Norse code: Many of us have Viking DNA as invaders made up for fall in Irish population
Many Irish people may have Viking blood because the 'native' population massively declined for two centuries in the Middle Ages, a new study has found.
A study from Queen's University Belfast has found the Irish population was in serious decline around the year 700.
The research team believes the population in Ireland before then was around three million, but that it had dropped to about two million two centuries later.
The reasons are unclear, according to researchers from the university's School of Natural and Built Environment, which has published its findings in the 'Journal of Archaeological Science'.
"Millions of people lived in Ireland during prehistory and the earliest Christian times," said research fellow Dr Rowan McLaughlin.
"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."
It was previously believed Ireland's population gradually increased, but the study - using archaeological data science algorithms - indicates that the reverse was true for almost two hundred years before the Vikings arrived on these shores.
"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," Dr McLaughlin added.
"Today, genetic evidence suggests many Irish people have some Viking blood."
Researchers based their study using a database of archaeological sites discovered during the ‘Celtic Tiger’ years, when there was a boom in motorway building and other development in Ireland.
Developers are required by law to employ archaeologists to record sites before they are destroyed.
This allowed the researchers to access information that was not previously available, he said.
“This large database has opened up a completely new perspective on the past that we simply could not obtain any other way,” Dr McLaughlin said.