Building momentum

Recent work indicates that there were high levels of genetic differentiation between the early farmers in the Levant, Anatolia, and western Iran. What this means that is that before the Holocene, they didn’t mix very much – probably less than one immigrant per generation. This seems to have been a general tendency in Eurasia – possibly in Africa as well, but we don’t have as much ancient DNA information out of sub-Saharan Africa yet.

On the other hand, we also see populations replacing other populations, over and over – and sometimes that resulted in admixture. Eurasians picked up a bit of Neanderthal ancestry when they expanded out of Africa. Altai Neanderthals picked up some AMH ancestry, possibly when their ancestors expanded back into the Middle East. Melanesians picked up some Denisovan ancestry.

If population A rolled over population B and occupied their territory, there was often a few percent of admixture – certainly enough to transmit key favorable alleles. But as neighbors, very little gene flow. So when people say that a little gene flow is likely to be the explanation of that vaguely Andamanese trace in Brazil, I kinda doubt it: replacement with a little admixture is known to have happened back in those days, but peaceful amalgamation had to have been rare, in order for genetic differentiation to remain high.

Of course the causes of this genetic isolationism matter. To some extent they must have been geographical barriers, particularly around the last glacial maximum. If such barriers were the only cause, then any relaxation or breach would have resulted in enough admixture to rapidly decrease genetic differentiation. On the other hand, isolation probably bred isolation: populations that had very low gene flow for long periods of time surely had very divergent languages and customs. And modern humans can effectively fission into groups that can act, sometime, almost like different species – low gene flow, even though there are no fertility barriers. Linguistic fission may go back a long time and help explain the long-term low effective population size – but we don’t know.

When people started farming, at first they were not biologically different from their immediate hunter-gatherer ancestors. Eventually they would be different: better adapted to the new diet, the increased crowding, the psychological demands of a very different way of life – but that took at least some time. After they were adapted to farming, the tendency towards farmers expanding, rather than the idea of farming being transmitted, would increase: the biological edge shows up. But at first, before much adaptation, idea transmission might have more competitive with demography. I throw this out as a possible partial explanation of the pattern we are seeing: first the idea of farming spreading through core populations in the Middle East (possibly combined with independent invention or stimulus diffusion), while a little later those core populations themselves begin spreading outward. In fact, on the ball really got rolling, those populations should have been adapting to expansion itself, just like cane toads.

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57 Responses to Building momentum

  1. MawBTS says:

    first the idea of farming spreading through core populations in the Middle East (possibly combined with independent invention or stimulus diffusion), while a little later those core populations themselves begin spreading outward.

    It seems like there would be economic issues, too. Just the idea of agriculture isn’t enough, you also need something of an industrial base (like irrigation, and grainaries). And didn’t Neolithic crops produce unimpressive yields, by modern standards? Getting a decent harvest would have required a large investment of seed.

    Cultures with some experience at it probably would have been far more competitive than ones that were just figuring it out. In the same way that a Papua New Guinean tribe that’s just invented the jet engine is never going to become a player in civil aviation. While they’re still figuring out how to set up an industrial base, Delta will have blanketed their island in foreign-owned airports. Can’t beat economies of scale.

    A commenter here once said that bison probably can’t be domesticated, because nobody’s succeeded in doing it. But of course we’ve never needed to domesticate them: why reinvent the wheel? Kill every bison you see and use their range for our already-domesticated cattle. Duh!

    It might have been a similar story with certain early populations. They never had a chance to get good at farming, they just got rolled over by better-adapted populations.

    If there’s a 2016 equivalent to farming (that is, a massive survival-boosting skill), it will probably be a similar story. By the time you realise you should be learning the skill, it will already be too late.

    • jamesd127 says:

      “A commenter here once said that bison probably can’t be domesticated, because nobody’s succeeded in doing it. ”

      Actually bison have been domesticated. Any herd or pack animal can be domesticated easily. Even non herd non pack animals are routinely domesticated. Falcons continue to be recruited from the wild.

      I saw on television a trucker persuading domesticated deer to get into his truck. They had only been domesticated for a few generations, and he had absolutely no experience in herding deer, but they got onto his truck obediently enough. Presumably they had become habituated or trained to treating humans as high status deer. And they quite calmly allowed themselves to be transported by truck.

