Between 8 and 2 million years ago, cosmic-ray energy from one or more nearby supernovae reached Earth and pummeled the planet’s atmosphere, initiating an avalanche of electrons and setting off a chain of events that ended with bipedal hominins, according to a radical study published in the Journal of Geology. Evidence point to one or more moderately nearby supernovae, with the strongest signal at 2.6 million years ago. Image credit: José A. Peñas...
