Study: Ancient Icelanders mix of Celtic and Norse ancestry

[Peterski]

Links:

http://science.sciencemag.org/content/360/6392/1028

http://science.sciencemag.org/conten...080.1527866256

http://science.sciencemag.org/conten...sdottir-SM.pdf

"Abstract:
Opportunities to directly study the founding of a human population and its subsequent evolutionary history are rare. Using genome sequence data from 27 ancient Icelanders, we demonstrate that they are a combination of Norse, Gaelic [Celtic], and admixed individuals. We further show that these ancient Icelanders are markedly more similar to their source populations in Scandinavia and the British-Irish Isles than to contemporary Icelanders, who have been shaped by 1100 years of extensive genetic drift. Finally, we report evidence of unequal contributions from the ancient founders to the contemporary Icelandic gene pool. These results provide detailed insights into the making of a human population that has proven extraordinarily useful for the discovery of genotype-phenotype associations."

Proportions of Insular Celtic/Gaelic and Norse ancestry in each individual:



Distribution of early settlers according to their ethnic origins:



PCA graph with ancient Icelanders:



Y-DNA haplogroup predictions:

[Peterski]

Here is a GEDmatch kit of a native from Iceland: T661186

There are Celtic toponyms in Iceland - do you think they predate Viking colonization or date back to the same period? When Pytheas of Massalia visited Scotland around 330 BC, its inhabitants (Picts or other Celts) informed him about a land in the north, that he later called Thule. That was most probably Iceland, implying that Celts had discovered Iceland long before Vikings (if Thule was Iceland).

In 56 BC Roman fleet of Julius Caesar fought a naval battle against Celtic fleet near the southern coast of what later became Bretagne (in 56 BC that part of Bretagne was inhabited by a tribe known as the Weneted). In his "Gallic Wars", Caesar left a unique description of Celtic ships:

http://www.sacred-texts.com/cla/jcsr/dbg3.htm

"(...) For their ships were built and equipped after this manner. The keels were somewhat flatter than those of our ships, whereby they could more easily encounter the shallows and the ebbing of the tide: the prows were raised very high, and, in like manner the sterns were adapted to the force of the waves and storms [which they were formed to sustain]. The ships were built wholly of oak, and designed to endure any force and violence whatever; the benches which were made of planks a foot in breadth, were fastened by iron spikes of the thickness of a man's thumb; the anchors were secured fast by iron chains instead of cables, and for sails they used skins and thin dressed leather. These [were used] either through their want of canvas and their ignorance of its application, or for this reason, which is more probable, that they thought that such storms of the ocean, and such violent gales of wind could not be resisted by sails, nor ships of such great burden be conveniently enough managed by them. The encounter of our fleet with these ships' was of such a nature that our fleet excelled in speed alone, and the plying of the oars; other things, considering the nature of the place [and] the violence of the storms, were more suitable and better adapted on their side; for neither could our ships injure theirs with their beaks (so great was their strength), nor on account of their height was a weapon easily cast up to them; and for the same reason they were less readily locked in by rocks. To this was added, that whenever a storm began to rage and they ran before the wind, they both could weather the storm more easily and heave to securely in the shallows, and when left by the tide feared nothing from rocks and shelves: the risk of all which things was much to be dreaded by our ships. (...)"

This description shows that Ancient Celts were good seafarers and that their ships were well-adapted to conditions in northern seas. The naval battle in 56 BC took place in the Quiberon Bay, between 100 Roman galleys and 220 Celtic ships:

http://en.wikipedia.org/wiki/Quiberon_Bay

Rome won that one thanks to using a clever fighting technique and exploiting weak points of the enemy:

"(...) The bay has seen several important naval battles. The first recorded in history was the Battle of Morbihan in 56 BCE, between the Romans led by Decimus Junius Brutus Albinus and the local Veneti [Weneted] tribe. The Romans had struggled to overcome the Veneti, who had coastal fortresses that could easily be evacuated by their powerful navy. Eventually the Romans built galleys and met the Veneti sailing fleet in Quiberon Bay. Despite being outnumbered 220 to 100 by a fleet of heavier ships, the Romans used hooks on long poles to shred the halyards holding up the leather sails of the Veneti, leaving the Veneti fleet dead in the water (...)"

