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Did Exploding Stars Force Humans to Walk Upright?
Some scientific ideas are far-fetched. This one is way out there. About 163 light-years, to be specific.
A spate of exploding stars is thought to have bathed Earth in excess cosmic rays that peaked about 2.6 million years ago. That much is known. Here’s where things get speculative: The outburst created “an avalanche of electrons in the lower atmosphere” that sparked “an enormous upsurge in cloud-to-ground lightning strikes that ignited forest fires around the globe,” researchers postulate May 28 in the online version of the Journal of Geology.
The fires turned northeast Africa’s forests into savannas, the thinking goes. Forced to walk farther to find the next tree to swing from, early human ancestors may have perfected their bipedalism.
“It is thought there was already some tendency for hominins to walk on two legs, even before this event,” says the study’s lead author, Adrian Melott, professor emeritus of physics and astronomy at the University of Kansas. “But they were mainly adapted for climbing around in trees. After this conversion to savanna, they would much more often have to walk from one tree to another across the grassland, and so they become better at walking upright. They could see over the tops of grass and watch for predators. It’s thought this conversion to savanna contributed to bipedalism as…
