The team of researchers, from the Technical University of Munich, announced on Wednesday that sediment found at the bottom of the Pacific Ocean could be from a star explosion 2.8 million years ago that may have coincided with massive climate change in the world.
About 15,750 feet (4,800 meters) below the surface of the Pacific Ocean, the scientists found layers of iron-60. The version of iron is very unusual in that it takes a lot of heat and pressure to make it, the kind of heat and pressure only a supernova can deliver.
The researchers theorized that a star explosion close to earth was the only explanation for the sediment's location on the bottom of the ocean. They said the layer indicated the star exploded 2.8 million years ago, showering down iron and cosmic rays.
Fleeing the trees, becoming human
Working on previous evidence that cosmic ray bombardment could have opened up the ozone layer, the researchers said the supernova could have cooked up the earth in such a way as to force climate change.
Anthropologists believe that climate change led to deforestation, forcing hominids to climb down from the trees and walk erect.
"The African climate shifted towards more arid conditions about 2.8 million years ago," the researchers, led by Gunther Korschinek, wrote. "Some of the major events in early hominid evolution appear to be coeval with African climate changes."
The discovery comes five years after Korschinek led the team that first discovered iron-60 sediment in a more shallow area of the Pacific Ocean. Scientists said at the time that the sediment was deposited on Earth at the same time as the planet was undergoing "mini-extinctions," where species die out at a higher rate than normal.
In a paper published in the New Astronomy Journal, Brian Fields and John Ellis wrote that the team's discovery would "constitute the first direct evidence that a supernova occurred near Earth in the fairly recent geologic past, with detectable effects on our planet."
This week's discovery appears to bolster the claim.