For decades, the Atacama Desert was considered the most Mars-like place on Earth. So dry that some areas have not recorded rain for centuries. So hostile that the surface seems completely sterile.
Therefore, no one expected that the biggest surprise would not be above, but under the feet.
At more than four meters deep, an international team of scientists found something that contradicts decades of certainties: a community of living beings that has been adapting to the subsoil of the planet’s driest desert for at least 19,000 years.
The discovery, published in the journal PNAS Nexus, marks a before and after in the exploration of extreme ecosystems.
The desert where life seemed impossible
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The discovery occurred in the Yungay Valley, one of the driest regions of the Atacama Desert, in northern Chile. There, annual rainfall barely exceeds a millimeter and solar radiation is so intense that for years it was believed that not even microbes could survive.
However, when drilling into the subsoil, researchers led by Dirk Wagner, from the German Research Center for Geosciences (GFZ), found something unexpected: an active ecosystem, isolated from the outside, functioning slowly for thousands of years.
These are not isolated organisms or fossil remains. It is a living, organized and stable community.
The protagonists of the discovery are mainly actinobacteria, microorganisms known for their extraordinary resistance. These bacteria serve key functions: they break down organic matter, participate in nutrient cycling, and withstand extreme environments that would kill most life forms.
In the subsoil of the Atacama, they survive thanks to an unusual combination of factors: minerals such as gypsum and halite, tiny traces of moisture trapped in salts, more stable temperatures underground, insulation from surface radiation.
According to genetic and geochemical analyses, these bacteria would have colonized the area during a more humid climatic period, about 19,000 years ago, and managed to adapt when the desert became even more extreme.
How a community stays alive without water
The study revealed surprising adaptations. Some bacteria produce exopolysaccharides, molecules that act like microscopic sponges capable of retaining water for long periods. Others form protected microhabitats within the saline soil.
Symbiotic relationships were even detected with deep roots of desert plants, exchanging nutrients in an environment where practically nothing is left over.
They don’t survive quickly. They don’t grow easily. But they resist. And that, for biology, is perhaps even more impressive.
Why this discovery matters more than it seems
The discovery not only redefines the limits of life on Earth. It also has direct implications for astrobiology.
The Atacama Desert is one of the main Mars analogues used by NASA and other space agencies. If a community can survive under this soil for millennia, underground life on other planets is no longer a remote hypothesis.
Furthermore, these bacteria could have future applications in biotechnology, agriculture in arid environments and recovery of degraded soils.
For almost twenty thousand years they were there, invisible, functioning silently beneath one of the deadest places on the planet. Science has just reminded us of something uncomfortable and fascinating: life doesn’t always need ideal conditions. Sometimes, you just need time.
