Current thinking is that the Neanderthals died out between 37,000 and 40,000 years ago as modern humans spread out from Africa. But a finding in Russia's arctic could indicate that at least there, they stuck around for another 8,000 years.

Neanderthals were either a subset of modern humans, Homo sapiens neanderthalensis or as a separate human species, Homo neanderthalensis, depending on who you talk to. They lived in Europe's river valleys for about 150,000 years.

Then 40,000 years ago modern humans spread out from Africa and the Near East. At the same time, the Neanderthals disappeared everywhere except a few small pockets in Spain and Portugal, where they, too, eventually went extinct.

Now a group of Russian, French and Norwegian paleontologists have reported on a 32,000-year-old bunch of stone tools in the Russian high Arctic that look for all the world like they were made by Neanderthals and not humans.

The Neanderthals were known for their Middle Paleolithic toolkit, specific rock scrapers and other instruments that, as far anyone knows, only they used. Humans had a different, Upper Paleolithic toolkit.

There aren't any human or Neanderthal bones at the site, which is in Byzovaya in Russia's Ural Mountains, as far north as Iceland. All archaeologists have to base their theories on are the tools.

That makes it difficult to say for certain exactly who made this cache of tools, 313 of them in all. They're accompanies by over 4,000 animal remains, mostly mammoths as well as some wooly rhinoceros, reindeer, musk ox, horse, brown bear, wolf and polar fox. Most of the bones have cut marks that indicate processing by humans.

But what kind of humans? Writing in this weeks edition of the journal Science, the authors say:

Most researchers agree that classical Mousterian (Middle Paleolithic) industries in Europe were exclusively produced by Neanderthals. However, whether Byzovaya represents a Neanderthal site or not cannot be demonstrated beyond doubt until human bones or DNA are found. If the Byzovaya artifacts were struck by modern humans, this would have major implications for understanding the Middle Paleolithic/Upper Paleolithic transition, as it would imply that these Arctic Homo sapiens groups preserved older, traditional Middle Paleolithic cultures far after the full expansion of Upper Paleolithic modern societies in the rest of Eurasia. If, like elsewhere in Europe, these technologies were realized by Neanderthals, then such late persistence of Mousterian traditions at this high latitude as late as about 10,000 years after the Upper Paleolithic first appearance at lower latitudes in Russia (Kootenai) would imply that the two human species coexisted over a longer time period than has been thought.

Meanwhile, another paper published in the Proceedings of the National Academy of Sciences suggests that reports that Neanderthals survived in the northern Caucasus into the Upper Paleolithic era are incorrect. In this paper, researchers from Ireland, the United Kingdom and Russia report that radiocarbon dating of Neanderthal bones found in Mezmaiskaya Cave in the northern Caucasus shows they were from approximately 39,000 years ago, "indicating at a high level of probability that Neanderthals did not survive at Mezmaiskaya Cave after 39,000." They go on to write that "this challenges previous claims for late Neanderthal survival in the northern Caucasus."