Europe had a lot of demographic turnover because there were never many humans

9 thoughts on “Europe had a lot of demographic turnover because there were never many humans”

1. Iron Gates fits great as a mix of Gravettian, Anatolians, ANE, and extra ENA. I don’t think any of them disappeared, but mixed with newcomers. WHG is a mix of Iron Gates-related groups and Magdalenians.

2. I would add though, even outside of the LGM, we’re talking about a climate here where there are glaciers covering Norway and the Alps. Steppe and tundra. The Holocene really is different in temp from period before. Low pop sizes in Western-Central Europe are kind of going to be explicable from that challenge.

   Also need to consider pop sizes within Southern Europe – Italy, Spain, Balkans. (There’s some evidence Balkans was source pop for Anatolia, which was a source pop for Levant, about same time as expansion of WHG ancestry into across Europe).

3. “it was the larger population sizes due to agriculture which changed things in a fundamental sense.

   This makes me wonder what was so advantageous about these marginal modern humans which allowed them to overwhelm and absorb the older Eurasian hominins?”

   Is the second sentence a trick question?

4. What “anatomically archaic” Neanderthals etc – and even more archaic early Homo sapiens -might have lacked was greater technological and and physical efficiency. The Middle Stone Age was characterized by smaller stone tools, use of bone, ochre, possibly poisons, and compound technologies and practices such as the atlatl to throw spears, blows and arrows, nets, and bolas. These “distance hunting” refinements were at first piecemeal and often ephemeral: perhaps indicative of temporary experiments in specialized tool designs to decrease danger and increase efficiency during lean times.

   Increasing marginal returns through extra effort may at first have appeared relatively unattractive; such innovations get people through some tough times but are then abandoned in favour of the sloppier and easier ways that were “good enough” when game was abundant.

   Our species was, however, subjected to more than temporary hardships starting around 300,000 years ago. Periods of “mega”-drought in equatorial areas seem to have occurred as glaciers advanced in the Northern Hemisphere. These droughts would have heralded the onset of massive and very dangerous wildfires; meanwhile lakes and rivers dried up. Lake Malawi repeatedly lost over 90% of its water. The use of smaller burns to reduce dry “fuel” loads, seen in economies of most hunter-gatherers, may well have begun as a defensive measure. As people noted and discussed the observed consequences of burning in terms of creating succession communities and thus effecting food plants and animals, people learned (and shared with neighbouring communities) effective ways of engineering their whole ecosystem, not just greater fire safety, but also long term productivity. Thus, these forms of cultural knowledge and many associated technological, conceptual, and practical innovations developed to solve problems of adaptation to severe climatic flux, and seasonal risk, during bottlenecks caused by droughts and ice ages.

   It need not have started with any change in the biology or genetics underlying cognitive prowess. In the evolution of Homo we see a more cognitively plastic behavioural potential and the emergence of a kind of hyperactive event sequence analysis. It is not simply rapid learning of cause and effect – all animals can be conditioned by regular event sequences. A few other animals even try to manipulate them. However, tinkering with a plan to more effectively stalk an antelope, or to drive a herd into an ambush – or over a cliff – is taken to a whole new level in the Middle Paleolithic. Sally McBrearty and Alison S. Brooks had a similar suggestion in The Revolution that Wasn’t: a new interpretation of the origin of modern human behavior: (Journal of Human Evolution (2000) 39, 453–563 Academic Press.)

   “It is clear that the features diagnostic of physical modernity emerge in conjunction with MSA technologies. In this paper we present evidence to support the presence of modern human behaviors in subsaharan Africa at remote times far predating any such traces outside Africa. We contend that the appearance of modern behaviors accompanied or even preceded the appearance of H. sapiens during the African MSA, suggesting that the behaviors may perhaps have driven the anatomical changes seen in the fossils. We also suggest that these behaviors developed gradually over a substantial period of time and sporadically in different parts of the continent.” (page 487 – my emphasis)

   When you begin to devise and execute plans that will reward you with higher numbers of buffalo in twenty years, and to devise and executive plans for increasing secondary growth meadowland and younger forest, to achieve resource goals unlikely to be realized in a single lifetime, it is no longer just reacting in instinctive or even conditioned ways to your environment.

   You are no longer just an animal in a ecological niche, you transform each ecosystem to your own needs by conceptualizing the needs of all the other living things in that ecosystem, and promoting an overall diversity and a stability that favours human survival. You need not find your niche, you make it.

5. You need a different order of conceptual models. You will have think more comprehensively, and in longer chains of causality that last for hundreds of years. These kinds of cultural paradigms cannot become normalized, nor even appear, overnight. It takes generations of observation and discussion to reach the level regularly found among hunter-gatherers. To give one example: when I first arrived to begin my fieldwork among the Kalahari hunter-gatherers, I expected to find them occasionally hunting giraffe. I had seen the film made in the far western Kalahari by John Marshall, a film called “The Hunters” – which showed a giraffe hunt. So I was puzzled to see plenty of giraffe herds but no evidence of their being hunted by the Kua. I asked about this. I was told that a giraffe that “offered itself” would not be refused, but that this was extremely rare, and that giraffes were not generally targeted. If I wanted the whole story, I was told, I should go and see a certain woman.

