There is a new paper out in Nature, mostly about the spread of the Indo-Europeans. They confirm that the Yamnaya ( from the Ukraine) were the main ancestors of the Corded Ware culture (northern Europe, from Germany far on east). The Sintashta culture, (base of the Urals down to the Caspian, first with chariots, and ancestors of the Indo-Iranians), looks like a migration of Corded Ware to the east.
The Yamnaya were also the source of the Afansievo culture in the Altai, possible ancestors of the Tocharians.
The European lactose tolerance mutation is not common in the early Bronze Age, but it does exist, particularly in the Yamnaya, where the gene frequency is about 30% (in this study – zero in the Haak study) This suggests that the European mutation originated on the steppe (not Bavaria !) – which would explain why the same mutation is fairly common in northern India and Pakistan. It’s not clear if it was common enough to have social and demographic significance back then – since it’s dominant, a gene frequency of 30% would mean that 51% of the Yamnaya were lactose tolerant. In other words, I said that I must be wrong about lactose tolerance mattering in the Indo-European expansion, but I am no longer sure about that. But these samples are small – time to excavate more kurgans. Conceivably the frequency varied significantly by social class. Anyhow, it had to have been spread by a massive invasion – it couldn’t have spread that fast as a Fisher wave.
West Hunter 
“since it’s dominant, a gene frequency of 30% would mean that 51% of the Yamnaya were lactose tolerant.”
Could you explain a bit further? I must not be understanding the math, or I didn’t read the paper carefully enough. I didn’t think there was high enough coverage to determine zygosity, and the 30% was based on a presence or absence for each person.
I don’t know much about genetics but I guess that Cochran’s calculation is 3/10 + 3/10 – 9/100 = 51/100.
right, but another way of doing the calculation it is that 7/10 of genes are intolerant, leading to (7/10)^2=49/100 people having double intolerant genes, thus being intolerant, leaving 51/100 tolerant.
That’s the neatest of these calculations.
Let p=0.3 the frequency of the Lactase persistance gene.
In a Hardy Weingberg equilibrium the frequency of homozygotes is p²=0.09 and heterozygotes 2p(1-p)=0.42. LP is dominant so both homozygotes and heterozygotes express lactase persistance. Hence to know the frequency of people with it, you just have to add homozygotes and heterozygotes which yields 0.51.
Yes, you have expressed this simple concept in the most complicated way possible. I see a great career for you.
Well I must be a total idiot (not being sarcastic) because I actually understood this one as opposed to the more symbolically expressed ones above.
I achieved a Hardy Wine* equilibrium last night and the explanation made sense to me.
I had to leave the berg out, it was too cold to carry.
Since you were fighting for cattle and grazing lands, you targeted whoever had the lowest ratio of men to cattle, which meant you always targeted the lactose intolerant people.
Which in turn resulted in a lactose tolerant ruling class and a lactose intolerant subject class.
Thanks Jim,
So I am guessing that 51% is an upper bound, with 30% (ignoring the 0% from the entire other study) being the lower bound.
Sorry, another dumb question. I just find it so interesting.
Since these genotypes were imputed from modern people’s data (which underwent a massive selective sweep), rather than actually being observed, and if the actual original mutation occurred within the exact haplotypes being investigated, how can this be in any way accurate?
I mean, if my grandson had a new mutation that later swept to fixation, then imputing my genotype in that region from later people’s would show that I had the mutation, when in fact it hadn’t even arose yet.
no, these numbers are not imputed, but are from ancient dna. that’s what gc meant by “time to excavate more kurgans”
The paper says they were imputed. Read the paper.
If it were the case that a class difference existed (and is it so likely the Yamnaya had enough population structure for that?), I might imagine it more the opposite way around.
“Milk?! What need have a beef eating warrior for your milk, commoner?”
Milk as a subsistence food for herders that don’t have much cattle, and even have few sheep. Boeuf for the lord’s table, cheese for the commoner, etc..