  2. engleberg says:

    We don’t know what a high hunter-gatherer society would be like- one that was always doing Mondol-style Great Hunts of mammoth and reindeer herds, and all the rest of the Pleistocene fecundity of Eurasia. One that could invent agriculture just for beer.

  3. RK says:

    Interestingly, the agriculturalist genomes from Iran are the first genomes recovered with long ROH and signs of consanguinity. The other agriculturalists and HG genomes have a lot of short ROH, indicating small group size, but studious outbreeding, as opposed to presence of long ROH but less short ROH in these Iranian agriculturalists, i.e. higher recent inbreeding despite larger long-term population size. Probably the emergence of inheritance and private property in Neolithic societies substantially changed the incentive structures surrounding marriage.

    • Tim says:

      Aren’t the long ROH and signs of consanguinity only observed in this study because of the excellent genome coverage, combined with new computational methods?

      I think you need close to 10x coverage to be very confident of homozygosity, especially in degraded ancient DNA. I wouldn’t trust any broad cultural statements from that information.

    • Matt says:

      The Upper Paleolithic Satsurblia sample also has an excess of long ROH compared to short ROH, compared to the Bichon and Mesolithic Loschbour and Kotias, etc – http://www.nature.com/ncomms/2015/151116/ncomms9912/images_article/ncomms9912-f3.jpg

      Compared to https://d2ufo47lrtsv5s.cloudfront.net/content/sci/early/2016/07/13/science.aaf7943/F3.large.jpg?width=800&height=600&carousel=1 would suggest Satsurblia had higher long ROH than WC1?

      I thought this might be due to Satsurblia being very recent after a LGM bottleneck. Plausible or not? For WC1, perhaps linked to be being just after a very recent population expansion – large founder effect?

      • RK says:

        I was more looking at the pulses in the ROH graph, as each episode of increased inbreeding will result in a pulse of long ROH being introduced on the right-hand-side of the curve which then decays to the left over the long term, creating a smooth decay curve in groups without recent inbreeding. While recent inbreeding will add a hump on the right hand side that disrupts this pattern, which WC1 shares with S Asians.

        I’ll admit that the pattern for Americans is strange in this context..

        • Matt says:

          I get that Satsurblia’s long ROH are matched by higher short ROH as in other ancient samples, while WC1 has only more long ROH and not more short ROH than EEF, however Jones et al do say:

          Both WHG and CHG have a high frequency of ROH and in particular, the older CHG, Satsurblia, shows signs of recent consanguinity, with a high frequency of longer (44 Mb) ROH.

          Recent consanguinuity + ancient restricted population size for Satsurblia, recent consanguinuity only for WC1. Excess of long ROH indicative of consanguinuity not a new phenomenon with WC1 only. Different kinds of population bottlenecks or founder effects?

  4. dearieme says:

    “you also need something of an industrial base (like irrigation, and granaries).” Early agriculture didn’t involve large-scale irrigation. Early granaries were probably holes in the ground.

    “Getting a decent harvest would have required a large investment of seed.” To start with it would probably require only dropped seeds germinating.

    • Tim says:

      “To start with it would probably require only dropped seeds germinating.”

      Maybe the idea started with someone noticing that dropped seeds germinated, but that is very far from successful farming.

      Most people don’t realize, but the biggest hindrance to farming isn’t getting seeds, it’s competition from wild animals, especially rodents, birds, insects, and larger grazing animals (including other humans).

      Farming probably couldn’t have taken off at all without the use of domesticated of dogs and cats to watch over the fields and granaries.

      • RK says:

        Huh? You’re pulling stuff from thin air?? Cats were domesticated comparatively recently… In fact its an open question as to whether they are a domesticated species at all, really. And Papuan, Amerind, Bantu and Pacific Islanders farmed without cats…

        • jamesd127 says:

          Pretty sure that Papuan farmers only farm stuff that is rat resistant.

        • Tim says:

          I didn’t say the cats were domesticated, but they developed a relationship with the first farmers in the Levant immediately, as did the house mouse. The established Neolithic villagers living on Cyprus 11,000 years ago brought both mice and cats with them, and a human grave there even contained a cat buried in the same position as the human.
          The Chinese farmers domesticated a different species, but they were replaced by the modern type later. The other farmers you mention didn’t seem to have had mouse and rat problems until the European species were introduced.

