Gardening in Eden

Nov 7, 2018 11: 50 pm

The capacity for a learned and shared system of transmitting information between individuals, and across generations,  is culture, a secondary adaptive system that many social animals have. Humans developed culture into a major adaptive system. In humans this is a learned and shared collective “cognitive niche”,  the “specialist” behavioural and cognitive adaptation of a highly plastic phenotype. Recently there was a paper published by two researchers affiliated with the Max Planck institute that suggested that anatomically modern Homo sapiens had successfully colonized the world and outcompeted “archaic” humans because it developed a new ecological “generalist specialist” niche. (ROBERTS AND STEWART. 2018. DEFINING THE ‘GENERALIST SPECIALIST’ NICHE FOR PLEISTOCENE HOMO SAPIENS. NATURE HUMAN BEHAVIOUR.)At first I hoped that this would be a further refinement of another Max Planck associated bit of research that at least suggested an “ecological engineering” niche. But I was disappointed. “Specialist generalist” describes aspects of a species’ specific behaviour – a biological rather than an “ecological” niche.

Ecological niches are parts of ecosystems that a biological organism can fit itself into. Hominins tend to use culture to fit themselves into a role within an ecosystem. Very few human behaviours, economic or organizational, are obligatory and can be predicted by the attributes of the phenotype. I suppose being a “specialist” in “generalist” adaptations to ecosystems is an inventive way to get around simply calling it culture, but from my perspective it is equivalent to prevarication: like calling rivers ‘collective water molecules responding to gravity’.

The reason I wrote all this, just now, is because I am concerned that this “specialist generalist” adaptation will be thought to arise through some change in gene frequencies. I would argue that this is an unwarranted causal directionality. What “anatomically archaic” humans might have lacked was the kind of environmental bottleneck that honed their culture for greater 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, bows and arrows, nets, snares, 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.

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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.

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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.

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.

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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 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.

I think this level of cognition was clearly in place before people could even begin to visualize how a whole ecosystem could be manipulated – “taken care of”- over generations.

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.

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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 SE 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. I once heard a specialist in paleo-anatomy remark that the only humans he knew of with a pattern of injuries in the same range as the ones he saw in Neanderthal skeletons were bull riders and rodeo clowns – whose job is to lure angry bulls away from thrown cowboys.

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 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. We might expect to see evidence gradually starting to grow more quickly, in hunter-gatherer sites.

The complete package of Middle Stone Age technologies were essentially markers for a cultural transformation that permitted a more successful hunter-gatherer economy. As these behaviours spread all around the African coastlines, despite on-going climatic fluctuation and hardship population growth seems to have increased. Current data on hunter-gatherers suggest population growth rates averaging 0.05% a year – which seems low by today’s standards of comparison, but it seems to have been relatively higher than that of archaic Homo sapiens. Even increasing it to this modest rate produces a doubling time of roughly 1400 years. From a starting point somewhere in the eastern African coast, and even starting with very low numbers of people involved in the initial group(s) that trickled into Eurasia, this is sufficient to reach Australia within 15,000 years, purely as a function of normal population growth along the coast. (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, propelled simply by this modest rate of growth, expanded throughout the rest of Africa, as well as throughout Eurasia, and encountered other, more “archaic” people, 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 I would suggest that 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: in Africa it had at least 100,000 years and possibly even longer.

I might add that by intermarrying with other groups, “anatomically modern” humans increased their own genetic diversity, even if it occasionally meant importing some problematical recessive alleles. At the same time, they were living demonstrations of a successful economic pattern. Indeed, as these technologies and practices permitted population growth, the tendency would have been to increase the flow of information and personnel in both directions. This would have happened each time this culture come into contact with others all over Africa, and it also happened between groups that had trickled into Eurasia. 

The genetic data appears consistent with all anatomically modern humans alive today stemming mainly from one ancestral culture area within Africa. This was most likely to have been one of a series of interconnect cultures developing along the coasts of the entire continent. Especially during the height of inland mega droughts, even at very slow rates of population growth (.01% a year) archaic Homo sapiens could still have eventually spread south toward the Cape as well as north past the Horn and up major rivers such as the Nile, and around the shores of the Mediterranean, as well as across southern Arabia towards the Tigris, and the Euphrates and onward. These people would, of course, neither be aware of leaving one continent and entering another. I doubt they were even likely have completely lost touch with the communities their ancestors had come from. It seems probable that many would have developed rafting and even boats from time to time, to explore offshore islands, and to cross deeper stretches of water. Such a culture would have developed exploiting several ecological zones. They could supplement the dwindling savanna with near-shore aquatic resources, as well marine resources like shellfish, fish, and sea-going mammals.

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Possibly, this culture area represented a set of linked demes speaking an array of dialects. I think it is plausible that the people in these remained intermittently interconnected by networking ties that permitted a flow of information and personnel. People in the coastal culture area less fragmented by these droughts would have been the likeliest candidates to become the first to pull all the strategies of ecological engineering together. Once this happened, this would furthermore be the one linked “culture area” capable of budding new communities up and down the coasts rivers even in the worst times of drought and hardship.

It is astonishing to realize that people likely did not have a goal of “leaving Africa”; rather, in the process of doubling every 1400 years would still fill up the world,  NO ONE need ever have moved more than a few hundred miles, in a whole lifetime.

