We’re Survivors Of A Double Supernovae Hit: The Cause Of A Mass Extinction Event And Speeding Up Evolution?

Scientists have found that two supernovae that exploded within a few million years of each other might have contributed significantly to not only a mass extinction event here on Earth but also to speeding up evolution for the surviving species. Computer modeling prompted by research announced in April concerning a couple of supernovae roughly 300 light years distant provided a view into the possible effects they may have had on the biology and the physical make-up of the planet as well. The findings suggested that cosmic rays emitted by the dying stars may have had a deeper impact on our world than was previously thought possible.

As Phys.org reported on July 11, physicist Adrian Melott of the University of Kansas led an international team of physicists in running computer models on a couple of stars that, after going supernovae 1.7 to 3.2 million and 6.5 to 8.7 million years ago, likely exposed the extant biology on Earth at those times to cosmic radiation for an extended period of time. The emissions likely affected the atmosphere of Earth as well.

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Melott said the results from running the models were a surprise. “I was surprised to see as much effect as there was. I was expecting there to be very little effect at all. The supernovae were pretty far way—more than 300 light years—that’s really not very close.”

The starbursts would have filled Earth’s skies with blue light for weeks, most likely disrupting sleep patterns for many living organisms during that period. But, Melott said, the most significant alterations would have come from the surprisingly large amounts of radiation to which the Earth was exposed (and, by extension, all life on the planet), not to mention the length of time the radiation would have persisted. According to the researchers, the cosmic rays could have bombarded Earth for as long as a thousand years after each star went supernova.

The research also suggested that the increased amount of cosmic rays would have had an effect on atoms in the Earth’s atmosphere as well. The cosmic rays would have stripped atoms from molecules in the atmosphere, resetting the chemical make-up. And since there would be roughly 20 percent more cosmic rays entering the Earth’s atmosphere, this would effectively triple the average radiation levels at the time, producing mutations over time.

The alterations to the atmosphere, researchers noted, per Tech Times, which could easily cause shifting weather patterns and overall climate change, and the propensity for genetic mutation in living organisms due to exposure to increased levels of radiation, the double hit by the supernovae could have given rise to the mass extinction event that occurred on Earth at the end of the Pliocene era and the start of the Pleistocene. During this time, Africa grew hotter, its forests turned to savannahs. Then ice ages began sporadically occurring.

“It’s controversial,” says Melott. “But maybe cosmic rays had something to do with it.”

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It should be pointed out that Melott and company’s research will likely lend itself to that even greater controversial issue — evolution and the rise of humans. Given that current scientific thinking places the emergence of modern hominids of the Homo genus at around 3 million years ago, which is roughly prior the second supernovae bombardment, this would have placed the emergence sometime between the two stellar explosions and in between the large, extended mutational radiation levels. With the massive die-offs of other animals and the climatic changes being conducive to hardy mammals, as modern evolutionary theory suggests, the opportunity for humans to push further down the path of evolution would have been enhanced.

Melott’s team’s research, though the first to use computer modeling, is not the first where it has been suggested that supernovae could have been responsible for the Pliocene mass extinction event. Back in 2002, a paper appearing in the Physical Review of Letters posited that a group of passing stars some 2 million years ago may have had one or more stars that went supernova, the resulting cosmic ray bombardment causing extensive damage to the ozone layer and, subsequently, causing climate change on Earth and the mass extinction of marine life.

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