by David Reich
Once the Bell Beaker culture reached central Europe through the dispersal of ideas, though, it spread further through migration. Prior to the spread of Beaker culture into Britain, not a single ancient DNA sample from among the many dozen we analyzed had any steppe ancestry. But after forty-five hundred years ago, each one of the many dozens of ancient British samples we analyzed had large amounts of steppe ancestry and no special affinity to Iberians at all. Measured in terms of its proportion of steppe ancestry, DNA extracted from dozens of Bell Beaker skeletons in Britain closely matches that of skeletons from Bell Beaker culture graves across the English Channel. The genetic impact of the spread of peoples from the continent into the British Isles in this period was permanent. British and Irish38 skeletons from the Bronze Age that followed the Beaker period had at most around 10 percent ancestry from the first farmers of these islands, with the other 90 percent from people like those associated with the Bell Beaker culture in the Netherlands. This was a population replacement at least as dramatic as the one that accompanied the spread of the Corded Ware culture.
It turns out that the discredited idea of the “Beaker Folk” was right for Britain, although wrong as an explanation for the spread of the Bell Beaker culture over the European continent as a whole. So it is that ancient DNA data are beginning to provide us with a more nuanced view of how cultures changed in prehistory. Prompted by the ancient DNA results, several archaeologists have speculated to me that the Bell Beaker culture could be viewed as a kind of ancient religion that converted peoples of different backgrounds to a new way of viewing the world, thus serving as an ideological solvent that facilitated the integration and spread of steppe ancestry and culture into central and western Europe. At a Hungarian Bell Beaker site, we found direct evidence that this culture was open to people of diverse ancestries, with individuals buried in a Bell Beaker cultural context having the full range of steppe ancestry from zero to 75 percent (as high as in people associated with the Corded Ware culture).
Figure 16. The spread of Beaker pottery between present-day Spain and Portugal and central Europe was due to a movement of ideas, not people, as reflected in their different ancestry patterns. However, the spread of Beaker pottery to the British Isles was accompanied by mass migration. We know this because about 90 percent of the population that built Stonehenge—people with no Yamnaya ancestry—was replaced by people from continental Europe who had such ancestry.
What made it possible for people practicing the Beaker culture to spread so dramatically into northwestern Europe and outcompete the established and highly sophisticated populations previously established there? Archaeologists view the Bell Beaker culture as extremely different from the Corded Ware culture, which was in turn extremely different from the Yamnaya culture. Yet all three participated in the massive spread of steppe ancestry from east to west, and perhaps they shared some elements of an ideology despite their very different features.
Speculations about shared features among cultures separated from each other by hundreds of kilometers make scientists and archaeologists uncomfortable. But we should pay attention. Prior to the genetic findings, any claim that a new way of seeing the world could have been shared across cultures as archaeologically different from one another as the Yamnaya, Corded Ware, and Bell Beaker could confidently be dismissed as fanciful. But now we know that these people were linked by major migrations, some of which overwhelmed earlier cultures, providing evidence that these migrations had profound effects. We also need to look again at the spread of language, a direct manifestation of the spread of culture. That almost all Europeans today speak closely related languages is proof that there was strong dissemination of a new culture across Europe at one time. Could the spread of shared languages across Europe have been propelled by the spread of people documented by ancient DNA?
The Origin of Indo-European Languages
A great mystery of prehistory is the origin of Indo-European languages, the closely related group of tongues that today are spoken across almost all of Europe, Armenia, Iran, and northern India, with a great gap in the Near East where these languages only existed at the periphery for the last five thousand years—a fact known to us because writing was invented there.
One of the first people to note the similarity among Indo-European languages was William Jones, a judge serving in Kolkata in British India, who knew Greek and Latin from his schooldays, and had learned Sanskrit, the language of the ancient Indian religious texts. In 1786, he observed: “The Sanskrit language, whatever may be its antiquity, is of a wonderful structure; more perfect than the Greek, more copious than the Latin, and more exquisitely refined than either, yet bearing to both of them a stronger affinity, both in the roots of verbs and in the forms of grammar, than could possibly have been produced by accident; so strong indeed that no philologer could examine them all three, without believing them to have sprung from some common source, which, perhaps, no longer exists.”39 For more than two hundred years, scholars have puzzled over how such a similarity of languages developed over so vast a region.
