge thing in Europe in the modern era – or at least a much more minor element than shifts to neighboring cultures via elite dominance.

    Regardless, in the Neolithic, Bronze Age, and even early Iron Age, I agree with you that conquest and ethnic replacement often played a big role in altering local demographics. But it really does seem like for the most part in post-Roman Europe natural selection has taken place across population clusters. If Germany, France, Britain, and Italy all got smarter, it wasn’t because genes spread from any one of them to the others. It was because culture and climate created roughly identical incentives for higher IQ people to produce more offspring who themselves reproduced in turn.

    • Replies: @candid_observer
    My point wasn't so much that in all cases population replacement was responsible for a stabilizing effect on various traits, though, as you indicate, such replacement was probably pretty common indeed in earlier, less civilized times.

    Even when one population doesn't fully take over another, or when it pushes back another population to the margins, and that other population eventually roars back, it may be that the population that survives the onslaught is altered by the effects of the onslaught itself so that it more closely matches the aggressive population in traits key to such fighting (or perhaps it is because the two populations are already pretty closely matched that one can't fully displace or exterminate the other). The model here is like that of bacteria that develop resistance to an agent that kills most of it on first contact. Obviously the bacteria aren't incorporating the genes of the agent, if any.
  27. @Karl Zimmerman
    Obviously in many circumstances conquest and replacement was a hugely important aspect of population genetics - and ultimately affected the selection of traits. But in the case of Britain in particular, it was apparently not hugely important over the common era. As of last year, it's finally been definitively proven the Saxon admixture into the British substrate was relatively minor (on the order of 20%). IIRC the same study concluded there was relatively little sign of a genetic legacy of the Romans, Vikings (outside of the Orkneys) or Normans despite these conquests. The English really are mostly "Celtic" in terms of their ancestry - if not their culture.

    Of course, Britain is just one example in Europe. But my general understanding is the Slavic demographic explosion and resulting migration was probably the last substantive change of the ancestry of Europe until the modern era. To the extent that I have seen papers addressing other elements, they have found either minor levels of admixture (i.e., Arabs and Berbers in Iberia and Sicily) or no detectable admixture at all (Hungarians, who are genetically indistinguishable today from nearby German or Slavic peoples). There were of course individual areas, like Banat, which were depopulated due to war and then resettled by a patchwork of ethnicities, but in general population replacement just doesn't seem like it has been a huge thing in Europe in the modern era - or at least a much more minor element than shifts to neighboring cultures via elite dominance.

    Regardless, in the Neolithic, Bronze Age, and even early Iron Age, I agree with you that conquest and ethnic replacement often played a big role in altering local demographics. But it really does seem like for the most part in post-Roman Europe natural selection has taken place across population clusters. If Germany, France, Britain, and Italy all got smarter, it wasn't because genes spread from any one of them to the others. It was because culture and climate created roughly identical incentives for higher IQ people to produce more offspring who themselves reproduced in turn.

    My point wasn’t so much that in all cases population replacement was responsible for a stabilizing effect on various traits, though, as you indicate, such replacement was probably pretty common indeed in earlier, less civilized times.

    Even when one population doesn’t fully take over another, or when it pushes back another population to the margins, and that other population eventually roars back, it may be that the population that survives the onslaught is altered by the effects of the onslaught itself so that it more closely matches the aggressive population in traits key to such fighting (or perhaps it is because the two populations are already pretty closely matched that one can’t fully displace or exterminate the other). The model here is like that of bacteria that develop resistance to an agent that kills most of it on first contact. Obviously the bacteria aren’t incorporating the genes of the agent, if any.

    • Replies: @Razib Khan
    your comments on this thread have been difficult for me to understand. karl on the other hand is rather clear. i appreciate concision, but if you want to continue to discuss this please elaborate so i can understand your model and its logic.
  28. @candid_observer
    My point wasn't so much that in all cases population replacement was responsible for a stabilizing effect on various traits, though, as you indicate, such replacement was probably pretty common indeed in earlier, less civilized times.

    Even when one population doesn't fully take over another, or when it pushes back another population to the margins, and that other population eventually roars back, it may be that the population that survives the onslaught is altered by the effects of the onslaught itself so that it more closely matches the aggressive population in traits key to such fighting (or perhaps it is because the two populations are already pretty closely matched that one can't fully displace or exterminate the other). The model here is like that of bacteria that develop resistance to an agent that kills most of it on first contact. Obviously the bacteria aren't incorporating the genes of the agent, if any.

    your comments on this thread have been difficult for me to understand. karl on the other hand is rather clear. i appreciate concision, but if you want to continue to discuss this please elaborate so i can understand your model and its logic.

    • Replies: @candid_observer
    Let me explain myself better than I have.

    Karl raised the issue of why people think so much in terms of continental level populations with respect to differences across various traits, given that it would seem that the many distinct populations within the continent have ample opportunity to diverge from each other on those traits.

    My point is that thinking of these groups as achieving their traits in isolation from each other doesn't take into account the interaction effects between these groups, especially the effects of aggression between the groups.

    The model I'd propose is that if two neighboring groups differ on a certain trait (or set of traits) by a certain threshold, then concerted, effective aggression between the two ensues. This aggression, I claim, should have an equalizing effect on the trait(s) in question. Over time, and across many such neighboring groups, the locally equalizing effects become far more extensive, perhaps working across entire continents -- and maybe in some cases between continents. This effect can be achieved in two ways: direct spread of the relevant gene pool, or effective selection for genes relevant to the traits.

    To use a concrete example, and to greatly simplify, suppose that IQ is such a trait, and that the threshold is 1 SD: that is, if one group has an IQ over 1 SD higher than a neighboring group, then major aggression ensues. Assume, for simplicity, that the group with the higher IQ will always be the victors, because of superior technology, organization, and strategy. A common outcome of such aggression will be replacement of one population by the victor, and elimination of the less favored population. Another will be the subjugation of the women in the other population. In either case, the effect is to reduce the difference in that region on that trait to something less than the threshold of 1 SD, and by direct genetic transmission.

    Now another possibility is that the less favored population under attack is not eliminated, and instead retreats to the periphery of the territory (this seems to have happened to some of the first farmer populations in Europe). But, I would claim, those that remain will likely have been very aggressively selected for the trait of importance in combat, so that, under our simplifying assumptions, only those with higher IQs (with greater organizational and strategic ability, and ability to match technology) will survive. They won't have received the genes directly from the conquering population, of course, but will have come to match this population on the trait by the aggressive selection for it. (Probably for IQ, most of the selection will be based on standing variants constant between the two populations, so that the two populations will come to look very much alike genetically on that trait.) Having gone through this selection, this population may in time roar back into the territory -- again, rather like bacteria which have been selected for resistance to a given agent.

    Now it's likely that in more recent civilized times and places that this model doesn't always work so well; punches are pulled. But I think that model may go a good distance to explain much of the relative homogenization across various traits that we do now see in continental populations.
  29. @NN
    Could the selection for height be related to Bergmann's rule? https://en.wikipedia.org/wiki/Bergmann%27s_rule

    Go and ask a Fijian (or a Samoan)

  30. @Steve Sailer
    Who is the blonde? Rosamund Pike?

    I used Jason Statham's fiance Rosie Huntington-Whitely to illustrate.

    “Who is the blonde? Rosamund Pike?”

    There is a film called Johnny English where Rosamund Pike falls in love with Mr. Bean. Hollywood has a history of making films where the non handsome man gets the beautiful woman.

    • Replies: @Sean
    Truth is always weirder than fiction.

    In real life she was with a man who realised he was gay after two years of living with her, and now is same sex married to another man. Then she was dumped again, because her new bloke did not like the risque formal invitations to their wedding she sent out. http://www.dailymail.co.uk/tvshowbiz/article-2788762/no-wonder-rosamund-pike-says-marriage-rated-hit-film-gone-girl-superstar-love-life-train-wreck.html#ixzz48N8ieA8V
  31. It is (still) not necessary to invoke sexual selection to explain lighter skin and any explanation along those lines has to offer an account of why such a thing would have taken off in the last two thousand years and not sooner. As I recall, Frost’s original theory invoked some unusual set of circumstances where male boreal hunters had a lot of choices when it came to which women had surviving offspring, so the stage was set rather farther in the past than this.

    If you look at women’s skin tone as a balancing act between avoiding vitamin D deficiency on the one hand and excessive folate destruction on the other, you can account for the recent selection just by assuming that over time women wore more clothes and spent more time indoors. Men too, of course, but the impact of slight vitamin D deficiency on them is probably not quite as severe from an evolutionary standpoint.

    • Replies: @Karl Zimmerman
    I suppose one could argue that people spent increasing amount of time indoors over the last 2,000 years. Even prior to the industrial era the invention of more advanced oxen-drawn heavy plows in Europe allowed for a massive reduction in the amount of hours peasants needed to spend in the fields. The labor savings meant more time could be spent indoors - both simple down time along with working as skilled craftsmen. Population growth, along with urban growth more specifically, unquestionably went into higher gear after the adoption of plow technology. At the same time, the places where people spent the most time indoors (cities and towns) were unsanitary and had negative fertility rates throughout the Middle Ages. European cities were demographic sinks - only surviving because of high in-migration from rural areas. Thus there was probably negative selection for whatever traits cities either selected for or attracted.

