There’s a simple model of the spread of an advantageous allele: You take σ, the typical distance people move in one generation, and s, the selective advantage: the advantageous allele spreads as a nonlinear wave at speed σ * √(2s). The problem is, that’s slow. Suppose that s = 0.10 (a large advantage), σ = 10 kilometers, and a generation time of 30 years: the allele would take almost 7,000 years to expand out 1000 kilometers.
The European lactose-tolerance allele, T-13910 has spread much further than this model would predict. It’s found all over Europe ( very common in northern Europe) but is also found in South Asia (30% in Pathans) and even in Africa (48% in Sudanese Fulani).
This big expansion didn’t just happen from peasants marrying the girl next door: it required migrations and conquests. This one looks as if it rode with the Indo-European expansion: I’ll bet it started out in a group that had domesticated only horses.
The same processes, migration and conquest, must explain the wide distribution of many geographically widespread selective sweeps and partial sweeps. They were adaptive, all right, but expanded much faster than possible from purely local diffusion. We already have reason to think that SLC24A5 was carried to Europe by Middle Eastern farmers; the same is probably true for the haplotype that carries the high-activity ergothioniene transporter and the 35delG connexin-26/GJB2 deafness mutation. The Indo-Europeans probably introduced the T-13910 LCT mutation and the delta-F508 cystic fibrosis mutation, so we should see delta-F508 in northwest India and Pakistan – and we do !
All these alleles had to confer an advantage, but population movements let them expand much farther and faster than girl-next-d0or ever could.
The same must be true for many of the European variants influencing skin, eye, and hair color. Blue eyes seem to come from WHG (the mesolithic hunters); likely the wide distribution happened as people expanded (rapidly) out of glacial refugia at the end of the Ice Age. Blond hair maps pretty well onto Corded Ware territory, which suggests that it came in with the Yamnaya. Blond, swarthy savages. Red-heads? Bell Beakers.
As long as the conquerors incorporate even a moderate fraction (~20% ?) of the previous inhabitants, the sweeping genes cross over and can become common by the present. Given enough time, this can happen even with far lower levels of admixture, as seen with the adaptive alleles that originated in Neanderthals and Denisovans.
In a region without so many rapid, large-scale expansions, you won’t see adaptive alleles spread as rapidly.
West Hunter 
A winning strategy long term in human evolution is exactly the opposite of a winning strategy in the board game Risk. In the game Risk you win by hiding in a defensible corner, Australia or South America. In human evolution you are best equipped to succeed if your ancestors fought it out like crazy and expanded from places like the Ukraine or China, the last places on the board you want in the board game risk.
Alternatively the better equipped you are genetically to succeed today the worse it was for your direct ancestors. The more miserable generations your direct ancestors went through where your direct ancestors barely survived while their slightly less genetically advantaged siblings didn’t, the better off you are. I suppose this to be generally true as long as fitness pressures don’t push you to have gigantic moose horns, peacock tail feathers, or be neurotic to the bone.
What is wrong with Peacocks, Mooses and Jews?
there is this theory that differences between populations come from different mating patterns. Regions were men had to compete very hard for women now tend to be masculine (both men and women, which is good for men, bad for women), the opposite is the case for regions were women had to compete for men. This aligns with your statement. Males of today wholes forfathers had a hard life competing for women now have an advantage on the partner market, and even in life in general, because food gets always provided by others, nobody has to care about that.
I can think of two places where men are overtly masculine, huge and muscular, Samoa and Iceland. They are both Islands where violent men practiced polygamy for enough generations for there to be an obvious effect on present day populations. People know about Samoa because many of them end up in the NFL. Not many people know about Iceland in part because their population is only 300,000, but they fare very well in the strongman competitions and provide us with freaks like the mountain from Game of Thrones .wikipedia.org/wiki/Hafþór_Júlíus_Björnsson
Typically it is females that pick the mate. That is why male birds have extra color. It would have been a lousy fitness strategy for women to have babies with the most handsome and/or masculine man they could, they choose to pair up with the man most likely to hang around and help raise the brood. So the extreme examples of sexual dimorphism that are expressed in peacocks and moose don’t show up in humans. One example of sexual dimorphism that does show up in humans is male baldness with age, which puzzles me. It makes men less sexually attractive yet it confers little to no advantage that I can think of. Cochran has written many posts about mutational load increasing with the age of the father, so i can see why it isn’t good for mankind to have lots of older fathers but I thought evolution was always selfish, rewarding only the successful breeder by pushing his or her genes into the next generation. The answer must be that at some point the good of the individual and the good of the group balance out. Perhaps long gone cultures that have winked out of existence practiced polygamy and old men produced enough children so that the mutational load of the group increased to such an effect that it helped lead to their eventual downfall. Cochran has speculated that this is why the Muslim world has declined since it’s height of power and I think he is on to something.
