The Journey of Man: A Genetic Odyssey (26 page)

If we accept that William Jones was right, and that all Indo-European languages descend from a common source, then the implication is that there must have been, at some point in the past, a single group of people who spoke this ancestral form of Indo-European. The search for the identity of the first Indo-Europeans, and their geographic location, has been one of the main areas of archaeological and linguistic investigation over the past 200 years. It has become a sort of quest – although like all good quests, it is in some ways rather quixotic. The attempt to disentangle the web of conflicting evidence surrounding the location of the Indo-European ‘homeland’ illustrates a particularly exciting new application of genetics to our understanding of human history.

Gordon Childe, who coined the term ‘Neolithic revolution’, proposed in the 1920s that the Indo-European homeland should be identified with a culture originating north of the Black Sea that had distinctive ‘corded’ pottery – marks that resembled impressions left by cord or twine. The theory was revived by archaeologist Marija Gimbutas in a series of articles published in the 1970s. Gimbutas argued that the remains left by nomadic horsemen of the southern Russian steppes, dating from around 6,000 years ago, mark the earliest signs of a culture that can be identified as proto-Indo-European (PIE), which included Childe’s Corded Ware people. The Kurgan culture, as she called it, left enormous burial mounds (known as kurgans) that are still dotted across the entirety of the Eurasian steppe, from Ukraine to Mongolia and south to Afghanistan. The golden treasure hoards recovered from kurgan excavations in the twentieth century confirmed the existence of a people who were known to Herodotus as the Scythians – fearsome horsemen of the Asian grasslands, and previously thought by many scholars to be mythical.

The evidence that the Kurgan people spoke PIE is based on an analysis of words common throughout Indo-European languages. If a word can be shown to derive from the same root, then it is likely (although not certain) that it was inherited from the common ancestor. For instance, the English word
ox
has cognates in the Sanskrit
uksan
and the Tocharian (an early Indo-European language spoken in western China)
okso.
Similarly, many words for animals and plants are common throughout the Indo-European languages, as are those for tools and weapons. Perhaps most interestingly, there is a rich vocabulary for horses and wheeled vehicles in common among all the languages, suggesting that the PIE speakers had domesticated the horse as a draft animal. Coupled with the archaeological remains showing that the horse was domesticated in the southern Russian steppes, this pointed toward the kurgan-builders being the PIE people.

But while the evidence in favour of the Kurgan people being early Indo-Europeans was compelling, there was no archaeological evidence for the spread of their culture into western Europe. Their culture, dominated by horses, was ideal for the steppes, but it was not well suited to European forests and mountains. It was difficult to see why the steppe horsemen would have been able to conquer Europe and
impose their language upon its inhabitants. For this reason, Colin Renfrew proposed in his 1987 book
Archaeology and Language
that the Kurgan culture did not mark the origins of Indo-European, but rather a later, eastern extension of it. Renfrew suggested that PIE had been a Middle Eastern language, originally spoken 9,000 years ago, which spread with the agricultural Wave of Advance into Europe. He identified Anatolia as the Indo-European homeland, on the basis of it being roughly central in the modern distribution of Indo-European languages, and also the home of several extinct examples. The hypothesis he advanced is that the early farmers carried their language – PIE – with them as they expanded their population, and thus the linguistic inundation of Europe should have involved a genetic wave as well. It was a bold suggestion, which had little initial support from the linguistics community. As we have seen, the Wave of Advance actually contributed little to the gene pool of modern Europeans, and its influence seems to have been largely limited to the Mediterranean region. The Indo-European speakers living in Ireland, for instance, have virtually no Neolithic Y-chromosome markers, while Greeks have a substantial Neolithic component. What this suggests is that, if farming spread Indo-European languages throughout Europe, it must have done so largely without the actual spread of farmers – thereby reducing the strength of Renfrew’s argument.