Likely, judging from people’s extrapolations of early Indo-European society.
David Anthony’s predictions in The Horse, the Wheel, and Language are looking more and more correct. Except…
David W. Anthony, an archaeologist at Hartwick College and a co-author on the Harvard study, said it was likely that the expansion of Yamnaya into Europe was relatively peaceful. “It wasn’t Attila the Hun coming in and killing everybody,” he said.
Instead, Dr. Anthony thought the most likely scenario was that the Yamnaya “entered into some kind of stable opposition” with the resident Europeans that lasted for a few centuries.
For which Razib Khan and a lot of others laughed at him on twitter. Archaeologists…
I imagine they would be as peaceful as necessary. They slowly came in with their cattle and horses and wagons. They let their animals eat all the nice crops they came across. They burned all the forests they encountered, so that it could provide nice fresh vegetation for their animals. It was all very, very slow and peaceful. And, they had metal weapons, and rode horses, peacefully.
I’m certain that the Yamnaya abhorred violence.
Just like the Mayans. All that read coming off their fingers in their portraits? Flower petals. I kid you not that was the establishment line for a long while. Blood was not blood but Flower petals because they had to be peaceful and flowers represented peace.
read = red.
They wouldn’t have much success if they tried to burn broadleaf woodland in NW Europe. It won’t burn. I dare say they stuck to burning conifers.
Fire created the thousands of acres of long-leaf pine savanna of the SE US which was used as a grazing common by the early immigrants. Fire was used to keep the eastern deciduous forest open and providing plenty of fresh greenery on the forest floor each year. Eastern woodland burning was done by the Native Americans and continued by the immigrants.
Broadleaf forests can burn, but they are not nearly as easy to burn purposefully as are many conifer-dominated, savanna-like forests. Natural fire-return intervals are much longer for broadleaf forests, i.e., they only burn from lightning strikes during severe droughts. There is a huge literature on the finer points of the relations between fire and forests. See Jackson, Adams and Jackson in American Naturalist, 1999.
Yeah: different trees have a different propensity to burn. Genetics, you know.
“Broadleaf forests can burn”: not in Britain they can’t, and therefore (I assume) not elsewhere in NW Europe. Moreover you can’t kill the trees by ring-barking either. Nobody has any idea how the wildwood was cleared, but it certainly wasn’t by slash and burn.
Dearieme, allow me to teach you the apparent lost art of killing a tree anywhere, nice and easy. All you need is your handy dandy stone axe and the ability to make a fire. Pile up dead leaves and fallen sticks in the fall around the base of the tree you want to kill and light it on fire. After the fire has burned out take your stone axe and chop away the burned bark down to the wood all the way around the tree. Unless you half assed girding the tree, that tree is dying. Kindly don’t tell me that a tree with a very high moisture content can’t be killed this way because it can. As long as the fire burns long enough it is an easy task to then chop away the burned outer bark and inner bark down to the wood even with a primitive stone axe.
To this day goat herds are used to finish the job of converting a forest into pasture land after the tall trees have been killed. Goats will eat anything green within reach. Once the tall leafy vegetation has been removed grasses can then outcompete taller vegetation because they absorb nitrogen faster and survive just fine from constant munching.
Cattle grazing under broadleaves will gradually create an open forest-grassy meadow environment. I saw this process down on the farm as a boy, we grazed cattle on oak forest woodlots. Cattle also browse the trees and eat saplings, so the forest ages and dies out, with no burning required. A slow process if just cows.
useful info
Yeah. And people all around Europe started talking PIE because they all thought it was cool. You know: from Yamnaya to Lusitania, because those cool guys had something like FM radio or somekind of dino-technology a la Flintstone. The model favored by Anthony could have work for a couple of small African tribes. It’s impossible for it to work for almost all Europe and part of Asia.
