This man turned out to have an M173 Y-chromosome, the canonical European lineage. M173 has never been identified in hundreds of samples from indigenous sub-Saharan Africans, so the obvious question was how did he come to have such an anomalous result? The other, non-Y markers we tested revealed him to be otherwise genetically African – including the presence of a marker I had first identified in a Zulu man in the mid-1990s. Clearly, the Y was telling a different story – one that helps to illustrate the main theme of this chapter.
The reason our Afro-Caribbean man had a European Y-chromosome was that, at some point in the past, one of his male ancestors must have had a European father. Given his family history, it is likely that this occurred when his family lived in the Caribbean, during the era of slavery. Clearly, knowing the history of recent migration was critical to interpreting this result. Once the circumstances were recognized, it became very easy to reconcile the Y data with the rest of the genetic story, giving us a glimpse into his complicated family tree.
Was this a unique case? Absolutely not. Among African–Americans, as many as 30 per cent of Y-chromosome lineages appear to be European in origin. The slave-trading era has left a distinct pattern in the DNA of people of African descent living outside Africa. They are not unique in having a mixed ancestry, though. In the past 500 years – encompassing the European Age of Exploration and the Industrial Revolution – humans have become far more mobile than ever before. Today, the descendants of those first modern humans to wander into Eurasia zigzag around the planet at a pace that would leave our Upper Palaeolithic ancestors breathless. The final Big Bang in human evolutionary history – which could be called the Mobility Revolution – has given rise to the era of globalization. While the cultural and economic consequences of living in a ‘global village’ are debated by businesspeople and policymakers, and the ecological fallout is seen in the accelerating loss of biodiversity, the genetic effects of the latest Bang are perhaps less clear.
A linguistic thread
Much of my work as a geneticist has focused on deciphering the relationships among the people living in central Asia. The former Soviet states of Uzbekistan, Kazakstan, Kyrgyzstan and their neighbours were locked away from most Western scientists during the Soviet era, and when they opened up in the early 1990s I jumped at the chance to go there. Sampling of the world’s genetic diversity had, until that time, concentrated mostly on Europe, east Asia (particularly China and Japan), South Africa and North America. Central Asia was pretty much unknown – a ‘black box’ in the genetic patterns of the world.
I first visited in the summer of 1996, and since then my work has taken me there several times. I have driven there from London in a Land Rover, flown in on shaky Soviet-era planes and walked across remote borders carrying bags of genetic sampling equipment. One of my most memorable trips, though, was when I visited Tajikistan in August 2000. Working with local scientists and physicians, our aim was to take blood samples from several of the ethnic groups living in the mountainous regions of the country. One of these was the Yagnob.
The Yagnob are a direct link back to the days of the Silk Road. Their language, Yagnobi, is a direct descendant of Sogdian, which was once the lingua franca of the Silk Road – in much the same way that English is the language of commerce today. In the mid-first millennium ad, Sogdian was spoken in trading centres across central Asia, from Persia to China. After the Muslim conquests of the seventh to ninth centuries its use declined, and by the twentieth century all of the dialects were extinct – except one. The Yagnob people, living in a few isolated villages in the remote Zerafshan Valley of northern Tajikistan, still speak this ancient language, a 1,500-year-old linguistic artefact. Our plan was to visit them and explain our project, hoping that they would want to participate in the research project to trace their history using the signals in their DNA.
The trek up to the Yagnob villages from the Tajik capital, Dushanbe, involved crossing a pass that had only recently been retaken by government forces in Tajikistan’s long and bloody civil war. After passing through several checkpoints guarded by Kalashnikov-toting soldiers and descending to the series of parallel valleys on the other side, we found a dirt road leading eastward, alongside the Zerafshan River. Several hours later, after pushing our old Soviet van through the rough patches, we reached a small kishlak, or village. Expectantly we hopped out and asked to speak to the local ‘head man’. We explained the project, sipping tea while the old man pondered what we had said. Eventually, he told us that we had made the trip in vain.
The Yagnob had lived here for generations, he explained – perhaps even since the days of the Silk Road. But in the 1960s, drought had led the Soviets to resettle them in villages in the lowlands. Also, in the late 1980s there had been an earthquake, and many of those who remained had moved to Dushanbe. Now it was actually very difficult to find Yagnob living in their ancient land. You might find cab drivers or cleaners in the capital who came from this region, but – except for a remote village several days’ hike into the mountains – the Yagnob had largely decamped from their ancient homeland. Disappointed, we thanked him and left. After another couple of days’ searching we managed to discover one Yagnob village, and the locals were very happy to help us with our work, but in the end we collected more samples from this ancient population by trolling around the capital. Our effort to find an isolated remnant of the Silk Road had nearly failed.
What the old man in Tajikistan had explained to us actually happens every day, all over the world. The Yagnob are not an unusual case – in fact, quite the opposite. It is a fact of modern life that villages are gobbled up by growing cities, their residents thrown into a mix of languages and ethnicities that becomes ever more complex as the city expands. And while some societies tolerate diversity, many view it as an impediment to unity. It is often shunned by governments keen on cultivating cultural harmony – especially in newly created states striving for a sense of identity. To understand why, we need to take a closer look at the model for statehood developed in nineteenth-century Europe.
