Nov 7, 2018 11: 50 pm
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)
We have documented that hunter-gatherers, all around the world, operated on sophisticated traditional knowledge systems that were about more than how to prevent dangerous wildfires. They used fire to keep the ecosystems in a mosaic of different succession stages, to maximize biomass as well as plant and animal diversity.
“The land gives us so many gifts; fire is a way we can give back. In modern times, the public thinks fire is only destructive, but they’ve forgotten, or simply never knew, how people used fire as a creative force. The fire stick was like a paintbrush on the landscape. Touch it here in a small dab and you’ve made a green meadow for elk; a light scatter there burns off the brush so the oaks make more acorns. Stipple it under the canopy and it thins the stand to prevent catastrophic fire. Draw the firebrush along the creek and the next spring it’s a thick stand of yellow willows. A wash over a grassy meadow turns it blue with camas. To make blueberries, let the paint dry for a few years and repeat. Our people were given the responsibility to use fire to make things beautiful and productive—it was our art and our science.”~ Braiding Sweetgeass by Robin Wall Kimmerer
You are no longer just an animal in a ecological niche, you transform each ecosystem, to meet 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 also 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 them 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 giraffe 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 to her grandchildren and eagerly agreed to answer my questions about giraffe. Apparently she was 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. This ensured that Acacia continued to “spread life” into the sands. 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 essential species that permitted grasses and herbs to flourish.
Giraffe and Acacia were also symbiotes, both equally critical in keeping the savanna green.
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 more widely 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.
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. It was the final change that produced the shift in selection factors leading to anatomically modern Homo sapiens.
This completed a package of Middle Stone Age technologies initiating a cultural transformation that permitted an even 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 0.04 to 0.05% a year – relatively higher than that of archaic Homo sapiens (estimated at 0.01%). 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.
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 population of anatomically modern people need have been large 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: cultural adaptation. Cultural behaviour is, of course, in a complex feedback with our genome, since it can alter the selection pressure operating on specific tissue systems. A well documented example is use of milk from domesticated cattle and goats, which led to the fixation of variants permitting adults to digest milk sugar. The shift to distance hunting in the middle Pleistocene, possibly began as a way of reducing “predator fear” in game confined to small refugia, but it also shifted selection pressures away from anatomical robustness in favour of a leaner, and more metabolically efficient, model.
There is more.
I was so affected, when I read, in a recent article inspired by the massive wildfires in Australia, about the slow, cool burning practices described and demonstrated by Aboriginal Elders in Australia. It is so close to the way I observed the cultural burning done in the Kalahari. The Kua hunter-gatherers there were very specific: about avoiding letting the fire get hot enough to harm the trees; also about the danger of the soil (“the mother is alive”) and to prevent this from getting scorched. They told me that a fire could get too hot; hot enough to kill the soil, and the roots, and the fungi. If the little creatures that lived in the soil were killed by the heat, they claimed, the earth would not recover, and all the water in the sands beneath the surface would be lost.
What they knew is gradually being confirmed by soil scientists today. There is even evidence now that hot fires mobilize arsenic in soil.
The fire ecology of hunter-gatherers appears to have developed through centuries of observation, testing, and discussion. The way this knowledge was developed is, fundamentally, scientific. And so I have become convinced that “scientific” behaviour began long before the European Enlightenment. The cultural practices of fire ecology among modern hunter-gatherers, therefore, reflect the original science and engineering project of Homo sapiens. I think this complex ecological science dates back a 300,000 years, or more. The remarkable consistency of the principles and practices were well developed by the time anatomically modern humans spread out across the rest of the globe. As has now been documented, this constituted a major cultural adaptation, and was known to at least some anatomically “archaic” Homo sapiens as well, since Neanderthals appear to have used fire to modify their local ecosystems as well.
Archaic Homo sapiens, like the Neanderthals, also modified landscapes by using controlled burns. In Eurasia, risks of wildfires would have increased during the drier climate that accompanied the glacial advances, and archaic Homo sapiens, in spreading across Africa and Eurasia, may have gradually learned to reduce seasonal fire risks with judicious early burning. However, in Africa, such use of fire ecology became absolutely critical for people trying to survive the African mega-droughts. The late Pleistocene Mega-droughts would have caused fires that far surpassed the level of devastation we witnessed recently in Australia, California, Siberia and elsewhere as global warming has made drought more severe.
