How Many Friends Does One Person Need? (6 page)

Our naming patterns seem to capitalise on this. In fact, the biological intuition of relatedness seems to be so strong that, in the absence of anything else, shared names can be used to trigger sentiments of kinship even where none actually exists.

Names are not the only way we identify family connections. Dialects are another. Dialects are actually rather odd things. Language, as we may reasonably assume, evolved to enable us to communicate with each other so as to get the communal jobs done better. Yet languages have an extraordinary capacity to fractionate into mutually unintelligible dialects at an astonishing rate – on a scale of generations rather than millennia. Not to put too fine a word on it, generations are parts of a population separated by language. But why on earth would something designed to make communication possible have the inherent property of preventing mutual comprehension?

The answer to this evolutionary conundrum is that dialects are a very reliable marker for your place of birth. Even as recently as the 1970s, it was possible to place a native English speaker to within thirty miles of his or her
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birthplace. In effect, because it is learned young and cannot easily be learned later in life, dialect provides a useful cue of which community you were born into, and so whom you are likely to be related to. It is one of many kinds of social badge that we use to identify membership of a local community, and thus who can be relied on and to whom one should owe obligations. In a study carried out by Jamie Gilday (then a student in our lab), people phoned at random were more likely to agree to help complete a task over the phone if they had the same local accent as the caller (raised in a Lanark village) than those whose dialects were markedly different (city Glasgow or northern English). In another study, my one-time graduate student Daniel Nettle showed that so long as dialects changed fast enough, they could prevent freeloaders who exploited social obligations from taking over a population.
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It is a truism to say that your past is in your genes. But for all its humdrum dullness, the fact is that modern genetics has uncovered some fascinating insights into our recent past that we could never have gleaned from the history books.

The DNA of our chromosomes is literally the history of our individual ancestries. Although we receive half our genes from each of our parents, some genes are transmitted only through one sex. The Y chromosome is passed on only from father to son, and identifies uninterrupted male lineages. In contrast, mitochondrial genes are inherited only from your mother. The mitochondria are the tiny powerhouses that fuel a cell’s activities. In the very remote past, they were free-living viruses that found a cosy home inside the cells of ‘proper’ animals; there they set up home within the cyto-plasm that surrounds the nucleus where the chromosomes are housed. As a result, they are passed on only in the egg, and so always come from your mother. They allow us to track maternal lineages.

If your family name happens to be Khan, there’s a fair probability that you are descended from the greatest of
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all Khans, the warrior king Genghis Khan whose Mongol armies swept through central Asia as far as Tashkent and northern Pakistan in the first decades of the thirteenth century. But even if your surname isn’t Khan, no need to be disappointed: modern genetics has shown that there’s still a fair chance that you are a descendant of the Khan. A recent survey of Y-chromosome genes revealed that an astonishing 0.5 per cent of all the men currently alive today have inherited their Y chromosome from the great Mongol warrior or his brothers. And if your ancestors are from the central Asian heartland of the old Mongol empire, that chance rises to one in twelve (8.5 per cent) of all men.

These extraordinary findings come from a study of the DNA of over two thousand men sampled from right across central Asia, from Japan to the Black Sea. While the Y chromosomes of most of the men in the sample showed the usual wide range of DNA types (known in the trade as haplotypes), nearly two hundred shared a set of very similar (sometimes identical) genetic signatures. This set of about eighteen haplotypes formed a very distinct cluster that set them apart from the other sixty or so haplotypes in the sample.

The research team was intrigued by two facts about this unusual cluster of haplotypes. First, they formed a particularly dense concentration in the region of modern Mongolia; second, there were pockets of them all over central Asia. In contrast, all the other haplotypes were very localised to particular hotspots.

