Neanderthal remains dating back 31,000 years – over 6,000 years after man’s prehistoric cousin was presumed to have disappeared – have been unearthed in Russia near the Artic Circle, according to a study in the journal Science.

“This site challenges the hypothesis that there was a complete replacement of the Neanderthal societies in all of Europe as early as around 37,000 calendar years,” the authors wrote about their research released on Thursday, and slated for the journal’s May 13, 2011 issue.

The French, Russian and Norwegian researchers discovered more than 300 stone tools and the remains of several mammals, including mammoths, black bears and woolly rhinos that appear to have been butchered.

The remains were unearthed during several excavations at the Byzovaya site in the foothills of the Urals on the right bank of the Pechora River.

In addition to radiocarbon dating, the researchers used a technique known as optically stimulated luminescence, which allows them to tell when sediment has been exposed to light for the last time.

While Neanderthal Man occupied Eurasia at lower latitudes, Byzovaya could have been their last Nordic refuge before their extinction, according to the study’s authors. Until now, Neanderthal remains have all come from areas at least 1,000 kilometres south of Byzovaya.

The objects discovered at Byzovaya, which appears to have been occupied just once in 3,000 years, belong to the Mousterian tool tradition used by Neanderthal Man, according to the authors.

This culture developed during the Middle Paleolithic era in Eurasia 300,000 to 37,000 years ago and is distinguished by a wide range of stone tools.