Scotland's DNA: Who do you think you are? - Part 4

Our series on the DNA make-up of Scots looks at how the Vikings left an indelible mark on this country and in particular Orkney, where around 20 per cent of all Orcadian men carry the bloodthirsty raiders' M17 marker

HIDDEN snug beneath oiled sheep- and goatskins, or tucked into tiny corners under gear, or nibbling at parcels of food, mice began sailing to Scotland in the 9th century. They came from Norway, mostly, and settled in Orkney, where their descendants still thrive. The mice brought other creatures with them who were neither tim'rous nor cow'rin, but they were certainly beasties. The mice sailed the North Sea with the Vikings.

DNA researchers conducted a series of tests on house mice in Orkney and discovered that their genetic make-up was quite different from mice on the Scottish mainland, even though they had been on the islands for about 1,000 years. But when they compared it with that of mice in Norway, they found it was an exact match. The only possible explanation was that mice had stowed away on Viking longships and when these ferocious warriors rasped up their keels on Orcadian beaches to attack terrified communities, their little passengers quietly scuttled through the rocks and seaweed to settle and multiply.

As with mice, so it was with men. The Viking attacks began in AD793 with the surprise assault on the Holy Island of Lindisfarne. Even across 12 centuries the shock is palpable. These pagan sea-raiders seemed to sail out of nowhere and attack without hesitation some of the most sacred places in the north. The footsteps of Columba and Cuthbert were spattered with blood as monks and nuns were tortured, killed and raped, and their churches echoed not with prayer and plainsong but with the screams of the dying as they were ransacked for gold, silver and other valuables. Iona was desecrated repeatedly.

An account of what happened in AD825 was written by Walafrid Strabo, Abbot of Reichenau in southern Germany. Like many raiders wishing to use the element of surprise, the Vikings attacked the monastery on Iona at first light and broke into the abbey where St Blathmac and his followers lay prostrate in prayer. In what must have been a terrible orgy of ferocity, they were all slaughtered before the altar except for their leader. Demanding to know where the monks had buried Columba's reliquary and other precious objects, the Vikings began to torture Blathmac. Using ponies they took ropes attached to their harness and tied the ends to his arms and legs, and when he continued to refuse to give up the holy relics, Walafrid wrote that the pious sacrifice was torn limb from limb.

The appalling fate of Blathmac was by no means unique. Among recorded atrocities – and there must have many that were not – the pagan ritual of blood-eagling was horrific. As a sacrifice to the war god, Odin, victims were tied face-first to a post or pillar before a Viking marked the blood-eagle on his back. In AD869 King Edmund of East Anglia suffered this dreadful death when his ribs were hacked from his spine and pulled outwards like an eagle's wings. Then his lungs were wrenched out and draped over his shoulders. On Orkney the Viking Earl Turf Einarr ordered the same ritual in the 870s. It is no wonder the monks called the Vikings the Sons of Death.

In the light of such sustained and well-documented barbarity it is perhaps surprising that many Scottish men hanker after a Viking legacy. Before having their DNA tested, they often express a wish to be the descendants of these bloodthirsty raiders and many are disappointed when another result is conveyed. But there is a significant group who glory in the DNA of the Vikings, and while there was much to abhor, it is fair to say that there was also much to admire. Great seamen and daring, they sailed in open longships to discover Iceland, Greenland, (eventually making landfall in North America), they founded the embryonic Russian state of Kievan Rus, composed epic sagas of verve and colour, and inspired the cartoon character Noggin the Nog – although his mild manners must have been an exception.

Recent DNA research has shown a very significant Viking inheritance in Orkney. Around 20 per cent of all Orcadian men carry the M17 marker, the classic signature of Viking settlement. If the statistics are narrowed to cover only men with ancient Orcadian surnames like Linklater, Foubister, Clouston, Flett or Rendall, the percentage of M17 rockets to 75 per cent.

M17 is also present in the Western Isles in large numbers. Clan names are a visible relic; MacIvors were originally the sons of Ivar, MacSween, the sons of Swein, Macaulay, the sons of Olaf, MacAskill, the sons of Asgeir and so on. Clan MacLeod is a fascinating case study. From a sample of the DNA of 45 Macleod Y chromosomes almost half, 47 per cent, clearly show social selection at work in that they descend from one individual. If this statistic is projected amongst the total number of MacLeods, it means that almost 10,000 men alive today are descended from this man. Among the remaining 53 per cent, researchers have found only nine other lineages present, showing that MacLeod men married women who were unfailingly faithful to them.

Nevertheless, the MacLeods do not carry the M17 marker group. Theirs is a recently discovered sub-group labelled S68. It is found in Lewis, Harris and Skye, core Macleod territory, but also in Orkney, Shetland and Norway, with a few examples in Sweden. Despite extensive screening, S68 is very specifically located, showing up only once in the east of Scotland and once in England. This is a classic pattern for a Viking marker in Britain, but one much rarer than M17. MacLeods determinedly claim descent from a common name father, a Norse aristocrat called Ljot, a relative of Olaf, King of Man. They are probably right to continue to claim that – science for once supporting tradition.