Another sampling of Yamnaya here in German, published 03/02/2015 –
http://ubm.opus.hbz-nrw.de/volltexte/2015/3975/
“Populationsgenetik kupfer- und bronzezeitlicher Bevölkerungen der osteuropäischen Steppe”
(“Population Genetics of Copper and Bronze Age populations of the Eastern Steppe”)
“This thesis presents the first genetic study of prehistoric populations in the Pontic-Caspian steppe from the Upper Thracian Plain to the Volga. Mitochondrial hypervariable region I and parts of the coding region were Analysed sequencing in 65 Eneolithic and Bronze Age individuals using multiplex PCR and 454. Additionally genotypes from up to 20 putatively naturally selected autosomal SNPs and a sex-specific locus were obtained. Published ancient DNA data from West Eurasia and modern DNA sequences were consulted for comparison. The results support the inference did early Neolithic farmers from Southeast Europe were involved in establishing pastoralism in the steppes by demic diffusion. The Consistently low FST values between the Yamnaya Culture of the steppe and a succession of Neolithic cultures in Central Europe suggest frequent contacts. The Catacomb Culture, Successor of the Yamnaya Culture, is characterised by a high incidence of haplogroup U4, Which is common in North and East European hunter / gatherer populations. Low FSTs Between the prehistoric steppe populations and modern European populations indicate genetic continuity. This is supported by nuclear genotype frequencies. According to current knowledge the modern European gene pool can be Explained by three roots: indigenous Mesolithic hunter-gatherers, early farmers from the Near East, and an ancient North Eurasian component of Upper Palaeolithic origin. The third component ancestry might have been Introduced Into the late Neolithic European genomes by the North Pontic population.”
Apparently 30 Yamnaya sampled for various genotypes, pages 199 and 352.
No “lactase a” (the main European SNP). At all. Maybe she’s got the wrong SNP or there’s some error or something? I’m somewhat doubtful of an error though, as the frequencies for SLC45A2 derived genotype and HERC derived genotype also look perfectly consistent in Wilde with the Haak / Mathieson work.
Allentoft et al have 6 samples, Haak another 9, and Wilde 30.
In terms of dates, look like the midpoint estimates from Haak’s Yamnaya average around 200 years older than Allentoft’s but that shouldn’t matter greatly (although if the one or two lactase persistent folks among the Yamnaya six include the sample contemporaneous with Corded Ware that might matter more).
Re: lactase from Bavaria, this new paper seems to think there is a signal of population movement from North-Central Europe to the Sintashta Culture, as you note, so there’s that.
Populations who dairy a lot, like late LBK offshoots, adapting to a high mobility lifestyle might end up selecting for lactase more than than populations who were just herders from the start and maybe didn’t bother hoofing around cheese strainers and whatnot much because of it.
The difference is that those genotypes were directly observed, while in the current paper from Allentoft, et al. they imputed the data from current genotypes.
I don’t see how that can be accurate.
The mutation is on a particular haplotype.
A haplotyoe which existed before the mutation. And before that mutation was selected, reducing the variation within that haplotype.
Rich, but do we really think that the “lactase haplotype” was common before the mutation which almost invariably occurs on it with modern populations? Although if you have any links that cast doubt on the “invariably occurs” part, please share.
@Matt
I have it on very good authority that this particular background haplogroup was at a frequency of around 30% of chromosomes in the Bronze Age Yamnaya. When the actual LCT mutation was looked for in ancient genomes (in a different study) they didn’t find it a single time.
Since the other study had only four individuals, there’s really no way to tell.
After a full analysis of the raw sequence reads, I can assure you that there is not a single actual positive read for lactase persistence mutations in this study, other than in Iron Age Sweden, or the Karasuk culture of Russia.
I wouldn’t draw any strong conclusions.
@Matt: according to this: http://www.nature.com/news/archaeology-the-milk-revolution-1.13471
the mutation arose among the LBK farmers. It seems very plausible that it first arose in farming populations, started spreading non-violently among them via trade and intermarriage, and then got picked up by Yamna’s ancestors, which eventually led to the more dramatic story of the allele’s explosion.