    I'm not sure about the women wearing more clothing aspect. I admit I haven't looked into it heavily, but I don't think that people in cold climates in Europe tended to keep less covered in inclement weather 2,000 years ago than they do today. Recent studies have shown that even if being scantily dressed in dry above-freezing weather doesn't kill you, it does raise the amount of calories you need to sustain yourself considerably - that you burn more calories running in 45 degree weather than running in 70 degree weather. Thus there would always be solid biological and cultural reasons to dress as warmly as needed to feel comfortable - at least when your population was near the local Malthusian limits, which was almost all of the time until the modern era, barring a plague or agricultural advancement.

    , @Sean
    Pale people at the equator and blacks in Finland seem to do OK .

    We aim to investigate the influence of positive selection on population differentiation, rather than studying the trajectory of individual alleles. For this we use whole ancient genomes (up to 45,000 years old) to improve our inferences on the origin of allele frequency differences across human populations. Specifically, we integrate modern and ancient genetic information in a new statistic that helps disentangle the effects of drift and adaptation on rapid, geographically localized allele frequency changes. Incorporating this information provides clear evidence for positive selection raising the frequency of advantageous genic SNPs in Europe and contributing to strong population differentiation. These alleles include both previously identified targets of positive selection (for example, those involved in pigmentation and lactase tolerance) as well as many new alleles. We also show that these alleles were mostly contributed by ancient hunter gatherers, who resided in Europe thousands of years before the arrival of southern farmer groups. [...]

    Our results thus indicate that genic alleles changed in frequency disproportionally in Europeans after divergence of the Ust′-Ishim population, a pattern absent in East Asians. Not surprisingly, simulations under a realistic demographic model of human populations26 (Fig. 2a; Supplementary Fig. 7) that include background selection but no positive selection cannot explain our observations (Fig. 1h; Supplementary Fig. 12). Simulations using a more complex demographic scenario in Europe, with several ancient groups including early hunter gatherers, farmers and Basal Eurasians (Fig. 2b; Supplementary Fig. 7 see below and Methods) also fail to explain the biased DAnc genic enrichment pattern (Supplementary Fig. 13). Allelic surfing (the random change in allele frequencies in the front of an expanding population27) is an unlikely explanation because it is not expected to be stronger in Europeans than in East Asians, as they both experienced similar population expansion26. Also, a specific transition that has higher mutation rate in Europeans than in other groups (codon TCC to codon TTC28) cannot explain the biased DAnc pattern because these alleles are overwhelmingly at low frequency28 and there is no overrepresentation of transitions in the DAnc European tail (rate of transitions: 0.39; resampling P value: 0.904). Finally, no allele in this tail is identified as having Neandertal origin in genome-wide maps of Neandertal introgression29.
    http://www.nature.com/ncomms/2016/160318/ncomms10775/full/ncomms10775.html
     
  32. I believe that lighting of skin and eyes were the side effects for selection of something else.

    Troglomorphism is clue.

    • Replies: @AG
    Or devolution due to disuse atrophy like cave animals. Devolution and evolution are depending on selection pressure.

    Only sexual selection hypothesis I can think of is that capable males with resource compete for females with most reproductive potentials. Younger the women, longer the reproductive potential. It is better deal for male to marry someone younger. Rich men married the youngest possible females. In Caucasoid people, younger features include less body hair, pale skin, blonde hair or lighter eyes. Without clear record of birth days, male can only judge female youthfulness on these features. Females with deceptive youthful features (genes) have edge against other females competitors. In the long run, this selective pressure causes entire population change since most those feature coded on autosomes.

    Pedophile like rich males and gold-digger blonde are the sexual selection pair. Does blonde prefer rich males than non-blonde? It is worthy research for that. Most likely there is some correlation since most blonde living in much harsher environment which needs male with resource to support a family.

    In East Asia, similar pressure might play part in change of body hair and skin tone.

    Very likely the true story is complicated interaction among environment, nature sun exposure, social class, reproductive potential signaling.
  33. I wonder is sexual selection in favor of tall, light skinned blonds in Britain is basically driven by culture in much the same way that language shift is.

    Anglo-Saxon invaders were tall, light skinned blonds more often than native Britons. They were also the superstrate population whom the upwardly mobile sought to emulate and did indeed emulate linguistically. If culturally, Anglo-Saxons had the upper hand and were disproportionately represented in elites, then you would expect that people with an Anglo-Saxon phenotype would be preferred in sexual selection to those who did not. You get there even without migration although Anglo-Saxon migration did occur in the last 2,000 years in a quantifiable amount.

    It could be the emulation of the Norman phenotype also played a part, but since I don’t know what Normans ca. 1,000 CE looked like relative to Native Britons, I couldn’t tell you. It seems as if modern people from Normandy have dark hair and darker pigmentation than Scandinavians.

    Also, once an idea like “light pigmentation is more beautiful” and “tall is good” makes its way into a culture, it takes on a force of its own, even if the original reason for that set of cultural values (Anglo-Saxon cultural dominance) ceases to exist.

    • Replies: @Sean
    It has been suggested east Asians had various hair colours originally, but they got suppressed by cultural disapproval, so I suppose selection for blonde (rather than red for instance ) colours in Britain could be entirely cultural.

    New Britain (in Melanesia) has blonde hair due to rs387907171 SNP in TYRP1, Bougainville Island only 500 kilometeres away does not have the allele at all. See here.
  34. @Razib Khan
    your comments on this thread have been difficult for me to understand. karl on the other hand is rather clear. i appreciate concision, but if you want to continue to discuss this please elaborate so i can understand your model and its logic.

    Let me explain myself better than I have.

    Karl raised the issue of why people think so much in terms of continental level populations with respect to differences across various traits, given that it would seem that the many distinct populations within the continent have ample opportunity to diverge from each other on those traits.

    My point is that thinking of these groups as achieving their traits in isolation from each other doesn’t take into account the interaction effects between these groups, especially the effects of aggression between the groups.

    The model I’d propose is that if two neighboring groups differ on a certain trait (or set of traits) by a certain threshold, then concerted, effective aggression between the two ensues. This aggression, I claim, should have an equalizing effect on the trait(s) in question. Over time, and across many such neighboring groups, the locally equalizing effects become far more extensive, perhaps working across entire continents — and maybe in some cases between continents. This effect can be achieved in two ways: direct spread of the relevant gene pool, or effective selection for genes relevant to the traits.

    To use a concrete example, and to greatly simplify, suppose that IQ is such a trait, and that the threshold is 1 SD: that is, if one group has an IQ over 1 SD higher than a neighboring group, then major aggression ensues. Assume, for simplicity, that the group with the higher IQ will always be the victors, because of superior technology, organization, and strategy. A common outcome of such aggression will be replacement of one population by the victor, and elimination of the less favored population. Another will be the subjugation of the women in the other population. In either case, the effect is to reduce the difference in that region on that trait to something less than the threshold of 1 SD, and by direct genetic transmission.

    Now another possibility is that the less favored population under attack is not eliminated, and instead retreats to the periphery of the territory (this seems to have happened to some of the first farmer populations in Europe). But, I would claim, those that remain will likely have been very aggressively selected for the trait of importance in combat, so that, under our simplifying assumptions, only those with higher IQs (with greater organizational and strategic ability, and ability to match technology) will survive. They won’t have received the genes directly from the conquering population, of course, but will have come to match this population on the trait by the aggressive selection for it. (Probably for IQ, most of the selection will be based on standing variants constant between the two populations, so that the two populations will come to look very much alike genetically on that trait.) Having gone through this selection, this population may in time roar back into the territory — again, rather like bacteria which have been selected for resistance to a given agent.

    Now it’s likely that in more recent civilized times and places that this model doesn’t always work so well; punches are pulled. But I think that model may go a good distance to explain much of the relative homogenization across various traits that we do now see in continental populations.

    • Replies: @Karl Zimmerman
    To the extent constant warfare would create selection in a population (which manages to survive) one would expect it would eventually select for more peaceful dispositions (as Larry Niven suggested decades ago regarding the fictional alien race of the Kzin). After all, the most glory-bound, violent men would be more apt to fight, and thus get killed, while the more cowardly could live on. Even if the successful violent warriors were considered highly desirable, it would only do so much to counteract this strong negative selection process - particularly given we now know cuckoldry was rare historically in Europe. One might point to some highly violent traditional cultures like the Yanomami as a counter, but it appears certain they are a successor culture which only reached their current configuration in the post-Colombian era (for example, they use machetes to clear land) so we don't know if the current cultural norm where every man is under constant threat of violent death would be stable in the longer run.

    I do wonder though how much selection by parents of which child to go into a likely demographic dead end (like the Church, or to a lesser extent, serving in the paid armed forces for the children of yeoman farmers) played a role in selection. If parents had unconscious stereotypes that spanned generations - that the quiet, smaller child would make the better priest, or the swarthy child would make for a better soldier - than selection towards height and fairness might make a great deal more sense.

