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Thread: Movements and genetic change between the Chalcolithic and Bronze Age in the Levant

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    Movements and genetic change between the Chalcolithic and Bronze Age in the Levant

    Hi! I have previously read about the surprising Chalcolithic Israel individuals with a lot of ANF and presence of genes for blue eyes in relation to the later Bronze Age samples from the same region. I have also often been very curious about how Proto-Semitic and its immediate descendants spread in the Near East, considering an unusual correlation: right between the Neolithic and the Bronze Age Proto-Semitic appears, expands and splits into many different languages from the Mediterranean to the fringes of the Zagros (North Mesopotamia), but at the same time it seems to have been a time of big increase of Iranian/Caucasian ancestry, not an expansion of Natufian/Levant_N components as you'd expect from a language that has its closest language groups in North & Northeast Africa and had a major presence in the Levant since its very beginning (Eblaite, in Ebla, Northwestern Syria). Considering all of that, I decided to try and make some models of geentic ancestry just to either reinforce or debunk some of my admittedly amateur speculations (by the way, I ended up finding out that the results tend to be much more coherent and plausible if you just use about 10 dimensions instead of the 25 or 50 you can find in databases). See:

    Using mostly Mesolithic/Early Neolithic references (distance rates ~0.8-1.1%)
    MESOLITHITC-NEOLITHIC
    NATUFIAN
    LEVANT_N
    LEVANT_CHL
    LEVANT_BA_S
    Natufian
    100
    53,0
    45,2
    47,5
    Barcin
    44,7
    41,0
    23,5
    Abdul Hosein
    10,6
    13,8
    CHG
    2,3
    3,2
    15,2
    Iberomaurusian
    Ethiopia Mota
    EHG
    Onge
    0

    There is a clear trend that parallels what happened in other parts of the Fertile Crescent. Firstly, a huge increase of Iranian (Abdul_Hosein_N) and Caucasian (CHG) ancestry after the Neolithic era. In this model, CHG increased particularly between the Levant_Chl (those ~49% blue-eyed Israelis) and Levant_BA_S; and secondly, an increase in the Natufian:Barcin ratio between the Chalcolithic and the Bronze Age. There are two possibilities I can see as most likely:
    1) Levant_BA_S mostly descends from a Chalcolithic South Levant population that remained much more Natufian-like than even Levant_Neolithic, with much lower Anatolian gene flow, and which later received some moderate, but heavily CHG and Iranian-related influxes;
    2) or Levant_BA_S was quite like Levant_Chalcolithic, but was profoundly transformed by at least two streams of different ancestry, one more enriched in Natufian, the other more enriched in Iran_Neolithic and particularly CHG.

    Could this indicate, perhaps, that the earliest Proto-Semitic speakers were mainly a mix of Natufian+CHG/Iranian_N, with little Anatolia_N? Assuming a simple two-way admixture from Levant_Chl all the way to Levant_BA_S, the difference in Natufian, CHG and Iranian_Neolithic (Abdul_Hosein) admixtures could be theoretically (just mathematical speculations, okay? Nothing scientifically reliable here) explained by a mix of 40% Levant_Chalcolithic + 60% of a population with ~49% Natufian, ~39% Iranian+CHG and ~12% Barcin/ANF ancestral components. Could that have been roughly the genetic makeup of the earliest Proto-Semitic speakers in Northeast Levant/North Mesopotamia (assuming the earliest evidences of Semitic are also near the place where Proto-Semitic spread from)?

    Or rather the Levant received several different streams of different populations, maybe one much more Natufian-like (Ancient Egyptians? People of the Arabian peninsula? Saudis are often modeled as very Natufian-like if compared to Lebanese or Palestinians even today) and the other much more Iranian/Caucasian-like.

    Now, using a much more chronologically proximate model, with mostly Chalcolithic reference populations (but Natufian and CHG to account for possible unsample populations that had more of those components than the scarce Chalcolithic DNA samples we have as of now)... Again, Levant_BA_South looks like a Levant_Chalcolithic population heavily (>50% of genetic replacement) changed by Natufian-rich (additional 23.6%) and Iranian/Caucasian-rich (16.6% Seh Gabi_CHL + 10.8% CHG) populations. Either this was a population descended from a much more Natufian-enriched and less Anatolian-enriched Levant_Chalcolithic people, or they did indeed receive a major stream of very Natufian-admixed people.

    Together with Iranian/Caucasian or independently? I don't know, but there's something interesting in Levant_BA_N
    , also associated with a Canaanite city:

    Levant_BA_N, under those same constraints, is modeled as simply Levant_Chl (60.9%) with a lot of additional CHG/Iranian_Chalcolithic-related ancestry (15% Seh_Gabi + Tepe Hissar + 14% CHG), as well as minor EEF-related (Varna) and North African (Morocco_EN) influences, which are maybe just inaccurate proxies for some other population rich in EEF and indigenous North African ancestry (something North African_Chalcolithic perhaps?). But what matters is that there is none of that big chunk of extra Natufian that exists in the South.

    So, that seems to indicate that a lot of Natufian didn't come with the same source that brought a lot of Iranian+CHG admixture after the Chalcolithic. It would've been mostly Iranian+CHG or maybe a Levant_Chl-like + Iranian+CHG-enriched population... Or we can also think that there was very ancient substructure within the Levant, so that the Levant_South had always (since the Neolithic at least) been more enriched in Natufian ancestry, whereas the North experienced a lot more Anatolian and (initially) Iranian influence. In that case, the major change would've been brought just by a lot more Iranian_N/Iranian_Chl+CHG ancestry... which then may have been or not brought by Proto-Semitic speakers...

    Therefore, another doubt appears: should we start to think of the possibility that the Iranian/CHG, J1-P58 and other things spread by Semites came from a successful and expansionist non-Semitic-speaking population, especially males, who just adopted the local Levant_Chalcolithic language? We know that even in historic times, with plenty of evidences of Semitic languages, Hurrians ruled much of the North Levant and were highly influential there.)


    What do you think is most likely? What do these results that suggest a profound change in the Levant between the Neolithic, Chalcolithic and BA can tell us about the historic cultures? I think this is a very important discussion that probably true scientists will investigate further in the future, because it has a lot to do with several of the first great civilizations.

    distance%=0.2393"

    Levant_BA_South

    Levant_ChL,48.7
    Natufian,23.6
    Seh_Gabi_ChL,16.6
    CHG,10.8
    Tanzania_Luxmanda_3000BP,0.3
    Ethiopia_4500BP,0
    Barcin_ChL,0
    Maykop,0
    Tepe_Hissar_ChL,0
    Varna,0
    Morocco_EN,0
    Bantu_S.W.,0

    [1] "distance%=0.1013"

    Levant_BA_North

    Levant_ChL,60.9
    Seh_Gabi_ChL,15
    CHG,14
    Varna,5
    Morocco_EN,3.1
    Tepe_Hissar_ChL,2
    Ethiopia_4500BP,0
    Natufian,0
    Barcin_ChL,0
    Maykop,0
    Tanzania_Luxmanda_3000BP,0
    Bantu_S.W.,0
    Last edited by Ygorcs; 12-04-19 at 05:42.

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