The degree to which indigenous people influence their ecosystems is what impressed one of the foremost ecologists of the recent past, Robert Paine. Paine was the originator of the concept of keystone species. Before his death, Paine co-authored a paper which suggested that humans evolved as a “hyper-keystone” species, because we were aware of which other species had keystone roles: affecting the trophic flows in the whole ecosystem in ways that were out of all proportion to their numbers. Long before spending out of Africa, people may also have learned that certain species of animals and plants were critical to the rest of the health of the system. At some point in the evolution of Homo sapiens, people identified and then safeguarded the critical species, and may even have come to consider them sacred. Beavers, bison, sea otters, giraffe, wolves, lions, elephant, and many other species were in the roster of the sacred “kin” species around the world, due to their critical ecological roles, even though these roles were often only discernible by modern science after many decades of assessment through observation and analysis.
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, it appears that it was Homo sapiens, beginning with anatomically archaic people in Africa and Eurasia, who deployed fire to alter ecology.
They may have already developed division of labour, by sex and age, 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, generally, in most cultures, 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?
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.
Note: The featured image of the giraffe etched on rock is from a site discovered in Niger. “…The engraved images of two giraffes, estimated to be some seven to nine thousand years old, have been found atop a 50-foot-high sandstone outcrop in the Sahara Desert of northeastern Niger. Recorded last November by documentary photographer David Coulson of the Trust for African Rock Art (TARA) and French archaeologist Jean Clottes, president of the Paris-based International Committee of Rock Art, the carvings, one of which is more than 20 feet in height, are among the finest examples of African rock art found to date; the larger of the two images may well be the largest-known single prehistoric work of art in the world.
Surrounded by hundreds of smaller engravings, the giraffes are carved in the so-called Bubalus style of the Large Wild Fauna period (ca. 9,000-6500 B.C.), typified by naturalistic renderings of the giant long-horned buffalo Bubalus antiquus (for which the period takes its name), rhinoceros, elephants, hippopotamus, giraffes, ostriches, lions, aurochs, and crocodile. Like many images from this period, the Niger petroglyphs are deep cut and polished. According to Clottes, the giraffes are among the finest images he has ever seen. “The technique is perfect,” he said. “If you put this in the Louvre, it would look just fine.”
The giraffe and its companion each have a long line emanating from their nose that terminates in the image of a small man. “We believe that this has important significance, perhaps representing shamanic association or symbolism,” said Coulson. “We simply do not know. What is certain, however, is that the giraffe was of vital importance to early African populations, possibly being associated with the bringing of rain.”
At the time the engravings were made the Sahara was a far more hospitable place. Rather than the parched landscape it is today, it was covered with trees, grasses, rivers, and lakes. The Sahara began drying some 3,000 years ago, reaching its current state around 2,500 years ago. “This art depicts another world,” says Coulson, “one in which diverse cultures flourished alongside herds of game.”
TARA, a non-profit research institution of which Coulson is chairman, was established in 1995 to document and where possible undertake measures to preserve the entire corpus of African rock art, which by Coulson’s estimates, is carved or painted at what may be well over a half million sites. Despite the remoteness of many sites this art is subject to serious threats such as vandalism, graffiti, target practice, and mass tourism. “In the face of such threats,” says Coulson, “TARA is endeavouring to create an awareness of the richness and value of the art. It is not only Africa’s heritage but the world’s heritage, whose significance is only now being recognized….”….” (Photo and caption courtesy of Leiren Patterson)
Note: On June 10 2021, the following report was published: “American Association for the Advancement of Science—In a Perspective, Bernardo Flores and Carolina Levis discuss the positive feedback between local peoples and food availability in tropical forests. Although they were once considered to be harsh and inhospitable environments, largely devoid of large populations, a growing body of research shows that, for more than 13,000 years, humans have resided and thrived in tropical forest environments, transforming the natural landscapes into forest gardens. Even the Amazon – a region often regarded as a paragon of pristine tropical forest – is dominated by edible plant species closely associated with humans. Flores and Levis highlight the social-ecological system of these tropical forests whereby local people enriched the forest with edible plant species, and the highly productive forests increased overall food availability, allowing forest societies to expand. According to the authors, leveraging this ancient relationship by ensuring local peoples’ access to their ancestral forest lands could help efforts to conserve these sensitive environments while also boosting food security and sovereignty in tropical regions. Globally, more than a billion people rely on forest resources for food, particularly in tropical regions. Indigenous and local peoples of these regions have historically – sometimes for thousands of years – contributed to the enrichment of forests with food. Even today, their territories act as buffers against deforestation and landscape degradation. “For this ancient feedback to continue functioning, societies need to recognize indigenous and local peoples’ rights to their ancestral forest land,” write Flores and Levis.”