Withering tongues
When you visit France today, it is difficult not to be impressed by the people’s love for their language. The Académie Française, official guardian of the national language, monitors spoken and written French like a hawk, helping to whip it into shape in the face of foreign influences. Yet just 150 years ago – roughly six generations – fewer than half the people living in France actually spoke French. Most spoke their local dialects and languages. In Italy around the same time, less than 10 per cent of the population was estimated to have spoken Italian. Austrian chancellor Clemens von Metternich quipped at the time that Italy was less a nation than a ‘geographical expression’ – clearly true if language was a factor.
Nineteenth-century Europe was a swirl of new ideas and movements. Romanticism, realism, industrialization, colonial expansion – all would make significant contributions to the development of our ‘modern’ worldview. One of the most important manifestations of the new thinking was the rise of nationalism, which was to create the modern political map of Europe – and have far-reaching effects on the rest of the world.
Before the nineteenth century, Europe was divided up into separate fiefdoms, kingdoms and duchies. Life was much more ‘local’ than it is today. People’s allegiance was to provincial rulers, and their lives revolved around regional events. This was reflected in their marriage patterns, which tended to be highly localized. The distance between spouses’ birthplaces was only a few kilometres throughout most of European history, leading to high levels of consanguinity, or intra-family marriages. These regional characteristics extended to language as well. For instance, while modern France has one official language, religiously guarded by the Académie, in the late eighteenth century there were many provincial languages tracing their existence back hundreds or thousands of years. Basque, Breton, Occitan, Corsican, Alsatian – all were distinct linguistic entities. Breton, for instance, is a Celtic language more c
losely related to Welsh and Gaelic than to French, despite the fact that it was the language of Brittany on the north coast of France. The speakers of these regional languages saw themselves as possessing unique identities – ethnicities, if you will – which were to be subsumed in the process of creating the French state.
As nationalism took hold in Europe, language was used by the newly unified states to create a sense of national identity. Governments sought cultural unity by favouring one language over the others. From the eighteenth century onward English was the primary literary and governmental language in the United Kingdom, but many people living in the UK spoke languages only distantly related to English. The effect was an expansion in the number of native English speakers at the expense of the Celtic languages. The Celtic Manx language (known locally as Ghailckagh), native to the Isle of Man, had 12,000 native speakers in 1874, but only 4,000 at the turn of the twentieth century. The last first-language Manx speaker died in 1974, and today it is kept alive only as a kind of living fossil by a few hundred aficionados.
During the nineteenth century compulsory schooling in the national language, as well as national military service, helped to spread the chosen tongue, and within a few generations the process was nearly complete. Nationhood had been transmogrified into monolingualism. One of the best examples of the entanglement of language and nationhood comes from Germany. The Grimm brothers, Jacob and Wilhelm, are famous for compiling the fairytales that most European children hear during childhood. It is perhaps not as widely known that Jacob was also an accomplished linguist, who defined the rule for the sound changes that occurred during the evolution of the Germanic languages – for instance, when a b in an ancestral Indo-European word became a p in German, and so on. The Grimms’ work was done, at least in part, in order to derive a sense of unity for the German-speaking peoples. In the case of the linguistic studies, it was an effort to define and codify the unity and history of the Germanic languages, as part of the creation of a national language standard. The fairytales, on the other hand, were an effort to record the folk culture of the Germans, in order to preserve and mould their national identity. Germany was in the process of becoming ‘German’, and the Grimms were among the intellectual architects of the new nation.
The identification of history with language was developed during this period of European nationalism, but it was simply a formal statement that languages tend to define cultures, and cultures are intimately tied to their languages. The reason for this is the length of time it takes to ‘create’ a language – around 500–1,000 years to develop something that is distinct from its sibling tongues. The Romance languages, for instance, have been diverging from each other for around 1,500 years, tracing their origins back to the days when Latin was the language of the Roman Empire. Today French, Spanish, Italian, Romanian, Catalan and Romansch (spoken in the Swiss canton of Graubunden) are all related through a common ancestry to the language of the Romans. Other languages, such as Basque, have been distinct from their surrounding languages for much longer. But in each case, a language represents the end result of many years of cultural isolation.
When languages are lost, then, we lose a snapshot of one part of our history. If the Basque language went extinct, we would lose the only remaining link back to the pre-Indo-European languages of Europe. If the estimated 2,000 Yagnobi speakers in Tajikistan are completely integrated into the Tajik-speaking majority, and their children stop learning Yagnobi, then we will have lost this living connection to the time of the Silk Road. In every case of language death, we lose a part of our cultural history. Particularly when the language in question has not been studied and recorded – which is the case for most of the world’s languages – we have lost an irretrievable snapshot of our past.
