Deep beneath the Earth’s surface, surviving terrible pressures and heat that were once thought to be completely inhospitable to organic life, a thriving biosphere is challenging our conception of the limits of organic life.
The Deep Carbon Observatory has been digging into the planet’s crust for the past 10 years. Comprising more than 1,000 scientists hailing from 52 countries around the world, they’re mapping the depths of strange—and what some more than 10 years ago might have called impossible—life forms (the very definition of extremophile).
I’m talking about what’s been described as Earth’s “deep biosphere.”
The deep biosphere is a mysterious patchwork of underground ecosystems of microbial life that exists between Earth’s surface and its core. It’s estimated that this biomass could reach as deep as ten kilometers into the mantle.
This raises quite a few questions about the evolution of life on our world, and has lead scientists to speculate whether or not planets like Mars and Venus could harbor deep biospheres themselves. And scientists already believe that Mars and Venus at one time had atmospheres similar to the Earth and possibly even life.
Fumio Inagaki, a geomicrobiologist at the Japan Agency for Marine-Earth Science and Technology and a member of the DCO, said this in a statement, “Even in dark and energetically challenging conditions, intraterrestrial ecosystems have uniquely evolved and persisted over millions of years. Expanding our knowledge of deep life will inspire new insights into planetary habitability, leading us to understand why life emerged on our planet and whether life persists in the Martian subsurface and other celestial bodies.”
Earth’s deep biosphere has even been referred to as a “subterranean Galapagos” whose secrets are just waiting to be unearthed. In fact, it’s thought that this biomass completely outnumbers carbon-based life on the planet’s surface.
The image pictured above is of Kidd Creek Mine. Located in Timmins, Ontario. The most notable feature of the mine is the massive hole that’s been excavated in the Earth. This is the deepest copper and zinc mine in the world. If it weren’t for a complex ventilation system, the labyrinthine tunnel system that rests three kilometers below the earth’s surface would reach temperatures as high as 34 degrees Celsius. (93 degrees Fahrenheit for those of you from the US).
This is where Barbara Sherwood Lollar, a hydrogeologist at the University of Toronto, ventures into the depths of the mine for signs of microbial life. In a statement made when interviewed by The Scientist, Barbara says: “You get into a small truck or vehicle and go down a long, winding roadway that corkscrews down into the Earth. We are literally walking along what was the ocean floor 2.7 billion years ago. It’s an utterly fascinating and magical place to visit.”
Instead of looking for metal ores, Sherwood Lollar and her colleagues are searching for pools of salty water. And not the kind you’d want to pump into your home and drink from, either. These pools of water that have been in contact with the rock for long geochemical timescales—they’re full of dissolved cations (positively charged ions) and anions (negatively charged ions) that they’ve leached out of the minerals. They give off a musty odor when you’re in the presence of one. Sherwood Lollar and her colleagues are constantly on the lookout for that odor when exploring the mines.
In 2006 Sherwood Lollar was part of a team led by Tullis Onstott at Princeton University that discovered an anaerobic, sulfate-reducing bacterium thriving in the sulfate-rich fracture waters of Mponeg gold mine in South Africa, 2.8 kilometers underground (Sulfate-reducing bacteria are common in oxygen-deprived habitats). A few years later, a different group described a diverse microbial community living at a similar depth in the Earth’s crust, accessed via a borehole drilled into the ground in Finland. With the recent discovery of 2-billion-year-old, hydrogen-and sulfate-rich water seeping out of the rock in Kidd Mine, Sherwood Lollar and her colleagues are hoping they might again find life again.
There are even complex drilling operations happening on the ocean floor, which have allowed for a myriad of discoveries to shed light on the microbial and eukaryotic life thriving inside the planet’s mantle.
Expeditions like these are creating a new and rapidly expanding field of research.
It’s amazing, how little we really know about our planet, and about the secrets it may hold. And while this might just be a bit of wild conjecture, I think it’s possible that this deep biosphere is the very reason why life has been able to evolve into such diverse forms several times over, even after events like the asteroid that killed the dinosaurs. How else could life come to thrive again when an incident like the KT impact wiped out 99% of all living things on the surface?
It’s certainly food for thought.
About the Author
Eric Malikyte was raised on a healthy diet of science fiction, fantasy, and a fear of the unknown. Thanks to shows like Sightings and The Art Bell Show, Eric developed a mixed interest in the sciences and the paranormal. He lives in Northern Virginia, where he spends time working odd hours and talking to his cat while he writes his novels.
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