by Bryan Sykes
The sea ice retreated way beyond the Shetland Isles and the sea level rose again as the ice melted. First Ireland was separated from the rest of the Isles at around 8,500 years ago. That put a stop to the colonization of Ireland by some land animals and explains why there are no moles, lizards or snakes in Ireland. That is, of course, unless you prefer to believe, in the case of snakes, that it was St Patrick himself who banished them. These animals, though, did have time to establish themselves in Britain before it was eventually cut off from the European mainland by the rising water levels in the North Sea 500 years later, about 8,000 years ago.
By now the Irish landscape had changed from tundra to an open forest of birch trees. As the temperature continued to rise, this open woodland slowly changed to a thicker cover of hazel and, by about the time the Isles became completely severed from the rest of Europe, they were covered in a mature forest of elm, lime and oak. The herds of large mammals moved north if they could, but in Ireland their way was barred by the sea. Many, including the magnificent Irish elk, with antlers some 3 metres across, became extinct. They were replaced in the now dense forests by wild pig, red and roe deer and the aurochs, the ancestor of modern domestic cattle, and by a host of smaller mammals like squirrel and pine marten. From the remains at Mount Sandel and other Mesolithic sites, it seems that anything that moved risked being roasted on the campfire. The ideal places to live were near rivers, such as at Mount Sandel on the River Bann, or by the sea. Here you could have the best of both worlds. Fish and shellfish from the sea and rivers, hazelnuts, pork and venison from the forest. Not a bad life at all. All the best shoreline sites accumulated huge mounds, or middens, of discarded shells built up often several metres high.
From the overall size of individual Mesolithic sites, archaeologists estimate that the number of people occupying them was quite low, possibly just single nuclear families. There was not the same need to join together in hunting bands of twenty or so as there had been in the colder, tundra phases. Then the main prey had been the herds of large and dangerous animals like bison, which called for organized ambushes and teamwork among the hunters. Neither was there any need to move over large distances to keep up with the herds as they migrated from summer to winter feeding grounds. Though many Mesolithic sites that have been found were obviously temporary, used for just a few days, others, like Mount Sandel, were occupied for long enough to make it worthwhile building the timber-framed houses.
Though the inhabitants of Mount Sandel were certainly hunter-gatherers, they were not above manipulating the environment to make life easier. They deliberately created open glades within the forest to encourage hazel trees to grow. They did not need to fell the mature elms and oaks to do this, but merely to ring-bark them and wait for them to die and be blown over. By stripping away a continuous band of bark from around the trunk, the capillaries that carry water to the leaves are disrupted and the tree begins to die. The next winter storm may blow it to the ground. The unremarkable life of the Mesolithic hunter-gatherers continued at Mount Sandel and elsewhere in Ireland for thousands of years, leaving little trace on the landscape and few permanent signs, shell middens apart, for archaeologists to follow.
Meanwhile on continental Europe radical changes were under way. From modest beginnings in the Middle East, farming was beginning its unstoppable march towards the Isles. Ten thousand years ago in the Fertile Crescent, in that part of what is now Syria and northern Iraq that is drained by the Tigris and Euphrates rivers, people had learned how to cultivate wild grasses and how to replace hunting with domestication. Farming ushered in the New Stone Age – or Neolithic, to distinguish it from the hunter-gatherer Mesolithic – with a whole range of new stone implements for farming. They also made pottery. The invention of agriculture seems such a small change in the tactics of subsistence, yet it has led to the complete reshaping of the world into its modern form. Whole books have been written about this, and I will resist the temptation to go off at a tangent, restricting myself instead to the implications for our remote ancestors, and for the gene patterns that await our scrutiny.
Carbon-dates from farming sites and the comparison of different pottery styles show that agriculture spread through continental Europe by two principal routes. The split probably came as the first farmers reached the Balkans and the lower Danube from Turkey around 8,500 years ago, about the time that Ireland finally separated from Britain and the residents of Mount Sandel were tucking into yet another bowl of limpet soup. One group of farmers headed north to reach the great Hungarian plains, then, after a thousand-year pause, moved rapidly north and west along the major river valleys of the Oder and the Elbe towards the Baltic and the North Sea. They needed to clear thick forest to make enough space for cultivation. This they did by ring-barking and burning the dead trees and undergrowth, thereby fertilizing the soil with ash. By 7,000 years ago they had reached northern France, southern Belgium and the Netherlands.
Meanwhile the other group moved along the Mediterranean coast of Italy, southern France and Iberia. By 7,500 years ago they had reached the Atlantic coast of France. At each point along the way, in the forest and on the seashore, each group of farming pioneers encountered the earlier Mesolithic inhabitants, but there is no archaeological evidence that their interactions were anything but peaceful. Just as in Ireland, the highest density of Mesolithic hunter-gatherers was around the coast, rather than in the dense inland forests. In several places, particularly around the coast near Lisbon in Portugal, Neolithic farming communities lived fairly close to Mesolithic settlements and carbon-dating shows that both were occupied at much the same time. However, the newcomers chose sites a little way away from the estuaries favoured by the hunter-gatherers, instead setting up camp inland on higher ground between the main river valleys. As they were not competing for the same living space, this reduced the potential for conflict.