Today, the fifteen most common languages, in terms of number of speakers, are spoken by half the world’s population. Some of these languages (English, Spanish and Arabic among them) were spread through colonialism. Others have increased in number through population growth, spurred on by agriculture – Chinese and Hindi being the two best examples. Even in these cases, though, the creation of a national language has contributed to their success. What is clear is that a few languages are becoming much more widespread. The top 100 languages are spoken by 90 per cent of the people in the world – despite the fact that linguists recognize over 6,000 distinct tongues. Clearly, most are spoken by only a few people.
The future of most of these languages is uncertain at best. Through the same processes that have reduced the number of Yagnobi and Manx speakers, most languages are headed for extinction. Most of these doomed languages are spoken by small populations that have been absorbed into or dispersed by larger groups. The Yaghan language – spoken by Darwin’s Fuegians whom we heard about in Chapter 1 – is probably already extinct, a victim of European colonialism. Linguists Daniel Nettles and Suzanne Romaine estimate that over half of the world’s languages could be extinct by the end of this century – a rate that equates to the loss of one language every two weeks. There were estimated to have been 15,000 languages spoken around the world in 1500, so we have already lost more than half of the linguistic diversity that once existed.
But, you may be thinking, the focus of this book has been on what our genome tells us about our history. Why, then, should we care about the rise of nationalism and the loss of languages? Because, as we saw in the previous chapter, languages are often correlated with genetic patterns. In that case, what does the loss of linguistic diversity reveal about the current state of our genomes – and their future?
The global melting pot
As we have seen, only a tiny fraction of the genetic diversity in the human species distinguishes populations from each other – the vast majority of variation is found within a single population. There are two reasons for this. The first is that we are a relatively young species. Around 50,000 years ago – only 2,000 generations – our ancestors all lived in Africa. Given that mutations happen only infrequently, and that it takes a while for them to increase in frequency to a point where they can be sampled in a population, it is likely that most of the diversity we see now already existed in this ancestral African population. This is particularly true for polymorphisms other than those on the Y-chromosome. Most of these other polymorphisms appear to be quite old, consistent with the fact that they were present in the ancestral population before our journey out of Africa.
Furthermore, human ‘races’ seem to have very recent origins. For the most part, physical traits that distinguish modern human geographic groups only appear in the fossil record within the past 30,000 years. Most older fossil Africans, Asians and Europeans are very similar to each other. While we know nothing about our ancestors’ skin colour, hair type or other surface features, the evidence from bones suggests that our concept of race is actually a very recent phenomenon. It was probably the fragmentation of human groups as a result of the last ice age that produced the distinct ‘racial’ morphologies we see in modern humans – not hundreds of thousands of years of separate evolution, as Carleton Coon and others had argued. For example, sinodonty – the distinctive tooth pattern common to north-east Asia and the Americas – first appeared in the fossil record less than 30,000 years ago. Before then Asian teeth were very similar to those seen elsewhere in the world.
The other reason for genetic uniformity among human populations is that humans are mobile, and groups have intermixed throughout their history. When this happens, their patterns of genetic variation become dispersed throughout the mixed population. So, even in cases where the genetic markers arose after modern humans migrated out of Africa – like most of the markers we have followed on the Y-chromosome – they will still be widely distributed as a result of subsequent mixing.
The dynamics of language extinction indicate that human mixing is now accelerating. Languages seem to die out primarily through the incorporation of small, previously isolated populations into a larger, dominant population – in the same way that Manx w
as subsumed into English-speaking Britain. It is rarely the case that a minority population actually dies – rather, it is simply incorporated into the majority. But is there any real data on the rate at which this is happening?
The answer is yes. Most developed countries have a national census, where the people living in the country are counted and subdivided into demographic units. The reasons for this may be pragmatic – apportioning political representation or government funds, for instance – but the data also reveals deeper truths about society. Perhaps the best-known census is that held every ten years in the United States, the most recent of which was in 2000. Aside from showing that the population of the USA was 281.4 million, an increase of 13 per cent over that in 1990, it also detailed a changing ethnic landscape. For the first time in 2000, people were able to subdivide their ethnicity accurately. The number of racial categories expanded from five to sixty-three, and for the first time combinations of minority groups could be reported.
In total, 6.8 million people described themselves as a mixture of ‘white’ and a ‘minority’ group. Of course, this ignores the mixing that has created the category of white, which could mean anything from Irish to Lebanese to Moroccan. As we have seen in previous chapters, this mix alone encompasses a wide range of populations and markers. In terms of the official ‘mixed’ category, many people who have mixed ancestry actually consider themselves to be one race to the exclusion of the other, suggesting that the true number of mixed Americans is actually much higher than what was actually reported. For instance, surveys carried out by the US Census Bureau show that, while only. 25 per cent of black/white mixed respondents considered themselves white, around half of white/Asian and white/Hispanic respondents, and 81 per cent of those with mixed white/Native American ancestry thought of themselves as white. One of the results of the 2000 census is that it became clear that America is far more of a melting pot than it may have imagined.
The Journey of Man: A Genetic Odyssey Page 22