  5. st says:

    Farming started simpler than it looks. Wild crops were already there before they got domesticated. They were also collected by the local hunter-gatherers for food (“gathered”) before they were domesticated. Availability of abundant edible wild crops would make a place attractive for living; In most parts of fertile crescent the best crops were growing on the banks of the rivers and on nearby meadows (still do). But since the seeds of collected crops could could last for months, after being picked from the meadows and river banks, they were also stored as food reserve in the settlements and storage places of the hunter gatherers (yes, they had settlements before the advent of agriculture. Some of the crop seeds collected would make it to the next spring and would in fact grow successfully into mature plants within the settlements.
    So it was not mind-bending to start intentionally growing and cultivating crops out of their natural habitat, within the frame of the settlement – it had been happening accidentally all the time, so why go to the river to collect crops when you can do it in your own home yard, where some of the crop seed bought for eating have grown into plants next spring? Domestication should have been almost natural, unintentional event (you collect only the biggest seeds and bring them home to eat or store them as a food supply during the winters – so when some of them develop into plants next spring, these plants will be somehow bigger than their wild counterparts). Do it for 10 years and you have selected a new breed of high yield crops not to be found in no river banks or meadows, so why go there gathering?
    Nothing of this would require revolutionary thinking or mind-bending inventions. The villages were there, the game was getting scarce and the seeds of the wild crops were mysteriously getting closer home – and were also getting bigger.

    • Tim says:

      “Nothing of this would require revolutionary thinking or mind-bending inventions.”

      Then why wasn’t it invented 200,000 years ago? Or even earlier? Of course it had to do with some kind of new invention or revolution.

      • Yudi says:

        Presumably because of climatic instability during the Ice Ages. The last time agriculture could have taken off and been sustainable for millennia at a time was the Eemian Period, about 115,000 years ago. Why it didn’t remains an interesting question–I believe C&H speculate on it in The 10,000 Year Explosion. Humans also failed to expand into Australia and the Americas at that time–they might have been different enough from moderns to prevent their doing some things that became possible later.

        • Why don’t squirrels discover agriculture? They collect and store seeds, and they can dig.

          The problem is they’re stupid.

        • Tom Bri says:

          Do we have any way of knowing there was no agriculture in the Eemian? Seems like not much material evidence would have survived the following cold era if it were limited to smaller scale gardening.

      • st says:

        “Then why wasn’t it invented 200,000 years ago?”
        I do not know. Perhaps because there were no humans in the fertile crescent 200 000 years ago.
        The transition to agriculture must have been catastrophic for HS – the average height dropped with 30 centimeters. Perhaps the life expectancy as well, (there are hints that adult hunter gathering population from chatal hiuuk had a life expectancy of 57 years. 57 years was the life expectancy at birth in British Empire at the end of 20th century. So it took about 12 000 years for the HS to recover to its pre-agricultural health standards. So it was a trap and disaster for HS, not a triumphant transition to a higher level. HS could hot have possibly known that his progenies would have adapted to sedentary, agricultural life stile that includes tractors and artificial fertilisers along with genetic adaptations – had only they have survived for another 12 thousand years of caloric restrictions, bad health, diet incomparability, epidemic diseases and whatever comes in mind. They did not envisioned any of this while transitioning to agriculture, which is obvious.
        When you collect crops and cereals from the wild grass with your fingers spread what’s left in the palm are only the biggest seeds – intuitive selection. With settlements of up to15 000 inhabitants in the pre agricultural state of FC – if archeologists are right about the demography, the game must have been scarce.
        Cochran had a speculation about how the animals were domesticated – he thinks that sick bovines were more prone to domestication, since a healthy bovine (or ram) would stay away from its predator – which is HS. I wonder if this could be valid for the first farmers as well -in a way, agriculturalists were first domesticated population of HS. Could this population had been sick in the same manner? I can’t imagine them going to agriculture, sedentary life stile and vegetarian diet they were unacceptable with voluntarily.

        • dearieme says:

          “57 years was the life expectancy at birth in British Empire at the end of 20th century.” The British Empire didn’t exist at the end of the 20th century.

