Oldest Living Microbes Found in 2-Billion-Year-Old Rock: How They Survived for Millennia

Ancient living forms have long captivated scientists, but a recent finding has elevated this intrigue to new heights. Researchers from the University of Tokyo have revealed living bacteria within a rock sample that dates back 2 billion years, making them the oldest known living organisms found in such conditions. This revolutionary revelation not only sheds insight on the endurance of microbial life but also asks fundamental concerns about the evolution of life on Earth and the potential for similar findings on other worlds.

The Discovery of Ancient Microbes

The bacteria were found in a sealed fracture of a sample of rock that was extracted from South Africa’s Bushveld Igneous Complex. Due to its geological stability and abundant mineral reserves, this region has gained notoriety since its formation. A 30-centimeter-long core sample that the scientists extracted after drilling about 15 meters below the surface showed pockets of microbial life tightly packed within the fissures in the rock. The researchers applied modern imaging techniques—electron microscopy, fluorescence microscopy, and infrared spectroscopy—to demonstrate that these bacteria were indigenous to the rock and not pollutants from the drilling procedure.

The study’s lead author, Dr. Yohey Suzuki, expressed enthusiasm about the ramifications of this finding, saying, “We didn’t know if rocks that were two billion years old were livable… It is possible that we can comprehend the evolution of really early life on Earth by examining the DNA and genomes of bacteria such as these. With the publication of the results in Microbial Ecology, our knowledge of extinct life forms has advanced significantly.

How Did They Survive?

These ancient bacteria’ special home within the Bushveld Igneous Complex is responsible for their survival. Because of the geological formation, microbial life has been able to survive for billions of years in an environment where volcanic magma has cooled slowly. These organisms were able to live in isolated areas free from outside influences thanks to the microscopic fractures in the rock. The spaces around these cracks were gradually filled in by clay sediment, which successfully trapped the microorganisms inside and shielded them from potential contamination and outside evolutionary pressures.

These creatures have been able to sustain an extremely slow metabolic rate and evolve at an exceptionally slow pace thanks to their extraordinary stability. Because of this, they haven’t evolved in eons, giving scientists a unique window into the earliest phases of life on Earth. Furthermore, this finding opens up fascinating new avenues for research into planets beyond our own. Hopes for discovering ancient microbial life on Mars were sparked by Dr. Suzuki’s observation that “NASA’s Mars rover Perseverance is currently due to bring back rocks that are a similar age to those we used in this study.”

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