Evolutionary theory offers us three possible explanations as to why a genetic lineage might be both as common and as geographically widespread as this. One is that it might
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arise simply by chance, and, being of no particular advantage or disadvantage to those who happened to inherit it, it spread gradually by a process known as genetic drift. A second is that the genes in question have been particularly advantageous and so have been subject to intense selection. The third is a form of sexual selection, whereby males who possessed these haplotypes were unusually successful in reproducing themselves.

A few quick calculations are enough to suggest that the first is unlikely: even by the most conservative estimates, the chances of such a distribution arising by chance are considerably less than 100 million to one. The second is not a lot more plausible: the Y chromosome is tiny and contains almost no genes other than those required to turn the foetus into a male (more on this later). That leaves us with the third possibility. And here history comes to the rescue. A glance through its pages quickly identifies one event that might just fit the bill: Genghis Khan’s empire.

Two pieces of the jigsaw make this explanation plausible. One is the fact that all the haplotypes in the cluster come exclusively from the areas that came under the great Khan’s rule. The unusual haplotypes are completely absent elsewhere in Asia that remained outwith the Mongol empire. The second is the time of origin of this cluster of haplotypes. Many of our genes have no function (i.e. don’t code for the proteins involved in actually building the body) and so they only change over time as a result of random mutations. This has allowed biologists to use them as a kind of molecular clock: count the number of neutral or ‘junk’ genes by which two individuals differ, divide by the rate at which genes mutate, and – hey presto! – we have a very reasonable estimate of how long ago they last
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shared a common ancestor. When the researchers did this for the eighteen or so haplotypes in their unusual cluster, they arrived at a figure of 860 years ago. Genghis Khan was born around ad 1160, just 840 years ago. This is close enough to be suspicious, as Sherlock Holmes might have said. More interestingly, perhaps, it suggests that the original mutation that produced the haplotypes in question derived not from the Khan himself, but a generation earlier in his lineage – from the Khan’s father, Yesugei.

When Yesugei’s young son Temüjin united the factious Mongol tribes in 1206 and earned himself the title Genghis Khan – ‘Khan’ meaning ruler or emperor – he brought under his control a formidable fighting force. In a series of lightning strikes, he conquered the two northern Chinese empires and then struck westwards through modern-day Kazakhstan as far as the Black Sea to create the biggest empire in all history. Although invariably heavily outnum-bered, his battle-hardened troops demolished everything the opposition placed in his way.

And then – to use his own words – having vanquished your enemies, ‘the greatest happiness is to chase them before you, to rob them of their wealth, to see those dear to them bathed in tears, to clasp to your bosom their wives and daughters’. It seems, from modern genetics, that the Khan and his brothers were as good as their word.

As that great assertion of Scots independence, the Declaration of Arbroath, succinctly put it in 1320: the Scots ‘journeyed from Greater Scythia... to their home in the west where they still live today’. And just who
were
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the Scythians, then? Well, actually, a very successful group of pastoralists who first appeared in the western edges of Mongolia around 3000 bc and gradually made their way westwards, spending time on the way in what is now Uzbekistan near the Aral Sea, then in the Caucasus region of Georgia, finally entering eastern Europe through the Ukraine.

Are the Scots
really
the descendants of the Scythians? Well, actually probably not – it was more of a political move to persuade the Pope, to whom the Declaration was addressed, that the Scots could not possibly ever have been English, and therefore should not have to be the vas-sals of the English king Edward II. But, as far-fetched as this specific claim might have been, it seems that the authors of the Declaration were not quite as far off the mark as all that – though how on earth they could have known that is another question. Most of us Europeans are in fact the descendants of the great Indo-European expansion that began around 3000 bc somewhere in the steppes of southern Russia. The Scythians were, to be fair, a rather late element in that story, and probably never did get much further than the Ukraine. But the wonders of modern genetics tell us that the great Indo-European invasion served to displace (or worse) most of the previous inhabitants of Europe over the next couple of thousand years. Today, all but a handful of the myriad languages spoken in Europe are descended from the language spoken by those early Indo-European immigrants.

