The Seven Daughters of Eve (26 page)

Old maps plot the spread of agriculture using large arrows curving across the surface of the globe with all the purpose of a well-planned military campaign. They show Europe embraced in a pincer movement from the bridgehead first established on the Greek mainland. On the southern flank, seaborne insurgents spread along the Adriatic and Mediterranean coast as far as Portugal. Meanwhile a massed attack on northern Europe was orchestrated from the Balkans as legions of farmers poured out of Hungary and occupied the continent from Belgium and France in the west to the Ukraine in the east. What hope did the locals have in face of this massive onslaught? But there was no such onslaught. Careful analysis of the archaeology of the early farming sites has certainly plotted the direction and timing of the spread of agriculture. These sites are easy enough to recognize, pottery and various agricultural implements, and the outline of huts in the ground, being among the obvious signs. But, as we saw with Jasmine's story, the whole essence of agriculture is that it can radiate quickly by word of mouth and by a few seeds and animals. It is an idea. It can spread. There is no need to insist that the spread of agriculture took the form of a large-scale invasion.

Recent archaeological investigations have shown that people took up farming at different rates in different places. The inhabitants of Denmark, for example, where the seafood harvest was rich enough to support a sedentary and prolific population, did not adopt agriculture on a large scale for over a thousand years after their neighbours only a hundred miles to the south. In other places, like Portugal, farming sites appeared not far from contemporary hunter–gatherer sites happily subsisting on the rich marine resources of the Tagus estuary. This does looks like a new injection of people, probably only small in number, that brought the knowledge of farming by sea to new lands.

The new evidence from Europe which this book presents argues strongly in favour of our genetic roots being embedded firmly in the Upper Palaeolithic. Six of the seven women who are our ancestral mothers and whose imagined lives we have glimpsed were part of that resident population. They knew every inch of their landscape. They had good contacts with each other. They traded raw materials and finished goods. They were opportunists. If it suited them to farm, then they would take it up. It only needed someone to teach them; and among their tutors were the descendants of Jasmine. The mere fact that her descendants are alive and well and living in Europe is proof of the substantial genetic input from the Near East – substantial, but not overwhelming. Less than one-fifth of modern Europeans are in Jasmine's clan. The rest of us, with only a few exceptions, have deeper roots in Europe. At some time in the past our ancestors switched from hunting and foraging to embrace the farming economy. In more recent times some of the descendants of these ancestors abandoned the land for an urban existence sustained by the machine age. That is just another of the transformations that take place as people make individual decisions to take them to a better life.

Today, just under 17 per cent of native Europeans that we have sampled are in the clan of Jasmine. Unlike the other six clans, the descendants of Jasmine are not found evenly distributed throughout Europe. One distinctive branch follows the Mediterranean coast to Spain and Portugal, whence it has found its way to the west of Britain where it is particularly common in Cornwall, Wales and the west of Scotland. The other branch shadows the route through central Europe taken by the farmers who first cultivated the fertile river valleys and then the plains of northern Europe. Both branches live, even now, close to the routes mapped out by their farming ancestors as they made their way gradually into Europe from the Near East.

The imagined lives of these seven women raise many questions. Were they the only women around at the time? We have seen very clearly that they were not. They lived and died among many other women. Ursula, for example, the oldest of our ancestral mothers, had many contemporaries. But she is the only one of them to whom a substantial proportion, about 11 per cent of modern Europeans, are connected by a direct maternal link. The maternal lines of her contemporaries did not make it through to the present day. At some point between then and now they petered out as women either had no children or had only sons. It is very likely that some of their genes which reside in the cell nucleus and which can swap between the sexes at every generation have made it through to today. But they will have arrived by a tortuous route which is impossible to trace. Many of Xenia's contemporaries, though not Xenia herself, would have been maternal descendants of the earlier Ursula. Likewise Helena, Velda, Tara and Katrine will have mixed with members of older clans. And when the descendants of Jasmine arrived from the Near East with other agricultural pioneers, they would have passed on their knowledge to the descendants of the other six women.

