Ancient Microbe May Have Killed 90 Percent of Earth's Species

Scientists believe a methane-creating microbe caused a mass extinction more than 250 million years ago that wiped out 90 percent of the Earth's population in just tens of thousands of years.

Called "The Great Dying," the extinction has been dated to the end of the Permian period, when vertebrates and invertebrates from both sea and land died out, The Washington Post reported.

In the past, scientists have thought that unusual Siberian volcano activity was the culprit for the "mysterious disruption to the Earth's carbon cycle" they believe killed 90 percent of the Earth's species in around 60,000 years. But new evidence points to something much smaller.

A team of seven Massachusetts Institute of Technology researchers, who published their findings this week in the Proceedings of the National Academy of Science, looked at evidence for the increase of carbon dioxide in the oceans. After studying Methanosarcina, scientists believe the methane-producing microbe is actually responsible for the The Great Dying.

Their findings suggest that volcanoes were actually a sideshow when it came to gas production: Methanosarcina seems to be the true culprit, while volcanic eruptions supplied the element nickel that they thrived on.

After analyzing carbon deposits, the team's calculations revealed that volcanic eruptions were likely not sufficient to account for the amount of carbon that remains. The volcanic model also doesn't match the way carbon increased over time.

"A rapid initial injection of carbon dioxide from a volcano would be followed by a gradual decrease," MIT researcher Gregory Fournier said in a school news release. "Instead, we see the opposite: a rapid, continuing increase."

Researchers hypothesize that the nickel from volcanic eruptions fueled the proliferation of Methanosarcina, resulting in the lethal dose of carbon dioxide.

"The burst of methane would have increased carbon dioxide levels in the oceans, resulting in ocean acidification--similar to the acidification predicted from human-induced climate change," said the news release.