It seems that only the Basques survived this human tsunami with anything like their national identity – or their genes – intact. Protected by their Pyrenean mountain fastness, the ancestors of the Basques must have
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watched the tidal surges of successive invasions and conquests that lapped the foothills of their mountain home with, shall we say, concern. But, by a quirk of geography, they survived relatively unscathed, aloof from the turmoil that changed the face of Europe.

At least, this is the conclusion that we are drawn to by the converging evidence from both linguistics and genetics. Linguists have known for a long time that the Basque language is an oddity. It is completely unrelated to – and quite unlike – any of the other languages of Europe, which, with the exception of a handful of exceptions, are all part of the great family of Indo-European languages. (Among the best known of these exceptions are Finnish and Hungarian, both of which derive from invasions by Mongolian peoples, the latter most famously associated with Attila the Hun and his chums.) Indo-European is a language family that spans the Gaelic tongues of the far west, almost all the other languages of modern Europe, the Farsi and Pushtu languages of modern Iran and Afghanistan, Sanskrit and Urdu and their many descendants in northern India, and reaches its easternmost extension with Bengali in Bangladesh. The closeness of these languages is reflected in the similarity of many of their everyday words. The Indian Sanskrit word
bhrater
is recognisably but a shade away from the Gaelic
bràthair
and the English
brother
, and manifestly a world away from, for example, the East African Swahili equivalent
kaka
. Unlike Swahili, Sanskrit, Gaelic and English share a recent common ancestry in the great Indo-European expansion.

Basque is the one European exception. It shares almost nothing in common with any of the Indo-European lan-
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guages, as is evident from the Basque word for ‘brother’ –
anaia
. As a language, it seems to be a complete outlier, although some linguists have claimed that its nearest language relatives are some small pockets of relict Caucasian languages scattered across the southern steppes of Russia, which in turn form part of the Dene-Caucasian family of languages. What makes this family interesting is the fact that the Dene half consists of the Na-Dene American Indian languages, spoken in a wedge straddling the present Canadian–US border inland from the Pacific coast about as far east as the Great Lakes. We would have to go back a very long way to find the common link between the Indo-European and Dene-Caucasian language families.

Genetics has given us a new window on this intriguing story. Once again, the Basques seem to sit aside from the rest of Europe, an isolate with few genetic links to anyone else in Europe, although they share some gene complexes with the early Celts (even though these were part of the early Indo-European expansion). Let me illustrate this with just one example. The incidence of the rhesus negative gene in modern Indo-Europeans is just about two per cent, and four to eight per cent in African Americans. But it is nearly thirty-five per cent in the Basques, and around fifteen per cent in Caucasians (that is, the people of the Caucasus with whom the Basques may share linguistic origins). So the Basques might be the last misty flicker of the original inhabitants of Europe just before our own Indo-European ancestors turned up. Some have even suggested that it was the Basques’ ancestors that were responsible for the truly astonishing inflorescence of cave paintings in northern
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Spain and southern France between twelve thousand and thirty thousand years ago.

So in these days of angst about homelands and migrants, we might spare a thought for the Basques, Europe’s original inhabitants. Which leads to an interesting thought. If the Basques really are the remnants of the original inhabitants of Europe, might they legitimately lay claim once more to the continent? What should we do if they asked, politely no doubt, whether the rest of us would mind getting back to southern Russia where we came from?

Wholesale migrations probably tend to result in the extinction or displacement of the luckless folk who find themselves in the way of a migrant wave. Something along these lines occurred in Europe when the Indo-Europeans turned up from further east and pretty much forced the original inhabitants of Europe westwards, where it is thought that, like the Basques, they might still survive in isolated, barely recognisable pockets. This is suggested by the fact that the Indo-European genetic signal declines in concentration from east to west in modern Europe. In more recent historical times, of course, much the same happened in North America and Australia, where the original inhabitants have been reduced to small, socially and economically isolated communities whose long-term prospects as a distinct ethnic community are probably bleak.