Scientists have uncovered a community of microbes living in 2 billion-year-old rock, smashing the previous record of 100 million years. These ancient microbes are buried 15 meters (50 feet) underground in the Bushveld Igneous Complex of northeastern South Africa. They have been thriving in isolation, untouched by surface life for billions of years.
A GROUNDBREAKING DISCOVERY IN MICROBIAL EVOLUTION
These microbes have been cut off from external environmental influences for billions of years. This isolation makes the discovery extraordinary. Geomicrobiologist Yohey Suzuki of the University of Tokyo, who led the research, calls it “a very exciting discovery.”
Microbes in isolated underground habitats tend to evolve more slowly. This is due to the lack of pressures found in more populated environments. This gives scientists a unique window into microbial evolution, revealing secrets of life’s history on Earth.
CLUES FOR FINDING LIFE ON MARS
This discovery also hints at the possibility of finding similar microbial life on Mars. Scientists think underground pockets on the Red Planet may harbor microbes. These pockets are where water once existed. This could happen long after surface water evaporated. “By studying these ancient Earth microbes, we may unlock clues to the survival of microbes on Mars,” Suzuki explains.
NASA’s Perseverance rover is already gathering rocks on Mars. These rocks are around the same age as those from the South African formation. This fuels excitement about potential discoveries beyond Earth.
EXAMINING THE 2 BILLION-YEAR-OLD ROCK SAMPLE
The sample drilled from the Bushveld Igneous Complex was a massive 66,000 square kilometer (25,500 square mile) formation. It formed from molten magma cooling deep beneath Earth’s surface about 2 billion years ago. Researchers found a microbial community within. A detailed analysis is underway, including a DNA study, to understand how these ancient microbes have survived in isolation.
The team took a 30-centimeter (1-foot) core sample. They were assisted by the International Continental Scientific Drilling Program. The purpose was to search for signs of microbial life.
RULING OUT CONTAMINATION
Researchers wanted to ensure the microbes were indigenous. They aimed to avoid contamination. Therefore, they used a sterilization technique developed in recent years. They first sterilized the outer layer of the rock sample before slicing it for examination.
Next, they stained the slices with a cyanine dye that binds to DNA, allowing any microbial DNA to glow under infrared spectroscopy. The test revealed the presence of DNA, confirming the existence of ancient microbial life.
CLAY-PACKED VEINS PROVIDED SHELTER FOR MICROBES
The rock sample was filled with clay veins, located near the microbial colonies. This clay served multiple purposes: it provided essential organic and inorganic materials for the microbes to metabolize, and it effectively sealed the microbes in, preventing them from escaping and keeping contaminants, including the drilling fluid, from entering the rock.
IMPLICATIONS FOR EARTH’S HISTORY AND LIFE ON OTHER PLANETS
This discovery adds to our understanding of microbial evolution and the conditions that allow life to persist over billions of years. Studying the DNA of these microbes could shed light on the early evolution of life on Earth.
It also reinforces the belief that similar microbial communities could still exist on other planets, like Mars, surviving long after surface conditions became inhospitable. As NASA continues to collect samples, scientists are hopeful that Mars could yield evidence of microbial life.