   So I did.

   I found her in a campsite deeper into the remote area, very near the Central Kalahari Game Reserve. She was tending her grandchildren and eagerly agreed to answer my questions about giraffe. Apparently she has the local expert; obsessively interested in anything to do with giraffe since childhood. She had assembled a massive number of observations, both on her own, and from accounts of hunters and other people, and handed down through many generations. I found this out in later interviews. Her answer to my query was masterful in its simplicity and accuracy. Hunting giraffe is unwise, she said “because they were the midwives of the Acacia trees.” God had made the giraffe, she told me, just tall enough to eat the leaves and harvest the pods of the tree, because they would then deposit the offspring of the tree far from the parent plant. She had often noticed the young sprouting from giraffe dung heaps.

   I noted all this down and essentially forgot about it until many years later when I learned that these Acacias are, in fact, woody legumes: through a symbiotic bacterial colony in their roots, they fix nitrogen. In the sandy Kalahari, these trees and other legumes were an essential species that permitted grasses and herbs to flourish.

   Giraffe and Acacia were also symbiotes, equally critical in keeping the savanna green.

   She knew.

   This level of conceptualization, of relationships between plants and animals, as parts of integrated communities, and the operationalization of this understanding into deliberate and practical interventions, goes beyond mere “planning ahead”.

   To develop such a sophisticated understanding, even among a minority within a population, involves the integration of many empirical observations, verified and accumulated, over many lifetimes. The wider this effort is shared, the more people are involved in discussions of all relevant data and concepts, and the larger the geographic area involved, the more comparative material can be assessed, and the more continuities – as well as exceptions and special cases – can be discovered. Provided the dedicated observers and discussants can explain and demonstrate that certain new ideas and practices achieve better results than the previous customs and technologies, there can be a shift within the whole society, a shift that may accelerate the “borrowing” of any successful innovation over much larger culture areas.

   The comprehension of whole cascades and feedbacks, involving multiple variables, may have begun with the processional learning involved in the manufacture of stone tools for specific purposes, and especially for making compound technologies. However it began, adding analogy to processional thinking enables other applications to longer and more complex feedbacks as well. This is however, exactly the kind of analytic thinking seen among modern people in all economies, even if they apply it to city planning, architecture, compound interest, fine cuisine, plotting novels, designing fashions, creating nuclear plants, testing and applying scientific hypotheses, calculating annual sales increments, planning retirement financing, or putting a man on the moon.

   The level of thinking, required to understand an entire ecosystem well enough to effectively manipulate it, had to already exist before this kind of cultural adaptation could happen. So I find it telling that the ecosystem management and technologies seen in today’s hunter-gatherers requires cumulative observations and processional learning, likely over many generations and across many resource landscapes, to create innovations that solve technical adaptive problems in conceptually challenging ways.

   As this cultural system was coming together, it is very plausible that successful components of it appeared here and there and were discovered and lost again, like elements of any other cultural knowledge. During the extreme drought bottlenecks, practices that worked were the kinds of long term ecological wisdom incorporated into practices that not only allowed parents to kept their children and grandchildren alive, but even to remedy the ecological destruction caused by African mega-droughts and Eurasian glacial advances. As these populations in refuge areas were doing whatever they could to hang on, knowledge of successful long term strategies may have spread rapidly if the different communities kept in touch through networks featuring “weak ties”.

   Very plausibly, the technology, ideas, and practical applications, were already occurring in a similar piecemeal fashion among all archaic humans in Africa and Eurasia throughout at least the last 400,000 years, as the scale and frequency of climate oscillation increased. I suppose it is possible that there was a shift in gene frequencies, during the middle Pleistocene, increasing proportions of people who were reflective, analytical, tinkerers, or possessed gifts of conceptual or integrative intelligence. I would be surprised, however, if such shifts were not also occurring in all human populations on the planet… and for the same reasons. It was just that the population in Eastern and Southern Africa appears to have been the single largest gene pool for well over 300,000 years. Throughout tumultuous climatic reversals of massive droughts in Africa that appear somewhat linked to glacial epochs in the northern Hemisphere, this larger and more interconnected set of communities along coastal and riverine refuge areas had more accumulated diversity, both genetic and cultural, to be going on with.

   The occasional use of fire to attract game or to clear camping sites of ticks and other vermin was probably much older, as was cooking food and using heat from hearths to alter the chemical properties of wooden digging poles and stone spear tips. The practice of hunting regularly also produced a recognition by game species – and other predators – that humans could be dangerous and were best kept a a bit of distance. This is the classic pattern of the keystone predator. But such a hunting strategy in more open environments requires the development of coordinated pack or group hunting: well illustrated by wolves, wild dogs, and lions. Archaic humans such as Neanderthals (and Archaic Homo sapiens in Africa?) appear to have used group hunting as well as ambush from blinds.

