The sealed rock fissures, some 50 feet underground, have been home to microorganisms for the past two billion years, the oldest form of life ever discovered in such conditions. A nearly one-foot sample excavated from beneath South Africa’s Bushveld Igneous Complex is 1.9 billion years older than previous microbial record-holders. The discovery could help researchers better understand the early stages of life’s evolution on Earth as well as Mars.
The findings were published Oct. 2 in the journal microbial ecologyby a team from the Department of Earth and Planetary Sciences at the University of Tokyo. Oldest known life form In 2020.
“We didn’t know if rocks from 2 billion years ago were habitable…so this is a very exciting discovery,” says study lead author Yohei Suzuki, associate professor at the University of Tokyo’s Graduate School of Science. stated in a statement on Thursday.
To uncover microbes long hidden from the surface world, researchers needed to build on their previous methodologies for determining the age and origin of organisms. To do this, three types of techniques are used: electron microscopy, fluorescence microscopy, and infrared spectroscopy to determine whether microbial life is really that old or whether it was due to accidental contamination during excavation or analysis. required a combination of imaging techniques. After staining the cells’ DNA, the researchers examined the microbial proteins and surrounding clay habitat and determined that they were alive and unique to the crack sample.
How microbes have been able to survive longer than most other life on Earth probably has a lot to do with their habitat. The Bushveld Igneous Deposit (BIC), located in northeastern South Africa, is an approximately 41,000 square mile area known for its rich deposits containing an estimated 70 percent of all platinum mined. Billions of years ago, volcanic magma gradually cooled in a region as thick as 5.9 miles beneath the Earth’s surface.
These geological formations have changed little since then, but they do contain small cracks filled with microorganisms. At the same time, clay deposits closed the gaps near these cracks, trapping small organisms inside and preventing anything else from entering. Experts theorize that this allowed the stability of microbial life to continue at a very slow pace with little or no evolutionary change. With further exploration, the researchers hope to learn more about what some of the earliest life on Earth looked like, billions of years before humans arrived.
Future discoveries will not necessarily be limited to expanding our understanding of how life evolved over time on Earth. The researchers hope that further discoveries will one day help them search for evidence of life on Mars.
“NASA’s Mars rover Perseverance is currently scheduled to bring back rocks of the same age as those used in this study,” Suzuki explained. “Finding microbial life in samples from Earth… we’re excited about what we might find in samples from Mars.”