Of course, as the name suggests, Indo-European languages are spoken not only in Europe. Modern Iran, Afghanistan and the Indian subcontinent all have a majority of Indo-European speakers. How did they come to speak languages related to Irish Gaelic, thousands of miles away? Again, there are competing hypotheses. The first, advanced by Childe, Gimbutas and others, is that the early steppe horsemen carried their language from central Asia into India when they invaded around 1500
BC
. The Rig Veda, an early Indian religious text, records the conquest of India by mounted warriors from the north. This received corroboration in the 1920s when Sir John Marshall and his colleagues excavated Mohenjo Daro and Harappa in the Indus Valley. These great cities date from around 3500
BC
, and by the second millennium
BC
they were massive settlements with thousands of houses, extensive agriculture and enormous populations. Then, around 1500
BC
they entered a period of decline, and by
AD
1000 the Harappan culture had
disbanded, its cities abandoned. What caused this sudden cultural collapse? To the archaeologists, it seemed to correlate perfectly with an invading force of Aryans from the Steppes. Archaeology seemed to be reinforcing Childe’s argument, and corroborating the Rig Veda.

More recent research has suggested that there were probably indigenous causes for the collapse of the Harappan civilization. Perhaps a river changed course, or social decay had set in (think of the Romans, 2,000 years, later). Whatever the cause(s), the invading Aryans were not necessarily the all-powerful conquerors that early archaeologists thought they were. In the wake of this reinterpretation, Renfrew suggested two models for how the Indo-European languages could have come to India.

Renfrew’s first model is that of an early Neolithic migration from the Middle East, with the settlers carrying their PIE language with them. In this model, the Harappans would already have been Indo-European, and thus there is no reason to infer an Aryan invasion in order to account for the languages of India. The second model, giving more credence to the Rig Veda, is that there was an invasion of the Indus region by Indo-European speaking nomads from central Asia, but it was carried out by relatively few individuals. Thus it had little impact on the population of the subcontinent, aside from the imposition of a language and culture. In both cases, the Indian genetic data shows a minor contribution from the northern steppes.

The test of the Childe–Gimbutas and Renfrew hypotheses awaited the development of markers that were capable of distinguishing between populations from the steppe and the indigenous Indian gene pool. As we saw in
Chapter 6
, M20 defines the first major wave of migration into India from the Middle East, around 30,000 years ago. It is found at highest frequency in the populations of the south, who speak Dravidian languages – a language family completely unrelated to Indo-European. In some southern populations, M20 reaches a frequency of over 50 per cent, while it is found only sporadically outside India. Thus, for our purposes, it is an indigenous Indian marker. What was needed to complete the analysis was a steppe marker, in order to see what contribution it may have made to the genetic diversity present in India.

This came with the discovery of a marker known as M17, which is
present at high frequency (40 per cent plus) from the Czech Republic across to the Altai Mountains in Siberia and south throughout central Asia. Absolute dating methods suggest that this marker is 10–15,000 years old, and the microsatellite diversity is greatest in southern Russia and Ukraine, suggesting that it arose there. M17 is a descendant of M173, which is consistent with a European origin. The origin, distribution and age of M17 strongly suggest that it was spread by the Kurgan people in their expansion across the Eurasian steppe. The key to solving our language puzzle is to see what it looks like in India and the Middle East.

The answer is that M17 in India is found at high frequency in those groups speaking Indo-European languages. In the Hindi-speaking population of Delhi, for example, around 35 per cent of men have this marker. Indo-European-speaking groups from the south also show similarly high frequencies, while the neighbouring Dravidian speakers show much lower frequencies – 10 per cent or less. This strongly suggests that M17 is an Indo-European marker, and shows that there was a massive genetic influx into India from the steppes within the past 10,000 years. Taken with the archaeological data, we can say that the old hypothesis of an invasion of people – not merely their language – from the steppe appears to be true.

And what of the Middle East? Interestingly, M17 is not found at high frequency there – it is present in only 5–10 per cent of Middle Eastern men. This is true even for the population of Iran, speaking Farsi, a major Indo-European language. Those living in the western part of the country have low frequencies of M17, while those living further east have frequencies more like those seen in India. What lies between the two regions is, as we learned in
Chapter 6
, an inhospitable tract of desert. The results suggest that the great Iranian deserts were barriers to the movement of Indo-Europeans in much the same way that they had been to late Upper Palaeolithic migration.

