About 99% of Earth is uninhabitable; in deep underground places with high pressure and temperature, even the toughest bacteria cannot survive. However, there are places where life thrives, from tiniest toughest bacteria to the largest elephant. Then there are places that are habitable but are devoid of life; lava flows are a great example, as is the space between microbes. A new paper looks at these uninhabited yet habitable areas and considers what we may learn as we search for life in the universe.
Life on Earth has taken millions of years to evolve to the state we see today and has invaded nearly every corner of the planet, except those places where the environment is so extreme that even the toughest extremophile cannot survive.
These regions include places like the Atacama Desert in Chile, one of the driest places on Earth, where rainfall is so rare that even microbial life struggles to survive. Similarly, parts of Antarctica's dry valleys feature subzero temperatures, minimal liquid water and high salinity in some soils, creating an environment hostile to most life forms. It raises interesting questions and perhaps poses limitations on life's ability to survive.
We can learn a lot from life on Earth as we hunt for life elsewhere in the universe. At the moment, there is just one place in the cosmos where we know life has evolved, Earth.
A paper recently authored by Charles S. Cockell from the University of Edinburgh and published in FEMS Microbiology Reviews explores what we might learn from the inhospitable places on Earth and how that might inform our search for extraterrestrial life. The paper discusses places where active microorganisms cannot be found; in particular, those places where the physical and chemical conditions are not far from areas that support life.
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