MODERN POPULATIONS

Two cultural centers merge

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The modern mind had emerged many times in many places in the course of the last two hundred thousand years, only to disappear as food became scarce and populations scattered and broke up into microsocieties that were unable to maintain the funds of knowledge, skills, linguistic forms and vocabulary that their ancestors had accumulated in more settled environments, but between 120,00 and 70,000 years ago rainfall increased throughout Africa, and this enabled a cultural nexus to form that expanded across half of Africa and then moved into the Middle East.

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Two cultural centers in Africa -- in southern Africa and eastern Africa respectively -- combined their cultural elements and then began to expand from east to west across Africa.  From there, this new, aggressive cultural center pushed north into the central African jungles.  There, bows and arrows, which had been invented in southern Africa, were found to be useful inn bringing down relatively slow-moving animals that hid in the trees.  The new killing system was also useful for killing fish.

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After crossing the jungles into northern Africa, the population waves again moved across Africa, this time from west to east, and then clear out of Africa.​

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First Anatolians and first Iranians

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It has often been assumed that the Out-Of-Africa movement began about 50,000 years ago, but the first fully successful out-of-Africa movement occurred more than 72,000 years ago, just before the explosion of the Toba Super-volcano.

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The early pioneers moved north into the Levant and then moved east and further north, into mountainous regions that are now in Syria, Iraq and Turkey.  Some of them moved still further east, to the Persian Plateau. 

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Those who moved into the mountains found the hunting good there, because the rugged terrain provided many opportunities for trapping sheep and goats.  Many descendants of these sheep- and goat-hunters are still there today, even though they were reduced to cooking and eating grass seeds with the onset of the Younger Dryas, 12,900 years ago -- about 55,000 years after they had arrived in the region.

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Those who continued on to the Persian Plateau found the hunting good there, also.  They interbred with the indigenous Homo neanderthalensis, but deprived them of resources as more and more Homo sapiens came into the region.  The local Homo neanderthalensis were driven into extinction, but when Homo sapiens tried to move north into Eurasia they were generally unable to compete with the indigenous people there, either to the east (Siberia) or to the west, in Europe.  This may be because they were not adapted to the colder climate of Eurasia and they failed to come in sufficient numbers.

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The Toba Super-volcano

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About 72,000 years ago the Toba Super-volcano on the Island of Sumatra (in present-day Indonesia) exploded, and South Asia was covered by a layer of volcanic ash five centimeters thick.

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Skies darkened, and a volcanic winter intensified the glacial maximum that followed.  Much of Africa became very dry, and a shortage of carbon dioxide in the air caused all kinds of green plants to grow very poorly.  Herbivore populations declined drastically, and most of Africa was denuded of its human population.

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However. the population along the southern rim of Africa was not greatly affected, and as a result the Khoisan peoples of southern Africa, who are descended from those who had lived along the southern rim of Africa at the time, now have the greatest genetic diversity to be found among African populations.

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The die-off caused by the explosion of Toba left relatively small pockets of human survivors scattered about in Africa, where they survived in small refugia, and founder populations emerged from these refugia to repopulate Africa.  The descendants of these founder populations have less genetic diversity than the Khoisan peoples.​

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Those who had moved north into The Middle East were relatively unscathed by the event, and indeed people who had moved there became acclimated to cooler temperatures, so that after the glacial maximum had passed they were able to move further north into Eurasia, eventually to displace indigenous populations there.

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First successes in Eurasia

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About 45,000 years ago modern humans in the Middle East met with some success when they moved further north, particularly those who then moved to the east across central Asia during a warm period and found that the newly warm climate had created a string of lakes by which they could slip between deserts to the south and Siberian mountains to the north.  In that region they came into contact with Homo longi/denisova, and as they moved across what is now China and into southeast Asia they found more of these archaic humans.  Cross-breeding occurred between the two species, so that DNA  from Homo longi/denisova can be detected in the genomes of many modern people, particularly offshore, in Oceania, where some Homo longi/denisova had been trapped by rising sea levels.

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Slow decline of Homo neanderthalensis

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Modern people also met with some success in Europe:  Archaeologist have found evidence that one subgroup of Homo sapiens successfully invaded Homo neanderthalensis territory in Europe at the same time that others met with success in an invasion to the east.  The result of their invasion of Europe was a string of camps across Europe, stretching from present-day Poland to present-day England.  (The British Isles were connected to Europe by a land bridge because of relatively low sea levels.)

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These inroads into Homo neanderthalensis territory weakened the indigenous people by killing off animals that would otherwise migrate into their territory, but Homo neanderthalensis hung on for another five thousand years or so before being driven into extinction by a massive invasion of their territory by Homo sapiens.-- Homo neanderthalensis were extinct by 38,000 years ago.

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The final collapse of the Homo neanderthalensis occurred at a time when the polar ice caps were advancing, and sea levels were low.  It should have been a time when Homo neanderthalensis had the upper hand, having survived many glacial periods in Europe.  But Homo sapiens used weapons that could kill at a distance:  bows and arrows, and javelins that could be launched with great force by using an atlatl.

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Moreover, even where the two species used the same hunting techniques and the same equipment, Homo sapiens had the edge, not only because Homo sapiens could tolerate a greater population density but also because they often followed the animals as the seasons changed; they could travel fast for long distances to keep up with the animals, due to their light build and long legs.  And they could travel or hunt in any kind of weather, because their garments were so well made and tight-fitting.

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As more and more Homo sapiens came into Europe, their hunters robbed Homo neanderthalensis of the high-quality food that they needed in order to maintain their population, and their population collapsed everywhere in Europe.