  35. Sean says:
    @ohwilleke
    I wonder is sexual selection in favor of tall, light skinned blonds in Britain is basically driven by culture in much the same way that language shift is.

    Anglo-Saxon invaders were tall, light skinned blonds more often than native Britons. They were also the superstrate population whom the upwardly mobile sought to emulate and did indeed emulate linguistically. If culturally, Anglo-Saxons had the upper hand and were disproportionately represented in elites, then you would expect that people with an Anglo-Saxon phenotype would be preferred in sexual selection to those who did not. You get there even without migration although Anglo-Saxon migration did occur in the last 2,000 years in a quantifiable amount.

    It could be the emulation of the Norman phenotype also played a part, but since I don't know what Normans ca. 1,000 CE looked like relative to Native Britons, I couldn't tell you. It seems as if modern people from Normandy have dark hair and darker pigmentation than Scandinavians.

    Also, once an idea like "light pigmentation is more beautiful" and "tall is good" makes its way into a culture, it takes on a force of its own, even if the original reason for that set of cultural values (Anglo-Saxon cultural dominance) ceases to exist.

    It has been suggested east Asians had various hair colours originally, but they got suppressed by cultural disapproval, so I suppose selection for blonde (rather than red for instance ) colours in Britain could be entirely cultural.

    New Britain (in Melanesia) has blonde hair due to rs387907171 SNP in TYRP1, Bougainville Island only 500 kilometeres away does not have the allele at all. See here.

  36. @bbartlog
    It is (still) not necessary to invoke sexual selection to explain lighter skin and any explanation along those lines has to offer an account of why such a thing would have taken off in the last two thousand years and not sooner. As I recall, Frost's original theory invoked some unusual set of circumstances where male boreal hunters had a lot of choices when it came to which women had surviving offspring, so the stage was set rather farther in the past than this.

    If you look at women's skin tone as a balancing act between avoiding vitamin D deficiency on the one hand and excessive folate destruction on the other, you can account for the recent selection just by assuming that over time women wore more clothes and spent more time indoors. Men too, of course, but the impact of slight vitamin D deficiency on them is probably not quite as severe from an evolutionary standpoint.

    I suppose one could argue that people spent increasing amount of time indoors over the last 2,000 years. Even prior to the industrial era the invention of more advanced oxen-drawn heavy plows in Europe allowed for a massive reduction in the amount of hours peasants needed to spend in the fields. The labor savings meant more time could be spent indoors – both simple down time along with working as skilled craftsmen. Population growth, along with urban growth more specifically, unquestionably went into higher gear after the adoption of plow technology. At the same time, the places where people spent the most time indoors (cities and towns) were unsanitary and had negative fertility rates throughout the Middle Ages. European cities were demographic sinks – only surviving because of high in-migration from rural areas. Thus there was probably negative selection for whatever traits cities either selected for or attracted.

    I’m not sure about the women wearing more clothing aspect. I admit I haven’t looked into it heavily, but I don’t think that people in cold climates in Europe tended to keep less covered in inclement weather 2,000 years ago than they do today. Recent studies have shown that even if being scantily dressed in dry above-freezing weather doesn’t kill you, it does raise the amount of calories you need to sustain yourself considerably – that you burn more calories running in 45 degree weather than running in 70 degree weather. Thus there would always be solid biological and cultural reasons to dress as warmly as needed to feel comfortable – at least when your population was near the local Malthusian limits, which was almost all of the time until the modern era, barring a plague or agricultural advancement.

  37. @candid_observer
    Let me explain myself better than I have.

    Karl raised the issue of why people think so much in terms of continental level populations with respect to differences across various traits, given that it would seem that the many distinct populations within the continent have ample opportunity to diverge from each other on those traits.

    My point is that thinking of these groups as achieving their traits in isolation from each other doesn't take into account the interaction effects between these groups, especially the effects of aggression between the groups.

    The model I'd propose is that if two neighboring groups differ on a certain trait (or set of traits) by a certain threshold, then concerted, effective aggression between the two ensues. This aggression, I claim, should have an equalizing effect on the trait(s) in question. Over time, and across many such neighboring groups, the locally equalizing effects become far more extensive, perhaps working across entire continents -- and maybe in some cases between continents. This effect can be achieved in two ways: direct spread of the relevant gene pool, or effective selection for genes relevant to the traits.

    To use a concrete example, and to greatly simplify, suppose that IQ is such a trait, and that the threshold is 1 SD: that is, if one group has an IQ over 1 SD higher than a neighboring group, then major aggression ensues. Assume, for simplicity, that the group with the higher IQ will always be the victors, because of superior technology, organization, and strategy. A common outcome of such aggression will be replacement of one population by the victor, and elimination of the less favored population. Another will be the subjugation of the women in the other population. In either case, the effect is to reduce the difference in that region on that trait to something less than the threshold of 1 SD, and by direct genetic transmission.

    Now another possibility is that the less favored population under attack is not eliminated, and instead retreats to the periphery of the territory (this seems to have happened to some of the first farmer populations in Europe). But, I would claim, those that remain will likely have been very aggressively selected for the trait of importance in combat, so that, under our simplifying assumptions, only those with higher IQs (with greater organizational and strategic ability, and ability to match technology) will survive. They won't have received the genes directly from the conquering population, of course, but will have come to match this population on the trait by the aggressive selection for it. (Probably for IQ, most of the selection will be based on standing variants constant between the two populations, so that the two populations will come to look very much alike genetically on that trait.) Having gone through this selection, this population may in time roar back into the territory -- again, rather like bacteria which have been selected for resistance to a given agent.

    Now it's likely that in more recent civilized times and places that this model doesn't always work so well; punches are pulled. But I think that model may go a good distance to explain much of the relative homogenization across various traits that we do now see in continental populations.

    To the extent constant warfare would create selection in a population (which manages to survive) one would expect it would eventually select for more peaceful dispositions (as Larry Niven suggested decades ago regarding the fictional alien race of the Kzin). After all, the most glory-bound, violent men would be more apt to fight, and thus get killed, while the more cowardly could live on. Even if the successful violent warriors were considered highly desirable, it would only do so much to counteract this strong negative selection process – particularly given we now know cuckoldry was rare historically in Europe. One might point to some highly violent traditional cultures like the Yanomami as a counter, but it appears certain they are a successor culture which only reached their current configuration in the post-Colombian era (for example, they use machetes to clear land) so we don’t know if the current cultural norm where every man is under constant threat of violent death would be stable in the longer run.

    I do wonder though how much selection by parents of which child to go into a likely demographic dead end (like the Church, or to a lesser extent, serving in the paid armed forces for the children of yeoman farmers) played a role in selection. If parents had unconscious stereotypes that spanned generations – that the quiet, smaller child would make the better priest, or the swarthy child would make for a better soldier – than selection towards height and fairness might make a great deal more sense.

    • Replies: @candid_observer
    I happen to be reading through Pinker's Better Angels, and the statistics it produces on violence in pre-state societies are rather breathtaking.

    The average ranges of the various subgroups from homicide (chiefly due to war, presumably) is in the range of 15%-25%. Taking into account these sorts of numbers, the thousands of generations over which human beings lived in pre-state societies, the presumably quite significant heritability of the trait talent-for-combat, and the breeder's equation, it's obvious that selection for being an effective warrior must have been massive over much of humanity's history. (One wonders if it may not have been the most powerful single factor in the creation of the human species.) You raise the possibility that a coward might fare better in these circumstances than a warrior, but I don't see how that can possibly work in the contexts in question. Basically, these groups fought each other usually to elimination when it is feasible (as do chimpanzees, typically, given the opportunity) -- there's no place for a coward to retreat to; he must fight or be killed. The average level of fighting ability in a group would typically be decisive in battle, and that's what would be selected for.

    Now I agree that the introduction of civilization must have altered the mix of what is important in reproductive success. But even civilized groups must have retained a good portion of its capacity for war. You can't even start to do agriculture if you can't protect your own turf.

    An overarching point here is that the arms race goes all the way back, and the most decisive element of the arms race is the genetics of it. That arms race imposes a relatively stable level of genetic capacity across broad regions.

  38. In my opinion and according to my research, selection for blue/light eyes (low melanin levels in the iris) in/among Northern Europeans has to do with melatonin secretion suppression by light, which, as lighter skin (low melanin levels in the skin) allows for increased Vitamin D production, is evolutionaryily advantageous in cloudy latitudes far away from the equator. This melatonin secretion suppression by light leads to insomnia and hyperactivity (good for non-stop foraging during the short summers in Northern Europe) during the light summer months, and ensures one does not become lethargic, unproductive, and depressed ( e.g., seasonal affective disorder (SAD)) during the dark winter months in extreme northern or southern latitudes.
    This is why Asians and Southern Europeans have light skin, but generally do not have/need or select for blue/light eyes, in my opinion, because they rarely inhabit areas beyond the 49th parallel north or south.