Plutarch (ca. 40 - 120 AD) wrote also about another island located far to the west of Britain, bearing a name similar to the name of titan Kronos from Greek mythology. The Sea of Kronos is how later waters between Iceland and Greenland were referred too. So that could be Greenland (Greenland is of course a name invented much later, probably by Eric the Red, to attract settlers).

Sagas (including the Saga of Eric the Red) mention the land of "Hvitramannaland" ("White Man's Land", Latin: "Albania") also known as "Írland it Mikla" ("Great Ireland", Latin: "Hibernia Maior") - located supposedly about six-day sail west from Ireland, and also not far away from Vínland (Vineland). Unless it was fictional, it could refer to some Celtic settlement existing in - perhaps - Greenland.

In year 825, an Irish monk named Dicuil wrote "Liber de Mensura Orbis Terrae", in which we can find a detailed description of the Faroe Islands, and a claim that hermit monks from Ireland had lived in those islands for 100 years before the "Northmen pirates" took them. He also describes the island of Thule (Iceland), beyond the Faroes, and writes that Irish hermit monks had been staying on Thule during the summer months for 30 years (since around 795 - about one century before first Vikings settled in Iceland). But were there also settlers, or just monks? And if just monks, then why?

The "Book of Settlements" (one of most important sources for early history of Iceland, alongside the "Book of Icelanders") claims that first Viking settlers in Iceland found traces of an earlier people, a Christian one, such as bells and crooks. Perhaps those were remains of hermitages of Irish monks.

"The Voyage of Saint Brendan the Navigator", a story first recorded around year 900 AD, indicates that certain Brendan (born in 484 AD in Kerry county, Ireland) reached Iceland, Greenland, the island of Jan Mayen in the Arctic Ocean, and maybe even the coast of America.

The Voyage of Saint Brendan is unique because it was recorded in 900 AD, before Viking travels to America took place. But there are more legends about Celtic travellers reaching America, such as this Welsh story about Madog ab Owain Gwynedd, who supposedly came to America in 1170:

http://en.wikipedia.org/wiki/Madoc

It is claimed that after 400 AD, when climate in the region started to gradually get warmer, Pictish and other Celtic sailors regularly visited Iceland, gathering exotic resources such as eiderdown, and exporting them to the Mediterranean world. For sea travels Picts and Britons were using wooden ships, while Irish people were using currachs, covered by bovine skins. Such ships could transport up to 20 people, they were propelled by sails and oars.

"People of the West" (Vestmenn), as they were later called by Norsemen, probably visited Iceland already before 400 AD - findings of coins from that period may indicate this. On the other hand, coins produced long before 400 AD could get there long after that date too.

But a more controversial issue is whether Celts actually established some settlements there or not (apart from some hermitages of monks). Farley Mowat in one of his books claimed that Eric the Red found an Irish house in Greenland.

Celts contributed with some advancements in shipbuilding techniques in Northern Europe (check for example Ellmers, "Celtic plank boats and ships 500 BC - AD 1000" and Casson, "Ships and seamanship in the ancient world").

A small archipelago of Vestmannaeyjar (near Iceland) is named so after Insular Celts, but the origins of this name are unclear. One theory is that it is relatively recent and comes from Celtic slaves who escaped from Viking captivity and settled there. So this is probably not a sign of Celtic settlement predating Viking settlement. There are some other Celtic toponyms in Iceland as well (for example Írafell, Írafellsbunga, Kjaransvík, etc.).

[Wrong]

No R1b in Norse?

[Peterski]

No R1b in Norse?

I don't know. You can check what admixture proportions did individuals with R1b have.

Some of R1b in Iceland is surely Celtic. There is a lot of typically Irish R1b-L21 there.