Figure 6

Another frequently asked and reasonable question is whether there was anything special about these women, anything that would make them stand out from the others around them. Sadly, the answer is no – other than the necessary condition that each had to have two surviving daughters, there was probably nothing remarkable about them. They were not queens or empresses – such titles did not exist. They may or may not have been especially beautiful or heroic. They were essentially ordinary. Their lives were very different from ours today, but within their own time and people they would not have been exceptional. They had no idea they were to become clan mothers and feature in this book, just as any woman alive today with two daughters has the potential to be the founder of a clan which, were this book to be rewritten in fifty thousand years' time, might feature prominently on the cover. By then one or other of the seven clans may have drifted into extinction, to be replaced by others the founders of which are living somewhere today.

But perhaps the most intriguing enquiry is about the ancestors of the seven women themselves. Amazingly, we have also been able to discover the genealogy of these seven women. We can track back from the present day to reconstruct the mitochondrial DNA sequences of the seven clan mothers, then work out the ancestral relationship between them. I have retraced these connections in Figure 6. Each of the circles represents a particular mitochondrial DNA sequence, and the area of each circle is proportional to the number of people who share this sequence. The larger the circle, the more people share this sequence. The lines joining the circles represent mutations in mitochondrial DNA, and the longer the line between two circles, the more mutations separate the sequences that they represent. The figure plots out the exact relationships, so far as we can tell, between the different sequences found in Europe today. Each of the pathways is a maternal lineage traced by DNA. We can not only see the relationships between sequences within the same clan, but also make out the relationships between clans. The clans of Helena and Velda are close to one another. They share a common ancestor, shown by the small circle where the clan lineages split off from each other. Jasmine and Tara also have a common ancestor, as do Ursula and Katrine. With the possible exception of the Helena/Velda ancestor, these common ancestors lived way before modern humans ever reached Europe, most probably in the Middle East. Towards the top centre of the figure is the common ancestor of all Europeans, where the Xenia branch leads off from the rest. Through this woman, the whole of Europe is joined to the rest of the world. This connection is shown by the dashed line. And since there is nothing fundamentally special about Europe, we can construct a much larger maternal genealogy that embraces the entire globe.

Although most of this book has been about Europe, what I have described here can be done anywhere in the world. Over the last ten years active research programmes have analysed and published mitochondrial DNA sequences from several thousand people from all corners of the globe. We have put all of these through the same process that we used to discover the Seven Daughters of Eve. The end result of this analysis is that we have discovered twenty-six other clans of equivalent status in the rest of the world. About some of these we know a lot; about others, very little. Even so, I have given them all names. The picture will no doubt change in the years to come as people from previously unsampled regions volunteer their DNA. But we know enough already to have a good idea and to make a start on interpreting their meaning.

Figure 7
WORLD CLANS AND WHERE THEY ARE FOUND

Of the thirty-three clans we recognize worldwide, thirteen are from Africa. Many people have left Africa over the last thousand years, a lot of them forcibly taken as slaves to the Americas or to Europe. But their recent genetic roots are quite clearly in Africa. Although Africa has only 13 per cent of the world's population, it lays claim to 40 per cent of the maternal clans. The reason for this is that
Homo sapiens
has been in Africa for a lot longer than anywhere else. The archaeology supports this statement, the study of human fossils supports it and now the genetics supports it too. There has been a very long time for mutations to accumulate in Africa. This means there has been time for new clans to form and become distinctive and recognizably different from one another. Different clans are more frequent than others in some parts of the continent, but there is no specific association between genetic clans and tribal structures. This is a reflection of the great antiquity of the genetic roots, which predate the formation of tribal and other classifications by more than a hundred thousand years.

Incredibly, even though the African clans are easily the most ancient in the world, we are still able to reconstruct the genetic relationships among them. Thus we probe the ancestors of the ancestors. At last, my dream of building a complete maternal genealogy for the whole of humanity was coming true. One by one the clans converge until there is only one ancestor, the mother of all of Africa and of the rest of the world. Her existence was predicted in the original scientific paper on mitochondrial DNA and human evolution in 1987. Immediately she was dubbed ‘Mitochondrial Eve' – hardly a convincing African name. She lies at the root of all the maternal ancestries of every one of the six billion people in the world. We are all her direct maternal descendants. But, just as Ursula and the others were not the only women alive at the time, nor was Eve. Estimates of the size of the human population one hundred and fifty thousand years ago are bound to be not much more than guesswork, but it may have been in the order of one or two thousand individuals. Of these, only Eve's maternal lineage survives unbroken right through to the present day. The others withered away. But they, like Eve, would also have had maternal ancestors; so there is another woman even further back who was the ancestral mother of Eve and her contemporaries. She in turn would not have been alone, and another ancestral mother becomes a logical inevitability. This line of thought goes on and on, becoming increasingly pointless as we reach back millions of years to the very beginnings of our species and the species from which we ourselves evolved. The dashed line on Figure 7 indicates this even deeper genealogy through which our species,
Homo sapiens
, is connected to the other, extinct, humans, the Neanderthals and
Homo erectus
, and eventually back to the common ancestor of humans and other primates.

