Ireland's Population Was in Serious Decline Before the Vikings

[Grace O'Malley]

Abstract
Using archaeological data, this paper investigates past population trends in Ireland as a response to recent genomic studies that have identified admixture signals in the genomes of Irish people caused by historically-recorded migration events. Among these was Norse settlement in the 9th-10th Centuries CE, which has a greater than expected signal in the contemporary population of the island. Here, we contextualise these discoveries using a large database of recently discovered archaeological sites with radiocarbon dates that we have analysed using Kernel Density Estimation techniques. We argue that the Viking migrations occurred following a 300-year period of population decrease in Ireland. This new, data-driven synthesis of the archaeological record contrasts with previous accounts of early medieval Ireland as a period of ever-growing expansion and progression. However, this new interpretation is also aligned to evidence for economic and environmental change, including recent discoveries concerning the soil nitrogen cycle and agricultural intensification. We compare historical evidence for Viking migrations to later episodes of migration between Britain and Ireland, where more details are known about the size of the incoming groups, ultimately wishing to confront the opinion that past population sizes cannot be fathomed for cultures without documentary records. Through comparison with historic analyses and census records, we make broad estimates of absolute population size in Ireland since prehistoric times, including during these demographic events, and argue that much value is added to genomic evidence for migration when these points in time are contextualised in terms of evolving population trends.

https://www.sciencedirect.com/scienc...05440318304977

Dr Rowan McLaughlin said Ireland's population appears to have gone into an unexplained decline around 700AD.

"Millions of people lived in Ireland during prehistory and the earliest Christian times," he said. "Around the year 700, this population in Ireland mysteriously entered a decline, perhaps because of war, famine, plague or political unrest. However, there was no single cause or one-off event, as the decline was a gradual process.”

He added: "The Vikings settled in Ireland in the 10th century, during the phase of decline and despite being few in number, they were more successful than the 'natives' in expanding their population. Today, genetic evidence suggests many Irish people have some Viking blood.

https://www.independent.ie/au/irish-...-38425449.html

[Peterski]

I strongly doubt that.

A recent study with ancient (Pre-Viking) Norwegian samples indicates that there is actually more of British-Irish admixture in modern Norway, than the other way around (than of Norwegian admixture in Britain-Ireland):

https://anthrogenica.com/showthread....276#post583276

https://anthrogenica.com/showthread....549#post585549

https://anthrogenica.com/showthread....334#post583334

Quote from the study:

"Present-day Norwegians vary between 12% and 25% in their ‘British-like’ ancestry."

This is based on comparing Pre-Viking Norwegians (who still did not have such admixture!) to modern Norwegians (who have it).

On the other hand, the Irish have probably 5-10% Viking admixture (various studies estimated 5-20%, but the highest figure of 20% was based on a model assuming that modern Norwegians are 0% British and therefore any similarity to Norwegians detected in Irish people must be due to Viking admixture in Ireland, not British-Irish admixture in Norway - an assumption that has been proven wrong thanks to ancient DNA samples from Norway).

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Results which show that Norwegians have more Irish admixture than the other way around seem counter-intuitive at first but they are actually very easy to explain - Viking Age Norway had very few people, still much fewer than Ireland, even if Ireland had experienced a demohraphic decline shortly before that.

1000 Irish moving to Norway would make a greater impact on Norway's autosomal gene pool, than even 2000 Norwegians moving to Ireland - simply because Ireland had few times more inhabitants.

[Grace O'Malley]

I strongly doubt that.

A recent study with ancient (Pre-Viking) Norwegian samples indicates that there is actually more of British-Irish admixture in modern Norway, than the other way around (than of Norwegian admixture in Britain-Ireland):

https://anthrogenica.com/showthread....276#post583276

https://anthrogenica.com/showthread....549#post585549

https://anthrogenica.com/showthread....334#post583334

Quote from the study:

"Present-day Norwegians vary between 12% and 25% in their ‘British-like’ ancestry."

This is based on comparing Pre-Viking Norwegians (who still did not have such admixture!) to modern Norwegians (who have it).

On the other hand, the Irish have probably 5-10% Viking admixture (various studies estimated 5-20%, but the highest figure of 20% was based on a model that modern Norwegians are 0% British and therefore any similarity to Norwegians detected in Irish people must be due to Viking admixture in Ireland, not British-Irish admixture in Norway - an assumption that has been proven wrong thanks to ancient DNA samples from Norway).