The Y-chromosome results from Iran and the Middle East also suggest that early Middle Eastern agriculturalists did not spread Indo-European languages eastward as they moved into the Indus Valley. The marker M172, associated with the spread of agriculture, is found throughout India – consistent with an early introduction from the Middle East, most likely during the Neolithic. But the frequency is
comparable in Indo-European and Dravidian speakers, suggesting that the introduction of agriculture pre-dated that of the Indo-European languages. Thinking in terms of actual behaviour, many Indian descendants of Neolithic farmers have learned to speak Indo-European languages, while fewer M17-carrying Indo-European speakers – up to this point – have given up their language in favour of Dravidian.

The low frequency of M17 in western Iran suggests that, in this case, exactly the sort of scenario envisaged by Renfrew in his second model has occurred. It is likely that a few invading Indo-European speakers were able to impose their language on an indigenous Iranian population by a process Renfrew calls
elite dominance.
In this model, something – be it military power, economic might, or perhaps organizational ability – allowed the Indo-Europeans of the steppes to achieve cultural hegemony over the ancient, settled civilizations of western Iran. One candidate for this ‘something’ was their use of horses in warfare, either to pull chariots or as mounts. Cavalry and chariots, both steppe inventions, would have given the early nomadic Indo-Europeans a distinct advantage over their adversaries’ infantry. The use of horses would provide a major technological advantage to armies over the next three millennia. It is not difficult to imagine that it gave an early advantage to the people of the Eurasian steppe.

Thus, while we see substantial genetic and archaeological evidence for an Indo-European migration originating in the southern Russian steppes, there is little evidence for a similarly massive Indo-European migration from the Middle East to Europe. One possibility is that, as a much earlier migration (8,000 years old, as opposed to 4,000), the genetic signals carried by Indo-European-speaking farmers may simply have dispersed over the years. There is clearly
some
genetic evidence for migration from the Middle East, as Cavalli-Sforza and his colleagues showed, but the signal is not strong enough for us to trace the distribution of Neolithic lineages throughout the entirety of Indo-European-speaking Europe. Cavalli-Sforza has suggested that an initial migration of Neolithic pre-PIE speakers from the Middle East could have introduced a language to Europe, including our Kurgan people, which later became PIE. There is nothing to contradict this model, although the genetic patterns do not provide clear support either.

There is another possibility, which comes from the distribution and
relationships among extinct languages in the Middle East and Europe. What if the language of the first farmers was not Indo-European, but another language entirely? The Basques, who live in north-eastern Spain, speak a language unrelated to any other in the world. Jared Diamond, in his book
The Rise and Fall of the Third Chimpanzee
, suggested that it might be a remnant of the agricultural Wave of Advance from the Middle East. Interestingly, some linguists have suggested that Basque is related to languages spoken in the Caucasus, while others find similarities to Burushaski, a language isolate spoken in a remote part of Pakistan. Similarly, there were other now-extinct languages spoken throughout the Mediterranean world, in south-eastern Spain (Tartessian and Iberian), Italy (Etruscan and Lemnian) and Sardinia (there is a non-Indo-European source for many place names). Place names in southern France similarly suggest that Basque was much more widely spoken in the past than it is today, and Greek place names indicate the presence of a pre-Indo-European element there as well. Overall, there is reasonable evidence for a ‘Mediterranean’ collection of pre-Indo-European languages that were later replaced by the expansion of Greek and Latin.

Taken at face value, then, we have a set of languages that were once widespread around the Mediterranean and Middle East, extending eastward into Pakistan. This is precisely the territory colonized by early Neolithic farmers during the period between 10,000 and 7,000 years ago. One possibility is that these early farmers spread ‘Mediterranean’ languages as they expanded their populations. The Palaeolithic populations of Europe took on the language of farming, and its culture, even if (as in the case of the Basques) there was hardly any genetic influx. These languages also spread to the east, introducing farming throughout the river valleys of central Asia and Pakistan. Later migrations, of Dravidian and Indo-European speakers in the case of Pakistan, and Indo-Europeans in the case of Europe, would have reduced the current speakers of the Mediterranean languages to the isolated pockets we see today.