In the vast, arid expanse of the Atacama Desert in northern Chile, researchers have made a groundbreaking discovery: life thriving four meters beneath the surface.
Covering 105,000 square kilometers, the Atacama holds the title of the world's driest hot desert. Rainfall here is a rare event, sometimes absent for decades or even centuries.
In such a parched environment, only a few life forms can thrive—among them are the resilient South American gray fox and specialized bacteria in the saline soil.
Life Beneath the Surface
Despite its seemingly barren surface, recent findings reveal that the Atacama Desert harbors a rich underground microbial ecosystem.
Previously, microbial life was documented at a depth of 80 centimeters. Now, scientists from the University of Potsdam have discovered more extensive microbial communities at a depth of four meters in the desert’s Yungay valley.
These robust bacteria, part of a newly thriving biosphere, have adapted to extreme conditions similar to those found in the Arctic's icy landscapes and boiling hot springs. These microbes are salt-tolerant and do not require oxygen, enabling them to thrive deep beneath the desert floor.
The researchers collected soil samples from four meters deep and utilized advanced DNA extraction methods to isolate cells with intact membranes—a definitive sign of living organisms. While microbial life was confirmed near the surface in clay-rich soil, the discovery of actinobacteria at deeper levels suggests a complex, deep biosphere previously unrecognized.
Implications for Extraterrestrial Life
This ongoing research not only expands our understanding of Earth’s biospheres but also has implications for extraterrestrial life, particularly on Mars.
Like the Atacama, Mars features gypsum (calcium sulfate) deposits that could theoretically support life. The stable microbial community in the Atacama suggests that similar underground reservoirs on Mars might once have harbored—and could perhaps still harbor—microbial life.
Researchers speculate that ancient rivers might have once flowed through the Atacama, leaving behind gypsum from which the microbes now draw water, echoing potential past conditions on Mars.
"The stable microbial community beneath the Atacama Desert suggests that rivers might have once flowed there, now buried deep underground," the researchers noted.
"These microbes survive by extracting water from the abundant gypsum in the soil, a scenario that could parallel conditions beneath the Martian surface."