They need pre-Viking Irish to study against Viking genomes. I hope that will be covered in Lara Cassidy's paper next year and of course how much Celtic admixture in Ireland. Here's hoping.

It is interesting that the population had declined steadily over 3 centuries and there's no reason to believe Norwegians have "British-like" ancestry if the Irish and Brits don't have "Norse-like" ancestry. They are obviously genetically close but you need to have an open mind on these subjects. Either way it's great that all this information is coming out.

Anyway you're proposing this unknown Irish migration to Scandinavia. It doesn't make sense that thralls would have such an effect on the population to me. They usually have less productive success than the victors.

[Peterski]

I think Late Bronze Age Scottish samples (which are already available) are a good proxy for Pre-Viking Irish. But yeah, I agree.

[Grace O'Malley]

I think Late Bronze Age Scottish samples (which are already available) are a good proxy for Pre-Viking Irish. But yeah, I agree.

Looking at Bronze Age genomes from Ireland/Britain shows they were very northern. Logic tells me that they have a lot of similarity from this. I'm sure the picture will be clearer in a few years. I just wish some of these studies would be released sooner than later.

[Peterski]

Looking at Bronze Age genomes from Ireland/Britain shows they were very northern.

It depends, the Bronze Age was a very long time period, and there were some genetic changes in Britain during the Bronze Age.

Late Bronze Age samples are less northern - with more of Neolithic Farmer ancestry - than Early Bronze Age samples.

This means that either there was another wave of migration from the continent, or pockets of surviving Neolithic Britons mixed back in and were assimilated which caused a small resurgence of Stonehenge-era ancestry (just like there had been a small resurgence of WHG ancestry in Middle Neolithic Europe before that).

and there's no reason to believe Norwegians have "British-like" ancestry

Norwegians have a lot of R1b-L21 haplogrup which is a marker that most likely emerged in Britain during Bell Beaker times.

There are no any ancient R1b-L21 samples from Scandinavia, so all L21 in Scandinavia is probably the result of immigration into Scandinavia from elsewhere after the end of the Bell Beaker Era.

The first man with L21 mutation was probably born in Britain and all of the oldest L21 samples known to date are from British Beakers.

Even if the first L21 man was born on the continent, it had to be somewhere around Belgium or Northern France - surely not in Scandinavia.

[Grace O'Malley]

It depends, the Bronze Age was a very long time period, and there were some genetic changes in Britain during the Bronze Age.

Late Bronze Age samples are less northern - with more of Neolithic Farmer ancestry - than Early Bronze Age samples.

This means that either there was another wave of migration from the continent, or pockets of surviving Neolithic Britons mixed back in and were assimilated which caused a small resurgence of Stonehenge-era ancestry (just like there had been a small resurgence of WHG ancestry in Middle Neolithic Europe before that).



Norwegians have a lot of R1b-L21 haplogrup which is a marker that most likely emerged in Britain during Bell Beaker times.

There are no any ancient R1b-L21 samples from Scandinavia, so all L21 in Scandinavia is probably the result of immigration into Scandinavia from elsewhere after the end of the Bell Beaker Era.

The first man with L21 mutation was probably born in Britain and all of the oldest L21 samples known to date are from British Beakers.

Even if the first L21 man was born on the continent, it had to be somewhere around Belgium or Northern France - surely not in Scandinavia.

L21 was definitely not born in Britain and it is more eastern than Belgium or Northern France. It's of course Bell Beaker and most likely originated more in Central Europe but that's something that more ancient genomes will clear up. They still haven't found where L51 came from yet.

[Peterski]

Anyway you're proposing this unknown Irish migration to Scandinavia. It doesn't make sense that thralls would have such an effect on the population to me. They usually have less productive success than the victors.

Many of them were not Irish thralls but Orkney Vikings and Western Isles Vikings and Norse-Gaels etc. moving back to Scandinavia.

And those Vikings were only culturally Norse.

Most of Orkney Islanders are autosomally British with only minor Norse ancestry, but culturally and linguistically they are Norse. And if such people moved back to Scandinavia, this explains why they spread this admixture.

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BTW, I disagree, in America slaves had a lot of reproductive success - plantation owners even encouraged their slaves to have many children because breeding new slaves is obviously much cheaper than buying new ones from other plantation owners or importing all the way from Africa.

