cientists have discovered that in a geothermal region of Earth, the environmental conditions are so harsh that they can not sustain any form of life, despite previous research that could have indicated otherwise. The study could be relevant for determining the limiting conditions of life even where there is liquid water. It is one of the harshest environments on Earth, namely the Dallol geothermal region, an extremely hot, salty, and acidic one.
The ponds stretch along a volcanic crater located in the Danakil Depression in Ethiopia, where daytime temperatures exceed 45 degrees Celsius even in winter. Some of the hyperacid salt ponds have extremely negative pH values. After a series of tests, researchers found that there is no life in the ponds, not even microorganisms. The findings were published in the journal Nature Ecology & Evolution.
“After conducting analyzes on a much larger number of samples than in previous research, we were able to confirm that there is no microbial life in these hot, hyperacid, and saline basins, nor in the adjacent magnesium-rich salt lakes, called Black and Yellow Lakes,” said the study’s author, Purificación López García, a biologist at the French National Center for Scientific Research.
Further research shows otherwise
On the contrary, in the desert areas and in the salt canyons around the geothermal region, there is life in the form of a diversity of primitive microorganisms (halophiles from the archaea group) to which the saline environment is friendly. Wind and visitors spread a wide variety of microbes to the Danakil Depression ponds and lakes — but it remains lifeless, scientists say, who came to this conclusion after several types of tests: mass sequencing of genetic markers.
In order to identify potential microorganisms, microbial cultures, cytometry for the detection of individual cells, chemical analysis of saline water, as well as electron microscopy in combination with X-ray spectroscopy.
The tests allowed them to differentiate between genuine microbial cells and silicon-rich mineral particles that could mimic them, as the latter could be “interpreted as fossilized cells, when in fact they form spontaneously in saline even in the absence of any form of life, ”said López García.
Researchers have typically used evidence of life in extreme environments on Earth as a reference point to identify similar environmental conditions that could support life on planets in or beyond our solar system. But researchers warn that in this case, where we have an extreme environment that could only be seemingly unfavorable to life, given that there is liquid water or where we find something that looks like cells or something biological, this way of proceeding by analogy does not stand.
“Our study shows that there are places on Earth like these Dallol basins that are sterile despite the presence of liquid water,” said the study’s author, explaining that life is not possible in these basins, as there are chemical barriers such as chaotropic magnesium salts that contribute to the decomposition of hydrogen. Their combination with the salty, acidic, and hot environment makes life unbearable.
“We do not expect to discover on other planets life forms that survive in similar environments, or at least not if we are dealing with biochemistry similar to the terrestrial one,” concluded López García.
This place seems incredible as we believe that our planet represents life and evolution, and without life, evolution cannot take place. If López García is correct in his research, we can look at our planet from a very different perspective, a more cruel perspective that shows the unforgiving side of life and humanity.