MIT News reports today that a team led by Prof. Daniel Rothman has found compelling new evidence about the cause of the “Great Dying,” an event 252 million years ago which wiped out 90% of the Earth’s species.

Ancient whodunit may be solved: The microbes did it!
Methane-producing microbes may be responsible for the largest mass extinction in Earth’s history.

David L. Chandler | MIT News Office
March 31, 2014

Evidence left at the crime scene is abundant and global: Fossil remains show that sometime around 252 million years ago, about 90 percent of all species on Earth were suddenly wiped out — by far the largest of this planet’s five known mass extinctions. But pinpointing the culprit has been difficult, and controversial.

Now, a team of MIT researchers may have found enough evidence to convict the guilty parties — but you’ll need a microscope to see the killers.

The perpetrators, this new work suggests, were not asteroids, volcanoes, or raging coal fires, all of which have been implicated previously. Rather, they were a form of microbes — specifically, methane-producing archaea called Methanosarcina — that suddenly bloomed explosively in the oceans, spewing prodigious amounts of methane into the atmosphere and dramatically changing the climate and the chemistry of the oceans.

Volcanoes are not entirely off the hook, according to this new scenario; they have simply been demoted to accessories to the crime. The reason for the sudden, explosive growth of the microbes, new evidence shows, may have been their novel ability to use a rich source of organic carbon, aided by a sudden influx of a nutrient required for their growth: the element nickel, emitted by massive volcanism at just that time. Read more…

Learn more about the science behind this research in several OCW courses by Prof. Rothman: