The Vikings' disappearance from Greenland in the 15th century came not in an epic battle but with a decline in the walrus ivory trade, according to researchers, who may have cracked "one of history's big mysteries," per Newsweek. Walrus ivory was a hot commodity in medieval Europe. Indeed, pre-1400s walrus tusk artifacts, from crucifixes to chess pieces, have been found across the continent. In studying 67 rostra—the skulls and snouts from which tusks were removed in medieval workshops—researchers found almost all came from walruses in seas accessible only to Norse colonies, meaning the Vikings basically had a monopoly, per a release. But that changed as elephant ivory flooded Europe in the 13th century. Researchers say rostra from this period came only from small walruses, perhaps females and infants, sourced farther north than before.
"We suspect that decreasing values of walrus ivory in Europe meant more and more tusks were harvested to keep the Greenland colonies economically viable" since Norse seafarers "mainly had walrus products to export in exchange" for iron and timber, Cambridge University's James Barrett tells AFP. But longer journeys deeper into the Arctic Circle "for increasingly meager ivory harvests" would have only "exacerbated the decline of walrus populations," says Barrett, lead author of the new study in Quaternary Science Reviews. As there's little evidence of walrus ivory reaching mainland Europe after 1400, researchers believe overexploitation eventually meant the end of the Vikings' main source of income. A previous study examined the downfall of the trade without linking it to the Vikings' disappearance, also attributed it to climate change. (Read more Vikings stories.)