For our purposes we need only go back in time as far as Mitochondrial Eve. The genetics tells us very clearly that modern humans had their origins in Africa within the last hundred and fifty thousand years. At some point, about a hundred thousand years ago, modern humans began to spread out of Africa to begin the eventual colonization of the rest of the world. Incredible as it may seem, we can tell from the genetic reconstructions that this settlement of the rest of the world involved only one of the thirteen African clans. It could not have been a massive movement of people. Had hundreds or thousands of people moved out, then it would follow that several African clans would have been found in the gene pool of the rest of the world. But that is not the case. Only one clan, which I have called the clan of Lara, was involved. It is theoretically possible from the mitochondrial DNA evidence that only one modern human female, one woman, left Africa, and that from this one woman all of us in the rest of the world can claim direct maternal descent. I think this highly unlikely, since she would have had contemporaries in her foraging band. But the numbers must have been very small. This was no mass exodus. Lara herself was not in the party. She probably lived in Kenya or Ethiopia; certainly in Africa. We know this because many Africans today are members of her clan. So she must have lived her life in Africa, unaware of her gift to the world, while it was her descendants that began to move out. Even so, it is a quite astonishing conclusion that the whole of the rest of the world can trace their maternal ancestry directly back to Lara. She is truly the mitochondrial Eve of the rest of the world.

All the evidence points to the Near East as the jumping-off point for the colonization of the rest of the world by modern humans. It was the only land route out of Africa, across Sinai. The only other possibility was to cross the Straits of Gibraltar at the entrance to the Mediterranean between north Africa and Spain. This is a deep channel which was never a land bridge, even when sea levels were at their lowest. Even so, the Straits of Gibraltar are only 15 kilometres across at their narrowest point, and the high Rock of Gibraltar is easily visible from the African side. But neither the archaeology nor the genetics suggest this route was taken.

There is good fossil evidence in Israel that
Homo sapiens
had reached the Near East at least one hundred thousand years ago. In this book we have traced the faltering spread of our species to the north and west into Europe, which finally succeeded only fifty thousand years ago. What held them up in the Near East for at least fifty thousand years before that? Europe was already inhabited by Neanderthals, physically adapted to the cold and experienced in the mechanics of making a living by hunting the large animals of the tundra.
Homo sapiens
in the Near East would have needed some advantage, however slight, over the Neanderthal occupants to make any headway. The long period spent in the Near East would have seen the slow developments in technology and, more important, in social interactions, that equipped them eventually to establish a permanent foothold in Europe.

The colonization of northern Asia was probably delayed for the same reasons. It too was a land dominated by steppe and tundra, running in a wide and uninterrupted ribbon from the Ukraine in the west to the high plateaux of Mongolia in the east. Archaeological sites in Mongolia dated to thirty-five thousand years ago witness the arrival of hunting bands with sophisticated flint arrow points in this bleak terrain at about the same time that modern humans were beginning to dominate the plains of western Europe. Their lives would have run along similar lines to the early Europeans we have already encountered, dominated by the seasonal migrations of the tundra animals and the fight to survive the unforgiving winters. We understand very little about the mitochondrial genetics of this vast region because it has not been widely sampled, but we do know enough to be able to be absolutely sure that it was from here that the colonization of the Americas was launched.

Four mitochondrial clans dominate the genetics of native Americans. All four have easily reconstructed and obvious genetic links with people living in Siberia or north–central Asia today. If they went by land, then their route into the Americas can only have been via Alaska. We have enough information about the sea-level changes over the past hundred thousand years to know that there were two periods when there was a continuous land bridge between Siberia and Alaska. The first bridge was formed fifty thousand years ago and lasted for about twelve thousand years. The second coincided with the last Great Ice Age, when the land was above sea level between twenty-five and thirteen thousand years ago.