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Millions of years ago, hundreds of light-years from Earth, massive stars started to explode. As they died, the stars spewed energetic particles into space, many of which rocketed toward Earth, tearing through the atmosphere and causing a surge in the electric charge of the layers of air closest to the planet’s surface. Researchers studying the Earthly effects of these stellar explosions hypothesize that this electric boost triggered lightning storms and sparked wildfires that burned the forests of Africa, turning them to grasslands.
One of these researchers, University of Kansas physicist Adrian Melott, says he thinks that these lightning storms and wildfires also could have played a role in hominins’ transition to walking on two feet. According to Melott, supernovae-induced fires would have left just a few trees scattered across the landscape. For our tree-living ancestors, “[this] encouraged bipedalism,” he says, “because we had to get from one ...