In 1987, Colin Renfrew proposed a unified theory for how Indo-European languages attained their current distribution. In his book Archaeology and Language: The Puzzle of Indo-European Origins, he suggested that the homogeneity of language across such a vast stretch of Eurasia today could be explained by one and the same event: the spread from Anatolia after nine thousand years ago of peoples bringing agriculture.40 His argument was rooted in the idea that farming would have given Anatolians an economic advantage that would have allowed new populations to spread massively into Europe. Anthropological studies have consistently shown that major migrations of people are necessary to achieve language change in small-scale societies, so a phenomenon as profound as the spread of Indo-European languages was likely to have been propelled by mass migration.41 Since there was no good archaeological evidence for a later major migration into Europe, and since once densely settled farming populations were established it was difficult to imagine how other groups could gain a foothold, Renfrew and scholars who followed him concluded that the spread of farming was probably what brought Indo-European languages to Europe.42
Renfrew’s logic was compelling given the data he had available at the time, but the argument that the spread of farming from Anatolia drove the spread of Indo-European languages into Europe has been undermined by the findings from studies of ancient DNA, which showed that a mass movement of people into central Europe occurred after five thousand years ago in association with the Corded Ware culture. By arguing from first principles—that after the spread of farming into Europe it would not have been demographically plausible for there to have been another migration substantial enough to induce a language shift—Renfrew constructed a compelling case for the Anatolian hypothesis, which won many adherents. But theory is always trumped by data, and the data show that the Yamnaya also made a major demographic impact—in fact, it is clear that the single most important source of ancestry across northern Europe today is the Yamnaya or groups closely related to them. This suggests that the Yamnaya expansion likely spread a major new group of languages throughout Europe. The ubiquity of Indo-European languages in Europe over the last few thousand years, and the fact that the Yamnaya-related migration was more recent than the farming one, makes it likely that at least some Indo-European languages in Europe, and perhaps all of them, were spread by the Yamnaya.43
The main counterargument to the Anatolian hypothesis is the steppe hypothesis—the idea that Indo-European languages spread from the steppe north of the Black and Caspian seas. The best single argument for the steppe hypothesis prior to the availability of genetic data may be the one constructed by David Anthony, who has shown that the shared vocabulary of the great majority of present-day Indo-European languages is unlikely to be consistent with their having originated much earlier than about six thousand years ago. His key observation is that all extant branches of the Indo-European language family except for the most anciently div
erging Anatolian ones that are now extinct (such as ancient Hittite) have an elaborate shared vocabulary for wagons, including words for axle, harness pole, and wheels. Anthony interpreted this sharing as evidence that all Indo-European languages spoken today, from India in the east to the Atlantic fringe in the west, descend from a language spoken by an ancient population that used wagons. This population could not have lived much earlier than about six thousand years ago, since we know from archaeological evidence that it was around then that wheels and wagons spread.44 This date rules out the Anatolian farming expansion into Europe between nine thousand and eight thousand years ago. The obvious candidate for dispersing most of today’s Indo-European languages is thus the Yamnaya, who depended on the technology of wagons and wheels that became widespread around five thousand years ago.
That there could have been a massive enough migration by steppe pastoralists to displace settled agricultural populations, and thereby distribute a new language, seems on the face of it even more implausible for India than for Europe. India is protected from the steppe by the high mountains of Afghanistan, whereas there is no similar barrier protecting Europe. Yet the steppe pastoralists broke through to India too. As is related in the next chapter, almost everyone in India is a mixture of two highly divergent ancestral populations, one of which derived about half its ancestry directly from the Yamnaya.
While the genetic findings point to a central role for the Yamnaya in spreading Indo-European languages, tipping the scales definitively in favor of some variant of the steppe hypothesis, those findings do not yet resolve the question of the homeland of the original Indo-European languages, the place where these languages were spoken before the Yamnaya so dramatically expanded. Anatolian languages known from four-thousand-year-old tablets recovered from the Hittite Empire and neighboring ancient cultures did not share the full wagon and wheel vocabulary present in all Indo-European languages spoken today. Ancient DNA available from this time in Anatolia shows no evidence of steppe ancestry similar to that in the Yamnaya (although the evidence here is circumstantial as no ancient DNA from the Hittites themselves has yet been published). This suggests to me that the most likely location of the population that first spoke an Indo-European language was south of the Caucasus Mountains, perhaps in present-day Iran or Armenia, because ancient DNA from people who lived there matches what we would expect for a source population both for the Yamnaya and for ancient Anatolians. If this scenario is right, the population sent one branch up into the steppe—mixing with steppe hunter-gatherers in a one-to-one ratio to become the Yamnaya as described earlier—and another to Anatolia to found the ancestors of people there who spoke languages such as Hittite.
To an outsider, it might seem surprising that DNA can have a definitive impact on a debate about language. DNA cannot of course reveal what languages people spoke. But what genetics can do is to establish that migrations occurred. If people moved, it means that cultural contact occurred too—in other words, genetic tracing of migrations makes it possible also to trace potential spreads of culture and language. By tracing possible migration paths and ruling out others, ancient DNA has ended a decades-old stalemate in the controversy regarding the origins of Indo-European languages. The Anatolian hypothesis has lost its best evidence, and the most common version of the steppe hypothesis—which suggests that the ultimate origin of all Indo-European languages including ancient Anatolian languages was in the steppe—has to be modified too. DNA has emerged as central to the new synthesis of genetics, archaeology, and linguistics that is now replacing outdated theories.