@dave chamberlin:
Human females have many secondary sex characteristics (well, some have none to speak of, but that’s besides the point), so mate choice was hardly one way in human history.
I hope you’re joking about the group selection part.
Human mate selection is incredibly complex, I didn’t mean to oversimplify how things work. It is always tricky in a blog post to address complex subjects because it is inconsiderate to go on for pages on a tangent not directly related to the main thread and it is misleading to boil everything down to a few sentences. I don’t believe in group selection per se. It is known why men go bald, but there is more to the subject than meets the eye. Caucasian males are far more likely to lose their hair at an early age than Chinese males for example. Why? I dunno. Recent evolution has been at work on this trait and it interests me enough to mention it. One would think in the pure Dawkin’s Selfish Gene theory of evolution that men would not go bald, that it would have been bred out of us long ago. But it hasn’t, why?
I wonder how T-13910 got to the Sudanese Fulani?
gold hunters -> west african gold fields -> pastoralist spread from there imo
(same thing i think happened along the Atlantic edge of western europe: gold, silver and copper hunters moving ahead of various expansions like trappers in the US west)
(pure guess though)
possibly influenced by reading “King Solomon’s Mines” in my youth.
“same thing i think happened along the Atlantic edge of western europe”
not completely btw: hare celtic and tortoise celtic
‘gold, silver and copper hunters moving ahead of various expansions like trappers in the US west’
maybe the ancients had trappers too, and the gold, silver and copper hunters expanded like the gold and silver rushes in the US?
“gold and silver rushes”
good analogy
The usual story about the Bantu is they were Renfrew/Bellwood-style First Farmers. But according to linguist Christopher Ehret, there is evidence for Cushitic and AfroAsiatic substrates in a lot of areas in East Africa that are now straight Bantu. So the Bantu may have been taking over where earlier farmers were already established. Could better malaria resistance, the sickle cell gene in particular, be their secret?
Australia looks for all the world (based on linguistics and archeology) like someplace that had a continent-scale demic expansion mid-Holocene. Not First Farmers, of course. Any evidence, or speculation, on what genes might have been involved, either causing the expansion, or just surfing along?
“”But Iron — Cold Iron — is master of them all.” Better weapons? We might be able to see genetic evidence of those substrates, if they exist.
Australia does look like that. I talked about it in A Three-Hour Tour – so did you. But I’m not sure that this idea of an Indian admixture is solid.
Not much comes out re Australian Aboriginal DNA: maybe they’re hiding something cosmically odd. Something wonderful.
Their genomes basically look like those of Papuans as far as I can see.
https://drive.google.com/file/d/0B9o3EYTdM8lQYlRZbHlyckhVLTQ/view?usp=sharing
A common source population into all three of Aborigines, Papuans and ASI rather than Indian admixture would be my guess.
Our picture of European genetics changed pretty substantially once we started looking at prehistoric DNA. My impression is that there are political obstacles in the way of this in Australia.
To entertain a (possibly mistaken) physical analogy, it sounds like you’re suggested a sort genetic convection through space, as opposed to conduction. I.e. Entire masses of folks, carrying a new selected variant, are displacing others – as opposed to the slow gene flow process of “girl-next-door.” Is that about right? (Hopefully I haven’t revealed my ignorance of basic thermodynamics here…)
Has there been any attempt to estimate sigma from these time periods?
Not a bad analogy! And if the expansions are driven by a cultural and/or biological advantage over their neighbors, it’s even better.
There are estimates of sigma for some contemporary populations. Can be pretty large for hunter-gatherers in unproductive environments, low for peasant villages.
That seems reasonable. Some recent-ish work by Kim Hill et al suggests that modern hunter gatherers have wide, far-reaching social networks… If memory serves me. More so than farmers, I think. This could reflect wider dispersal / bigger sigma.
@RCB:
Kudos that was nicely done!
σ, the typical distance people move in one generation, is not 10 km, and never was. Most people is ambulant and mobile, there was long distance trade as far as prehistory (in flint for example) and outcast boys (like among Arizona Mormons) walked to the end of the world to find a bride and land. My own daughter just finished a 1000 kilometer trail – for sport. I would say σ, the typical distance a gene moves in a generation, is more close to 100 km than 10 km. In peacetime. In war, distance shortens: Alexander covered 3000 km in ten years. Well, this is just a comment.