Of course after Christianization and the end of the Viking Age thralls were eventually incorporated into the general society as regular commoners and mixed into the general gene pool - this never happened in the USA so far because Blacks look so different that they couldn't blend in.

But it did happen in places like Brazil.

L21 was definitely not born in Britain and it is more eastern than Belgium or Northern France. It's of course Bell Beaker and most likely originated more in Central Europe but that's something that more ancient genomes will clear up. They still haven't found where L51 came from yet.

I'm not talking about L51, but about L21.

All of the oldest L21 samples are British:

Sample ID, place of burial, dating:

I2457, Amesbury, England, 2480–2031 BC
I2565, Amesbury, England, 2470-2140 BC
I2447, Yarnton, England, 2400–2040 BC
I2453, West Deeping, England, 2289–2041 BC
I2568, Dryburn Bridge, Scotland, 2287–2039 BC
I3256, Cambridge, England, 2204–2029 BC

Y-Full estimates the TMRCA of L21 as 2500-2300 BC:

https://www.yfull.com/tree/R-L21/

This means that the ancestor of all living men with L21 could be born already on the island of Great Britain, rather than being a first-generation immigrant.

First Beakers who moved into Britain (born on the continent, but died in Britain) were probably S461 - directly ancestral to L21:

https://www.yfull.com/tree/R-S461/

[Grace O'Malley]

Many of them were not Irish thralls but Orkney Vikings and Western Isles Vikings and Norse-Gaels etc. moving back to Scandinavia.

And those Vikings were only culturally Norse.

Most of Orkney Islanders are autosomally British with only minor Norse ancestry, but culturally and linguistically they are Norse. And if such people moved back to Scandinavia, this explains why they spread this admixture.

=====

BTW, I disagree, in America slaves had a lot of reproductive success - plantation owners even encouraged their slaves to have many children because breeding new slaves is obviously much cheaper than buying new ones from other plantation owners or importing all the way from Africa.

Of course after Christianization and the end of the Viking Age thralls were eventually incorporated into the general society as regular commoners and mixed into the general gene pool - this never happened in the USA so far because Blacks look so different that they couldn't blend in.



I'm not talking about L51, but about L21.

All of the oldest L21 samples are British:

Sample ID, place of burial, dating:

I2457, Amesbury, England, 2480–2031 BC
I2565, Amesbury, England, 2470-2140 BC
I2447, Yarnton, England, 2400–2040 BC
I2453, West Deeping, England, 2289–2041 BC
I2568, Dryburn Bridge, Scotland, 2287–2039 BC
I3256, Cambridge, England, 2204–2029 BC

Y-Full estimates the TMRCA of L21 as 2500-2300 BC:

https://www.yfull.com/tree/R-L21/

This means that the ancestor of all living men with L21 could be born already on the island of Great Britain, rather than being a first-generation immigrant.

First Beakers who moved into Britain (born on the continent, but died in Britain) were probably S461 - directly ancestral to L21:

https://www.yfull.com/tree/R-S461/

L21 is in too many other parts of Europe. They haven't got enough ancient genomes yet but I'll bet you L21 didn't originate in Britain.

You can't mix up American slavery with what happened with the Vikings. They are very different. The Viking study looked at some Viking genomes in Orkney but that wasn't all of them. I wouldn't jump to conclusions too quickly. Look at what happened in Iceland with Gaelic ancestry decreasing from the original population? You agreed they need more ancient genomes and you need these from all periods to compare. You are saying that because the Orkney genomes are more British Isles that is why there is British/Irish admixture in Norway but in Ireland the Vikings were Norse and you don't make that conclusion about Ireland. I think you need to wait for more comprehensive studies before drawing too many strong conclusions.

These are the graphics from the Viking study.

[Peterski]

These are the graphics from the Viking study.

These heatmaps show autosomal data for Viking Age DNA samples (represented by black dots), not for modern populations.

L21 is in too many other parts of Europe.

But at very low frequency. People move around, just because there is some L21 in Romania, doesn't mean it isn't originally British.

Look at what happened in Iceland with Gaelic ancestry decreasing from the original population?

The sample size was low (so could be not representative), and also Gaelic ancestry could be dilluted by new Norse immigrants.

You are saying that because the Orkney genomes are more British Isles that is why there is British/Irish admixture in Norway

I'm saying that most of British-Irish admixture in Norway is probably from Scotland and a smaller part of it is from Ireland.