Millions of years ago, a series of nearby supernovae sent radiation and debris raining down to Earth. The events left traces of radioactive iron-60 embedded in the sea floor and even on the Moon, and now, researchers are saying they may have had life-altering effects on the early inhabitants of our planet. At just hundreds of light-years away, two major stellar explosions may have spurred changes to the environment, and even increased the rates of cancer and mutation.