      • epoch2013 says:

        Because the need wasn’t there (yet)?

      • Tom Bri says:

        Gardening is ridiculously easy. Follow the link for an article I wrote some years ago on gardening without hard work, using only saved seeds or seeds scattered from adult plants.
        http://hub.me/adte4
        I had a bon-fire this spring, which left a large burnt patch in my lawn. I scattered radish, lettuce and tobacco seeds on the ashes. All grew. The only work involved was thinning out the excess plants that sprouted.
        I buy a few packs of commercial seed each year, but the bulk of my garden is always self-seeded.
        It’s a good question why agriculture didn’t start much earlier, and the ice age isn’t an acceptable answer, since most of the world was not covered in ice. The fertile crescent was lusher during the ice age than it was later in the Holocene. I’d guess it was the loss of a good climate that pushed people into agriculture, not the advent of a better climate.

        • Frank says:

          You live in a land almost devoid of real wildlife and surrounded and criss-crossed by countless roads and fences.

          I have worked with lots of not-so-intelligent people in various countries who thought they could easily grow certain unnamed crops and/or native plants in the hills and valleys and roadsides by simply planting thousands or even millions of seeds into unploughed soil.

          From what I’ve seen, this is usually a terrible strategy, and rarely works at all.

          Farming is a full time job. Without ploughing, it is much, much tougher to get a high yield of anything.

          If you were also in a true wilderness, without dogs or cats or fences or hedges or poison to keep away pests? Forget about it.

          • Tom Bri says:

            Fenced, no. Devoid of real wildlife, also no, unless you consider deer, rabbits, woodchucks, racoons, rats, mice, coyotes, and on and on as not real. True, no elephants or hippos, and very few and occasional wolves, cougars or bears. If I were trying to supply my family with 100% of my food, I would shoot them or trap them. As it is, we ‘share’.
            I am experimenting with non-tillage in various ways. My big garden is tilled, by tractor, and if I were farming to get 100% of my calories I would want tillage. If you are supplementing a HG lifestyle, it is provably unnecessary. I use burning on two small plots, and it works great, with absolutely zero tillage. I just burn off the existing vegetation and scatter seeds into the ash, and rake it. This year I planted radishes, lettuce, tobacco, melons, using this method. All are producing well as I write. On the hand tilled area, I also get tomatoes, potatoes, sunflowers etc, plus all the above mentioned. It is dead easy, if you use varieties that reseed easily. I use domesticated varieties, but the original wild varieties would be even easier to reseed.
            Where I have a huge advantage over early farmers is 10,000 years of accumulated habits and knowledge, distilled into books, plus, an entire world’s crops available to get started. A HG had very few crops amenable to farming in any one area, and had to figure things out for himself, plus the risk of starvation if he got it wrong or had a bad year.
            One risk I had not appreciated until the last few years is the potential for loss of a crop species. Last year was miserably wet and cool, and the watermelons did not produce even enough fruit to get new seed. In a village environment, if a crop species were lost like that, it might be lost forever.
            Gardeners make a big deal about producing ever-more fragile varieties, and how difficult it is to balance insect control, fertility, acidity of soil and on and on. Stick with basic, hardy crops and varieties and it is dead easy.

            • jamesd127 says:

              ” I just burn off the existing vegetation and scatter seeds into the ash, and rake it. ”

              Otherwise known as slash and burn – the predominant form of agriculture where land is abundant. You chop down as much as you conveniently can. When it dries out, set fire to it. Then scatter your seeds. We can reasonably assume that the first agriculturists were slash and burners. They only got into hoeing when there was a shortage of land, and a corresponding abundance of slaves, the abundance of slaves being a byproduct of quarrels over land.

    • dearieme says:

      The big deal isn’t to get bigger seeds, it’s to get seeds that will generate a grain crop that all ripens at the same time so you can harvest it efficiently.

  6. Greying Wanderer says:

    I think the key is sedentary HGs.

    HGs would become sedentary where there was a sufficient static food source to provide all their food.

    In the beginning… any yield from farming would be low, just adding to whatever food sources made the local HGs sedentary in the first place.

    If correct then the static food sources that originally made the local HGs sedentary would initially be a large proportion of their total food and the early farming proportion would be small so they couldn’t move.