Despite striking examples of extreme violence, the Vikings were often anxious to keep their captives alive. At Dublin they set up a great slave market and many poor souls were sold on to the agents of wealthy individuals. Some were taken as far south as the Mediterranean and the developing Muslim states of Spain and North Africa where fair-skinned thralls or slaves commanded a premium. The discovery of both the pan-British Isles DNA marker of S145 and the Irish and Scottish-specific M222 in coastal Norway has suggested a remnant legacy of slaves shipped back to the Viking homeland. Even very small numbers of M284, one of the founding lineages in Scotland, have been detected. Although many Scots visited and even settled for long periods in Norway, from the later middle ages onwards, it is quite possible that some of these S145 and M222 descendants are, in fact, the children of slaves. The British-specific mtDNA or female group of J1b1 has also been found in coastal Norway, and it almost certainly represents another survival of slaving.

There is a fourth distinctly Irish subtype of the great S145 marker but, like the Pictish subgroup, it has yet to be identified with a single, slowly evolving marker. Instead geneticists rely on a particular signature of more quickly evolving markers to identify members of this group. It is concentrated in Munster, and particularly in counties Cork and Kerry. It is very rare in Scotland and has only been found in the Northern and Western Isles. This suggests that it is unlikely to have spread outwards from Dalriada – as M222 appears to have done. Rather it looks as it was taken directly from South-west Ireland to north and west Scotland. A likely explanation would be that these lineages represent the descendants of Irish slaves taken north by the Vikings. This is supported by the fact that the major genetic lineage of the surname of Macaulay, the sons of Olaf, belongs to the group. It seems that some slaves contributed to the ancestral gene pool of the peripheral regions of Scotland.

One of the most fascinating mixes of DNA in Scotland can be seen in the most southerly part of the country. The territory of Greater Galloway stretched east to Annandale and north to include Carrick and it may be seen as a palimpsest of our linguistic and cultural history, a mirror to what happened in perhaps more familiar parts of the country. The most westerly peninsula, the Rhinns of Galloway, lies close to Ireland and at the same time as Dalriada was emerging in Argyll and the south-western Hebrides, Gaelic was certainly also spoken there. The ancient kingdom of Rheged understood itself in Old Welsh and it had royal centres near Stranraer, Kirkcudbright and probably at Carlisle. When it faded and died at the end of the 6th century, the English-speaking Bernicians pushed westwards to establish an episcopal see at Whithorn and colonise fertile costal areas.

Even Pictish became part of the mix – by mistake. The Bernicians may have believed the Gaelic speakers of Galloway to have been Picts because the first two bishops at Whithorn took symbolic names. Peohthelm means "Leader of the Picts" and Peohtwine "Friend of the Picts".

In the late 9th and early 10th century the kaleidoscope was twisted once more when some of the Celto-Norse peoples of the Hebrides migrated south. Because they spoke Gaelic but were descended from Vikings, they became known as the Gall-Gaidheil and they gave their name to Galloway.

It means the Land of the Stranger-Gaels. For six centuries at least, dialects of Old Welsh, Gaelic and English were spoken by substantial communities who lived alongside each other.

Multiculturalism may not be fashionable in certain quarters nowadays but it has a long history in Scotland. A very early linguistic mix like this is usually reflected in DNA, and when more testing is completed in Galloway, a rich and complex picture is likely to emerge.

Perhaps the most attractive achievement of the Viking settlers and their descendants was the great medieval Atlantic principality of the west, the Lordship of the Isles. It was essentially the creation of Somerled, also the founder of Clan Donald and the progenitor of its major name-fathers. There is accurate data available from a large sample, from 164 MacDonald Y chromosomes, and they contain a fascinating twist on tradition.

Somerled was known to chroniclers as Somerled the Viking and it turns out that the large number in the sample descended directly from him, 23 per cent, carry a specific signature type within the Norse subgroup of M17.

Somerled's own ancestors did indeed originate in Scandinavia. And the tradition lives on, for Clan Donald have genotyped the chiefs of their various clan branches and they all carry the old Vikings' marker.

It seems in the north, west and south of Scotland the legacy of the sea-raiders carries on. Most of the significant in-migrations to Scotland had taken place by the years around AD1000, but in the later 19th and the 20th century, the age of mass transport, more peoples came to enrich our collective DNA.

• The Scots: A Genetic Journey by Alistair Moffat and Dr Jim Wilson is available now. Readers of The Scotsman and Scotland on Sunday can buy copies of the book at the special price of 12.75 (p&p free in the UK) by calling 0845 370 0067 and quoting reference SMAN211.