The largest extinction in history may have been caused by a microorganism.

What caused the great extinction on Earth about 252 million years ago? Volcano eruptions? Meteor impact? Apparently, according to a new study, it was none of that. According to some scientists, what would have caused the annihilation of thousands of species in the world was only the action of a certain type of microorganism.

This theory, which has been under investigation for some time, has been reinforced by new research by scientists from the Massachusetts Institute of Technology (MIT) - led by geophysicist Daniel Rothman. They found new evidence about the most devastating mass extinction in our planet's history.

Methane

The team's research indicates that the catastrophic event was in fact triggered by the tiniest of organisms, a bacteria that released a methane gas called Metanosarcin . According to the studies, these microorganisms have appeared in large numbers in all oceans of the world, spreading vast clouds of methane and carbon gas into the atmosphere.

This phenomenon resulted in a climate change effect on the planet, so intense that it made it inhospitable to most other life forms that inhabited the Earth at that time, at the end of the Permian period.

The other theories about mass extinction (strong volcanic activity and meteors) could also be plausible, but, according to scientists, there are inconsistencies that do not match the new results found in this research.

Theories and Evidence

According to what the experts found (using carbon cycle assessments), an extinction event due to extreme volcanic activity would not be possible because, according to new evidence investigated by MIT, these eruptions would not represent the carboniferous levels present in the rock sediments (studied in China).

Gregory Fournier, one of the project's researchers, stated that "the initial rapid injection of carbon dioxide from a volcano would be followed by a gradual decrease" and this gradual decrease was not present in the sediment evaluated. Instead, carbon levels continued to rise exponentially, thus generating even more doubt about volcanic theory and most evidently supporting the microbial hypothesis.

However, there is a link between volcanic activity and the action of microorganisms. Although the team does not believe that high levels of volcanism were responsible for their own extinction, they believe it could have been the catalyst.

Contaminated oceans

The sudden and devastating increase in carbon-containing gases during the end-Permian era extinction is linked to a huge spread of Metanosarcin . However, for this to happen, microbes would require an abundant source of carbon and nickel, both of which were discovered in this new sediment analysis in China and could have been widely spread through a volcanic eruption.

Metanosarcin theory is further reinforced by research results showing that, at the time of the end of the Permian period, bacteria had been subjected to a genetic transfer from another microbe. As a result, Metanosarcina increased its ability to produce methane at an abundant rate.

Having volcanic activity as a catalyst, these bacteria were able to spread across our planet's oceans uncontrollably. The release of methane would have the effect of increasing carbon dioxide levels in the waters, causing ocean acidification to alter the entire maritime and terrestrial ecosystem.

While the team is keen to point out that no evidence can definitively prove what caused the end-Permian extinction, the combination of volcanism and methane release seems to be the most convincing theory.