    Only after they became good enough at farming to provide the bulk of their food could they cut their umbilical cord to the static food source.

    So perhaps in the beginning farming ideas could pass peacefully from one group of sedentary HGs to another because in the beginning they couldn’t move?

    #

    What creates sedentary HGs?

    One option is trees (fruit and/or nut).

    (Hence all the mythology relating to trees imo.)

    #

    https://www.google.co.uk/maps/place/Almaty+Region,+Kazakhstan/@43.7249114,75.9013185,7z/data=!4m5!3m4!1s0x3883694dd4e28733:0x5b5bb9f5b7b97177!8m2!3d45.0119227!4d78.4229392

    couple of big lakes and forests of apple and pear trees – just saying

  7. IC says:

    Good point: Behavior change (learning) first and fast; Genetic change later and slow.

    The degree of behavior change is based on mental ability. High mental ability, high behavior adaptability.

    Low mental ability, low ability to learn, low degree of behavior change, low trainability. Extreme example: plants (which have no brain tissue) – genetic adaptation only.

  8. Eugine_Nier says:

    Recent work indicates that there were high levels of genetic differentiation between the early farmers in the Levant, Anatolia, and western Iran.

    I wonder who the language isolates (or near-isolates) that used to exist in those regions (Hurro-Urartian, Sumerian, and Elamite) are related. Where there other language isolates all over the world at the time, and these three simply managed to be recorded before being overrun by Semites and Indo-Europeans?

  9. Urisahatu says:

    Similar ideas for agriculture can be found in sometimes difficult to reach distant locations.

    Example is the so-called Kuk-Swamp Agriculture in the highlands of Papua New Guinea (PNG) which occured as early as 10.000 – 7.000 BP (Before Present), much earlier than the so-called Austronesians ever set foot on the Papuan shores. Therefor the Papuans did not learned agriculture from Austronesians.
    Even when at probably 3.000 – 2.000 BP the Austronesians set foot on PNG there was little admixing. There seems to have been more cultural exchange and exchange of technology (ideas) than mixing people together.
    Having said that; The Austronesians did replace (and / or mixed with) many of the Papuan related populations in Eastern Island Southeast Asia.

    Populations have replaced other populations for ages and will continue for years to come.
    The only difference now is that modern transportation makes it more easy to travel long distances and reach a point of destination in less time.

  10. Karl Zimmerman says:

    I do wonder if one of the main causes of the Neolithic “blending” of many populations was essentially slavery.

    There is basically no reason if you are a hunter-gatherer group to take on an extra mouth which is not your kin. Even if you could get around the hard-wired “stranger danger” that all hunter-gatherers seem to have, the amount of surplus generated by any one individual was pretty marginal. In addition, a bigger group will need to range more widely in order to hunt and forage enough.

    Things changed with agriculture, particularly once social hierarchy was added. Suddenly it didn’t make sense to kill everyone who is a competitor, as agricultural societies could initially generate significant surpluses until they reached the Malthusian trap. Hence instead of merely killing your neighbors, you could take least likely to fight back (women and children in particular) and put them to work in the fields. This is particularly the case given those most likely to make the decisions to take captives would also be the ones least likely to actually have to do anything to support the captives – that would be up to other, lesser people in the community.

    Of course peaceful interactions may have played a role as well. As trade became a real thing, some people would migrate out of their home cultures into different ones. But I tend to think that coercive population exchange played a much larger role.

    • another fred says:

      “I do wonder if one of the main causes of the Neolithic “blending” of many populations was essentially slavery.”

      No doubt.

    • gcochran9 says:

      Slavery is a big step up from extermination.

    • Greying Wanderer says:

      “I do wonder if one of the main causes of the Neolithic “blending” of many populations was essentially slavery.”

      If
      – a lot of groups were endogamous
      – the Clarkian mechanism applied
      – inter group marriages were largely alliance marriages between chiefs
      then
      – maybe most of the mixing that produced successful offspring happened at the top and spread down.

      this would create another possible explanation for stark disproportions in male/female dna

      • Karl Zimmerman says:

        Wife trading among elites is basically a form of slavery isn’t it? Women are being used against their will to gain something of value (peace between neighboring peoples, in this particular case).

