Viking mice: Norse discovered Azores 700 years before Portuguese

November 10, 2021
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By Krisy Gashler

The history books say the Azores were discovered by Portuguese explorers in 1427. But mouse DNA and lake sediment suggest that the mid-Atlantic archipelago was actually discovered as much as 700 years earlier, by Vikings.

In 2015 Jeremy Searle, professor of ecology and evolutionary biology, and two co-authors posited, based on mouse mitochondrial DNA, that the first humans to visit the Azores came from Northern Europe, not Portugal. Their study, published in the Journal of Evolutionary Biology, has taken on new relevance in light of a new, international study published in the Proceedings of the National Academy of Sciences (PNAS), which looked at sedimentary layers in Azores lakes and historical climate patterns and came to the same conclusion Searle’s group did: Norse explorers discovered parts of the Azores between 700 and 850 A.D.

“This is a completely different set of data, but their findings confirm what we hypothesized in 2015,” Searle said. “Having this variety of available evidence: the sedimentary record, historical climate data, our mice – our living artifacts – these are all tools for archaeologists and historians to use in piecing together the past.”

For 20 years scientists have been studying the mitochondrial DNA of house mice to learn more about human visitation and settlement in far-flung places; because house mice live alongside humans, the presence of one almost guarantees the presence of the other. Studying the genetics of living mice can give clues about their ancestors because mitochondrial DNA – the portion of the genome that is exclusively passed by females – remains virtually unchanged through generations particularly in a closed, island environment, Searle said. While later-arriving males may outcompete and genetically displace existing males, the DNA of first-arriving females seems to remain permanently dominant, he said.

More:
https://cals.cornell.edu/news/2021/11/viking-mice-norse-discovered-azores-700-years-portuguese