There are no walruses in Iceland, but there were hundreds at one time. The time of the walruses' disappearance suggests that loss of population is one of the earliest known examples of people extinishing a marine species locally.
The Spirit of Walruses in the Past
Walruses were once an important feature of life in Iceland. Some settlements and landmarks on Iceland's coast still carry names that refer to walruses, and some of the medieval legends (the stories of the island's early settler families) even mention them. The saga of Hrafin Sveinbjarnarson, written down sometime at the end of the 11th century, tells the story of a chief who killed a walrus and brought his tusks and skull to Canterbury Cathedral in England. The walruses themselves, however, were reduced to a few old bones and tusks.
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Did the walruses disappear before or after the arrival of the Northerners? In other words, did the Norsemen kill the walruses or did the population die for natural reasons? Because there are no living walruses in Iceland today, historians have discussed whether the place names refer to places where walruses lived when humans arrived, or only to places where settlers found the skulls and tusks of long dead animals. The walrus tusks that Hrafin Sveinbjarnarson provided to England may have been part of a thriving Icelandic walrus population, but it could also have been a lost wanderer from further afield to the University of Copenhagen and their colleagues using radiocarbon-dated and sequenced DNA from 34 samples of bone and tusks of walruses in the Icelandic Museum of Natural History. The DNA studies also showed that Iceland's long-lost walruses were an independent branch of the walrus family. The oldest walrus remnants of the museum from the years 5502-5332 BC. Were related to the ancestors of today's Atlantic walrus population. However, more recent samples belonged to a separate mitochondrial branch of the walrus pedigree that is genetically distinct from any group known in the North Atlantic ̵
A colonization event that replaced the ancestry represented by the old sample, rather than the old sample being a direct ancestor of the newer clade, "said co-author Morten Olsen, also an evolutionary genomicist at the University of Copenhagen, to Ars.
The Vikings accuse
What happened to Iceland's walruses? As always, the answer is complex, but much of the blame lies with the Northerners. Settlers came to Iceland and began to hunt walrus for the European ivory trade, as the Icelandic walrus population was already struggling with a changing environment and a series of volcanic eruptions. Walrus ivory was an important commodity in markets throughout Europe of the early Middle Ages, and the Norsemen were hunting walruses for most of their territory in the North Atlantic. According to a 2018 study of walrus skull and tusk DNA found in Western European archaeological sites, most of Europe's supply of walrus ivory came from a walrus clade (a group of related animals with a common ancestor) that lived in Greenland tens of thousands walruses. By contrast, Iceland's much smaller walrus population would have been a drop in the ocean, but the ivory trade was still putting pressure on Iceland's small population.
When the first Nordic hunters reached them, the Icelandic walruses were already facing the challenges of the Middle Ages of the Warm Period (700 to 1100 CE). A few centuries of relatively warm North Atlantic climate were helpful to human explorers, but not so good for walruses that rely on sea ice to get out of the water. At the same time, volcanoes erupted several times near some of the most important land reclamation sites. No wonder the walruses could not survive all this and the Vikings.
Some evidence suggests that a Roman fishery eradicated gray whales some hundred years before the Viking Age in the North Atlantic, otherwise the Northerners were the first to profitably destroy an entire animal population.
Molecular Biology and Evolution, 2019. DOI: 10.1093 / molbev / msz196 (About DOIs).
This story originally appeared on Ars Technica.
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