    NN above is correct, in my opinion, on why Northern Europeans also select for height/size:

    Could the selection for height be related to Bergmann’s rule? https://en.wikipedia.org/wiki/Bergmann%27s_rule

    All the selections are made to adapt as well as possible to the colder and darker climate of Northern Europe.

    Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light.
    Higuchi S1, Motohashi Y, Ishibashi K, Maeda T.
    http://www.ncbi.nlm.nih.gov/pubmed/17332164

    Abstract

    This experiment tested effects of human eye pigmentation depending on the ethnicity on suppression of nocturnal melatonin secretion by light. Ten healthy Caucasian males with blue, green, or light brown irises (light-eyed Caucasians) and 11 Asian males with dark brown irises (dark-eyed Asians) volunteered to participate in the study. The mean ages of the light-eyed Caucasians and dark-eyed Asians were 26.4 +/- 3.2 and 25.3 +/- 5.7 years, respectively. The subjects were exposed to light (1,000 lux) for 2 h at night. The starting time of exposure was set to 2 h before the time of peak salivary melatonin concentration of each subject, which was determined in a preliminary experiment. Salivary melatonin concentration and pupil size were measured before exposure to light and during exposure to light. The percentage of suppression of melatonin secretion by light was calculated. The percentage of suppression of melatonin secretion 2 h after the start of light exposure was significantly larger in light-eyed Caucasians (88.9 +/- 4.2%) than in dark-eyed Asians (73.4 +/- 20.0%) (P < 0.01). No significant difference was found between pupil sizes in light-eyed Caucasians and dark-eyed Asians. These results suggest that sensitivity of melatonin to light suppression is influenced by eye pigmentation and/or ethnicity.

    • Replies: @Megalophias
    Eye colour and/or ethnicity? Seriously?

    Following the references gets you to: https://www.researchgate.net/publication/276058175_Effect_of_Iris_Pigmentation_and_Latitude_on_Chronotype_and_Sleep_Timing.Which at least surveyed a large sample of North Americans, but does not appear to have asked the subjects their *ancestry*, only their eye colour.

    https://www.researchgate.net/publication/26678954_Phase_delaying_the_human_circadian_clock_with_a_single_light_pulse_and_moderate_delay_of_the_sleepdark_episode_No_influence_of_iris_color
    Reported race, but tiny sample sizes; also previously found a difference based on race.
  39. If your daughters have rickets, your grandchildren don’t get past the pelvis. The End.

    Waffle all you like about “recent selective sweeps”, clothes-wearing, , “sexual selection” and “lactose intolerance”.
    Why are the North Chinese white? Tofu tolerance?

    • Replies: @Rick
    I am very curious. So from what source do you suggest that all the dark skinned peoples of the North obtained their vitamin D before the last few thousand years? They were definitely not all fishermen. So eggs or livers or something? Those couldn't have been in good supply year round. Or were they just outside every single day, and that was enough? Even when heavily clothed? And then something changed.

    The question is what caused Northern people to begin to be very susceptible to rickets. Assuming that is the source of the selection pressure. It makes sense that it was either diet or clothing or lack of sunlight. Saying that the selection pressure was just rickets is not very interesting or informative.
  40. @FKA Max
    In my opinion and according to my research, selection for blue/light eyes (low melanin levels in the iris) in/among Northern Europeans has to do with melatonin secretion suppression by light, which, as lighter skin (low melanin levels in the skin) allows for increased Vitamin D production, is evolutionaryily advantageous in cloudy latitudes far away from the equator. This melatonin secretion suppression by light leads to insomnia and hyperactivity (good for non-stop foraging during the short summers in Northern Europe) during the light summer months, and ensures one does not become lethargic, unproductive, and depressed ( e.g., seasonal affective disorder (SAD)) during the dark winter months in extreme northern or southern latitudes.
    This is why Asians and Southern Europeans have light skin, but generally do not have/need or select for blue/light eyes, in my opinion, because they rarely inhabit areas beyond the 49th parallel north or south.

    NN above is correct, in my opinion, on why Northern Europeans also select for height/size:

    Could the selection for height be related to Bergmann’s rule? https://en.wikipedia.org/wiki/Bergmann%27s_rule
     
    All the selections are made to adapt as well as possible to the colder and darker climate of Northern Europe.

    Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light.
    Higuchi S1, Motohashi Y, Ishibashi K, Maeda T.
    http://www.ncbi.nlm.nih.gov/pubmed/17332164

    Abstract

    This experiment tested effects of human eye pigmentation depending on the ethnicity on suppression of nocturnal melatonin secretion by light. Ten healthy Caucasian males with blue, green, or light brown irises (light-eyed Caucasians) and 11 Asian males with dark brown irises (dark-eyed Asians) volunteered to participate in the study. The mean ages of the light-eyed Caucasians and dark-eyed Asians were 26.4 +/- 3.2 and 25.3 +/- 5.7 years, respectively. The subjects were exposed to light (1,000 lux) for 2 h at night. The starting time of exposure was set to 2 h before the time of peak salivary melatonin concentration of each subject, which was determined in a preliminary experiment. Salivary melatonin concentration and pupil size were measured before exposure to light and during exposure to light. The percentage of suppression of melatonin secretion by light was calculated. The percentage of suppression of melatonin secretion 2 h after the start of light exposure was significantly larger in light-eyed Caucasians (88.9 +/- 4.2%) than in dark-eyed Asians (73.4 +/- 20.0%) (P < 0.01). No significant difference was found between pupil sizes in light-eyed Caucasians and dark-eyed Asians. These results suggest that sensitivity of melatonin to light suppression is influenced by eye pigmentation and/or ethnicity.
     

    Eye colour and/or ethnicity? Seriously?

    Following the references gets you to: https://www.researchgate.net/publication/276058175_Effect_of_Iris_Pigmentation_and_Latitude_on_Chronotype_and_Sleep_Timing.Which at least surveyed a large sample of North Americans, but does not appear to have asked the subjects their *ancestry*, only their eye colour.

    https://www.researchgate.net/publication/26678954_Phase_delaying_the_human_circadian_clock_with_a_single_light_pulse_and_moderate_delay_of_the_sleepdark_episode_No_influence_of_iris_color
    Reported race, but tiny sample sizes; also previously found a difference based on race.

    • Replies: @FKA Max
    Yes!

    Our group has previously noted three effects of light iris pigmentation in patients with seasonal affective disorder(summarized in Goel et al., 2002): (a) a larger summertime increase in photopic sensitivity than patients with darker pigmentation; (b) lower depression and fatigability scores in winter; and (c) earlier awakening during dawn simulation therapy
     
    - https://www.researchgate.net/publication/276058175_Effect_of_Iris_Pigmentation_and_Latitude_on_Chronotype_and_Sleep_Timing
  41. @Megalophias
    Eye colour and/or ethnicity? Seriously?

    Following the references gets you to: https://www.researchgate.net/publication/276058175_Effect_of_Iris_Pigmentation_and_Latitude_on_Chronotype_and_Sleep_Timing.Which at least surveyed a large sample of North Americans, but does not appear to have asked the subjects their *ancestry*, only their eye colour.

    https://www.researchgate.net/publication/26678954_Phase_delaying_the_human_circadian_clock_with_a_single_light_pulse_and_moderate_delay_of_the_sleepdark_episode_No_influence_of_iris_color
    Reported race, but tiny sample sizes; also previously found a difference based on race.

    Yes!

    Our group has previously noted three effects of light iris pigmentation in patients with seasonal affective disorder(summarized in Goel et al., 2002): (a) a larger summertime increase in photopic sensitivity than patients with darker pigmentation; (b) lower depression and fatigability scores in winter; and (c) earlier awakening during dawn simulation therapy

    https://www.researchgate.net/publication/276058175_Effect_of_Iris_Pigmentation_and_Latitude_on_Chronotype_and_Sleep_Timing

  42. @Expletive Deleted
    If your daughters have rickets, your grandchildren don't get past the pelvis. The End.

    Waffle all you like about "recent selective sweeps", clothes-wearing, , "sexual selection" and "lactose intolerance".
    Why are the North Chinese white? Tofu tolerance?

    I am very curious. So from what source do you suggest that all the dark skinned peoples of the North obtained their vitamin D before the last few thousand years? They were definitely not all fishermen. So eggs or livers or something? Those couldn’t have been in good supply year round. Or were they just outside every single day, and that was enough? Even when heavily clothed? And then something changed.

    The question is what caused Northern people to begin to be very susceptible to rickets. Assuming that is the source of the selection pressure. It makes sense that it was either diet or clothing or lack of sunlight. Saying that the selection pressure was just rickets is not very interesting or informative.

  43. AG says:
    @AG
    I believe that lighting of skin and eyes were the side effects for selection of something else.

    Troglomorphism is clue.

    Or devolution due to disuse atrophy like cave animals. Devolution and evolution are depending on selection pressure.

