Two-Billion-Year-Old Microbes Found Alive in Rock: How Did They Survive?

Scientists have discovered microorganisms residing in a rock that is over two billion years old, buried approximately 50 feet beneath the surface. This discovery, found beneath South Africa’s Bushveld Igneous Complex, represents the oldest known microbial life ever found, predating the previous record by 1.9 billion years.

The research, carried out by the University of Tokyo’s Department of Earth and Planetary Sciences and reported in the journal Microbial Ecology on October 2, aims to shed light on early evolutionary life on Earth and potentially Mars. This team had also identified the previous record for the oldest known life forms back in 2020.

“The possibility of 2-billion-year-old rocks being habitable was unknown, making this discovery particularly thrilling,” stated Yohey Suzuki, the study’s lead author and an associate professor at the University of Tokyo’s Graduate School of Science.

To determine the age and origin of the microbes and ensure the samples were not contaminated during extraction or analysis, the team utilized a combination of electron microscopy, fluorescent microscopy, and infrared spectroscopy.

These microbes inhabit the Bushveld Igneous Complex in northeastern South Africa, an area spanning about 41,000 square miles and containing the world’s largest reserves of platinum, about 70% of the total mined. The region features volcanic magma that solidified under Earth’s surface billions of years ago, forming structures as deep as 5.6 miles with small cracks densely packed with microbial life. These fissures were eventually sealed off by clay sediment, effectively isolating and preserving the microbial life at a very slow metabolic rate, without significant evolutionary changes.