If you leave your village to travel, you deplete the home population by one, and you don’t really spread but rather just move. Population growth has to create a surplus that can expand, and pop growth for stone-age people is going to be low percentages.
At 10km you encounter the neighboring village, with whom you and your ancesters have been exchanging head-hunting parties for generations.
Stone Age tribe kills fishermen who strayed on to island
and the boat drifted into the shallows where they were attacked and killed. … the Indian coastguard tried to recover the bodies using a helicopter but was met by the customary hail of arrows.
Did Marco Polo have sex during his journey? 😉
He, his father and his uncle too.
Blue eyed but dark skinned and haired Euro hunter gatherers, meet red haired (possibly then still dark skinned and eyed Bell Beakers, and blonde Indo Europeans (possibly then still dark skinned and eyed) finish the mix. That is what I think the post is saying.
Hair: Red hair always goes with noticeable pale skin (and with quite light eyes) . They are linked. How did they become linked, if not because red hair was selected for in a population where white skin and red hair were both advantageous? And as red hair has unpteen disadvantages including AOTBE lower vitamin D synthesis, 100 times more of the lethal form of UV caused cancer, “UV-independent pathways of oxidative stress” , Elevated Plasma Levels of the Pituitary Hormone Cthrc1 (associated with inflammatory conditions) it was surely the appearance of red hair which was advantageous. If follows that it was the appearance of blonde hair was also advantageous. It If we attempt a scientific explanation of the origin of these colours a side effect seems out as is drift. Camouflage is silly. Frequency dependent selection for novel hair eye catching colours is the only explanation that makes sense. If hair colour has no functional significance, why all the colours in Europe?
Lets see if eye colors fit into the same conceptual scheme: “.ACCORDING to a recent study of six SNPs associated with eye color. When both copies of the so-called blue-eye allele are present, the resulting phenotype is more variable in women than in men(Martinez-Cadenas et al., 2013). This translates into a greater range of female eye colors in regions, like northern and eastern Europe, where blue eyes are the single most common phenotype (Walsh et al.,2012). As the study’s authors observe, “in populations with very high blue-eye frequency, such as Iceland or Holland, females show greater proportion of green eyes at the expense of blue eyes” (Martinez-Cadenas et al., 2013). The authors also confirmed earlier findings that eye color doesn’t follow a simple Mendelian model. Although the blue-eye allele (C) is less dominant than the brown-eye allele (T), CT heterozygotes aren’t necessarily brown-eyed and CC homozygotes aren’t necessarily blue-eyed. Even TT homozygotes are sometimes blue-eyed.”
Sexual selection of women due to high male mortality of male providers and obligate monogamy in the ice age steppe tundra as the explanation of novel and noticeable hair and eye color diversity. Skin isn’t diverse in Europe though. So skin must be related to sexual selection, but a bit different.
(Chimps tend to batter females a lot. Imagine chimps living in environmentally obligate monogamy. The male chimp would be knocking seven bells out the female constantly. Evolution might develop markings for the female that made him less inclined to do that. And conceivably those markings might have a downside inasmuch as they could inhibit his sexual instincts. When in a different environment there was pressure to be attractive, the female chimps might learn to obscure those markings. Hence, girls trying to increase their appeal go tanning. Take a look at the tan on the average star female porn performer.)
“And as red hair has unpteen disadvantages”
Would it have those disadvantages on its own or only in conjunction with other skin lightening genes i.e. is the red hair gene in mixed white / black advantageous in northern latitudes but become less so when the SLC genes are added on top?
“MC1R variants increased the risk of sporadic cutaneous melanoma in darker-pigmented Caucasians: A pooled-analysis from the M-SKIP project.”
“THE identification of a surprisingly high number of MC1R natural variants strongly associated with pigmentary phenotypes and increased skin cancer risk has prompted research on the functional properties of the wild-type receptor and frequent mutant alleles. linked to lighter skin.”
Moreover, hair colour is more diverse in women, women are more likely to have red hair, and blue eyed men tend to have a more feminine face shape.
“THE human predilection for fancy phenotypes that ignore disorders and genetic defects is a major driving force for the increase of pleiotropic effects in domestic species and laboratory subjects since domestication has commenced approximately 18,000 years ago.”
I’m not so sure about this, but I think if you look at the context of young women tanning, and the jobs where women who have a tan are most common, it is fairly obvious that white skin is not regarded as conducive to eliciting sexual desire from men. But some people seem to have trouble accepting that the appearance of blonde hair is sexually attractive to men, despite it being omnipresent in porn. You might as well say large breasts don’t appeal to men.
