The two most prolific genetic sons of Krishna, however, are also by far the most dominant in terms of territory covered. They each illuminate the separate trails of the Palaeolithic peopling of Eurasia and America. One of these branches, Group O, is found nearly exclusively in East and Southeast Asia. I shall call this branch Ho, after both the Chinese explorer Admiral Cheng Ho and the revered Vietnamese nationalist hero Ho Chi Minh. If we imagine that this branch was born, like the maternal lines B and F, when a beach-combing Krishna arrived in Burma from India, then Ho splits easily into three branches. All three branches now have representatives in China, Indo-China, and Southeast Asia, but they differed in their degree of northern spread. One remained in southern China, Indo-China, and Southeast Asia and still makes up 65 per cent of Malaysian aboriginal types. The second spread up the Pacific coast into southern China, although concentrating on Taiwan. The third spread much farther into China and north along the Chinese coast right up to Japan, Korea, and Northeast Asia, with a small amount of spread west along the Silk Road into Central Asia.48 Notably, none of these three related East and Southeast Asian male branches ever made it to the Americas (see Figure 5.9).
In contrast to the East and Southeast Asian dominance of Ho, North and Central Asia and the Americas were to have their Y chromosomes supplied almost exclusively by the other major Asian son of Krishna – Polo (M45). The structure of Polo’s origin from Krishna in India (Figure 5.8) shows an early branch giving rise to Y markers and their offspring, who are still found among the former inhabitants of the Lake Baikal region (the Kets and Selkups). What is most exciting historically about this root is that it is the same son of Krishna who also gave rise to the westward influx into north-east Europe through Russia, thought to be associated with the Gravettian culture (see Chapter 3). We can now put all this together with the Upper Palaeolithic record of the Altai from 23,000 to 43,000 years ago, and with the story of the mitochondrial lineages of North and Central Asia. Polo would have arrived in Central Asia from Pakistan 40,000 years ago, and spread out in a giant ‘T’ formation, both east and west across the steppe – east to Lake Baikal and much later to America, and west into Russia and eastern Europe (see Figure 5.9).49
We also have confirmation of this extraordinary twin distribution in the mitochondrial X marker in the Americas and Europe, and we have a genetic basis for the North Eurasian origins of the Native American mammoth culture, so eloquently implied by the title of a 1990s book, From Kostenki to Clovis: Upper Paleolithic – Paleo-Indian Adaptations.50
A picture emerges of peoples moving north out of India and Pakistan to occupy the Russian Altai, coping with extraordinary environmental stress but reaping the rich rewards of big game. This North Asian founder population split east and west to occupy the great steppe. Those who went east eventually reached America, while those who went west contributed greatly to northern and western Europe. Those who stayed through the last great ice age shrank southward to refuges in Central Asia, and later re-expanded to become some of the Siberian and Uralic populations we see today.
Figure 5.9 First entry of Y-chromosome lines into Central Asia. As with mtDNA (Figure 5.7), the entry routes correspond with major Asian rivers. Seth’s grandsons Polo and TAT entered to the west of the Himalayas, dominating North Asia. The rest of East Asian Y lines entered from the Indo-Pacific coast, with Ho dominating China and Southeast Asia, and Cain further north.
We have seen how the early beachcombers could have split successively at various points on their journey round the Indo-Pacific coast and how, by 40,000 years ago, they had colonized most of Asia and the Antipodes. The first inland branch going north from India gave rise to the Upper Palaeolithic hunters of the Central Asian Steppe; later branches forging up the great rivers of Southeast Asia ultimately gave rise to a populations we now call Mongoloid. Evidence for so-called Mongoloid types, however, did not appear in Asia until the time of the last glacial maximum, around 20,000 years ago. So the forces that produced this physical divergence may have continued to build up for a long time after the first Asians arrived in North Asia. This leads us on to the next climatic phase of our story – the Great Freeze.