        Of course, the norm among most structured agricultural societies up until very recently was that wives (and often husbands) had little to no say in who they married. That’s one reason I have always found “sexual selection” arguments for modern human evolution a bit suspect. The wealthier you were, the more likely your marriage would be arranged, and the more likely that that you would have surviving offspring who would reproduce themselves. Sexual selection likely only works if the parents were the ones doing the selecting.

        • Greying Wanderer says:

          “That’s one reason I have always found “sexual selection” arguments for modern human evolution a bit suspect.”

          Yes, you’d need a suitable marriage culture for it to work.

        • SonOfRekab says:

          But in practical terms has anything really changed?
          And if so, has it changed for the worse?

          Looking around it seems that smart people are marrying other smart people at a faster pace then ever….
          As far as marriage is concerned it seems that the “free market” is doing a good job.
          Just because the parents are not picking the future spouse, does not mean their opinion is not being heard.
          The only problem, and a serious one at that, is the low child barring rates.

          • Karl Zimmerman says:

            I’m not assigning any value judgement to either arranged or “free-market” marriages. I do think that the importance of passion in marriage (presuming a lifelong commitment) is overstated, given that typically within five years or less the level of passion in any romantic relationship falls to a low level, meaning the long-term dynamics of arranged versus amorous marriages are probably not too different (except in odd cases, like shim-pua marriage in China, where brides went to live with their future husbands when still children, so the Westermarck effect took place).

            All I’m saying is that sexual selection, while it might have been important in the Paleolithic and Mesolithic, steadily waned in importance during the Neolithic up until a few centuries ago.

    • Matt says:

      IRC, the Inuit took slaves at time and Comanche hunter gatherers. San and Hadza probably not so much but may be other reasons for that than their subsistence method (the only people they could take as slaves might not like it very much, hard).

      • Jim says:

        Comanche raiders took many captives. Quanah Parker was the son of a white captive woman. Quanah Parker’s Uncle escaped as an adult and later became a leading rancher in South Texas. A Parker family reunion would certainly have been an interesting event.

        I,ve read that the Comanche took so many captives that it significantly altered their genetics. I don’t know if anyone has actually compared their genetics with that of the Shoshoni though.

        The Comanche did hunt buffalo and also raided for cattle and horses.Their culture was totally dependent on raiding.

      • Karl Zimmerman says:

        I’m not sure it’s really correct to call the Comanche during the historic period hunter-gatherers in the classic sense. While not full-on pastoralists, use of horses allowed them to range much more freely over a wide swathe of territory. They also had a huge surplus of horses at their height, and would even eat the horses in hard times. Due to their recent adoption of new technology, and expansion into a mostly empty area, they were not in the Malthusian trap yet, and could expand rapidly and take on a greater surplus.

        • Jim says:

          The Comanche ate some of the cattle they raided but traded most of them to Anglo traders for guns, metal tools, leather goods, and other stuff on which their culture was totally dependent. During the early part of the nineteenth century they were the principal suppliers of beef to the American market. They weren’t anywhere near a Malthusian trap. They raided all over South Texas and deep into Mexico.

          • Jim says:

            The Comanche, Kiowa, Apache and Wichita were all in the same basic racket. Steal cattle from the Spanish and settled Indians and trade the stolen cattle to Anglo traders for guns, metal implements, leather goods, etc.. It was a good living while it lasted which was about 1700 to just after the Civil War.

    • Yudi says:

      Forced population transfer was undoubtedly a big part of admixture in the last 5,000 years, but you might want to read up on slavery among Pacific Northwest HGs before adopting all these conclusions…

      • Karl Zimmerman says:

        The Northwest Coast was very unique for a hunter-gatherer culture because the local food supply was so steady and abundant that it allowed for levels of social complexity which were otherwise unknown for hunter-gatherers in historic eras. Some argue that in the Mesolithic it was not so unique – that there were many hunter-gatherer areas which had local abundance which was high enough for cultures to advance to the “chieftain” level. Certainly it seems plausible for the Near East in particular.

