Timing the Wave

A recent paper in PNAS talks about ancient DNA results in Ireland. The story is getting to be a familiar one: 5000 years ago Ireland was inhabited by a Sardinian-like population, 4000 years ago by people pretty similar to the Irish today. Looks like near-total replacement. Since the Corded Ware culture was in place by 4900 years ago, we know that the replacement process in northern Europe took less than 900 years, maybe a lot less. Ongoing ancient DNA investigations should give us a pretty good chronology in the next few years.

Some questions are going to be harder to answer. Why near-replacement in northern Europe, but not in southern Europe? Obviously Indo-Europeans imposed their languages, lots of Y-chromosomes, and made an autosomal contribution to southern Europe, but it doesn’t look like replacement. Sometimes these things boil down to choices, as when the Mongols started taxing the southern Chinese rather pursuing extermination. Maybe a prehistoric Yelü Chucai convinced the invaders that the EEF population was good for something (pizza?), or on the other hand, maybe some of those southern populations put up stronger resistance. Yet the G2a Y chromosomes, once dominant, are very much reduced in number.

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39 Responses to Timing the Wave

  1. patrick Boyle says:

    Isn’t this a simple matter of geography? If a new group invades an island the old group will be easier to replace because they will have a hard time escaping. If a new group invades a new territory that is in the middle of a land mass the defeated population will always be able to scatter.

  2. BB753 says:

    Higher density of population and more advanced civilizations in the South making wholesame replacement difficult.
    Also, the First Farmers the Yamnaya met in Northern Europe were probably less adapted to survival in northern climates. Not only biologically, but also in terms of agriculture and animal husbandry. They were an easier target.

    • Higher density of population and more advanced civilization in the Americas did cause a similar situation here after 1491. The amerind population was almost completely replaced in the north and highly interbred with in South and Central America. But I don’t think the same reasons were in play for these two population replacements. Utterly different times and utterly different circumstances allowed one population to annihilate another one and take over it’s country in a relatively short period of time. I am not going to propose a glib answer as to why the Yamnaya steppe herders kicked ass and didn’t take prisoners, but I sure would like to read a scholarly book that does try to answer this question. I suspect multiple factors were involved and we may never know for sure, this is pre history where we unfortunately know very little about the people.

    • georgesdelatour says:

      Northern Europe is more of a plain. Southern Europe has the Alps, Apennines, Balkans, Pyrenees.

  3. ohwilleke says:

    There is pretty good evidence that the second wave was filling a void created when there was a collapse of the farming economy of the first wave Sardinian-like farmers almost everywhere they went. In some places, like Ireland, the collapse was so severe that the farmers reverted to primarily hunting and gathering with dramatic population losses and a rise in hunter-gatherer admixture as those skills became more desirable than the busted innovation of their style of farming. In other places, such as those where fishing and herding may have been more important and where the climate was closer to the ideal for the Fertile Crescent crop package, the collapse was less complete. Newcomers not tied to the same economic model and instead relying on a model developed in a more arid, northerly area may have been better adapted and dramatically supplanted the much reduced local people.

    Some of the collapse of farming may have been due to exhausting of the land’s fertility due to lack of fertilization or crop rotation or adequate use of legumes. Some of the collapse may have been due to a climate event. The 5.9kya event was the most intense arid period of the Holocene. https://en.wikipedia.org/wiki/5.9_kiloyear_event

    There is also data from pre-Beaker v. Beaker Iberia tending to show that dairy-meat consumption by the newcomers resulted in longer lives and less mortality among the newcomers. https://books.google.com/books?hl=en&lr=&id=iwBDCwAAQBAJ&oi=fnd&pg=PA243&ots=2OZA9raBp9&sig=ohvuxbTIcCFdAgCB4yreC-NLORw#v=onepage&q&f=false

    It could be that indirect consumption of grass (often native) through milk and meat was more robust to the highly arid climate event than produce for direct consumption from non-Native plants which was relied upon by the first farmers, and that the edge was greatest where the environment was furthest from the native climate of the Fertile Crescent package plants.

    • gcochran9 says:

      I don’t believe a word of it.

      • ohwilleke says:

        Does that mean that you think that the newcomers genocidally eliminated a thriving pre-existing Sardinian-like farmer culture?

        • gcochran9 says:

          Yep. Just like they did in many other places. In Germany, all the villages disappeared.

          In England, all evidence of farming ended for centuries – only livestock raising continued.

          Hell is not climate change – it’s other people!

          As for a crisis based on soil exhaustion, that’s impossible. The problem is mainly nitrogen exhaustion, and even fallowing the land every other year is enough to allow long-term continued production. Even if you had no idea of how to do this, you would notice that land abandoned for a few years was perfectly useful – people would return to it.