“some people seem to have trouble accepting”
options
1) solely non-sexual
2) solely sexual
3) bit of both
For 1 and 3 to be tenable there would have to be a nonsexual selection advantage in the diverse appearance traits found in Europeans. One and only one population in the world had diverse eye and hair colour and delicate facial features (plus light skin). It’s illogical to say they are not are connected and came from separate populations. There is precisely one proposed unified explanation of the alleles for all these characteristics spreading, it’s got to be the frontrunner.
Nope.
@Sean
young women tanning,
white skin is not regarded as conducive to eliciting sexual desire from men.
Tanning has only been in style for some years (out of 6,000) in the industrialized West (< 5% world pop). Historically women wore large hats and and garments that covered most of the skin. I doubt there is any painting of the female figure made before 1910 that has any hint of a tan.
Romans use white makeup made from lead paste. Japanese geisha dancers went all-out with white makeup like mimes (also made from lead.
India’s Ugly Obsession with Lighter Skin Hits Close to Home, Too
“Growing up my grandmother would give me a bath in chickpea flour, an old Indian homemade recipe, to get a child’s skin lighter. …
The campaign also hopes to raise more awareness and eventually stop sales of controversial skin lightening products like Fair & Lovely cream”
Can Advertising Change India’s Obsession With Fair Skin?
@Toad:
“Tanning has only been in style for some years (out of 6,000) in the industrialized West (< 5% world pop). Historically women wore large hats and and garments that covered most of the skin. I doubt there is any painting of the female figure made before 1910 that has any hint of a tan."
True. But only one group in the world (Europeans) have embraced it. And boy have they (visit any warm European beach). That is also interesting.
“Chimps tend to batter females a lot. Imagine chimps living in environmentally obligate monogamy. The male chimp would be knocking seven bells out the female constantly. Evolution might develop markings for the female that made him less inclined to do that.”
And/or make tears and babies reduce testosterone levels.
Red hair also occurs in Asian and Africa; but because the red pigment is in the shaft of the hair, it is usually covered-up by the melanin on the surface of the hair. Bleaching or albinism reveals the red. That also means that red hair is more common among Europeans than is generally realized. Full disclosure: I am a ginger, although over the decades my hair colour has faded from auburn to sandy.
Thanks for the pleasure of forcing me to reread Fisher’s The Wave of Advance of Advantageous Genes. Fisher considers a littoral population where a linear wave advances. He presumes that the individuals are basically immobile, like plants.Therefore the diffusion of an advantageous mutation is slow, very slow, which is totally contrary to what we see in real life. For example the diffusion of simazine and atracine resistant weeds in the seventies was like a wildfire. OK, weeds are not immobile, the wind carries their seeds many kilometers afar. Human seed travels on foot, on boat or horseback, in every direction, turning Fisher’s speculations even more complicated.
The population density of the disadvantaged population being moved into might be one source of friction in this process also the disadvantaged population living in extreme environments requiring specific adaptations might outweigh other advantages and add a lot of friction also.
“This one looks as if it rode with the Indo-European expansion: I’ll bet it started out in a group that had domesticated only horses.” Are we supposing that it developed to let them digest mares’ milk?
More than 50% of the energy content of mare’s milk is lactose, considerably more than in humans or cows
Cystic Fibrosis is more interesting the more I look at it:
I wonder why they restricted themselves to looking at bacterial pathogens?
LBK, so far lactase free, farmers apparently had high mobility, based on strontium isotope ratios in their burials. Large percentages of non-locals. This isn’t quantified as a per generation movement though.
Marriage and birth registries for recent agricultural people could give estimates of how far people moved to marry.
Hector is repeatedly called “breaker of horses” — weird for the prince of a coastal commercial hub, but this epithet makes sense if he began as a character in a story told by nomadic horse-breakers of the steppes.
Go back and read the Iliad closely, the most prized possessions after slave girls were horses. http://en.wikipedia.org/wiki/Balius_and_Xanthus
I would also note they used ships to drag chariots to Troy in 1100 BC- which is pretty much proof of steppe origins for most of the Achean Greeks- after all, most of Greece does not have large plains, yet they had the technology of the steppes. I would also note they were on mainland Anatolia, which used chariots and fought also on horseback.
Further, they were fighting over control of the Bosphorus, which http://en.wikipedia.org/wiki/Karamenderes_River flows into.
I would also suspect the “wine dark sea” was the Black Sea, and Xanthos- which is blond, also see http://en.wikipedia.org/wiki/Diomedes_of_Thrace
One of the most interesting things coming out of this is I now think the sea peoples were alliances of Greeks- including the new aristocracy that came from off the steppes- the biggest innovation was putting horses and chariots onto ships.
