The largest extinction in Earth's history
SUMMARY: Methane-producing microbes may be the culprit for the largest mass extinction in Earth's history. The extinction has an intriguing connection to bad breath.
Posted: April 2, 2014
You thought the dinosaurs' extinction was bad?
After examining fossil remains, scientists might have solved the mystery behind the largest mass extinction in Earth's history.
According to researchers from the Massachusetts Institute of Technology (MIT), about 252 million years ago a microbe spewed huge quantities of methane into the Earth's atmosphere, triggering a global catastrophe that wiped out more than 90 percent of all species - by far the largest of this planet's five known mass extinctions. What's more, this microbe has a fascinating link to bad breath.
Researchers who have been seeking to unveil what happened at the end of the Permian period recently released a new hypothesis:
The implicated microbe, Methanosarcina, is a single-celled organism that is distinct from a bacteria called archaea due to its lack of a nucleus. Methanosarcina grew out of control in the seas, emitting catastrophic amounts of methane into Earth's atmosphere, according to the researchers. This drastically heated up the climate and fundamentally changed the chemistry of the oceans by raising acid levels, making for unlivable conditions for many species.
All shell-forming organisms, for instance, were eradicated, since such shells cannot form in acidic waters. The horseshoe crab-like trilobites and sea scorpions simply vanished. On land, most of the dominant mammal-like reptiles died off. However, there were exceptions with a number of lineages, such as the ancestors of modern mammals that evolved into humans.
"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," MIT biologist Greg Fournier, one of the researchers, told Reuters. The new solution for the age-old question was published during the first week of April in Proceedings of the National Academy of Sciences by Fournier, professor of geophysics Daniel Rothman and five other researchers at MIT and in China.
The breath connection
Methanosarcina is still found today in places like trash dumps, oil wells and the guts of animals like cows, which is why cows produce smelly manure. Its byproduct is methane. Although methane itself is odorless, the gas is closely related to the anaerobic, sulfur-producing bacteria that's at the core of bad breath.
For example, a white-coated tongue, which is a frequent indicator of bad breath, is comprised of sulfur compounds that have risen to the tongue's surface. Old dental work can lead to a rough surface that also provides an area for the bacteria to colonize.
Previous theories on the Permian extinction include an asteroid and large-scale volcanic eruption. While volcanoes are not entirely off the hook based on this new scenario, they have been demoted to accessories in the crime.
The carbon deposits indicate a significant uptick in the amount of carbon-containing gases, including carbon dioxide and methane. The researchers suggested a microbial expansion that is among the few phenomena capable of increasing carbon production exponentially. So, living organisms belched out all that methane? Well, sort of.
The outburst of methane that led to the sudden and extreme rise in temperatures mixed with the acidification of the oceans is similar to those predicted by current models of global climate change.
"One important point is that the natural environment is sensitive to the evolution of microbial life," said Dr. Daniel Rothman, an MIT geophysics professor who led the study published in the journal Proceedings of the National Academy of Sciences.
To put this in perspective, the dinosaurs appeared 20 million years after the Permian mass extinction.
Earth isn't doomed because of stinky breath. However, if you do have a case of halitosis, don't exhale too hard - or use TheraBreath.