Luck of the Vikings: Their Arrival Reversed Ireland's Decline, Say Archaeologists

Study debunks notion that Ireland had been populous when the Nordic migrants arrived in the 10th century: The island had been in decline for 200 years by then

Members of the Viking Jarl Squad pose for pictures with a Viking Galley ship on the morning of the annual Up Helly Aa Festival, in Lerwick, Shetland Islands, on January 26, 2010.
CARL DE SOUZA / AFP

Medieval Ireland's population had been shrinking for 300 years by the time the Vikings arrived in the 10th century C.E., a new study published in the Journal of Archaeological Science contends. The conclusion contradicts the widespread assumption that the island had been in a state of growing expansion and progression ahead of the Vikings' arrival.

The research, led by Rowan McLaughlin at Queen’s University Belfast, began from census records, genetic analyses of the Irish and the historic record – including the Norse settlement of the island in the 9th and 10th centuries C.E. It sought archaeological data to back the findings. To this day, as previous studies have found, the Irish have a small component of Viking ancestry.

The only specimen of a whole Viking-era iron helmet ever found, from Gjermundbu, Norway.
NTNU Vitenskapsmuseet

It bears adding that our understanding of past population levels is vague: The long-term history of human population is largely guesswork, as historic records only cover recent centuries, as the writers explain. There is always a question about the reliability of historic records, too.

Until recently, the thinking had been that Ireland continued to flourish, with its population gradually increasing, as unchecked populations do. But it was not so, according to estimates based on archaeology.

Today the Republic of Ireland has about 4.8 million people; North Ireland has about 1.9 million people. During prehistory and early recorded history, the temperate island also housed millions of people, says Dr Rowan McLaughlin.

Members of the Jarl Squad dressed in Viking costumes marching through the streets through in Lerwick on the Shetland Isles, Scotland, during the Up Helly Aa Viking Festival, January 30, 2018.
Jane Barlow,AP

The archaeological record of Ireland includes tens of thousands of early medieval sites, indicating a large rural early Medieval population.

However, it apparently peaked in the late 7th century, and possibly the Irish were hard put to fight off the Vikings, who proceeded to establish settlements in Dublin, Cork, Waterford, Wexford, and Limerick. 

Why the population of Ireland entered this protracted decline in the late 7th century is not clear – "perhaps because of war, famine, plague or political unrest," McLaughlin suggests, adding: "However, there was no single cause or one-off event, as the decline was a gradual process.”

Viking enthusiasts set fire to a longboat on Carlton Hill, Edinburgh, Scotland to mark the start of the capital's Hogmanay celebrations, Thursday Dec. 29 2005.
AP Photo/Danny Lawson/PA

Evidence of the population decline includes signs that arable land was regained by scrub, and indications of a diminishment in cereal farming and animal husbandry. 

In other words, if one considers decline in numbers a bad thing, it's the luck of the Irish population that the Vikings invaded in the 10th century. Without them the decline would have been much worse, the researchers conclude. And this is why? Because they were more successful at procreation than the locals.

“Despite being few in number, they [the Vikings] were more successful than the ‘natives’ in expanding their population. Today, genetic evidence suggests many Irish people have some Viking blood,” McLaughlin says. 

The Viking and other genetic components of the Irish going back to the Bronze Age – there, about 3,500 years ago - were reported in Nature by a separate group in 2017.

A Viking home.
Wikimedia Commons

That study found that today's Irish can be divided in 10 genetic clusters: seven of ‘Gaelic’ Irish ancestry and three of Irish-British ancestry. They also demonstrated high levels of "North-West French-like" and "Norwegian-like" ancestry – and evidence of Viking inflow.

As the authors point out, people living in closer proximity tend to be more closely related than people who live from away. "In Britain and Ireland, this is exemplified by the kinship shared across the shortest sea crossing between northeast Ireland and southwest Scotland, and the genetic similarities between English people and those of Ireland's eastern coast," they write. And then there is that Viking component – which modelling dates to the age of Viking expansion, from about 900 C.E. to 1200.

The Viking canal on the Isle of Skye, Scotland.
A' chachaileith

Viking blood isn't all the Irish have: their language derived from Celtic, an Indo-European tongue that seems to have reached the island about 2,500 years ago. In time, the language that would become known as Irish replaced the original tongues of Ireland.

If Ireland and Israel have one thing in common, it isn't the weather, it's builders discovering ancient sites when clearing ground or digging. Israel has been inhabited since the dawn of human history, and every contractor has to get clearance from the antiquities authority before laying a brick. In Ireland, developers must under law employ archaeologists to record sites before they are destroyed, and numerous sites were discovered during the building boom of the so-called Celtic Tiger years.

Dr McLaughlin commented: “This large database has opened up a completely new perspective on the past that we simply could not obtain any other way.”

Emma Hannah is the lead author of the paper and is taking the work further with her PhD research. She explains: “Often in archaeology we are focused on interpreting the evidence from a single site, but analyzing quantities of data in this way allows us to think about the long term. Now we know these broad trends, we can better understand the details of everyday life.”