          In places like Germany, the mtDNA haplotypes common in the LBK culture ( like N1) decrease in frequency by a factor of a hundred or so in later pops -which implies almost complete extermination.

          . All over Europe, the dominant y-chromosome haplotypes among the early farmers become rare, found today mainly in mountain refugia and Islands. This happened even in southern Europe, where the degree of autosomal replacement is much lower than in northern Europe..

  4. epoch2013 says:

    Not near total replacement. They state (shortened quote):

    “These analyses indicate that the Irish Bronze Age is composed of a mixture of European MN and introgressing Steppe ancestry. To estimate the proportion of Yamnaya to MN ancestry in each Irish Bronze Age sample, we took three approaches. First, from ADMIXTURE analysis, we examined the green Caucasus ancestry component. We presume an ultimate source of this as the Yamnaya where it features at a proportion of 40% of their total ancestry. In our three Irish Bronze Age samples, it is present at levels between 6–13%, which, when scaled up to include the remaining 60% of Yamnaya ancestry, imply a total of 14–33% Yamnaya ancestry and therefore 67–86% MN in the Irish Bronze Age. Second, for each Bronze Age Irish individual, we calculated the proportion of MN ancestry by using the ratio f4(Mbuti, Ballynahatty; X, Dai)/f4(Mbuti, Ballynahatty; Gok2, Dai), which gave estimates between 72 ± 4% to 74 ± 5%, implying again a substantial Yamnaya remainder. Third, we followed the methods described in Haak et al., which use a collection of outgroup populations, to estimate the mixture proportions of three different sources, Linearbandkeramik (Early Neolithic; 35 ± 6%), Loschbour (WHG; 26 ± 12%), and Yamnaya (39 ± 8%), in the total Irish Bronze Age group. These three approaches give an overlapping estimate of ∼32% Yamnaya ancestry. “

    • gcochran9 says:

      I cheated – I read and understood the whole paper. Looks like total replacement. There are substantial EEF-like and WHG-like components in the Bronze Age Irish samples, but they were apparently picked up elsewhere: “the Rathlin samples show no trace of significant introgression from Ballynahatty”. They look a lot like central European Bronze age populations.

      Gradually picking up substantial amounts of ancestry from the previous tenants of Europe as the wave moves west is compatible with near-complete replacement in any particular part, maybe in every part, of northern Europe.

      • epoch2013 says:

        O dear. That was right in the line above my quote.

        This has an interesting consequence, though. Rathlin shows little affinity to Iberia whereas Ballynahatty does, and it is clear that these Iberia look-alikes are not the source of the MN part of Rathlin. But the latest consensus was that Bell Beaker culture originated in Iberia.

      • rkr says:

        There’s a rather old branch of haplogroup I2 in Ireland/UK and it is not exactly the rarest thing you can find on those islands.

        http://www.yfull.com/tree/I-S2639/

        In theory it could be associated with NFs but it forms a clade with the Lochsbour WHG so it’s not likely that it is from Anatolia. Granted this isn’t incompatible with the idea of near-complete replacement but my understanding is that most R1b men descend from prominent individuals who lived long after the Indo-European invasion era so there is a possibility that low class males with local haplogroups were more common in the past.

  5. Matt says:

    The proportion of Yamnaya ancestry in the Bronze Age Irish looks around 35% per the paper.
    Paper: “To estimate the proportion of Yamnaya to MN ancestry in each Irish Bronze Age sample, we took three approaches…. These three approaches give an overlapping estimate of approx 32% Yamnaya ancestry.”

    There aren’t particularly strong links from the Bronze Age Irish to the Neolithic Irish, probably because the Neolithic ancestry came from various different places, not all from the Neolithic Irish.
    Or could’ve been complete replacement of Neolithic Irish by a continental MN Farmer-Yamnaya synthesis. Or not.

    In Spain Yamnaya ancestry seems likely to be around 20%, based on the previous studies on the Yamnaya and on proportions of the Yamnaya related EHG ancestry in amateur ADMIXTURE runs using ancient dna.

    Difference in Yamnaya vs non-Yamnaya associated Y Chromosome between Irish and Spanish haplogroups doesn’t look much different than that 15%.

    The questions about Y Chromosome vs autosome balance (why disproportionate?) may be be mainly around Central European populations that mixed Yamnaya with MN European. Why do you get these Bronze Age and post Bronze Age Central European populations who are virtually all R1 (which some y-dna I) yet have mostly European Neolithic ancestry?

  6. dearieme says:

    I can see that extermination of agriculturalists might make sense for a conquering herding population, but wouldn’t enslavement make more sense for conquering agriculturalists? Which sort were the incomers?

