[troutman]

A String of Supernovae May Have Caused Earth’s Recent Ice Ages

http://www.pbs.org/wgbh/nova/next/sp...cent-ice-ages/

These supernovae weren’t close enough to incinerate life on Earth. But all that iron in the air may have changed the planet’s climate. The timing of the explosions happens to correspond to the transition into the Pleistocene epoch, the icy glacial period dominated by mastodons, mammoths, and saber-toothed cats.