In Ireland the same process of peaceful co-existence seems to have accompanied the arrival of farming communities. There were thriving Mesolithic settlements all around the coast, some of which, like Sutton in County Dublin, had been occupied for long enough to accumulate enormous middens of discarded shells over 100 metres long. They certainly would not have thrown in the towel as soon as the first farmer paddled round the coast. At Ferriter’s Cove on the Dingle peninsula in County Kerry, the presence of polished stone axes – which, like pottery, are a reliable signal of the Neolithic – among the otherwise Mesolithic remains at this shoreline site, shows that the hunter-gatherers were in contact with farmers. Cattle bones at the site also show this interaction. So, in Ireland, just as elsewhere in Atlantic Europe, the transition to farming from hunter-gathering was gradual and piecemeal and did not necessarily involve sharp changes in the make-up of the Irish population.
These signals of the arrival of the Neolithic in Ireland are small and subtle, noticed only by the professional archaeologist. How different, then, from the gigantic stone structures that also appeared in Ireland 1,000 years later. These are the jewels of Irish archaeology, drawing tens of thousands of visitors each year to stand in awe and reflect on the grandeur, the construction and the purpose of these magnificent structures. The Oxford archaeologist Barry Cunliffe has studied megalithic structures in the Isles and also in Brittany and along the Atlantic coast of France and Iberia. Rather than a phenomenon solely linked to the Neolithic and the spread of farming, Cunliffe traces their origin to the shell middens of Mesolithic Portugal. Within the piles of shells accumulated over centuries on the banks of the River Sado, excavations have found human remains that have all the appearance of being deliberate ritual burials. The middens are enormous, some over 100 metres in diameter and several metres high, and within some of them over 100 burials have been discovered. Further north, on the southern coast of Brittany, later dated midden graves have been found lined with stone. In others, bodies were buried with personal ornaments such as drilled sea shells and stone pendants. Traces of red ochre show that, like the Red Lady of Paviland, the bo
dies were covered in this pigment, the purpose of which may perhaps have been to restore the flush of health to a lifeless corpse.
Barry Cunliffe sees a natural progression from these shell-midden graves to the two earliest styles of Neolithic monumental architecture: the long barrow, where soil has taken the place of shells, and the passage graves. And it is the passage graves of the Boyne valley in Ireland that visitors flock to see. Although there are over 230 passage graves in Ireland, it is the tombs at Knowth, Dowth and Newgrange that, deservedly, command the most attention. All three are roughly the same size, 85 metres in diameter and 11 metres high. These dimensions may be similar to the shell middens which provided the archetypal design, but the effort put into their construction was phenomenal. The stone-lined passage and the tomb that lies at its end involved the quarrying, transportation and setting in place of over fifty giant stone slabs, some weighing more than 5 tons. Once the tomb was in place, the whole structure was covered in the gigantic mound, which is made up of more than 200,000 tons of rocks and earth.
At Newgrange, the narrow passage which leads to the tomb itself is 25 metres long. It was aligned in such a way that the light of the rising sun at the midwinter solstice shone directly along the passage on to an intricately carved triple spiral motif on the opposite wall of the central tomb. The Knowth mound, about a kilometre to the north-west, contains not one but two passage graves, as does the Dowth mound to the east of Newgrange. Around these massive tombs are other smaller tombs and numerous standing stones. Carbon-dates of organic remains found buried within the mound date the construction of Newgrange at about 5,000 years ago, well after the dates for Ireland’s first unambiguously Neolithic site at Ballynagilly in Ulster.
It is only natural to imagine that these gigantic structures, and the complex and mysterious social rituals which their presence suggests, must have been brought about by a wave of new arrivals to Ireland. Yet the clear link to similar, even if not identical, structures along the entire Atlantic coastline, coupled with the early genesis of these structures in the middens of the Mesolithic, could equally well mean that these impressive megaliths are actually one step along the path of a continuous development of monumental architecture along the entire Atlantic fringe from Iberia to the Isles. That is definitely something to bear in mind when we contemplate the living archaeology of the genes.