That article is based on an embarrassingly wrong study by Ruval Itan and Mark Thomas. They tried to estimate the origin of the lactose tolerance allele using the current distribution (population movements make this approach almost always wrong) , and they didn’t even get that right – they apparently didn’t notice the second peak in North India.
Well if you go that way Denmark or something is the origin of lactose tolerance. Which of course makes loads of sense. It was the vikings that brought lactose tolerance to India. Genius!
There is one that was positive for LCT b (which is the G-22018-A version) among the 28 Jamnaja fit for this sample, 2 for Katakomber.
If the handful of west european ydna clades that exploded around this time were the handful with LP (or married to them) then there might have been a dramatic founder effect.
This might require / imply some kind of climate effect reducing crop yields in north west Europe.
Recently found out one of the things that makes the Atlantic coast a separate bio-region is it has acid soil (caused by leaching from the heavy rainfall).
Wheat doesn’t like acid soil (but oats and millet do).
“Afansievo culture in the Altai, possible ancestors of the Tocharians.”
-The Afanasevo is probably too dissimilar to the Tocharians:
youtube.com/watch?v=-Q_tqVQHwFw
I think the Tocharians’ origins should be sought further South, in the fertile fields of Turkmenistan (and maybe Uzbekistan and northern Afghanistan). The far Northeast is likely a dead end.
Even if rates of lactase persistence were low among the Yamnaya, couldn’t the migration into Europe have acted as a selective filter? That is to say, since forested Europe couldn’t sustain as large herds as the Eurasian grasslands, the only people who could survive there were the ones drinking milk.
Something along those lines is what seems likeliest to me – some kind of extreme regional calorie filter.
So maybe two selection pressures: a very strong regional one based purely on calories that led to a dramatic explosion in the west and northwest and a much less strong non-regional selective pressure based on something else that led to it expanding slowly out of the core region since that explosion.
Maybe a bit like breast milk being 95% nutrition and 5% magic medicine (if that is what breast milk turns out to be one day).
Doesn’t breast milk contain antibodies that bolster the newborn’s immune system?
yeah and also stem cells which do – no idea – but possibly / probably something pretty cool
Q: “What is best in life?”
A: “Milk!…plus some other things”.
plus oats for the iron 🙂
Greying Wanderer, here’s the magic: breast milk has pluripotent stem cells.http://www.fasebj.org/content/28/1_Supplement/216.4
yeah, cool huh
Holy Chimeras Batman!
Atlantic coast cow-human hybrids
Greg what do you make of Paul Haggerty’s claim that these findings also fit the ‘out of Anatolia’ hypothesis? That is, the yamnaya are a kind of secondary outgrowth from pie-speaking middle eastern farmers, who then went on to colonize northeast Europe and central Asia. He seems to think that the Uralic speakers in these samples having a high yamnaya component — higher than south euro ie speakers — makes it difficult for the steppe hypothesis. See here…
http://dlc.hypotheses.org/807
I think he’s wrong. I may have more to say on that.
“The Sintashta culture, (base of the Urals down to the Caspian, first with chariots, and ancestors of the Indo-Iranians), looks like a migration of Corded Ware to the east.”
The evidence has now swung very strongly in favor of a steppe origin for Proto-Indo European. Even before the recent aDNA evidence, the case was a strong one: http://www.annualreviews.org/doi/pdf/10.1146/annurev-linguist-030514-124812.
