The infamous Black Death -- a pandemic that killed as many as one third to one half of Europeans within just a few years -- may have been aided in its devastation by an unknown volcanic eruption.That's the hypothesis presented in research published December 4 in Communications Earth & Environment, which argues that the eruption triggered several seasons of climate instability and crop failures. That instability, in turn, forced several Italian states to import grain stores from new sources -- specifically, from regions surrounding the Black Sea. Riding along on those grain stores, the researchers posit, were fleas infected with...