    Only sexual selection hypothesis I can think of is that capable males with resource compete for females with most reproductive potentials. Younger the women, longer the reproductive potential. It is better deal for male to marry someone younger. Rich men married the youngest possible females. In Caucasoid people, younger features include less body hair, pale skin, blonde hair or lighter eyes. Without clear record of birth days, male can only judge female youthfulness on these features. Females with deceptive youthful features (genes) have edge against other females competitors. In the long run, this selective pressure causes entire population change since most those feature coded on autosomes.

    Pedophile like rich males and gold-digger blonde are the sexual selection pair. Does blonde prefer rich males than non-blonde? It is worthy research for that. Most likely there is some correlation since most blonde living in much harsher environment which needs male with resource to support a family.

    In East Asia, similar pressure might play part in change of body hair and skin tone.

    Very likely the true story is complicated interaction among environment, nature sun exposure, social class, reproductive potential signaling.

  44. @Karl Zimmerman
    To the extent constant warfare would create selection in a population (which manages to survive) one would expect it would eventually select for more peaceful dispositions (as Larry Niven suggested decades ago regarding the fictional alien race of the Kzin). After all, the most glory-bound, violent men would be more apt to fight, and thus get killed, while the more cowardly could live on. Even if the successful violent warriors were considered highly desirable, it would only do so much to counteract this strong negative selection process - particularly given we now know cuckoldry was rare historically in Europe. One might point to some highly violent traditional cultures like the Yanomami as a counter, but it appears certain they are a successor culture which only reached their current configuration in the post-Colombian era (for example, they use machetes to clear land) so we don't know if the current cultural norm where every man is under constant threat of violent death would be stable in the longer run.

    I do wonder though how much selection by parents of which child to go into a likely demographic dead end (like the Church, or to a lesser extent, serving in the paid armed forces for the children of yeoman farmers) played a role in selection. If parents had unconscious stereotypes that spanned generations - that the quiet, smaller child would make the better priest, or the swarthy child would make for a better soldier - than selection towards height and fairness might make a great deal more sense.

    I happen to be reading through Pinker’s Better Angels, and the statistics it produces on violence in pre-state societies are rather breathtaking.

    The average ranges of the various subgroups from homicide (chiefly due to war, presumably) is in the range of 15%-25%. Taking into account these sorts of numbers, the thousands of generations over which human beings lived in pre-state societies, the presumably quite significant heritability of the trait talent-for-combat, and the breeder’s equation, it’s obvious that selection for being an effective warrior must have been massive over much of humanity’s history. (One wonders if it may not have been the most powerful single factor in the creation of the human species.) You raise the possibility that a coward might fare better in these circumstances than a warrior, but I don’t see how that can possibly work in the contexts in question. Basically, these groups fought each other usually to elimination when it is feasible (as do chimpanzees, typically, given the opportunity) — there’s no place for a coward to retreat to; he must fight or be killed. The average level of fighting ability in a group would typically be decisive in battle, and that’s what would be selected for.

    Now I agree that the introduction of civilization must have altered the mix of what is important in reproductive success. But even civilized groups must have retained a good portion of its capacity for war. You can’t even start to do agriculture if you can’t protect your own turf.

    An overarching point here is that the arms race goes all the way back, and the most decisive element of the arms race is the genetics of it. That arms race imposes a relatively stable level of genetic capacity across broad regions.

    • Replies: @Karl Zimmerman
    I think it's important to remember that inter-group conflicts among hunter-gatherers and other pre-state societies are more akin to gangland murders than anything we would consider warfare. Whenever possible, attackers relied upon ambush - or attacking only when numbers were overwhelmingly in their favor - to minimize the risk of personal injury or death. Often causalties were massacres of non-combatants. Thus what was being selected for wasn't so much being aggressive warriors it was being ruthless towards outsiders, and being sneaky.

    All of this changed though with the development of modern warfare however. Obviously things like raids could still take place, but increasingly battles took place on open fields of combat among large groups of men. As time went on, the likelihood of massacres of non-combatants began to drop as well. Therefore the incentives of being a professional killer flipped. Consider a yeoman farmer who has two teenage sons in 14th century England. The elder one is the heir apparent of the family farm, and in no serious danger of being killed. The younger enlists as a longbowman, is sent to France, putting his life in mortal danger. Multiply this by a thousand, and it seems clear the sons who were not soldiers will have more surviving children. Hell, the rise of professional armies might have inadvertently played a major role in the pacification of society in the era of the state, by boiling off those most glory-bound every few generations. It might also explain why states were perpetually threatened by nomads until the modern era, as horse-bound nomads could maintain themselves as raiders, and didn't expose themselves to the same level of mortal risk as infantry did, meaning they were "pacified" through natural selection more slowly.

    On another note, I think it's worth mentioning that, in general, humans are more gracile in terms of our build than chimps and most other hominids. Hunter gatherers are typically not muscular either - unlike modern professional soldiers. To me this suggests that there's been a general trend towards lower levels of hand-to-hand combat through human evolution. We may have been killing each other in huge numbers, but if things like grappling must have become increasingly rare as time went on in favor of sharper cutting edges, thrown projectiles, and eventually poison.

  45. Sean says:
    @bbartlog
    It is (still) not necessary to invoke sexual selection to explain lighter skin and any explanation along those lines has to offer an account of why such a thing would have taken off in the last two thousand years and not sooner. As I recall, Frost's original theory invoked some unusual set of circumstances where male boreal hunters had a lot of choices when it came to which women had surviving offspring, so the stage was set rather farther in the past than this.

    If you look at women's skin tone as a balancing act between avoiding vitamin D deficiency on the one hand and excessive folate destruction on the other, you can account for the recent selection just by assuming that over time women wore more clothes and spent more time indoors. Men too, of course, but the impact of slight vitamin D deficiency on them is probably not quite as severe from an evolutionary standpoint.

    Pale people at the equator and blacks in Finland seem to do OK .

    We aim to investigate the influence of positive selection on population differentiation, rather than studying the trajectory of individual alleles. For this we use whole ancient genomes (up to 45,000 years old) to improve our inferences on the origin of allele frequency differences across human populations. Specifically, we integrate modern and ancient genetic information in a new statistic that helps disentangle the effects of drift and adaptation on rapid, geographically localized allele frequency changes. Incorporating this information provides clear evidence for positive selection raising the frequency of advantageous genic SNPs in Europe and contributing to strong population differentiation. These alleles include both previously identified targets of positive selection (for example, those involved in pigmentation and lactase tolerance) as well as many new alleles. We also show that these alleles were mostly contributed by ancient hunter gatherers, who resided in Europe thousands of years before the arrival of southern farmer groups. […]

    Our results thus indicate that genic alleles changed in frequency disproportionally in Europeans after divergence of the Ust′-Ishim population, a pattern absent in East Asians. Not surprisingly, simulations under a realistic demographic model of human populations26 (Fig. 2a; Supplementary Fig. 7) that include background selection but no positive selection cannot explain our observations (Fig. 1h; Supplementary Fig. 12). Simulations using a more complex demographic scenario in Europe, with several ancient groups including early hunter gatherers, farmers and Basal Eurasians (Fig. 2b; Supplementary Fig. 7 see below and Methods) also fail to explain the biased DAnc genic enrichment pattern (Supplementary Fig. 13). Allelic surfing (the random change in allele frequencies in the front of an expanding population27) is an unlikely explanation because it is not expected to be stronger in Europeans than in East Asians, as they both experienced similar population expansion26. Also, a specific transition that has higher mutation rate in Europeans than in other groups (codon TCC to codon TTC28) cannot explain the biased DAnc pattern because these alleles are overwhelmingly at low frequency28 and there is no overrepresentation of transitions in the DAnc European tail (rate of transitions: 0.39; resampling P value: 0.904). Finally, no allele in this tail is identified as having Neandertal origin in genome-wide maps of Neandertal introgression29.
    http://www.nature.com/ncomms/2016/160318/ncomms10775/full/ncomms10775.html

    • Replies: @Razib Khan
    Pale people at the equator and blacks in Finland seem to do OK .

    can you seriously stop being a total dumbshit? this sort of stupid comment is exasperating. it's like you think of the first thing that comes into your mind and post it here. that is not pleasing to me. STOP DOING THAT.

    i'm very myopic. i seem to be doing fine. hundreds of millions of others are in the same state. can you figure out why this is a moronic statement in terms of an evolutionary time scale?

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it's not as easy as you seem to stupidly think)

  46. @Sean
    Pale people at the equator and blacks in Finland seem to do OK .

    We aim to investigate the influence of positive selection on population differentiation, rather than studying the trajectory of individual alleles. For this we use whole ancient genomes (up to 45,000 years old) to improve our inferences on the origin of allele frequency differences across human populations. Specifically, we integrate modern and ancient genetic information in a new statistic that helps disentangle the effects of drift and adaptation on rapid, geographically localized allele frequency changes. Incorporating this information provides clear evidence for positive selection raising the frequency of advantageous genic SNPs in Europe and contributing to strong population differentiation. These alleles include both previously identified targets of positive selection (for example, those involved in pigmentation and lactase tolerance) as well as many new alleles. We also show that these alleles were mostly contributed by ancient hunter gatherers, who resided in Europe thousands of years before the arrival of southern farmer groups. [...]

