By Tobias Carroll Was there once a land bridge between what we now know of as Europe and Asia? There’s some debate over whether the two should even be considered separate continents at all. The National Geographic Society, for example, refers to “[a]n imaginary line, running from the northern Ural Mountains in Russia south to the Caspian and Black Seas” as the dividing point between the two, rather than any specific break in the landmass. Now, some archaeologists have a theory that the boundaries between the two might have been more pronounced than previously believed. A new article at Hyperal…