The raiding of the sea people is immortalized in the Iliad- they were the Kings from the north.
@Sean
“There is precisely one proposed unified explanation of the alleles for all these characteristics spreading, it’s got to be the frontrunner.”
If hair, eye and skin color were all selected for at once then maybe but personally I wonder if eyes and skin were separate. It might even be the initial reason was a minor one and your reason made it a much bigger deal. Either way I think the eye question is interesting as if true it might relate to eye problems so finding out might be quite useful.
Spreading was the wrong word because however the appearance traits originated they could have spread all over the place by expansions.
“In a region without so many rapid, large-scale expansions, you won’t see adaptive alleles spread as rapidly.”
Which is fine if you are talking about alleles for digesting milk loaded with lactose, because we can all see the advantage and that those without the allele tend to be at a disadvantage even today when it comes to drinking cows milk they get problems with their guts. So it was advantageous in the original population, and they used it to spread it . But if you are talking about farmers with white skin where the original advantage of that by itself could have lay is totally obscure, because black Africans living at high latitude (and there are some very dark ones in very northern countries) are not keeling over because their skins are not white. (if you disagree with that assessment take it up with the Institute of Medicine) . This is a problem for the hypothesis being advanced in the post, which is that the appearance traits originated in, and then became common in, different populations, and that these separate populations then mixed together to produce a new ‘European’ phenotype. Because, for hair, eyes skin to each rise to become common in a separate population before they came together there would have to have been an advantage for each separately. hair colours don’t just drift off into red hair with associated cancer ect, natural selection and all that.
Mooting a separate origin of hair colour(s), eye color and white skin is multiplying the explanations that are required for the origin of these characteristics. And those explanations still have not been provided
We pretty well know they did originate in different populations, is the problem. Blue eyes were WHG, we know that. We know that the next layer was EEF: a fairly pure example exists today, Ogliastran Sardinians: redheads and blondes are rare to nonexistent there. But you can find redheaded Uighurs, while redheads are more reputedly more common among Udmurts than in Scotland.
Blue eyes from the Mesolithic hunters, fair skin from the early farmers, color variation from the Indo-Europeans.
it does no good to talk about how things ought to be simpler.
The Interplay between Natural Selection and Susceptibility to Melanoma on Allele 374F of SLC45A2 Gene in a South European population L374F is the white skin one if I read this correctly “In order to assess also the association of L374F to hair or eye color, we genotyped a subset of 344 individuals from which we had paired information for these traits. We observed that the ancestral allele G (374L) was associated with black (OR = 2.14; p = 0.0018) and dark brown hair (OR = 2.24; p = 0.0189), and the darkest eye color (brown/black; OR = 1.89; p = 0.0082) “
374F is 0.8 in Sardinia and 0.93 in Denmark.
@Sean
But if you are talking about farmers with white skin where the original advantage of that by itself could have lay is totally obscure,
Vitamin D and Melanin
“Acting as a natural sunscreen, melanin in skin absorbs ultraviolet-B, or UVB, light — the same kind of light that initiates vitamin D synthesis. Thus, the higher concentration of melanin in your skin, the longer it will take for you to absorb UVB rays from sun exposure. According to University of Pennysylvania, in one experiment, a light-skinned person experienced a 50-fold increase in blood levels of vitamin D within 8 hours of UVB exposure, while it took a darker-skinned person at least five times as long, or at least 40 hours, to register a 30-fold increase in vitamin D concentrations.”
Rickets
Vitamin D Supplementation To Prevent Rickets in Breast-Fed Babies
“For this reason, dark-skinned infants and children who are exclusively breast fed should receive 400 IU of vitamin D supplementation daily, beginning by at least 2 months of age. This is the finding of a study, “Prevalence of Vitamin D-Deficient Rickets in Minority Infants,”
…
Of 30 babies with nutritional rickets seen at the Wake Forest and UNC medical centers, all were black and all were breast fed.”
Rickets
“Some researchers estimate that prior to 1915, almost 85 percent of children in these industrialized areas of Europe and North America suffered from rickets. …
Dark-skinned people require almost six times as much sunlight exposure to make the same amount of vitamin D as those with lighter skin.”
Nutritional rickets is common in black Africans living in equatorial Africa. I repeat, Africans living in northern latitudes do not need more vitamin D . The conclusion of the exhaustive vitamin D report commissioned by US and Canadian government from the Institute of Medicine of the National Academies brief:- “Scientific evidence indicates that calcium and vitamin D play key roles in bone health. The current evidence, however, does not support other benefits for vitamin D or calcium intake. More targeted research should continue. Higher levels have not been shown to confer greater benefits, and in fact, they have been linked to other health problems, challenging the concept that “more is better.” . Got that, they said blacks don’t need more vitamin D in north America (and they also found heart disease correlated with above average vitamin D levels in African Americans).