   But group hunting with spears is inefficient and dangerous compared to “distance hunting” with compound technologies and poison. Furthermore, there is plenty of skeletal evidence in “archaic” Homo sp. ( like Neanderthals) of injuries like broken bones. Hunting with spears – whether they were wooden or tipped with stone, was very dangerous. Even if you had a larger group of hunters, trying to kill an animal – even a smaller deer, can mean grappling with a terrified animal fighting for its life – and a blow to the head can be fatal, and broken arms and legs were probably pretty common.

   Frequent injury rates obviously would have favoured robust bones, especially skull bones, and powerful musculature, as this would have reduced the risk of severe injuries, especially head injuries resulting in concussion or bleeding on the brain. With distance hunting, risks like this were reduced, and a leaner finer-boned hunter would even be at an advantage as he would expend fewer calories hunting the same size of animal.

   Safer hunting technologies would have really helped to keep populations stable if not growing during these hardships of cold and ice. As during the massive droughts in Africa, one of the major shifts that happened in the middle stone age was safer “distance hunting” technology. That might have had an immediate effect on the rates of adult injury and death, and of course children have a better chance of survival if both parents and grandparents and other relatives are healthy and regularly returning to camp with provisions. Beside the positive effect of preventing populations collapse and local extinction, such technologies would have altered the selection pressures.

   Furthermore, hunters could go out individually or in pairs. They need only call on the larger group, to help track and butcher, if they were successful in mortally injuring a large animal. Regularly dividing the hunting labour force into smaller units would also increase the chances of success. Most studies have found a success ratio of one in four hunts. Two hunts per week by two teams going in different directions double the odds in favour of getting regular meat. In smaller refugia, where game populations were smaller and vulnerable to extinction, humans, even today in the Arctic, successfully practice prey switching and reduce predator fear by limiting numbers of other predators.

   Did humans gradually become behaviourally and anatomically “modern” as they developed a hyper-keystone niche by combining a keystone predator niche with ecological engineering that used other keystone species to diversify and thus stabilize food sources and aquifers? I think it is plausible. By means of distance hunting, they inadvertently set in motion changes selection pressures that reduced skeletal robustness and created a leaner musculature.

   Individual and group survival, was enhanced by a steadier food supply; indeed a new degree of coordinated meat provisioning, that was calculated over a period of weeks (rather than one-hunt-at-a-time), may have been a major advantage of the Homo sapiens culture that developed in the larger refuge areas along the eastern and south African coast and river deltas. This was plausibly enhanced when it incorporated the use of aquatic and marine resources as well. Each hunter going forth in a different direction would almost guarantee at least some fish, or game, meat several times a week.

   Thus, the changed technologies of the MSA in Africa plausibly represented a safer, and more efficient use of hunting labour. In turn this may have increased childhood survival rates and led to the modest rates of population growth we see even today among hunter-gatherers even in the harshest environments. Current data on hunter-gatherers suggest population growth rates averaging 0.05% a year – a doubling time of roughly 1400 years, and this is sufficient to reach Australia as early as 90,000 years ago via a coastal route. (Doubling time is calculated by the formula: Td = log(2) / log(1 + r) Where: Td = doubling time and r = a constant growth rate)

   When representatives of this culture encountered other, more “archaic” people throughout Africa, it is possible that they passed on practical concepts and technical elements. This, very plausibly, consolidated the patterns already in play among these other communities as well. Furthermore, as this gradually spread throughout Africa I would expect that intermarriage and the exchange of information and materials to the next group and the next, even over vast distances, gradually started that same altered selective process in the anatomy of these other groups. This would have taken thousands of years to have a visible effect on skeletons, but we know now that this process literally had thousands of years: at least 200,000 and possibly even longer.

6. helga, i saw you liked that comment attacking me on facebook a while back. don’t ever leave a comment here again.

7. “And the impact of both the later Gravettian and the Magdalenian seems to have been marginal. The primary ‘hunter-gatherer’ contribution to modern Europeans is through a group which expanded after ~15,000 BC.”

   From what I’ve read, the groups which made it through the LGM (such as the Magdalenians) were later absorbed by hunter-gatherers incoming from Anatolia. Is there a sense for roughly how much of the WHG comes from Paleolithic Europeans, and how much from the “Mesolithic” Anatolian hunter-gatherers?

8. “This makes me wonder what was so advantageous about these marginal modern humans which allowed them to overwhelm and absorb the older Eurasian hominins?”

   Why do we have to assume an advantage? Is there any reason we should consider the replacement of Neanderthals by the first modern humans any different from the replacement of those first modern humans by later waves of the same species?

   The further you get from the glaciers, the larger a population you can support, the more you can resist natural disasters and genetic deterioration, and the better equipped you are to infringe upon the territory of neighboring groups with less people. As soon as modern humans started expanding out of Africa the process was probably inevitable, even assuming no other advantages over earlier hominins.

9. So Neanderthals were a victim of global warming, as warm weather AMHs expanded into newly warm areas and cold weather Neanderthals were forced into smaller and smaller cold areas.

   But were Neanderthals really that restricted to cold areas? If not, why hadn’t they gone south and expanded their population and pre-empted the land that, in reality, out of Africa AMHs found and exploited?

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