Researchers say they’ve found evidence of supernova explosions that spewed radioactive fallout over Earth during the age when humanity’s ancestors were evolving into upright-walking, big-brained creatures.
One of two studies published in the journal Nature identifies deposits of radioactive iron-60 in deep-sea cores extracted from the bottom of the Indian, Pacific and Atlantic oceans. The deposits were traced back to one time frame ranging from 1.5 million to 3.2 million years ago, and another period 6.5 million to 8.7 million years ago.
The researchers behind that study, led by Anton Wallner of Australian National University, say the iron-60 was blasted toward us by “multiple supernova and massive-star events” that occurred within 325 light-years of Earth.