There are several mechanisms to limit vitamin D synthesis which modern Europeans have retained. There is the switch off in skin synthesis after 10-20 minutes (or 1 minute in some circumstances see Vitamin D production depends on ultraviolet-B dose but not on dose rate: a randomized controlled trial.); there is the system of vitamin D metabolism which even Vieth 99 calls ‘a system better designed to cope with an abundance of supply, not a lack of it” (that’s right white people switch off vitamin D synthesis in minutes) there are also not uncommon alleles which reduce the effectiveness of the vitamin-D binding protein,. So the idea that UV-B exposure is directly proportional to vitamin D synthesis and/or vitamin D levels is wrong. The only evidence that vitamin D has been in short supply for humans in temperate latitudes is that in Europeans skin turned white, but the simple latitude /UV hypothesis is not supported by the date for skin lightening mutations and the fact that fair skinned white people such as blondes and redheads do not manufacture more vitamin D for a given amount of UVb exposure that olive skinned people, or blacks ( see Vitamin D production after UVB exposure depends on baseline vitamin D and total cholesterol but not on skin pigmentation.) shows white skin has nothing to do with vitamin D . So white (and black) skin is there for something else.
“Nutritional rickets is common in black Africans living in equatorial Africa”
“they said blacks don’t need more vitamin D in north America”
“There are several mechanisms to limit vitamin D synthesis which modern Europeans have retained.”
“‘a system better designed to cope with an abundance of supply, not a lack of it”
For some x the combination of diet + sunlight might explain all of that:
enough x in diet + enough x from sunlight -> protection from too much
enough x in diet + not enough x from sunlight -> no change
not enough x in diet + enough x from sunlight -> no change
not enough x in diet + not enough x in sunlight -> dramatic change
enough x in diet + enough x from sunlight -> too much
.
“The only evidence that vitamin D has been in short supply for humans in temperate latitudes is that in Europeans skin turned white”
And East Asians.
.
So the actual case might be regions within temperate latitudes that lack a specific food source – somewhere in the interior maybe like the Himalayas / Denisovans / East Asians.
Greying Wanderer, despite living as farther north than Sardinians, East Asians are not anywhere near as white skinned though they live as far north. A Swedish hunter-gatherer from 8,000 years ago had the allele for light skin at SLC24A5. So it wasn’t food.
East Asians have black hair despite having Neanderthal loss of function alleles for hair colour that surely must have produced different hair colours at one time. East Asians were the result of less intense selection, or possibly strong natural selection that reversed the effect of earlier sexual selection.
‘I’ll bet it started out in a group that had domesticated only horses.’
Intolerance 1% – Mongolians and Dutch
Could it have happened twice? the Schleswig-Holstein region seems like a prime candidate – could have been triggered by associated Doggerland, changes in environment?
The Tarim mummies, ie Proto Indo Europeans, were found pretty damned close to Mongolia. Lactase persistence allele could’ve introgressed into Mongolians even with a fairly low rate of admixture.
Evolution is like a poker game with alleles as cards. Best cards and best combination with lottery style luck win each round. After each round, the pool of cards change with fewer bad cards and more good cards in the pool which are shuffled again (through migration, long distance traders, invasion, diffusion, natural events, meiosis genetic recombination, exotic taste for sex partners, escaping convicts to far away places, ect).
But the game is played continuously without distinct line between rounds. After thousands or more round, the end product can be dramatically different from the beggining (maybe even new species with `ancestor extincted’).
http://www.nature.com/ncomms/2014/141021/ncomms6257/fig_tab/ncomms6257_F3.html
Re: hair colour, when Gamba 2014 looked at Hungarian genomes, the late Copper Age and Neolithic genomes, otherwise typical EEF, already showed light brown / dark blonde colouration by the late Neolithic. Similarly SLC45A2 emerges mid way through the Neolithic samples.
The Bronze Age and Iron Age (presumably post-Indo European) samples seem have a lighter average hair, eye and skin pigmentation against the whole Neolithic sample back to 5310BC, not compared against Neolithics from 4490BC onwards. SLC45A2 distinguishing Europeans from non-Europeans seems to have emerged late into this Neolithic millenium.
It’s not clear whether Hirisplex is inadequate to pick all the differences though, at least for “classic blonde hair” (http://www.nature.com/ng/journal/v46/n7/full/ng.2991.html).