    Our results thus indicate that genic alleles changed in frequency disproportionally in Europeans after divergence of the Ust′-Ishim population, a pattern absent in East Asians. Not surprisingly, simulations under a realistic demographic model of human populations26 (Fig. 2a; Supplementary Fig. 7) that include background selection but no positive selection cannot explain our observations (Fig. 1h; Supplementary Fig. 12). Simulations using a more complex demographic scenario in Europe, with several ancient groups including early hunter gatherers, farmers and Basal Eurasians (Fig. 2b; Supplementary Fig. 7 see below and Methods) also fail to explain the biased DAnc genic enrichment pattern (Supplementary Fig. 13). Allelic surfing (the random change in allele frequencies in the front of an expanding population27) is an unlikely explanation because it is not expected to be stronger in Europeans than in East Asians, as they both experienced similar population expansion26. Also, a specific transition that has higher mutation rate in Europeans than in other groups (codon TCC to codon TTC28) cannot explain the biased DAnc pattern because these alleles are overwhelmingly at low frequency28 and there is no overrepresentation of transitions in the DAnc European tail (rate of transitions: 0.39; resampling P value: 0.904). Finally, no allele in this tail is identified as having Neandertal origin in genome-wide maps of Neandertal introgression29.
    http://www.nature.com/ncomms/2016/160318/ncomms10775/full/ncomms10775.html
     

    Pale people at the equator and blacks in Finland seem to do OK .

    can you seriously stop being a total dumbshit? this sort of stupid comment is exasperating. it’s like you think of the first thing that comes into your mind and post it here. that is not pleasing to me. STOP DOING THAT.

    i’m very myopic. i seem to be doing fine. hundreds of millions of others are in the same state. can you figure out why this is a moronic statement in terms of an evolutionary time scale?

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it’s not as easy as you seem to stupidly think)

    • Agree: RaceRealist88
    • Replies: @Sean
    I don't mean to be annoying and as several are complaining about that lately I will take a long rest here and elsewhere starting now. I do have knowledge of and consequently was dismissive of that particular theory of Jablonski and Chaplin, but of course in general it is undeniably true that modern populations can get by with things like myopia with the help of technology and the ability to lead sheltered lives. Given how many clever people wear thick glasses a strong inference can be made for a gene having an IQ advantage and a myopia side effect being overwhelmingly selected relatively recently with a bad effect on eyesight at short distance and compensated for by corrective lenses.

    Europeans are paler than is healthy in California or for redheads even in Scottish summer sun (which is comparable to the equator over 24 hours because of the longer days up north ) but the birth defects Jablonski stakes her Folate/Vitamin D hypothesis on don't seem to show up in European sunbathers in sunny countries and heavy tanning bed users.

    Sticking with your analogy it's as if almost no one had myopia so bad that they needed corrective lenses, except for small print. I have looked at the research and medical reports on this and despite the Nina Jablonski theory being well known to doctors and the subject of warning to pregnant women in recent years, they are short on actual cases of birth defects ever occurring, so I just don't think the ill effects are severe enough for the selection pressure for white skin or black skin to be those ill effects.

    The big study I linked to looked very sophisticated and with conclusions opposite to comparable ones, to the extent I can judge these things, any opinions of it yet?
    , @Bill P

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it’s not as easy as you seem to stupidly think)
     
    Somalis refugees in Seattle were identified as having dangerously low vitamin D levels.It's a problem in Sweden, too. Those chadors can't be helping much.

    Personally, I think the "Great Migration" of blacks to the north was only feasible because of federal programs to put vitamin supplements in food. The timing is pretty close.
    , @Sean
    A belated point about natural selection and skin colour:-

    http://www.sbs.com.au/news/article/2014/01/07/comment-east-asian-genes-may-solve-skin-cancer-puzzle The data indicated that people with European ancestry are approximately 20 times more susceptible to melanoma than those of African or East Asian descent.
     
    East Asians are no more likely to get skin cancer than black Africans.
  47. Sean says:
    @Jefferson
    "Who is the blonde? Rosamund Pike?"

    There is a film called Johnny English where Rosamund Pike falls in love with Mr. Bean. Hollywood has a history of making films where the non handsome man gets the beautiful woman.

    Truth is always weirder than fiction.

    In real life she was with a man who realised he was gay after two years of living with her, and now is same sex married to another man. Then she was dumped again, because her new bloke did not like the risque formal invitations to their wedding she sent out. http://www.dailymail.co.uk/tvshowbiz/article-2788762/no-wonder-rosamund-pike-says-marriage-rated-hit-film-gone-girl-superstar-love-life-train-wreck.html#ixzz48N8ieA8V

  48. @candid_observer
    I happen to be reading through Pinker's Better Angels, and the statistics it produces on violence in pre-state societies are rather breathtaking.

    The average ranges of the various subgroups from homicide (chiefly due to war, presumably) is in the range of 15%-25%. Taking into account these sorts of numbers, the thousands of generations over which human beings lived in pre-state societies, the presumably quite significant heritability of the trait talent-for-combat, and the breeder's equation, it's obvious that selection for being an effective warrior must have been massive over much of humanity's history. (One wonders if it may not have been the most powerful single factor in the creation of the human species.) You raise the possibility that a coward might fare better in these circumstances than a warrior, but I don't see how that can possibly work in the contexts in question. Basically, these groups fought each other usually to elimination when it is feasible (as do chimpanzees, typically, given the opportunity) -- there's no place for a coward to retreat to; he must fight or be killed. The average level of fighting ability in a group would typically be decisive in battle, and that's what would be selected for.

    Now I agree that the introduction of civilization must have altered the mix of what is important in reproductive success. But even civilized groups must have retained a good portion of its capacity for war. You can't even start to do agriculture if you can't protect your own turf.

    An overarching point here is that the arms race goes all the way back, and the most decisive element of the arms race is the genetics of it. That arms race imposes a relatively stable level of genetic capacity across broad regions.

    I think it’s important to remember that inter-group conflicts among hunter-gatherers and other pre-state societies are more akin to gangland murders than anything we would consider warfare. Whenever possible, attackers relied upon ambush – or attacking only when numbers were overwhelmingly in their favor – to minimize the risk of personal injury or death. Often causalties were massacres of non-combatants. Thus what was being selected for wasn’t so much being aggressive warriors it was being ruthless towards outsiders, and being sneaky.

    All of this changed though with the development of modern warfare however. Obviously things like raids could still take place, but increasingly battles took place on open fields of combat among large groups of men. As time went on, the likelihood of massacres of non-combatants began to drop as well. Therefore the incentives of being a professional killer flipped. Consider a yeoman farmer who has two teenage sons in 14th century England. The elder one is the heir apparent of the family farm, and in no serious danger of being killed. The younger enlists as a longbowman, is sent to France, putting his life in mortal danger. Multiply this by a thousand, and it seems clear the sons who were not soldiers will have more surviving children. Hell, the rise of professional armies might have inadvertently played a major role in the pacification of society in the era of the state, by boiling off those most glory-bound every few generations. It might also explain why states were perpetually threatened by nomads until the modern era, as horse-bound nomads could maintain themselves as raiders, and didn’t expose themselves to the same level of mortal risk as infantry did, meaning they were “pacified” through natural selection more slowly.

    On another note, I think it’s worth mentioning that, in general, humans are more gracile in terms of our build than chimps and most other hominids. Hunter gatherers are typically not muscular either – unlike modern professional soldiers. To me this suggests that there’s been a general trend towards lower levels of hand-to-hand combat through human evolution. We may have been killing each other in huge numbers, but if things like grappling must have become increasingly rare as time went on in favor of sharper cutting edges, thrown projectiles, and eventually poison.

  49. @Razib Khan
    Pale people at the equator and blacks in Finland seem to do OK .

    can you seriously stop being a total dumbshit? this sort of stupid comment is exasperating. it's like you think of the first thing that comes into your mind and post it here. that is not pleasing to me. STOP DOING THAT.

    i'm very myopic. i seem to be doing fine. hundreds of millions of others are in the same state. can you figure out why this is a moronic statement in terms of an evolutionary time scale?

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it's not as easy as you seem to stupidly think)

    I don’t mean to be annoying and as several are complaining about that lately I will take a long rest here and elsewhere starting now. I do have knowledge of and consequently was dismissive of that particular theory of Jablonski and Chaplin, but of course in general it is undeniably true that modern populations can get by with things like myopia with the help of technology and the ability to lead sheltered lives. Given how many clever people wear thick glasses a strong inference can be made for a gene having an IQ advantage and a myopia side effect being overwhelmingly selected relatively recently with a bad effect on eyesight at short distance and compensated for by corrective lenses.

    Europeans are paler than is healthy in California or for redheads even in Scottish summer sun (which is comparable to the equator over 24 hours because of the longer days up north ) but the birth defects Jablonski stakes her Folate/Vitamin D hypothesis on don’t seem to show up in European sunbathers in sunny countries and heavy tanning bed users.