A great lesson of the ancient DNA revolution is that its findings almost always provide accounts of human migrations that are very different from preexisting models, showing how little we really knew about human migrations and population formation prior to the invention of this new technology. The vision of Indo-Europeans or “Aryans” as a “pure” group has sparked nationalist sentiments in Europe since the nineteenth century.45 There were debates about whether the Celts or the Teutons or other groups were the real “Aryans,” and Nazi racism was fueled by this discussion. The genetic data have provided what might seem like uncomfortable support for some of these ideas—suggesting that a single, genetically coherent group was responsible for spreading many Indo-European languages. But the data also reveal that these early discussions were misguided in supposing purity of ancestry. Whether the original Indo-European speakers lived in the Near East or in eastern Europe, the Yamnaya, who were the main group responsible for spreading Indo-European languages across a vast span of the globe, were formed by mixture. The people who practiced the Corded Ware culture were a further mixture, and northwestern Europeans associated with the Bell Beaker culture were yet a further mixture. Ancient DNA has established major migration and mixture between highly divergent populations as a key force shaping human prehistory, and ideologies that seek a return to a mythical purity are flying in the face of hard science.
6
The Collision That Formed India
The Fall of the Indus Civilization
In the oldest text of Hinduism, the Rig Veda, the warrior god Indra rides against his impure enemies, or dasa, in a horse-drawn chariot, destroys their fortresses, or pur, and secures land and water for his people, the arya, or Aryans.1
Composed between four thousand and three thousand years ago in Old Sanskrit, the Rig Veda was passed down orally for some two thousand years before being written down, much like the Iliad and Odyssey in Greece, which were composed several hundred years later in another early Indo-European language.2 The Rig Veda is an extraordinary window into the past, as it provides a glimpse of what Indo-European culture might have been like in a period far closer in time to when these languages radiated from a common source. But what did the stories of the Rig Veda have to do with real events? Who were the dasa, who were the arya, and where were the fortresses located? Did anything like this really happen?
There was tremendous excitement about the possibility of using archaeology to gain insight into these questions in the 1920s and 1930s. In those years, excavations uncovered the remains of an ancient civilization, walled cities at Harappa, Mohenjo-daro, and elsewhere in the Punjab and Sind that dated from forty-five hundred to thirty-eight hundred years ago. These cities and smaller towns and villages dotted the valley of the river Indus in present-day Pakistan and parts of India, and some of them sheltered tens of thousands of people.3 Were they perhaps the fortresses, or pur, of the Rig Veda?
Indus Valley Civilization cities were surrounded by perimeter walls and laid out on grids. They had ample storage for grain supplied by farming of land in the surrounding river plains. The cities sheltered craftspeople skilled in working clay, gold, copper, shell, and wood. The people of the Indus Valley Civilization engaged in prolific trade and commerce, as reflected in the stone weights and measures they left behind, and their trading partners, who lived as far away as Afghanistan, Arabia, Mesopotamia, and even Africa.4 They made decorative seals with images of humans or animals. There were often signs or symbols on the seals whose meaning remains largely undeciphered.5
Since the original excavations, many things about the Indus Valley Civilization have remained enigmatic, not only its script. The greatest mystery is its decline. Around thirty-eight hundred years ago, the settlements of the Indus dwindled, with population centers shifting east toward the Ganges plain.6 Around this time, the Rig Veda was composed in Old Sanskrit, a language that is ancestral to the great majority of languages spoken in northern India today and that had diverged in the millennium before the Rig Veda was composed from the languages spoken in Iran. Indo-Iranian languages are in turn cousins of almost all of the languages spoken in Europe and with them make up the great Indo-European language family. The religion of the Rig Veda, with its pantheon of deities governing nature and regulating society, had unmistakable similarities to the mythology of other parts of Indo-European Eurasia, including Iran, Greece, and Scandinavia, providing further evidence of cu
ltural links across vast expanses of Eurasia.7
Some have speculated that the collapse of the Indus Valley Civilization was caused by the arrival in the region of migrants from the north and west speaking Indo-European languages, the so-called Indo-Aryans. In the Rig Veda, the invaders had horses and chariots. We know from archaeology that the Indus Valley Civilization was a pre-horse society. There is no clear evidence of horses at their sites, nor are there remains of spoke-wheeled vehicles, although there are clay figurines of wheeled carts pulled by cattle.8 Horses and spoke-wheeled chariots were the weapons of mass destruction of Bronze Age Eurasia. Did the Indo-Aryans use their military technology to put an end to the old Indus Valley Civilization?
Since the original excavations at Harappa, the “Aryan invasion theory” has been seized on by nationalists in both Europe and India, which makes the idea difficult to discuss in an objective way. European racists, including the Nazis, were drawn to the idea of an invasion of India in which the dark-skinned inhabitants were subdued by light-skinned warriors related to northern Europeans, who imposed on them a hierarchical caste system that forbade intermarriage across groups. To the Nazis and others, the distribution of the Indo-European language family, linking Europe to India and having little impact on the Near East with its Jews, spoke of an ancient conquest moving out of an ancestral homeland, displacing and subjugating the peoples of the conquered territories, an event that they wished to emulate.9 Some placed the ancestral homeland of the Indo-Aryans in northeast Europe, including Germany. They also adopted features of Vedic mythology as their own, calling themselves Aryans after the term in the Rig Veda, and appropriating the swastika, a traditional Hindu symbol of good fortune.10