Some of this will certainly need large sample sizes to check.
The light-skinned allele at SLC24A5 has been dated to around the ice age by 3 teams: 19,200 – 7,600 BP (Canfield et al., 2014); 19,000 – 11,000 BP (Beleza et al., 2013); and ≈ 12,000 – 3,000 BP (Norton & Hammer, 2007). The light-skinned allele at SLC45A2 has been dated to much the same time period by two research teams: 19,000 – 11,000 BP (Beleza et al., 2013); ≈ 11,000 BP (Soejima et al., 2005)
The Interplay between Natural Selection and Susceptibility to Melanoma on Allele 374F of SLC45A2 Gene in a South European Population “To assess the meaning of 374F within the evolutionary history of Europeans we decided to estimate the selection coefficient and the age of expansion of this allele […] The age of the expansion of the allele, assuming a generation time of 29 years was estimated to be of 29,450 years (95% CI, 25,270–35,290). Using the HapMap data, the highest likelihood for the estimation of the selection coefficient was of 0.0243 (95% CI, 0.0111–0.0375) (Figure 6). The age of the expansion of the allele in this case was estimated to be of 16,480 years (95% CI, 10,680–36,070).”
Sardinians are 0.8 for 374F, Danes are 0.93.
The estimates are probably wrong.
@Sean
“despite living as farther north than Sardinians, East Asians are not anywhere near as white skinned though they live as far north.”
“not anywhere near as” is not the same as “The only evidence” though.
There is plainly some overlap between East Asian changes and European changes which may be a clue.
.
“A Swedish hunter-gatherer from 8,000 years ago had the allele for light skin at SLC24A5. So it wasn’t food.”
I think it might be the interplay between diet and sunlight i.e. regions where vitamin D (or something sunlight related) was in short supply from both diet and sunlight. For example if a fish diet or strong sunlight provided the required amount of x (whatever x might turn out to be) then interior HGs in northern latitudes might not get enough x.
Archaic HGs in the northern interior may have developed adaptations to fix the problem.
.
“East Asians have …”
They also had (seems to me anyway) a more comprehensive farmer expansion so the East Asian changes may be a marker for what was necessary for that. At the same time having a more comprehensive farmer expansion may have led to northern HG changes being lost that weren’t lost in Europe leading me to think the changes in Europe may have been additive i.e. lighter skin but not lighter hairs or eyes from the farmers combined with lighter eyes (and maybe hair and skin also) from the HGs.
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Like I say I’m willing to believe sexual selection was a big part of this in the north and maybe even a bigger reason than whatever the original reason was but I think there was an original reason.
“I think there was an original reason”
Or at the very least the latitude provided less resistance to the change whereas further south it would have.
The research is puzzling. Accepted opinion does link vit D with pale skin through latitude. But as Sean points out, there are discrepancies when it comes to understanding this link. Grey resolves these through a diet-latitude trade-off.
Likewise, Calcium is not considered the only driver of LP. One paper I came across suggested that amylase metabolism resulting from LP acts as oral rehydration for people consuming gluten. Another paper showed LP dist correlates better with IBD than with UVB or latitude. But LP does enable a supply of Ca.
As I recall, D is required for Ca absorption. So, the combined influences of diet and latitude, on the one hand, and LP and pale skin, on the other, are possibly all part of a complex of metabolic changes that evolved to enable people to exploit the cold, wet, fertile, resource-rich region of north Europe?
Multifactorial aetiology.
More UVb hits northern Europe in summer than hits equatorial Africa. (The atmosphere and ozone cover is less and the days are longer in the north). Natural selection for vitamin D would not make for white skin.
something else in fish then
Something that gives Europeans their delicate facial features, but not Inuit. Something that going by Magdalenian girl’s crowded teeth seems to date to the Late Glacial Maximum (just as both the main European light skin alleles do according to studies of each allele each by 3 different teams ). Something that Darwin thought of.
Doesn’t look as if SLC24a5 originated in Europe. The Mesolithic hunter-gatherers didn’t have it. This, by which I mean you, is getting old.
The grracile facial features seem to be Caucasoid, rather than European specific. It’s very common among Mediterraneans/Middle Easterners, who don’t exhibit eye and hair color diversity. Some of the classical physical anthropological literature describes the Nordic type as a “bleached Mediterranean” type to describe the light coloration coupled with gracile facial features. The Alpine type on the other hand is a European type with eye and hair color diversity, but less gracile than the Mediterranean/Middle Eastern type. Compare, for example, Brendan Gleeson to Saudi ambassador Adel al-Jubeir:
This Caucasoid gracility is generally attributed to agriculture. With agriculture, you see a change from more robust fossils to more gracile ones.
