Scientists Split Open a 2-Billion-Year-Old Rock — What They Found Inside Was Just Incredible

Deep within the Earth in South Africa’s Bushveld Igneous Complex, a secret world had been exploding with aliveness for the past 2 billion years. The mysterious world thrived in the dark, remaining undetected, until quite recently, when the researchers from the University of Tokyo drilled down into the rocky bed and extracted rock samples. As they washed, flamed, and cracked the rocks, this ancient life unfolded like a doorway into the past. The results were documented in a paper published in Microbial Ecology.

The magma oozing from the mantle kept flowing in the upper crust, carving an intrusion that became solidified, like a layered cake, over time. For billions of years, these layers, stuffed with igneous rocks, remained intact on the surface, but within them, ancient microbes somehow managed to survive for thousands of years, staying alive as subterranean time capsules. Bushveld is one of the largest igneous layer deposits that holds as much as 70% of the world’s platinum within its bosom. It's only in the recent decade that scientists from the International Continental Scientific Drilling Program (ICDP) have initiated ultradeep drilling into the layers of the complex’s rocky outcrop, roughly the size of Ireland.

For this study, they dug about 49.2 feet into the ground and extracted a 30-centimetre-long rock core sample for studying in the laboratory. The rock was lodged inside tony fractures between the rocks, completely isolated from the outer world. The veins of the rock were tightly packed with clay minerals, which didn’t allow the microbes to escape from the rocks. As a result, these microorganisms became trapped in the rocks billions of years ago, until the scientists cracked them open in the lab. That’s when the ancient little organisms crawled out and revealed the entire backstory of life to the kind scientists of Tokyo.

According to the BBC Discover Wildlife, this is the “oldest known example of living microbes found in an ancient rock.” It is believed that the basement of oceanic and continental crust is typically dominated by igneous rocks. Microbiological studies involve extracting fluid samples from these rocks. But since basic extraction wasn’t possible in this case, researchers had to employ the “drill core method” to draw out the samples and then crack them open. The drill core sample of the mafic rock revealed thin slices whose veins were bubbling with ancient microbes.

“We didn’t know if 2-billion-year-old rocks were habitable,” Yohey Suzuki, lead author of the study, said in a press release. “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. By studying the DNA and genomes of microbes like these, we may be able to understand the evolution of very early life on Earth.”

The story of these billion-year-old microbes didn’t end here. As scientists investigated deeper and further, a stunning connection revealed itself between these microbes and the Red Planet. NASA’s Mars Reconnaissance Rover recently suggested that there is a probability that Mars rippled with water around 2 to 2.5 billion years ago. Then, the gradual thinning of the planet’s atmosphere caused this water to freeze, until nothing but a vast frozen desert was all that was left. But if the hypothesis about water turns out to be true, it implies that the planet once hosted conditions suitable for the survival of microbial life, just the way the newly-discovered microbes became trapped in South Africa’s rocks.