6
THE GREAT FREEZE
IN THE LAST CHAPTER we saw how East and Central Asia as a whole was peopled by a three-pronged pincer style of genetic colonization, starting originally from India. The oldest settlers followed the ancient beachcombing route right round the coast, from India through Indo-China and up north to Japan and Korea, leaving colonies as they went. From these coastal Asian colonies, pioneers penetrated the Central Asian heartland up the great Asian rivers through gaps in the huge east–west wall of mountains that flanks the Himalayas. South-east Tibet and the Qinghai Plateau may have been the first part of Central Asia to be breached 60,000 years ago, from Burma and Indo-China, while those who went up the Indus from Pakistan to the Russian Altai farther west settled during a mild period around 43,000 years ago. People who had reached northern China by the coastal route could have gone west up the Yellow River (the Huang He) into Central Asia around the same time or later.
The map of Northern Asia was now starting to fill up. By 30,000 years ago, a large swathe of the wooded southern part of the former Soviet Union (see Figure 6.1a), from the Russian Altai through Lake Baikal in southern Siberia to the Aldan River in the east, had been colonized by modern pioneers carrying a technology similar to that of the contemporary European Upper Palaeolithic. Even the Arctic Circle was penetrated north of the Urals nearly 40,000 years ago. There is some evidence that the Upper Palaeolithic technology of North Eurasia may have travelled south to Inner Mongolia on a northern bend of the Yellow River, but on present evidence it seems that at this time such cultural influences spread no farther south into China.1
Dale Guthrie’s vision of the hunter-gatherers wandering the great Asian Mammoth Steppe, stretching from eastern Siberia right across to Europe (see Chapter 5 and Figure 6.1a), takes shape in the archaeological record of around 30,000 years ago. His prediction of the incipient ‘Mongoloid’ homeland in the southern Steppe is, however, highly speculative for this period and for Siberia. For a start, as mentioned, no indisputably Mongoloid remains have been found from such an early date. For all we know, those early southern Siberians could have looked like the Cro-Magnons of Europe. They shared a similar culture and, at least according to the story told us by the Y-chromosome lines, they shared genes with North Europeans (see Chapter 5). As evidence perhaps of a Western cultural centre of gravity, the first flowering of the mammoth culture at this time seems to have taken place much farther west, in Central and Eastern Europe (see Plates 13 and 14). Evidence for the mammoth culture seems to have reached Mal’ta near Lake Baikal only by perhaps 23,000 years ago (see Plate 21). This is just 2,000 years earlier than the first possible evidence of Mongoloid features from a little to the west of the same region of southern Siberia, at Afontova Gora.2
The Big Freeze: ice, lakes, and deserts
As the Palaeolithic clock rolled on towards 20,000 years ago, however, events in the Earth’s spin axis and influences on its orbit hundreds of millions of kilometres away from our planet took tighter hold. Three great heavenly cycles of the solar system moved into a conjunction that ensured a minimum of the Sun’s heat reached the northern hemisphere during summer.3 The weather became colder, and the recurrent brief warm periods, or interstadials, which had characterized the period of 30,000–50,000 years ago, just stopped. It was these warm periods and their summer sunshine that had helped to melt the accumulated northern ice and prevent the ice caps from advancing across Scandinavia into Northern Europe. Now, the ice caps were able to expand in the north. The sea level started to fall again, eventually by 120 metres (400 feet). In short, the Earth was approaching its most recent ice age, or glaciation. (There had been quite a bit of ice on and off for the previous 100,000 years, and archaeologists tend to call the height of the Big Freeze the Last Glacial Maximum, or LGM for short, rather than an ice age.)
Figure 6.1 World habitat changes at the LGM. Around 30,000 years ago (a), a huge open conifer woodland stretched from the Pacific to the Arctic and Atlantic coasts, allowing hunters to expand. At the LGM (b) this was reduced to a thin tongue of steppe tundra still occupied by hunters. While most of the world saw loss of habitable land Southeast Asia or Sundaland saw a dramatic increase.