Try the calculation.

a) Assume a SE African culture area of hunter-gatherers who occupied the savanna and coastal region. Around, let us say, 90,000 years ago, a small daughter colony of this coastal culture has been established here and there “outside of Africa” – 1000 people scattered in 40 camps along the eastern Mediterranean coast, 1000 people scattered in 40 camps in the southern Arabian peninsula. There is some archaeological evidence of this, although at a slightly later date.

Note: I am assuming a set of demographic units that range over a territory of about 8,000 to 12,000 square km, a pretty average figure for a mobile hunter-gatherer group of about a thousand. Since they have a riparian, lacustrine, or coastal adaptation with some inland hunting, one can imagine an elongated territory stretching 200 kilometres along the lake shore, the coast, or the river, augmented by gathering and hunting resources perhaps 50 kilometres inland. Both of these would be, in our OOA model, derived from one of the northernmost groups of the chain of African cultures which appear to have had this dual ecosystem adaptation – using the aquatic as well as terrestrial resources, as well as the rich mixture of both represented by river deltas.

b) So we assume a starting population in the Middle East and along the south coast of Arabia of 2000 people. Now let us calculate how many there would be, at the modest rate of 0.05% increase per year, after 10 to 12,000 years.

After 1400 years, it is 4000, after another 1400 years, it is 8000, then 16,000, then 32,000, then 64,000, then 128,000, then 256,000, then 512,000, then 1,024,000 – and it is only 67,400 years ago.

c) Over a million people in Eurasia within about 12,000 years. Even if we assume all kinds of setbacks through diseases and adverse climatic events, and double that time, there could still be still be nearly a million Homo sapiens in Eurasia within a very short time. Does this make the genetic data that supports the idea of “out of Africa” more plausible? I doubt was as neat as this, but the exponential function is relentless. One way or another, our hunter-gatherer ancestors were pretty successful, not just in Africa, but all over the world.

We could change the starting date.. make it 100,000 or 50,000 years ago. But the main point here is that, no matter when we start the clock, there would still be over a million modern Homo sapiens in Eurasia within 12,000 years, for example, and it would be two million 1400 years later.

Given the shorter doubling times that prevail in modern Homo sapiens (at least until the annual rate of population increases was further raised by improved sanitation, medical care, antibiotics, vaccines, and so on) it really did not take repeated “waves of migration” out of Africa to populate the world.

A little squirt across the Red Sea, mission accomplished. Nor did the ancestral roll call of anatomically modern people have been lengthy even in Africa. It was obviously a longer roll call – the population remaining in Africa was likely at least ten times larger: most genetic variation was left behind. But we can easily derive various calculations, from a starting population as small as 20,000 or 30,000, and fill up all of Africa remarkably quickly, and test the plausibility of how modern humans enveloped and absorbed, both genetically and culturally, most of the “archaic” populations they encountered in the process.

All in all, I think what was “special” about the generalist hunter-gatherers with modern anatomy was indeed, a new ecological niche. But it was not because we became a new kind of biological animal, it was because we doubled down on what humans were, and still are, really good at adapting through feedback between culture and biology.

Developing a highly durable cultural system, one that manipulated whole ecosystems, was doing something new, ecologically. Despite evidence of use of fire for cooking and modification of material technology dating back at least two million years, no previous humans used fire ecology, or deliberately replanted, to promote plants and animals that they liked to eat. They may have had division of labour, but not the level of specialization in economic activities and conceptual realms common among hunter-gatherers today. You find quirky tinkerers as well as obsessive geniuses among all modern humans. I think cognitive variability may be a necessary and biological consequence of the kind of genome that can actually support long term investment in culture as a main adaptive strategy. Of course these kinds of minds are but leavening: for human culture to work, you also need a solid doughy lump of retentive rationality.

Even if only a tiny minority of people in any deme pondered particular issues and came up with wild ideas as well as practical innovations, any real conceptual breakthroughs, and resulting practices, could be demonstrated to others. The successful application of concepts generally is what reinforces their utility. Thus, even when few people in the rest of the culture actually understand the causal relationships, they can still make use of the resulting practical ideas. Any culture can change successfully as long as a sufficient minority of observers ponder and tinker with materials and ideas exist within them, and such people are indulged – or at least, given an audience and a fair opportunity to show how their discoveries work.  In the later Pleistocene, when people were coping with extremes of fire and ice, receptivity to new technologies and ideas must have peaked at times.

I find it significant that all the survivors, of this exercise in cognitive shape-shifting, appear to be the anatomically modern human beings we identify today as “ourselves”.

Is it plausible, then, that the absorption of any remaining “archaic” people was as much cultural as biological? Why not consider a model of intermarriage, not “interbreeding”?  Why not envisage the children of unions between these “archaic” and “modern” people being raised by their parents and grandparents, speaking two or more languages?  Why not explore the implication that these children, although showing more robust anatomy initially, would be leaving descendants who were more and more anatomically “modern” as time went on, transformed by the elixir of humanity’s cleverest culture: the one that gardened Eden?

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The ecological engineering associated with these early “hyper-keystone” human economies represents the single most successful collective cognitive niche that humans ever developed.

Sadly, today, only a small number of humans on the planet still know how to do this.

I wonder if Woodstock got this one right – maybe we really must get back to the garden, before our current global civilization foolishly undoes what took thousands of years of observation, empiricism, work, and passion, to create.

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