    Sticking with your analogy it’s as if almost no one had myopia so bad that they needed corrective lenses, except for small print. I have looked at the research and medical reports on this and despite the Nina Jablonski theory being well known to doctors and the subject of warning to pregnant women in recent years, they are short on actual cases of birth defects ever occurring, so I just don’t think the ill effects are severe enough for the selection pressure for white skin or black skin to be those ill effects.

    The big study I linked to looked very sophisticated and with conclusions opposite to comparable ones, to the extent I can judge these things, any opinions of it yet?

  50. @Razib Khan
    Pale people at the equator and blacks in Finland seem to do OK .

    can you seriously stop being a total dumbshit? this sort of stupid comment is exasperating. it's like you think of the first thing that comes into your mind and post it here. that is not pleasing to me. STOP DOING THAT.

    i'm very myopic. i seem to be doing fine. hundreds of millions of others are in the same state. can you figure out why this is a moronic statement in terms of an evolutionary time scale?

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it's not as easy as you seem to stupidly think)

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it’s not as easy as you seem to stupidly think)

    Somalis refugees in Seattle were identified as having dangerously low vitamin D levels.It’s a problem in Sweden, too. Those chadors can’t be helping much.

    Personally, I think the “Great Migration” of blacks to the north was only feasible because of federal programs to put vitamin supplements in food. The timing is pretty close.

    • Replies: @Sean
    Are they getting actual disease or is it a theoretical optimum level that is not being achieved? I ask because Africans' vitamin D levels may be for the year round UVB synthesis of D in their original evolutionary environment and they do best at relatively low levels compared to European who have been selected to build a store for the northern UVB-less winter.

    The amount of vitamin D in food is tiny compared to what even the darkest of Africans will get from a 20 minute walk outside in normal clothing. A lot of people followed the line reasoning that extra vitamin D was necessary especially for blacks in the north but after being commissioned by the Canadian and American governments to research the issue, a team of experts from the Institute of Medicine of the National Academies declined to recommend extra vitamin D for more pigmented people (including black Africans) in northern latitudes. The IOM cited the lack of evidence of benefit and indications of harm for the normal Europeans' vitamin D level when achieved by blacks.

    My understanding is the modern findings are of Europeans being much darker than currently until until a millennium into the Neolithic, so you can forget about vitamin D being any problem. I live at the same latitude as Moscow, Russia and I am still immediately uncomfortable in bright sun at 7 pm in a lowland Scottish summer. I would not say the Finns on average are pale compared to Scots or Irish. Indeed the Finns got the same late but no more of rest of the light/ diverse pigment charges as everyone else, and somewhat less of the red hair variants that make me burn so easily.


    Haplotypes, Fig 6We identify one single significantly enriched functional category (cellular component): melanosome membrane (P value=0.004, Supplementary Table 2) for the European tail alleles present exclusively in Loschbour. Two genes drive this signature: OCA2 with 10 SNPs and SLC45A2 with 5 SNPs. Both of them harbour variation known to affect pigmentation39 and have classical signatures of positive selection40, 41, recently supported by a targeted SNP analysis in several ancient European samples17, 19. The derived allele upstream of OCA2 (rs12913832 in HERC2) is associated with blue iris colour in Europeans42 and light skin pigmentation43; both this variant and its linked variation show that Loschbour carried the predominant European haplotype (Fig. 6a). The derived allele in SLC45A2 non-synonymous rs16891982 is associated with lighter skin pigmentation and increased melanoma risk in Europeans44, 45. No ancestral genome carries rs16891982’s derived allele, but Loschbour carries the haplotype that, in present-day populations, is linked to the derived allele (Fig. 6b). Therefore hunter-gatherer populations likely contributed both OCA2 and SLC45A2 advantageous alleles to the European gene pool.
     
    If I am reading the above aright it is evidence for SLC45A2's major lightening mutation being introduced by nonEuropean interlopers much later than the other indigenous mutations. Razib says SLC45A2 originated in central Asia. OK, but the minor ones like SLC45A2 were from the line of the indigenous European hunter gathers it seems. So I accept that the biggest lightening allele (on SLC45A2) only spread widely in Europe quite late, and before Europeans had got the the SLC45A2 one they likely still had skin that was very far from white.

    I expect the pre neolithic Europeans of the north with the other lightening mutations but lacking SLC45A2 had a bronzed appearance and were comparable to this Swedish woman with heavy sun exposure in natural skin tone (ie they were naturally that way without any tanning). So they were not white. I never thought white skin was particularly sexual (quite the opposite), and Peter Frost has speculated it has something to do with eliciting care and provisioning rather that sexual attraction.

    Still the lady above with her indigenous to Europe mutations for light / diverse hair, eyes and her dark- tawny skin is not too different to the standard look of being heavy tanned, bleached and wearing colored contact lens so common for women earning a living as a glamour model or porn performer. I think it is quite in order to take it seriously that most of the Nordic phenotype was the result of sexual selection in Europe, then much later came SLC45A2 (whatever it is for) which made them what we would call white today.

  51. @RK
    Some of the most interesting signals we see here are for increased first age at menarche, increased infant head circumference and increased hip width in women, which is expected due to corresponding requirements for a wider birth canal. This gives some evidence that agricultural-commercial civilisation pushed directionally on human life history strategy, in Britain at least, with a more K-selected phenotype being favoured, and later reproduction and more costly offspring. If we also include height, the complex signal seems to point towards more investment in growth and maintenance at early ages at the expense of reproduction.

    It would be great if this study were repeated across Europe. We could check if signals for K-selection are especially strong within the Hajnal Line, where late reproduction was culturally favoured.

    increased first age at menarche, increased infant head circumference and increased hip width in women, which is expected due to corresponding requirements for a wider birth canal.

    Weird! This lines up with what Rushton says. Black girls have earlier menarche, due to leptin.

    http://notpoliticallycorrect.me/2016/04/02/the-role-of-leptin-and-sexual-maturity-in-black-girls/

  52. No way those are British teeth.

    • Replies: @Avery
    Best comment of the thread.
  53. @The Grate Deign
    No way those are British teeth.

    Best comment of the thread.

  54. This is pure speculation, coming from someone with little knowledge in this field. But one idea bouncing around in my head is that soil quality could be an overlooked variable in much of this research. Take skin pigmentation, for instance. Presumably producing more melanin requires higher levels of certain micronutrients. If those micronutrients are rare in British soils, then increased melanin production could cause deficiencies, leading to decreased overall health. Darker skin could come to be culturally associated with such deficiencies, even among perfectly healthy people, magnifying the reproductive effect.

    Selection for lighter skin because of latitude should have hit diminishing returns long ago. But farming techniques over the past several thousand years are known to have caused slowly deteriorating soil quality, which could be causing continuously greater pressure on any micronutrient related genes.

    If my guess is right, Borlaug’s “Green Revolution” should lead to a whole new set of selective pressures, roughly beginning with the millennial generation. It’s a possible explanation for the explosions in rates of autism, diabetes, and food allergies. (though I suspect those are largely products of more extensive testing, and cultural hypochondria) Modern farming techniques are disastrous for soils in the long term, so we might be on the edge of a huge bump in evolutionary change.

    • Replies: @Sean
    The digestion of milk (which contains a massive amount of calcium) may be connected to the spread of light skin SLC24a5 because it, like lactose tolerance, came from farming incomers.
  55. Sean says:
    @Bill P

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it’s not as easy as you seem to stupidly think)
     
    Somalis refugees in Seattle were identified as having dangerously low vitamin D levels.It's a problem in Sweden, too. Those chadors can't be helping much.

    Personally, I think the "Great Migration" of blacks to the north was only feasible because of federal programs to put vitamin supplements in food. The timing is pretty close.

    Are they getting actual disease or is it a theoretical optimum level that is not being achieved? I ask because Africans’ vitamin D levels may be for the year round UVB synthesis of D in their original evolutionary environment and they do best at relatively low levels compared to European who have been selected to build a store for the northern UVB-less winter.

    The amount of vitamin D in food is tiny compared to what even the darkest of Africans will get from a 20 minute walk outside in normal clothing. A lot of people followed the line reasoning that extra vitamin D was necessary especially for blacks in the north but after being commissioned by the Canadian and American governments to research the issue, a team of experts from the Institute of Medicine of the National Academies declined to recommend extra vitamin D for more pigmented people (including black Africans) in northern latitudes. The IOM cited the lack of evidence of benefit and indications of harm for the normal Europeans’ vitamin D level when achieved by blacks.

    My understanding is the modern findings are of Europeans being much darker than currently until until a millennium into the Neolithic, so you can forget about vitamin D being any problem. I live at the same latitude as Moscow, Russia and I am still immediately uncomfortable in bright sun at 7 pm in a lowland Scottish summer. I would not say the Finns on average are pale compared to Scots or Irish. Indeed the Finns got the same late but no more of rest of the light/ diverse pigment charges as everyone else, and somewhat less of the red hair variants that make me burn so easily.