Asia fared rather better than Europe. Most of North and Central Asia remained ice-free (see Figure 6.1b). Just to the eastern side of the Urals, a large cap covered the Tamyr Peninsula and spread some way to the south. The other part of the continent which could have sported an ice cap was the huge Tibetan Plateau much farther south, its great elevation making it a very cold place. Even here there is some doubt of the extent of ice cover, since surprising forensic evidence of the presence of humans in Tibet dates back to the LGM.4
North America was particularly severely affected, with Canada, the Great Lakes, and the north-eastern states – in other words the entire northern two-thirds of the continent – weighed down by two massive ice sheets that connected on the east with the Greenland ice cap. Alaska, on the other hand, was then connected to Siberia by a huge ice-less bridge of now submerged land, Beringia, and to some extent shared Asia’s freedom from ice. The largest of the two American ice sheets, the Laurentide in the east, left its vast imprint as a deep dent in the Earth’s crust in the form of the great inland sea now known as Hudson Bay (see Figure 7.4).
In some places, in both Eurasia and America, huge lakes (known as periglacial lakes) surrounded the ice caps. The best-known remnants of these lakes are the Great Lakes of North America. The ice sheets themselves were not static, but flowed like the glaciers they were. Not only did these frozen rivers grind out new valleys and fjords, they also obliterated much evidence that humans had ever lived in the north.
Ice was not the only barrier to human occupation during the big freeze. The world’s deserts expanded to an even greater extent. Around the ice caps, huge regions of North Eurasia and America became polar desert in which only the hardiest of plants and animals could survive. In Europe, the polar desert stretched east from the southern edge of England and due east across northern Germany, to the south of the Finno-Scandinavian ice sheet. The whole of the region from the Levant and the Red Sea to Pakistan, normally pretty dry, became a continuous extreme desert. Southern Central Asia, from Turkmenistan and Uzbekistan by the Caspian Sea in the west, through Xinjiang (north of Tibet), to Inner Mongolia in the east became continuous desert either side of the 40th parallel. This desert, which effectively replaced Guthrie’s Mammoth Steppe heartland, also split North and northern Central Asia from the whole of East and Southeast Asia.
Ice-age refuges
Africa’s human population suffered, as their forebears always had during every big freeze of the previous 2 million years. The Sahara expanded to cover the whole of North Africa; the Kalahari spread over most of south-west Africa; dry, treeless grasslands covered most of continent south of the Sahara. The great rainforests of Central and West Africa shrank into small islands in Equatorial Central Africa and the southern parts of the West African Guinea coast. In East Africa, the expansion of the dry savannah again separated humans in East Africa from those in South Africa. Only scrubby refuges surrounded by dry grassland were left as islands for the hunter-gatherers (see also Figure 1.6).
With North and Central Europe taking the lead along with America in building ice castles, we might wonder what happened to anatomically modern Europeans. Did they all leave or die, to be replaced later with another batch from the Middle East? Our cousins the Neanderthals had already disappeared 10,000 years before the LGM (see Chapter 2). Well, the archaeological record tells us that the pre-LGM Europeans hung on in there, but as happened in Africa, their range contracted southward to three or maybe four ice-age temperate zones. The genetic trail also tells us an enormous amount about the origins and human composition of these glacial refuges, but first we shall go into the archaeological record to paint in some background.
Most of Northern Europe was unoccupied at the LGM. There were three main refuge areas of Southern Europe to which the Palaeolithic peoples of Europe retreated (Figure 6.2). From west to east, the first consisted of parts of France and Spain either side of the Pyrenees, in the Basque country, characterized by the finely knapped stone ‘leaf points’ of the Solutrean culture (named after a French village called Solutre). Receiving, perhaps, their technologies from north-west Europe, this south-western refuge was culturally distinct from other southern refuges, whose stone technology is described more generally as Epi-Gravettian. The second refuge area was Italy, with more or less continuous local occupation. The third was the Ukraine, a large area north of the Black Sea defined by two great rivers, the Dnepr and the Don, and separated from the rest of Southern Europe by the Carpathian Mountains, which were partially glaciated at the LGM. Two other regions of Central Europe have some claim to small-scale occupation at the LGM. These were western Slovakia, just south of the Carpathians, and the Dnestr River basin of Moldavia, just east of the Carpathians on the north-west coast of the Black Sea.5
Figure 6.2 European refuges at the LGM. Cold and loss of habitat forced humans down to refuges in south-west France and Spain, Italy and parts of the Balkans, Slovakia and Moldavia. The Ukraine, in Eastern Europe, paradoxically continued to thrive. (Shaded areas show maximum extent of cultures between 15–20,000 years ago.)
The Eastern European sites were home to the final flowering of the Upper Palaeolithic mammoth culture. As the LGM reached its climax, one focus of activity shifted away from western Slovakia, mainly eastward towards Moldavia and the Ukraine, but also south into Hungary. It is in the Ukraine and farther north up the rivers Dnepr and Don into the Russian plain, however, where we find the best record of continuous human occupation – even expansion – in Eastern Europe during the Big Freeze.6
Genetic continuity and the last glaciation
Can the genetic record tell us more about the ebb and flow of populations in the real human sense of where they came from and went to, rather than the inferred cultural picture of what they were doing, as the cold grip of the ice took hold? Genetic tracing can and does fit the archaeological record of that time rather nicely, but it also tells us something much more relevant and general to European roots: that 80 per cent of modern European lines are essentially derived from ancestors who were present in Europe before the Big Freeze.
In Chapter 3 we saw how the important European maternal clan HV spread from Eastern into Northern and Western Europe, perhaps heralding the beginning of the Early Upper Palaeolithic 33,000 years ago. The HV clan is now widespread and fairly evenly distributed in Europe. H is the single, commonest line of all. It was not always so, and a specific sister cluster of the H clan, V, who were probably born in the Basque country, tells us why.7
The archaeology sh
ows us how the south-western refuge of the Basque country drew cultures and presumably people down from north-west Europe during the lead-up to the LGM. Since Western Europe is separated from Italy by mountains, we would expect the reverse process after the ice age as people re-expanded again from the Basque country and north along the Atlantic coast. This is exactly the picture left by the post-glacial spread of the maternal subgroup V, which has its highest frequency, diversity, and age in the Basque country, falling off as one goes north and only present in rather low frequencies in Italy. V arose in the Basque country shortly after the LGM. Her pre-V ancestor has been dated to 26,400 years ago, long before the LGM. Pre-V is still found farther east in the Balkans and Trans-Caucasus, consistent with her ultimate eastern origin. Even the post-glacial dates of expansion of V (16,300 years in the west) fit this scenario. Exactly the same pattern was seen for the Y-chromosome marker Ruslan, who we saw had moved into northern Europe from the east and found his home in Northern and Western Europe (Chapter 3). The present-day picture shows Ruslan at his maximum frequency of 90 per cent in the Spanish Basque country, with the next-highest rates in Western and Northern Europe.8
Italy, on the other hand, capped as it is by the Alps, was less a refuge for northern populations than a temperate region of continuous occupation by Mediterranean folk present from before the LGM. This is reflected again in the high proportion (over one-third of the total) of persisting preglacial mtDNA lines found in that region. We can see from these examples that the refuge zones are characterized by dramatic expansions of lines born locally in the refuge zones during the LGM, and also by high rates of persisting lines left over from the preglacial period. The latter pattern is certainly a feature of the Ukraine refuge, which as predicted by the archaeology retains 31 per cent of its preglacial maternal lines. A slightly less convincing case can be made for south-eastern Europe and the Balkans, which retained 24–26 per cent of preglacial lines.9
Out of Eden: The Peopling of the World Page 24