“Something that gives Europeans their delicate facial features, but not Inuit. ”
The ******lack******* of something in fish.
The surprisingly northern location of Amiens for the ‘Venus’ statuette (representation of a naked woman) find dated to 22,000 years ago that was announced today means must have been carved by someone who lived on steppe-tundra. It was made out of limestone, which is not dark.
Given the population movements and back migration that seem to have occurred, I think anyone turning out to be even half right about how the populations interacted would have done brilliantly. (Robert E Howard’s fictional Hyborians were not supposed to have been originally from the north they went north after the great cataclysm then came back, changed somewhat, returning as conquerors). Indo Europeans could easily have originated in Europe. Maybe you are more that half right about the Indo Europeans’ contribution. But my reading of this post is you say the Indo Europeans had blonde hair and dark skin and eyes which as far I know no one has ever suggested before . There are some reasons to think white skin originated alongside light hair and eyes, and they ought to be mentioned and argued for under a post like this, which I have done.
OP is missing an important point. If people move only and uniformly 10 km, then yeah, you get a wave, but if an occasional person moves quite far, perhaps an exile, nomad family, travelling merchant, you get many local nucleations. Think of fungus growing in agar or something; you get local colonies and expansions, but also spores.
No need to invoke population replacement in this case (though it’s obviously pretty common). Mere long-tail “spore” mobility works just fine to explain selective sweeps of advantageous alleles.
Broad sets of alleles are obviously conquest.
The Botai culture seems to have tamed horses, or had obtained tamed horses very early, and did not not have domesticated cattle.
You know, if you had bothered to understand Bedford Forrest, this would all be clear enough. But you haven’t.
http://www.bbc.co.uk/news/health-29805374
Unlike cheese and yogurt, milk may not be too good for you. The galactose (from breaking down lactose into glucose and galactose) creates oxidative stress. I suppose the less of an advantage something is the more likely conquest is the explanation.
There is a rather weak alcoholic drink which can be made from mare’s milk, could that have something to do with lactase spreading?
‘Blond hair maps pretty well onto Corded Ware territory, which suggests that it came in with the Yamnaya.’
I guess you base your conclusion on Wilde et al. (2014), where the ‘blond’ TYR gene was attested in two samples from the Yamna culture, including one that was homozygous (A/A) – extracted from a site in Kalinovka I, Middle Volga, the other being from Riltsi, Bulgaria – and one from the Catacomb culture (Temrta V near Stavropol, Russia) – just three out of 47 sampled individuals! However, much older (> 5,000 calBC) heterozygous samples were recently retrieved from three Neolithic samples in Hungary (NE2 at 5,060–5,290 calBC, NE3 at 5,010–5,210 calBC and NE5 at 4,990–5,210 calBC). Unfortunately, using the 24 SNPs included in the Hirisplex system, the impact of this gene is very relative. Gamba et al. (2014) arrived at four out of nine Neolithic Hungarian individuals having lighter shades of hair color, the oldest being KO2 (5,570–5,710 calBC) while NE2 and NE3 had the usual black or dark brown. One of the samples had light brown of dark blond hair, but this was NE7 (4,360-4,490 calBC), not NE5 (Fig.3 and supplementary table 17).
Thus, Corded Ware probably didn’t get their blond genes from Yamnaya at all. No surprise at all. All ‘genetic evidence’ of Yamnaya meant to prove they had any impact on Corded Ware tends to suck: Why Yamnaya Didn’t Contribute to Corded Ware – On Circularity and Perpetuated Talks.
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Concerning migrations and lactose tolerance, it occurs to me that lactose tolerance is only an advantageous trait if you are likely to encounter lactose as an adult.
So if Studly the Lactose-Tolerant Mighty European somehow ends up in a Pathan village, and knocks up every female there, single-handedly getting the gene established beyond the risk of extinction from drift in only one generation, what use will those lactose-tolerance genes be to Studly’s children when they reach adulthood? Very little, unless they are being encouraged to consume milk or lactose-rich milk products as adults.
The spread of the gene makes much more sense if Studly is part of a migration that introduces adult milk-consumption along with the genes.
A generation time of 30 years seems high. Prior to conception control, when the life expectancy was 30 or 40, I would bet that most people had their first child by the time they were 15. Sure, people had multiple children, and a few would continue having children into their forties (there might be a gender difference here), but I bet that the generation time is closer to 20 than 30.
I haven’t crunched the numbers to see if it would affect your main point.