Scientists have identified living microbes within a 2-billion-year-old rock formation, marking the oldest known instance of such organisms found in ancient geological structures.

The remarkable finding was made at the Bushveld Igneous Complex in South Africa, an area renowned for its abundant ore deposits, including a significant portion of the planet’s platinum.

The research, published in the journal Microbial Ecology, underscores the potential of these ancient microbial colonies to provide insights into the early evolution of life on Earth. It also raises intriguing possibilities for the search for life beyond our planet, particularly in similarly aged Martian rock samples.

“We didn’t know if 2-billion-year-old rocks were habitable. Until now, the oldest geological layer in which living microorganisms had been found was a 100-million-year-old deposit beneath the ocean floor, so this is a very exciting discovery,” the lead author, Yohey Suzuki, an associate professor at the University of Tokyo’s Graduate School of Science, said.

“By studying the DNA and genomes of microbes like these, we may be able to understand the evolution of very early life on Earth,” he said.

The BIC’s unique formation process, which involved magma cooling beneath the Earth’s surface, has resulted in minimal deformation over time. This stability likely provided a conducive environment for microbial life to persist.

Aided by the International Continental Scientific Drilling Program, researchers were able to retrieve a rock core sample from about 15 meters underground. The sample, when sliced and analyzed, uncovered microbial cells densely packed within fractures in the rock. The fractures were tightly sealed with clay, preventing any exchange with the external environment.