Supernovas May Have Helped Humans Walk Upright

As human ancestors went from swinging through trees to walking on two legs, they may have received a boost from an unlikely source: ancient supernovas. These powerful stellar explosions may have showered Earth with enough energy to shift the planet's climate, bathing Earth in electrons and sparking powerful, lightning-filled storms, according to a new hypothesis. Lightning then could have kindled raging wildfires that scorched African landscapes. As savanna replaced the forest habitat, early humans that lived there may have been pushed to walk on two legs, the new study suggests. However, don't go jumping to conclusions just yet. Many factors likely contributed to the evolution of bipedalism, a process that began many millions of years before these stellar explosions took place, one expert told Live Science.