A lot of the remaining arguments will be about details. From that perspective the quote above is interesting. The simplest theory of Indo-Iranian origins within IE would be that II speakers rode right off the steppe. But the genetics suggests it was more complicated. There was first a northwestward movement off the steppe into East-Central Europe, (Yamnaya to Corded Ware) then an eastward movement, through the forest steppe north of the steppe proper, arriving at the southern Urals, and giving rise there to the Sintashta culture, in the Proto-Indo-Iranian homeland. Both archaeology and linguistic phylogeny have already been pointing in the same direction. David Anthony summarizes evidence for a series of cultures (eg Fatyanovo) consistent with Corded Ware heading east. And probably the best phylogenetic tree we’ve got (below) for IE is consistent with this, making Indo-Iranian and Balto-Slavic sister groups. (Note that Germanic appears twice in the tree. Germanic has some affiliations with Italic and Celtic, and some with Baltic and Slavic, and may be a hybrid.)
Anatolian
(Tocharian
(((Italic Celtic) Germanic)
((Greek Armenian)
(Germanic (Balto-Slavic Indo-Iranian))
)
)
)
Not entirely off topic, if some advertising is allowed: Over the course of this year I’ve been blogging and tweeting the history of the universe, day by day, starting with the Big Bang January 1 and finishing up covering the year 2015 on December 31. I do this on a logarithmic scale, so time slows down and there’s more time for later history. At the moment I’ve gotten as far as early Homo erectus. I’ll be getting to matters Indo-European in September.
Blog: logarithmichistory.wordpress.com and Twitter: @logarithmic_h
Good to hear from you! Sounds like an interesting site: does the last second of the year correspond to 2012, when as we all know the world ended?
Yeah, I was thinking along similar lines concerning Corded Ware -> Sintasha helping explain the funny relationships between German, Balto-Slavic, and Indo-Iranian. We still need to elucidate the Anatolian story, but the rest is really coming into focus.
Re logarithmic history: the last day of 2015 corresponds to the whole year 2015. Calendar time and universe time coincide at midnight. December 30 on the calendar corresponds to 2014 plus a little bit at the end of 2013 in the history of the universe, and so on backwards. There are other ways I could have done it. For example I could have made December 31 on the calendar correspond to December 31 in the history of the universe. But this would mean spending the last week in December commemorating the last week or two in December. Not very exciting.
Very nice blog site you have set up logarimichistory. I will have to get over there and read it in detail when I have time. I found your concept of presenting history from your logarithm perspective to be interesting and useful. It works very well in transitioning thoughts from a here and now perspective to a historical perspective. It is more than a math trick, it works to help a student of history visualize how human history has very recently accelerated to crazy quick speeds since the industrial revolution.
I have been looking at Gamkrelidze and Ivanov chapter 7 on the breakup of Indo-European into dialects and then separate languages. On the basis of phonological, morphological and lexical isoglosses they envisage a seven-stage process in which this grouping is the fifth stage.
Indo-Iranian-Greek-Armenian
Balto-Slavic-Germanic
Italic-Celtic
Tocharian
Anatolian
However, there are supposed to have been different degrees of contact between the dialects at different stages. In particular:
Indo-Iranian was entirely isolated at stage 2 (on the basis of isoglosses affecting all other dialects including Anatolian) but renewed contact with the others at a later stage. Reverse migration to Sintashta?
Tocharian seems to shift position relative to the others, showing early affinities with Italic-Celtic, later with Baltic-Slavic-Germanic-Indo-Iranian and finally becoming an isolate. A long eastwards trek to Afanasievo?
They regard the centum-satem split as a late development, stage 6 or 7, when Indo-European was widely dispersed geographically and innovations did not spread throughout the entire area.
@logarithmichistory Interesting blog, I mean to follow it.
“They confirm that the Yamnaya ( from the Ukraine) were the main ancestors of the Corded Ware culture (northern Europe, from Germany far on east).”
The Allentoft paper, both with words, and with data, do not confirm that the “main” ancestors of CWC were from the Yamnaya people.
They see signs of admixture, but the Haak paper is better. It uses a new and more powerful method to analyze Corded Ware ancestry, finds that they are something like 75% Yamnaya. Possibly more.
What new and more powerful method would that be?
Could you describe the new and more power algorithm used on the Haak paper? I don’t recall seeing such an algorithm published.
