Microorganisms have been discovered thriving in microscopic cracks within a 2-billion-year-old rock in South Africa, marking the oldest known instance of life found within geological formations. This groundbreaking finding may provide new perspectives on the origins of life on Earth and could inform the ongoing search for extraterrestrial life.
Researchers have long known that resilient microorganisms can survive deep within the Earth’s crust, far removed from sunlight, oxygen, and food sources. These slow-growing microbes can divide at an incredibly slow rate, sometimes taking thousands to millions of years to reproduce.
The team has pushed the record back nearly 2 billion years, as they obtained a 30-centimeter-long cylindrical rock core from 15 meters beneath the surface of the Bushveld Igneous Complex, a vast volcanic formation. Upon examination, they found living microbial cells in the rock’s tiny fractures.
To confirm the presence of the indigenous microbes, the team stained their DNA and utilized scanning electron microscopy and fluorescent microscopy. They verified that the cell walls of the microbes were intact, indicating that these cells were alive and active.
The researchers hypothesize that the microorganisms were introduced to the rock through water shortly after its formation. Over time, clay accumulation may have supplied the necessary nutrients for their survival.
This discovery sheds light on primitive microbial life, with the team now looking to extract and analyze the DNA to further understand these ancient organisms. Insights gained could reveal characteristics of Earth’s earliest life forms and illustrate how life evolved over billions of years.
Additionally, the implications of this study extend to astrobiology. The rock formations in the Bushveld Igneous Complex share similarities with Martian rocks, particularly in age, suggesting the possibility of similar microbial persistence beneath the surface of Mars. Employing the same techniques to differentiate between contaminant and indigenous microbes in Martian samples could enhance the search for life on the Red Planet.
This research underscores the importance of deep subsurface environments as potential reservoirs for microbial life. However, the timing of when these microorganisms colonized the rock, post-crack formation, remains an area for further investigation.
