2-billion-year-old rock harbors living microbes, rewrites life’s history

Microbiologists have made a groundbreaking discovery in a 2-billion-year-old rock located in northeastern South Africa. This incredibly ancient rock was not only habitable but still contained living microbes within its “sealed fractures,” as per a recent press release.

“It is the oldest example of living microbes being found within ancient rock so far discovered,” it said.

Remarkably, these ancient life forms could hold the key to understanding life in the far reaches of the universe, particularly in rock samples retrieved from Mars. The search for extraterrestrial life continues, and this discovery fuels our curiosity.

“By studying the DNA and genomes of microbes like these, we may be able to understand the evolution of very early life on Earth,” Yohey Suzuki, lead author from the University of Tokyo, said.

Analyzing 2-billion-year-old rock

In a new study published in Microbial Ecology , microbiologists focused their research on the Bushveld Igneous Complex in northeastern South Africa. This geological formation originated from magma cooling beneath the Earth’s surface and is renowned for its abundant ore deposits, including 70% of the world’s mined platinum.

The immense age of this geological wonder intrigued the researchers from the University of Tokyo. They were uncertain if the 2-billion-year-old rock could harbor life and embarked on a mission to uncover the truth.

To conduct this revolutionary work, the team had to perfect a technique involving three types of imaging: infrared spectroscopy, electron microscopy, and fluorescent microscopy. Their first step was to obtain a sample.

Drilling 15 meters or 49 feet into the ground, they retrieved a 30-centimeter-long rock sample. To prevent contamination, Suzuki drew inspiration from the techniques pathologists use to prepare thin tissue samples for disease diagnosis, building on his previous work where his team discovered microbes in rock beneath the seafloor.

He coated the rock in “a special epoxy” to prevent it from crumbling during slicing. Then, he washed the thin sections in a special dye that stained the DNA of the microbial cells. Using infrared spectroscopy, a chemical analysis technique, they discovered that the microbes were densely packed within the cracks. The surrounding clay had prevented them from spreading or interacting with other substances.

Could these microbes be living on other planets?

“Deep in the earth lies something ancient and alive,” states the press release. Miraculously, these microbes survived and were preserved within the rock. The rock’s unchanging formation provided a stable habitat for these ancient microbes to thrive for two billion years.

Lead author Yohey Suzuki previously analyzed the oldest geological layer ever found on the ocean floor, dating back 100 million years. However, this new sample offers a glimpse into a much more distant past – two billion years ago. This raises the tantalizing question: could life beyond Earth exist within the cracks of ancient rock ?

“I am very interested in the existence of subsurface microbes not only on Earth but also the potential to find them on other planets,” Suzuki concluded in the press release .

“NASA’s Mars rover Perseverance is currently due to bring back rocks that are a similar age to those we used in this study. Finding microbial life in samples from Earth from 2 billion years ago and being able to confirm their authenticity accurately makes me excited for what we might be able to now find in samples from Mars .”

The study was just published in Microbial Ecology .