Hidden beneath our feet, kilometers underground, life has been existing for billions of years. A recent discovery may reshape our understanding of the origins of life on Earth.
Japanese researchers have revealed the existence of living microbes trapped in a 2-billion-year-old rock, an unexpected finding from the Bushveld Igneous Complex in South Africa.
Appearance of the well core sample studied and visual inspection of contamination by drilling fluid.
- A: Photos of the core sample.
- B: Photos after opening the fractures.
- C: Rock fragment collected for further analysis without UV lighting.
- D: Rock fragment with UV lighting.
- E: Fracture surface without UV lighting.
- F: Fracture surface with UV lighting.
The yellow arrows in B and C point to the fracture, and the yellow rectangle in E shows the area visible in F. This rock, extracted 50 feet (15 meters) underground, housed incredibly ancient microorganisms. They are 1.9 billion years older than previous records. It is the first time life forms this ancient have been identified in such stable conditions.
The Bushveld Complex, rich in platinum and other metals, provides a unique environment. Due to its geological stability, microcracks in these rocks have preserved intact microbial colonies. Using new imaging techniques, scientists confirmed these microbes were not recent contaminations. They ensured their authenticity by carefully analyzing their habitat and proteins.
This discovery could shed light on the early stages of life's evolution on Earth. The stability of underground environments could have allowed these microorganisms to survive without major mutations for millions of years.
The implications extend beyond our planet. Researchers hope samples collected from Mars by the Perseverance mission could reveal similar life forms, further advancing the search for extraterrestrial life.
Visualization of microbial cells after SYBR Green I dye staining.
- A: Fluorescent microscopic images of a wide area.
- B: Images of a small area.
The pink arrows in A point toward the veins.
Yohey Suzuki, the study's lead author, expressed his excitement. This major breakthrough opens a new era in the understanding of underground worlds and their potential to harbor life. Earth's hidden history may also be the story of other planets. The search for ancient life is just beginning.
How can microbes survive for billions of years underground?
The microbes found in billion-year-old rocks survive due to metabolic slowdown mechanisms. Their biological activity is very low, enabling them to subsist with minimal resources. This lifestyle is often described as “life in slow motion,” comparable to a form of hibernation.
Deep underground, these microbes feed on resources in their immediate environment, such as organic and inorganic compounds contained within clay. This isolation, combined with stable geological conditions, prevents their degradation, allowing them to survive for extreme durations.
What is the Bushveld Igneous Complex?
The Bushveld Igneous Complex (BIC) is a massive geological formation in South Africa, formed around 2 billion years ago. It was created when molten magma slowly cooled beneath the Earth's surface. Covering an area of 25,500 square miles (66,000 km²), it contains a large concentration of valuable metals, including about 70% of the world's platinum.
Due to its geological stability over time, the Bushveld Igneous Complex has allowed the preservation of ancient microorganisms in rock fractures. This site has become a prime location for studying primitive life forms and the biological evolution of the Earth.
Author of the article: Cédric DEPOND