    Haplotypes, Fig 6We identify one single significantly enriched functional category (cellular component): melanosome membrane (P value=0.004, Supplementary Table 2) for the European tail alleles present exclusively in Loschbour. Two genes drive this signature: OCA2 with 10 SNPs and SLC45A2 with 5 SNPs. Both of them harbour variation known to affect pigmentation39 and have classical signatures of positive selection40, 41, recently supported by a targeted SNP analysis in several ancient European samples17, 19. The derived allele upstream of OCA2 (rs12913832 in HERC2) is associated with blue iris colour in Europeans42 and light skin pigmentation43; both this variant and its linked variation show that Loschbour carried the predominant European haplotype (Fig. 6a). The derived allele in SLC45A2 non-synonymous rs16891982 is associated with lighter skin pigmentation and increased melanoma risk in Europeans44, 45. No ancestral genome carries rs16891982’s derived allele, but Loschbour carries the haplotype that, in present-day populations, is linked to the derived allele (Fig. 6b). Therefore hunter-gatherer populations likely contributed both OCA2 and SLC45A2 advantageous alleles to the European gene pool.

    If I am reading the above aright it is evidence for SLC45A2’s major lightening mutation being introduced by nonEuropean interlopers much later than the other indigenous mutations. Razib says SLC45A2 originated in central Asia. OK, but the minor ones like SLC45A2 were from the line of the indigenous European hunter gathers it seems. So I accept that the biggest lightening allele (on SLC45A2) only spread widely in Europe quite late, and before Europeans had got the the SLC45A2 one they likely still had skin that was very far from white.

    I expect the pre neolithic Europeans of the north with the other lightening mutations but lacking SLC45A2 had a bronzed appearance and were comparable to this Swedish woman with heavy sun exposure in natural skin tone (ie they were naturally that way without any tanning). So they were not white. I never thought white skin was particularly sexual (quite the opposite), and Peter Frost has speculated it has something to do with eliciting care and provisioning rather that sexual attraction.

    Still the lady above with her indigenous to Europe mutations for light / diverse hair, eyes and her dark- tawny skin is not too different to the standard look of being heavy tanned, bleached and wearing colored contact lens so common for women earning a living as a glamour model or porn performer. I think it is quite in order to take it seriously that most of the Nordic phenotype was the result of sexual selection in Europe, then much later came SLC45A2 (whatever it is for) which made them what we would call white today.

    • Replies: @Sean
    Correction: I got SLC45A2 mixed up with SLC24a5 . If you substitute SLC24a5 for every use of SLC45A2 except "OK, but the minor ones like SLC45A2 were from the line of the indigenous European hunter gathers it seems." it is correct in the sense of being what I meant to say, I think.
  56. Sean says:
    @Sean
    Are they getting actual disease or is it a theoretical optimum level that is not being achieved? I ask because Africans' vitamin D levels may be for the year round UVB synthesis of D in their original evolutionary environment and they do best at relatively low levels compared to European who have been selected to build a store for the northern UVB-less winter.

    The amount of vitamin D in food is tiny compared to what even the darkest of Africans will get from a 20 minute walk outside in normal clothing. A lot of people followed the line reasoning that extra vitamin D was necessary especially for blacks in the north but after being commissioned by the Canadian and American governments to research the issue, a team of experts from the Institute of Medicine of the National Academies declined to recommend extra vitamin D for more pigmented people (including black Africans) in northern latitudes. The IOM cited the lack of evidence of benefit and indications of harm for the normal Europeans' vitamin D level when achieved by blacks.

    My understanding is the modern findings are of Europeans being much darker than currently until until a millennium into the Neolithic, so you can forget about vitamin D being any problem. I live at the same latitude as Moscow, Russia and I am still immediately uncomfortable in bright sun at 7 pm in a lowland Scottish summer. I would not say the Finns on average are pale compared to Scots or Irish. Indeed the Finns got the same late but no more of rest of the light/ diverse pigment charges as everyone else, and somewhat less of the red hair variants that make me burn so easily.


    Haplotypes, Fig 6We identify one single significantly enriched functional category (cellular component): melanosome membrane (P value=0.004, Supplementary Table 2) for the European tail alleles present exclusively in Loschbour. Two genes drive this signature: OCA2 with 10 SNPs and SLC45A2 with 5 SNPs. Both of them harbour variation known to affect pigmentation39 and have classical signatures of positive selection40, 41, recently supported by a targeted SNP analysis in several ancient European samples17, 19. The derived allele upstream of OCA2 (rs12913832 in HERC2) is associated with blue iris colour in Europeans42 and light skin pigmentation43; both this variant and its linked variation show that Loschbour carried the predominant European haplotype (Fig. 6a). The derived allele in SLC45A2 non-synonymous rs16891982 is associated with lighter skin pigmentation and increased melanoma risk in Europeans44, 45. No ancestral genome carries rs16891982’s derived allele, but Loschbour carries the haplotype that, in present-day populations, is linked to the derived allele (Fig. 6b). Therefore hunter-gatherer populations likely contributed both OCA2 and SLC45A2 advantageous alleles to the European gene pool.
     
    If I am reading the above aright it is evidence for SLC45A2's major lightening mutation being introduced by nonEuropean interlopers much later than the other indigenous mutations. Razib says SLC45A2 originated in central Asia. OK, but the minor ones like SLC45A2 were from the line of the indigenous European hunter gathers it seems. So I accept that the biggest lightening allele (on SLC45A2) only spread widely in Europe quite late, and before Europeans had got the the SLC45A2 one they likely still had skin that was very far from white.

    I expect the pre neolithic Europeans of the north with the other lightening mutations but lacking SLC45A2 had a bronzed appearance and were comparable to this Swedish woman with heavy sun exposure in natural skin tone (ie they were naturally that way without any tanning). So they were not white. I never thought white skin was particularly sexual (quite the opposite), and Peter Frost has speculated it has something to do with eliciting care and provisioning rather that sexual attraction.

    Still the lady above with her indigenous to Europe mutations for light / diverse hair, eyes and her dark- tawny skin is not too different to the standard look of being heavy tanned, bleached and wearing colored contact lens so common for women earning a living as a glamour model or porn performer. I think it is quite in order to take it seriously that most of the Nordic phenotype was the result of sexual selection in Europe, then much later came SLC45A2 (whatever it is for) which made them what we would call white today.

    Correction: I got SLC45A2 mixed up with SLC24a5 . If you substitute SLC24a5 for every use of SLC45A2 except “OK, but the minor ones like SLC45A2 were from the line of the indigenous European hunter gathers it seems.” it is correct in the sense of being what I meant to say, I think.

  57. Art says:
    @Rick
    I thought that actual first age at menarche has been decreasing for over 100 years.

    I thought that actual first age at menarche has been decreasing for over 100 years.

    Why is this happening – why are our girls coming of age sooner – is the species in danger – are our genetics telling us something?

    Do we need to reproduce sooner – if so why? What selection process is at work?

  58. @Ted Bell
    This is pure speculation, coming from someone with little knowledge in this field. But one idea bouncing around in my head is that soil quality could be an overlooked variable in much of this research. Take skin pigmentation, for instance. Presumably producing more melanin requires higher levels of certain micronutrients. If those micronutrients are rare in British soils, then increased melanin production could cause deficiencies, leading to decreased overall health. Darker skin could come to be culturally associated with such deficiencies, even among perfectly healthy people, magnifying the reproductive effect.

    Selection for lighter skin because of latitude should have hit diminishing returns long ago. But farming techniques over the past several thousand years are known to have caused slowly deteriorating soil quality, which could be causing continuously greater pressure on any micronutrient related genes.

    If my guess is right, Borlaug's "Green Revolution" should lead to a whole new set of selective pressures, roughly beginning with the millennial generation. It's a possible explanation for the explosions in rates of autism, diabetes, and food allergies. (though I suspect those are largely products of more extensive testing, and cultural hypochondria) Modern farming techniques are disastrous for soils in the long term, so we might be on the edge of a huge bump in evolutionary change.

    The digestion of milk (which contains a massive amount of calcium) may be connected to the spread of light skin SLC24a5 because it, like lactose tolerance, came from farming incomers.

  59. @Razib Khan
    Pale people at the equator and blacks in Finland seem to do OK .

    can you seriously stop being a total dumbshit? this sort of stupid comment is exasperating. it's like you think of the first thing that comes into your mind and post it here. that is not pleasing to me. STOP DOING THAT.

    i'm very myopic. i seem to be doing fine. hundreds of millions of others are in the same state. can you figure out why this is a moronic statement in terms of an evolutionary time scale?

    (and by the way, when my finnish friends came to california several had to take a shit ton of precautions not to burn constantly, so even today it's not as easy as you seem to stupidly think)

    A belated point about natural selection and skin colour:-

    http://www.sbs.com.au/news/article/2014/01/07/comment-east-asian-genes-may-solve-skin-cancer-puzzle The data indicated that people with European ancestry are approximately 20 times more susceptible to melanoma than those of African or East Asian descent.

    East Asians are no more likely to get skin cancer than black Africans.

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