[Aren]

"Sequencing revealed that the settlers had a roughly even split of Norse (from what are today Norway and Sweden) and Gaelic (from what are now Ireland and Scotland) ancestry. But when the researchers compared the ancient genomes to those of thousands of modern people in Iceland and other European countries, they found that contemporary Icelanders, on average, draw about 70% of their genes from Norse ancestry. That suggests in the approximately 1100 years between Iceland’s settlement and today, the population has undergone a surprisingly quick genetic shift, the researchers report today in Science."

Icelandic population has obviously as they have stated gone through some extreme drifts and bottlenecking. The ancient Icelandic samples were not complete ancestors of modern day Icelanders who seem to be pred. Norse. They also mentioned a more recent Scandinavian input, particularly Danish in Iceland.

[Aren]

Also what are they using as a proxy for Gaelic heritage? Modern day Irish/Scots? That can't be entirely accurate...

[Peterski]

The ancient Icelandic samples were not complete ancestors of modern day Icelanders who seem to be pred. Norse. They also mentioned a more recent Scandinavian input, particularly Danish in Iceland.

LOL, JaM claimed the opposite - that modern day Icelanders are more Celtic than ancient ones due to genetic drift after the Black Death (which decimated the population of Iceland). They are not predominantly Norse, they are almost 1/2 Celtic autosomally (I showed you before that they plot almost in the middle between Norway and Ireland), more in terms of mtDNA and less in terms of Y-DNA.

Estimated Scandinavian and British-Irish ancestry in terms of haplogroups:

[Aren]

LOL, JaM claimed the opposite - that modern day Icelanders are more Celtic than ancient ones due to genetic drift after the Black Death (which decimated the population of Iceland). They are not predominantly Norse, they are almost 1/2 Celtic autosomally (I showed you before that they plot almost in the middle between Norway and Ireland), more in terms of mtDNA and less in terms of Y-DNA.

Estimated Scandinavian and British-Irish ancestry in terms of haplogroups:

That's haplgroups though, the small Icelandic population has probably gone through some extensive bottlenecking throughout history.
From the study itself:

"Sequencing revealed that the settlers had a roughly even split of Norse (from what are today Norway and Sweden) and Gaelic (from what are now Ireland and Scotland) ancestry. But when the researchers compared the ancient genomes to those of thousands of modern people in Iceland and other European countries, they found that contemporary Icelanders, on average, draw about 70% of their genes from Norse ancestry. That suggests in the approximately 1100 years between Iceland’s settlement and today, the population has undergone a surprisingly quick genetic shift, the researchers report today in Science."

And that's with probably using modern day Irish and Scots who have a decent amount of Norse input themself, as a proxy for 9th-10th century Gaelic admix.

[Peterski]

That's haplgroups though, the small Icelandic population has probably gone through some extensive bottlenecking throughout history.

So why are modern frequencies of Y-DNA haplogroups very similar to frequencies in this sample of 27 ancient Icelanders? Modern Icelanders are a mix of mostly R1b (including Celtic subclades), I1 and R1a. Just like these ancient samples, no difference, so bottlenecking did not change ancestry proportions.

And that's with probably using modern day Irish and Scots who have a decent amount of Norse input themself, as a proxy for 9th-10th century Gaelic admix.

Modern day Norwegians also have Celtic ancestry, both from the Viking Age and from later immigrants. After the Viking Age - and especially after the Black Death - Norway welcomed thousands of foreign immigrants including Scots (and other British people), Danes, Germans (including South Germans and East Germans), Swedes, Finns, Dutch, Romani, Russians, Jews, Faroese, Icelanders, Basques, Italians and Belgians. A whole lot of surnames in modern Norway are of Non-Norse origin. This includes many German surnames.

[Aren]

So why are modern frequencies of Y-DNA haplogroups very similar to frequencies in this sample of 27 ancient Icelanders? Modern Icelanders are a mix of mostly R1b (including Celtic subclades), I1 and R1a. Just like these ancient samples.

But the autosomal DNA of modern Icelanders doesn't match that of the 27 ancient samples. The study itself is pointing out that modern day Icelanders are 70% Norse autosomally.