  7. AllenM says:

    Duh, why not use Occam- how about disease spread by trade and new neighbors- after all we don’t easily die from flu now, but remember when you bring cows, you bring disease- just look at the columbian exchange.

    • Boris Bartlog says:

      ‘They killed them all’ is a really, really simple theory.

      • epoch2013 says:

        There may be issues with that.

        The Dutch archaeologists have methodically uncovered a large number of neolithic sites. The Dutch are relevant here because the area has really no sexy ancient leftovers whatsoever, such as Rome has, or the French have with these huge cauldrons at Celtic burials, or New Grange. So the Dutch archaeologists are left with the remains stupid little villages of stupid small time farmers, and their only option for glamour is to be as methodically as is possible.

        This means that the Dutch record may serve as a good proxy for what happened. And as far as I have seen the picture is that while there was no whole scale destruction, the transformation from TBR to CWC was immediate, and happened within the century. However, continuity of habitation has been established. But especially for comtemporary non-TBR cultures, which are likely to be post-Ertebölla-ish WHG continuity. There are some signs of some continuity with TBR sites.

        This may even explain the WHG uptick as descibed by Allentoft. But it also grants some credit to not total people replacement.

  8. dearieme says:

    I thought this a bit naughty: “The oldest Gaelic literature describes the origins of the Irish people as a series of ancient invasions”. Really, they should have pointed out how recent the oldest Gaelic literature is.

  9. dearieme says:

    The neolithic and the Bronze Age arrived in Western Europe by conquest/immigration. How about the Iron Age?

  10. Bob says:

    In “Ecological Imperialism: The Biological Expansion of Europe, 900-1900”, Alfred Crosby writes about how the “Franks” i.e. northern European crusaders had a difficult time maintaining a permanent settlement in the Levant due to the greater native population density there, the warmer climate, and the diseases that the warm climate and higher population density incubated. Perhaps similar factors were at work in the patterns of replacement in Europe.

    https://en.wikipedia.org/wiki/Ecological_Imperialism:_The_Biological_Expansion_of_Europe,_900-1900

  11. Bob says:

    Incidentally, when I visited Ireland I noticed that the people in general were pretty short. Also dark hair and the “black Irish” phenotype were not uncommon. Short, dark types are also not uncommon among native Britons. I wonder if this is from the older Sardinian-like population that inhabited the British Isles.

    There are Stonehenge like megalithic structures in Ireland such as Newgrange that were built by the Sardinian-like population and were apparently places of religious worship. They are sort of like ancient cathedrals and around the winter solstice sunlight becomes aligned with the structure and enters into it. Presumably some sort of sun worship. Stonehenge and other similar megalithic structures in Britain that date to the Sardinian-like population are also associated with this sort sun or other religious worship. Perhaps Ireland’s long attachment to Catholicism is also a legacy of this older Sardinian-like population.

  12. RCB says:

    Pizza is very good, so I’m going with that theory.

  13. eurogenes says:

    Yeah, it looks like there was an almost total population replacement in Ireland, and probbaly throughout Northwest and North-Central Europe.

    I think the problem with the current models is that they basically assume that the LN/EBA steppe population relevant to Northern Europeans was a lot like eastern Yamnaya from near the Volga and Caspian, but this might turn out to be false.

    There’s another type of steppe or steppe-related (forest steppe?) population that appears to take over large areas of Europe and Asia from about 2500 BC, and it’s only around 65% eastern Yamnaya-like.

    We’ve now got plenty of examples of this group, including early Cordd Ware, Bell Beaker, Andronovo, Sintashta, Srubnaya, Potapovka etc. genomes. They all look basically the same, and include admixture from as yet unidentifed Midle Neolithic/Copper European groups.

    If it turns out that these more westely steppe people were in fact from western Yamnaya, then the levels of Yamnaya ancestry across Northern Europe will be revised up, possibly to something like 80-90%.

    • epoch2013 says:

      On of the Iberian papers did some D-stats to figure out what WHG looked the most like the WHG part of the Neolithics. It appeared to be KO1. Have you considered doing something to see what MN group that was? Balkan or Hungarian Neolithics maybe could serve as proxy for Cucuteni-Trypillian.