Before we do that, let us pause to examine the archaeological evidence in Ireland of what nearly every popular account refers to as the arrival of the Celts. We have looked at the linguistic evidence elsewhere, but what is there to see among the material remains exposed by the trowels of the excavator? Even supposedly authoritative popular world histories describe ‘the Celts’ as loose mobile units of warriors, on the move and destroying all in their path. The main archaeological evidence comes from the beautifully fashioned and distinctive metalwork associated with, first, the Hallstadt and then the La Tène cultures of central Europe. Certainly these have been found in many parts of Europe, including Ireland. But to take this as proof of a large-scale movement of people into Ireland is surely, in the absence of other compelling evidence, even more of a risky assumption than that the spread of agriculture can only have been accomplished by wave after wave of Middle Eastern farmers.
The ‘Celtic’ artefacts that have passed the test of survival and discovery are, almost without exception, high-value goods that, like a Rolex watch or a Cartier necklace today, are at least as likely to be given as a gift as to be worn by the original owner. To find a La Tène brooch in an Irish bog is no proof that a central European put it there. And, like a fake Rolex, just because a piece of jewellery looks like the original, it doesn’t stop it being a copy. In fact, artefacts in the La Tène style are rare in Ireland. Many of them have been examined by the Irish archaeologist Barry Raftery, who is convinced that, far from being made in central Europe, they were actually manufactured in Ireland itself. We continually underestimate the skill and capabilities of our ancestors. Why should it come as a surprise that an Irish goldsmith could learn a new, fashionable continental style? It seems to me that the constant tendency to interpret past events in terms of movements is completely the wrong assumption. Surely the correct starting point is to assume that our ancestors were sufficiently resourceful and skilful to pick up virtually any skill. But to find out we need to look at the DNA.
9
THE DNA OF IRELAND
A good reason for choosing Ireland as the starting point of our genetic tour of the Isles is that, unlike in Britain, a concerted research programme into Irish cultural and genetic history has already been running for some years, organized through the auspices of the Royal Irish Academy based in Dublin. In Britain an even more ambitious millennium initiative came to nothing, which was one of the reasons why my research team and I decided to complete the survey of the entire Isles ourselves. You might be surprised, as I was when I first heard of the Academy, that it still retains the Royal prefix, but it is one of the institutions that has survived the 1921 partition of Ireland. It was founded in 1785 and soon became the premier learned society for the study of Irish civilization. It is in many respects the Irish equivalent of the elite academic societies in the rest of Britain, like the Royal Society and the British Academy in London and the Royal Society of Edinburgh and, also in Edinburgh, the Royal Scottish Academy. One of the enjoyable aspects of visiting these places is that they are almost always housed in grand Georgian terraces. It is always a treat for the eyes to attend meetings in such sumptuous surroundings, with the olympians of academe, Newton, Darwin and co., peering down from their portraits high up on the walls.
Unlike its British counterparts, the Irish Academy is not restricted to particular fields of endeavour. While in England, for example, the Royal Society deals with the sciences and the British Academy covers the humanities: literature, history, philosophy and so on, the Royal Irish Academy does not restrict itself, embracing both the sciences and the arts under one roof. This breadth made the Academy the natural home of a comprehensive survey of Ireland which would integrate all the diverse strands of science, history, language and archaeology. This irresistible combination, together with some fundraising, led to a substantial amount of money being made available to the Academy from the National Millennium Committee of Ireland. Invitations to bid for money from the fund went out to all the Irish universities and I found myself on a plane to Dublin to help to judge the applications.
In the elegant surroundings of the Academy’s headquarters in Dawson Street, the hopefuls presented their proposals in the form of short talks. Naturally enough, when a new pot of money unexpectedly becomes available, people build their bids around their existing expertise. The aim is to persuade the judges that what they are already doing will, with a bit more money, produce an essential and indispensable contribution to the project. Our job, as judges, was to weigh up these diverse claims and to recommend where we thought the money would best be spent. You’ll not be surprised to hear that I didn’t need much persuading that a survey of mitochondrial and Y-chromosome DNA would be not only relevant but completely essential.
Fortunately, all the other judges felt the same way. Which is how Dan Bradley and his team from Trinity College Dublin got the green light – and the funds – to take charge of that central aspect of the project. Dan had pioneered the use of DNA to find out how and when farm animals, in particular cattle, had been domesticated. We had worked together a little on this when Jill Bailey, one of the research students in my team, had been working on retrieving DNA from the bones of the extinct ancestor of domesticated cattle, the fearsome aurochs. After getting her degree at Oxford, Jill had spent a year in Dan’s lab in Dublin and I had been over a couple of times to give talks and be an examiner for Dan’s graduate students. All of which is entirely irrelevant, except that it meant that a highly experienced and competent geneticist, whom I knew and liked, would be covering the same genetic ground in Ireland as I was already starting to do in the rest of the Isles. Wh
ich in turn meant that I could concentrate on Scotland, Wales and England, knowing that Dan’s lab would produce compatible genetic data from Ireland that could be integrated with the results of our Irish customers at Oxford Ancestors and, eventually, all the data from the rest of the Isles. Which is precisely what did happen and it is from this grand coalition of data that we begin our tour.