Scientists have found the oldest living microbes in a two-billion-year-old rock buried almost 50 feet below the ground. The finding suggests that a sealed rock fracture has been hosting the oldest known life in such conditions.
A one-foot sample was excavated beneath South Africa’s Bushveld Igneous Complex and is 1.9 billion years older than the previous microbial record-holder.
Experts are hoping to understand the earliest stages of evolutionary life on Earth as well as Mars using the new information.
A team at the University of Tokyo’s Department of Earth and Planetary Sciences made the discovery and published the findings in the journal Microbial Ecology on October 2. The same team had also confirmed the previous oldest known life forms in 2020.
“We didn’t know if 2-billion-year-old rocks were habitable… so this is a very exciting discovery,” Yohey Suzuki, the study’s lead author and an associate professor at the University of Tokyo’s Graduate School of Science, said in a statement.
The researchers used previous methodologies for determining an organism’s age and origin and built upon them to find the unknown microbes. They needed to figure out whether the microbial life found was in fact as old as it presented itself, or whether it got contaminated during excavation and analysis.
They combined three types of imaging approaches, electron microscopy, fluorescent microscopy, and infrared spectroscopy, to do so.
Scientists say that their habitat has likely helped them live longer than any other life form on Earth. Located in northeastern South Africa, the Bushveld Igneous Complex (BIC) sits in a roughly 41,000-square-mile region known for rich deposits of ore. It also has an estimated 70 per cent of all mined platinum.
Volcanic magma cooled billions of years ago under the Earth’s surface in regions as thick as 5.6 miles. These haven’t changed since then, but have tiny fissures where microbial life is packed densely. Later, clay sediment closed the gaps and trapped the tiny organisms inside. Nothing else was able to enter because of this.
This helped microbial life to continue to remain stable at an extremely slow pace without witnessing any evolutionary changes.