  14. st says:

    You can’t answer this question without ancient dna samples from Italy and Balkan peninsula. There could have been multiple waves of population replacements in southern Europe and the levant for the last 3000 years. At least part of the contemporary mosaic in the area could be due to a relatively resent events, postdating indo european dispersal – the inflow of mideastern genes during the imperial stage of Rome (both slave trade and inclusion of the levant as imperial subject), phoenician and carthaginian colonial expansion, sicilian and iberia emirates during the early middle ages, inclusion of the levant in ottoman empire, might have played some role in shaping the contemporary genetic landscape of Southern Europe. None of it happened to most of northwest Europe. If you use a time machine and go 2 centuries further in time, and check the dna results of the inhabitants of the british isles as they will be then, you will not be able to explain them without taking into consideration the connection that emerged between places like India, Pakistan or Jamaika on one hand and the expansion of British Empire 4 centuries earlier. Not taking it into consideration will make the archeologists from the future interpret the results from the UK or, say, Sweden as if the indo european expansion has incorporated peacefully some massive middle eastern substrate 5 millennia earlier. Of course, a dna predating 19-th century would refute it. We do not know the degree of replacement that occurred in the initial ie expansion in southern europe without analyzing dna predating and post expansion, as well as from the times of the Roman Republic. Not too many people particularly willing to track changes of roman demography regardless of the abundance of dna material in the basilicas of Rome. Mountain refugia like alps, pyrenees and dinaric mountains could have played some role for the rebound of pre-indo european population as well, otherwise how can one explain the survival of basque language. Mountainous areas of Swiss alps or Kaukasus are still reservoirs of haplogroup G.
    Or it could have been just as you suggest – milking taxes instead of cows. Yet, there is a 1000 years long hiatus in the farming pre-civilisations in the balkan area nearly coinciding with the hypothetical times of first indo-european dispersion. Who would they milk if the if the farming settlements are long dead and abandoned and the arable land had been empty for 1000 years? And what would be the reason for this hiatus?

  15. IC says:

    I favor introgression process. These northern people could only go so far south before they felt it unbearable to their bodies.

    Just look at the New World colonization as clue: Northerners to cold region (Canada, North America), Southern european to tropical regions.

    • IC says:

      Most time human competition is in economy over long term and violence in short term. Recent human histories seems suggesting that long term economical competition determined the final outcome. Most European farming colonizers were far more more productive and could raise more offsprings in a small piece land, than native Americans (mostly hunter-gatherers) could in a large chunk of land. In midwest, a friend’s farm has a small area not allowed to farm since it was indian camp site which was in active use during his father time. Now it looks abandoned for long time since most indians were no long do migration for living any more.

      Somewhere I read (might be wrong) that a productive farmer can raise a family with more offsprings in just couple of acres. But a single hunter-gatherer need a square mile (640 acre) to survive. After couple hundred years, you do the math.

      If military winners are not economically productive, their fate is less promising in the long run. Roaches might low on evolutionary trees but they beat the dinosaur in the game of survival.

  16. bob sykes says:

    http://oldeuropeanculture.blogspot.com/

    has numerous posts on the cultural connections between the Bronze Age people of the Balkans and Ireland, and by implication the Indo-Europeans of the Russian steppe.

  17. genhorst says:

    The obvious answer is climate. All those Germanic kingdoms established in the South also perished pretty quickly. Equally, the Arab/Muslim onslaught failed as soon as they came into more Northern climate.

  18. some troll's legitimate discussion alt says:

    Maybe it was genetic. Subpopulations within the invaders, one that found exterminating down to the last dregs adaptive and one that did not.

    If that was the case, we might see northern Europeans try and exterminate people down to the last dregs and replace them, occasionally, if they feel like they had a chance too. Anyone heard of anything like this in history?

  19. Scott Locklin says:

    Livy certainly seemed to think the Etruscans were a tough nut to crack.

  20. Ponto says:

    I am a Southerner. It always amazes me how invading newcomers make the natives into foreigners or blow-ins from outside their native land. Take Britain, the Germans (Anglo-Saxons if your prefer, I prefer Germans) made the native Britons into foreigners. Basically that is what Wales and Welsh means in Old English, foreigners. In mainland Europe, the Celtic speakers were called Walloons by the German speakers, foreigners again. Northern Europeans did not live in all those countries they now live in 5,000 years ago, blow-ins, invaders from Europe’s backside. They most likely killed off all the young Old European men and boys, the mix of Western Hunter Gatherers and Neolithic farmers with the farmers genetic contribution in majority. Eventually these invaders came to believe they were indigenous and people live the Old Europeans the foreigners. Northern Europeans have made being European in their image in genetic tests, and Old Europeans into Middle Easterners. That is what they have done to Southern Europeans, made them aliens in Europe where they have lived for thousands of years before the invaded and made Europeans into their own image. R1a, R1b are haplogroups with an out of Europe origin, probably Siberia, yet they are the exemplar European male haplogroups.

    What have i to say about that: Get out of Europe and go back to where you come from, nasty ill-bred Wogs that you are. Or immigrate to North America, they are always happy to have more “White” people.

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