Read the Haak paper. I’s in supplementary information section 9.
“The method (Supplementary Information section 9) is based on the idea that if a Test population has ancestry related to reference populations Ref1, Ref2, …, RefN in proportions α1, α2, …, αN, and the references are themselves differentially related to a triple of outgroup populations A, B, C, then:
By using a large number of outgroup populations we can fit the admixture coefficients αi and estimate mixture proportions. “
Ah, I see. I don’t think this is a new algorithm. It’s just searches for linear combinations of references populations to fit a population (in this case, CWC).
If this algorithm where applied properly, over time, you could form CWC from a large combination of potential reference populations across time and from various sources. Forming CWC from a “main” Yamnaya ancestor in the Bronze Age is only one possible solution among many.
For instance, in the Allentoft paper, you can see that Neolithic Hungarians had some ancestry from a Yamnaya population. If this Neolithic Hungarian population contributed to CWC, that would lower the contribution of Bronze Age Yamnaya to CWC.
Also, the Yamnaya samples in Allentoft have low level admixture that does not appear at the same level in CWC, and not uniformly in CWC (compared to Yamnaya samples) so something is going on with that.
These issues should raise some questions about assuming that CWC is “mainly” derived from Yamnaya in the Bronze Age.
There is such a thing as a best fit. Go learn some linear algebra.
No, it’s a generalization of f4 ratio estimation…
“Go learn some linear algebra”
In fact, geochran9, I’m an expert in linear algebra.
In this case, if you read my comment carefully, you would see that there really isn’t a best fit for CWC at the major component level. The reason for that are the minor blue components in Yamnaya that do not appear uniformly in CWC, nor at the level you would expect if Yamnaya were THE major contributor to CWC.
Also, the notion of a best fit isn’t valid with so much missing data, both in terms of geography, and in terms of time.
Gregory,
I just checked your background. You have a physics background. So do I. I also have an EE background and do linear systems analysis, as well as error analysis, as part of being a Silicon Valley engineer (with a number of patents in the field of analog and mixed signal design.)
It is quite inappropriate for you to be blowing off a member of the public on your blog, telling them to “go learn some linear algebra.”
As a physicist, you should of course know that in the absence of a lot of data, it is improbable that a “best fit” solution is valid.
Marnie Dunsmore
Analog Mixed Signal Design Engineer
San Francisco and Santa Clara
California
Having read the analysis in the Haak paper, it makes sense to me. Take a look at it.
I’m glad you know some linear algebra: but I still think you’re wrong. Each genome is a vast data set, not a data point: if two genomes share drift (which you can measure with D-statistics) , there’s no explanation other than shared ancestry. For example, we could determine (beyond any doubt) that Eurasians had Neanderthal ancestry while sub-Saharan Africans had next to none from just one Neanderthal genome. We actually had two or three partials, but one was sufficient. In much the same way, when you looked at the D-statistics in that big Neanderthal paper in 2010, you could see that Melanesians were significantly more distant (in terms of shared drift) from Africans than other Eurasians were, which could only have happened if they picked up an extra dose of archaic ancestry: which proved to be the case.
It’s one thing to argue for shared ancestry, and quite another to argue for “mass migration” within several hundred years, and that ” the Yamnaya ( from the Ukraine) were the main ancestors of the Corded Ware” [only during the Bronze Age, according to Haak].
These arguments have been made when it is quite apparent that other populations, prior to the Bronze Age, have Yamnaya like ancestry components in their gene makeup.
Haak et al have not addressed these issues.
The Allentoft statements are more measured. For instance, they state: “Our findings show that these transformations involved migrations, but of a different nature than previously suggested: the Yamnaya/Afanasievo movement was directional into Central Asia and the Altai-Sayan region and probably without much local infiltration, whereas the resulting Corded Ware culture in Europe was the result of admixture with the local Neolithic people.”
” it is quite apparent that other populations, prior to the Bronze Age, have Yamnaya like ancestry components. ”
Like who?