        I’ve done some research in the past for other reasons on the Tlinglit, and they had a pretty fascinating technological history just prior to and after contact. There’s evidence now that they picked up the potato somehow from New Spain and had begun cultivating and storing large numbers. Within a few decades of more regular contact with the west, they figured out how to cold-work steel and repair broken guns. There are even sets of Tlinglit “chainmail” – metal armor they made by sewing coins of Chinese origin onto hide in an effort to deflect Russian bullets. I’ve always felt if it wasn’t for Smallpox causing a population collapse the Tlinglit just might have had the moxie to “make it.”

    • IC says:

      Just observing the relationship between HG and farmers in today’s world would give you a lot of information, especially in Africa (Bhutan expansion and pygmies) or south America before colonial farmers coming in.

      Speculation is fine. But shaky.

  11. epoch2013 says:

    When the HG’s op Europe lived alongside the first immigrant farmers (LBK) for centuries they slowly piked up some of the habits. Ertebolla was known for keeping pigs. If you have a look at mtDNA of archaeological remains of pigs you see that LBK pig remains show a clear affinity to Anatolia. The first pig remains of Ertebolla as well. Then, when more pig remains are found, local pigs start to pop up among Ertebolla ans after a while also at LBK. We also see Ertebolla cousin Swifterband picking up cereal farming.

    At that point both groups own land. With owning land comes inheritance and thus political and arranged marriage. I think that is the cause HG’s and LBK started to mix at that point to become the middle Neolithics cultures, which have a larger share of HG’s.

  12. Lots of questions, few answers, but there is a steady opening of windows shedding light on what had been our long lost past thanks to the wonderful work by various groups studying ancient DNA.

    People were pushed into isolated areas during the ice age and times were so hard that only the smartest survived. As soon as the world warmed and at the same time got a lot wetter these smarter people not only expanded they mastered all kinds of new skills hence the ten thousand year explosion.

    It is hard to say why people got smarter, what we do know is they did. Hopefully the windows will keep on opening in genetics and we shall soon know.

    stay tuned

    • RK says:

      Honestly, farming probably had very little to do with smarts, and everything to do with the unintentional selection effects of subsistence strategy on the human animal and the surrounding plants, in turn affected by climatic factors…. Otherwise you wouldn’t expect it to emerge in Papua New Guinea, or multiple Neolithic populations in the Middle East simultaneously.

      • SonOfRekab says:

        “Honestly, farming probably had very little to do with smarts”

        Compared to what?
        Compared to modern humans in the developed world probably not, but compared to the hunter gatherer population that existed at the time, not so sure.

    • Frank says:

      “People were pushed into isolated areas during the ice age and times were so hard that only the smartest survived.”

      But then we would expect that Neanderthals and Denisovans and other Eurasian hominins would have been super smart. That can’t be the thing that made the difference. There are lots of ways to adapt to harsh conditions.

  13. syonredux says:

    Any thoughts?

    “The Ashkenazi Jewish (AJ) population is important in medical genetics due to its high rate of Mendelian disorders and other unique genetic characteristics. Ashkenazi Jews have appeared in Europe in the 10th century, and their ancestry is thought to involve an admixture of European (EU) and Middle-Eastern (ME) groups. However, both the time and place of admixture in Europe are obscure and subject to intense debate. Here, we attempt to characterize the Ashkenazi admixture history using a large Ashkenazi sample and careful application of new and existing methods. Our main approach is based on local ancestry inference, assigning each Ashkenazi genomic segment as EU or ME, and comparing allele frequencies across EU segments to those of different EU populations. The contribution of each EU source was also evaluated using GLOBETROTTER and analysis of IBD sharing. The time of admixture was inferred using multiple tools, relying on statistics such as the distributions of segment lengths and the total EU ancestry per chromosome and the correlation of ancestries along the chromosome. Our simulations demonstrated that distinguishing EU vs ME ancestry is subject to considerable noise at the single segment level, but nevertheless, conclusions could be drawn based on chromosome-wide statistics. The predominant source of EU ancestry in AJ was found to be Southern European (≈60-80%), with the rest being likely Eastern European. The inferred admixture time was ≈35 generations ago, but multiple lines of evidence suggests that it represents an average over two or more admixture events, pre- and post-dating the founder event experienced by AJ in late medieval times. The time of the pre-bottleneck admixture event was bounded to 25-55 generations ago.”

    http://biorxiv.org/content/early/2016/07/10/063099?rss=1%2522

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