That’s the hypothesis offered on Monday by researchers aiming to solve one of science’s enduring mysteries: what happened at the end of the Permian period to cause the worst of the five mass extinctions in Earth’s history. “I would say that the end-Permian extinction is the closest animal life has ever come to being totally wiped out, and it may have come pretty close,” said Massachusetts Institute of Technology biologist Greg Fournier, one of the researchers. Previous ideas proposed for the Permian extinction include an asteroid and large-scale volcanism. “One important point is that the natural environment is sensitive to the evolution of microbial life,” said Daniel Rothman, an MIT geophysics professor who led the study published in the journal Proceedings of the National Academy of Sciences. The best example of that, Rothman said, was the advent about 2.5 billion years ago of bacteria engaging in photosynthesis, which paved the way for the later appearance of animals by belching fantastic amounts of oxygen into Earth’s atmosphere. The growing amount of nickel, transported globally by ocean currents, would have allowed more Methanosarcina to convert organic matter into methane, which would be converted to carbon dioxide through reactions with oxygen. Second, a surge in volcanic activity led to a sudden influx of nickel, a vital nutrient that helped the microbes proliferate. The most famous of Earth’s mass extinctions occurred 65 million years ago when an asteroid impact wiped out the dinosaurs that ruled the land and many marine species. Over the course of about a million years, huge eruptions in Siberia spewed basalts that cover an area that was about seven times the size of France.
– Name your favorite culprit for the mass extinction that wiped out nearly every life form on Earth 250 million years ago. A spectacular asteroid, perhaps? Massive volcanic eruptions? Both are popular theories, but a new study encourages sleuths of the Permian era to think much, much smaller, reports the Guardian. As in microscopically smaller. MIT scientists propose that a microbe called Methanosarcina proliferated in the oceans, disgorging huge amounts of methane into the atmosphere and making life in the water and on land all but impossible for most species. "In short, a microbial innovation may have tipped over the balance to cause the Great Dying," explains Ars Technica. So what caused the microbes to explode in numbers? That's where those volcanoes may have played a role, though a lesser one than has been long surmised. Scientists think a flurry of eruptions in Siberia resulted in a huge increase in nickel, upon which Methanosarcina happens to thrive. An estimated 90% of marine species were wiped out in the changed atmosphere, along with 70% of land vertebrates. It took millions of years for both to recover, with the first dinosaurs showing up about 20 million years later, reports Reuters. (Scientists recently determined that the Permian mass extinction happened really, really quickly.)