Some of the Neolithic Hungarian samples in the Allentoft paper, and the Karelia sample in the Haak paper, for example.
You’re leaning on ADMIXTURE results, but they can be deceptive. To determine ancestry ingredients you need to look at f4 D-statistics, and as far as I know, the amount of ANE in the old farming culture of Europe (before the Bronze Age) was zero. With the possible exception of some guys in Bulgaria and Romania, the first place where Old Europe was crushed.
If Allentoft etc thought that they had found evidence of ANE earlier, they would have been excited and said so. They do not.
Finding ANE in Karelia is nothing surprising: it probably originates in Siberia, and a little existed in Scandinavian hunter-gatherers. Karelia is in-between.
But none in Loschbour, none in Stuttgart (EEF farmer).
The ‘mass migration’ sure looks more like extermination to me. The Y chromosome haplotypes that had been dominant in the Neolithic farmers (G2A) almost vanish – they persist at low frequencies in mountain fastnesses and islands. There is also a dramatic turnover in mtDNA haplotypes: N1 had a frequency of something like 25% back in the Neolithic, 0.25% today.
“To determine ancestry ingredients you need to look at f4 D-statistics, and as far as I know, the amount of ANE in the old farming culture of Europe (before the Bronze Age) was zero.”
Only because when they run D-stats on these ancient samples, they group all the samples together, which blurs out variation in the samples.
You can argue extermination or whatever you want. CWC has some shared ancestry with Yamnaya . . . Is that all directly from Yamnaya into CWC in the Bronze Age only? Unlikely.
off topic but might interest people – health effects of early puberty
http://www.bbc.co.uk/news/health-33168864
Have they got the arrow of causation around the wrong way?
If you have a set of genes that biases you towards getting cancer or diabetes, perhaps earlier puberty helps to keep your reproductive success up.
Nah, simpler: obesity causes both early puberty and diabetes. In fact, the article mentions this.
I thought it would be a correlation but the one I was thinking of was class i.e. average age of puberty varying with SES but yes, obesity fits.
Meanwhile, Kennewick Man has become a Native American again:
http://dienekes.blogspot.com/2015/06/kennewick-man-was-native-american.html
OT:
How is it that large swaths of women–like the Millennials–“choose” not to have children? Doesn’t this cry out for a pathogen explanation as surely as homosexuality?
Women choosing not to have children ought to be as weird as someone choosing not to eat, or hold one’s breath until one dies.
It’s interesting to think that humans have created societies where the only reason most people ever had kids was due to social bullying, and, once that’s gone, they simply can’t be bothered.
“Doesn’t this cry out for a pathogen explanation as surely as homosexuality?”
No.
“How is it that large swaths of women–like the Millennials–“choose” not to have children?”
Say the prime reproductive years are 16-36 that’s 20 years total so if you take out 5-8 of those years for education that’s 25% to 40% of those years – so not surprising really.
Given current longevity it might make more sense for women to have kids young and then do the education / career bit afterwards (which is pretty much what all the women in my extended family do but we’re pretty weird).
Personally I do not give a rat’s arse about Yamnaya and the Indo-Europeans basically as I am from Southern Europe, and Yamnaya and those Indo-Europeans stuff is just all about Northern Europeans and some Central Europeans being self indulgent, staring at their navels or all standing around bent over, nude, all gazing at whose anus is pinker, and who can drink a gallon of milk and not fart once. You all are acting like you come from a long line of bastards yearning for mum and dad. It does not occur to anyone that those Yamnaya folk were composed of hunter/gatherers from the asian side of the Eurasian steppes, and the womenfolk were from the Caucasus region. How European is that?
What I am looking for is finding out more about the Mesolithic, Neolithic and Bronze age inhabitants of North Africa, the Near East and West Asia. Enough about the boring Northern Europeans. There are many other humans around in Europe and the world who are not Northern Europeans for which I thank every man created diety and God.