In Ethiopia, researchers have identified places without any life. The investigation in three bodies of water proves that there are water resources on earth in which no life is possible.
The research group led by Purificación López-García of the National Center for Scientific Research (CNRS) in Orsay, near Paris, therefore advises caution when astronomers interpret the existence of water on distant planets as an indication of life.
The lakes studied are located in Dallol, an area of volcanic activity in the north of the country, near the border with Eritrea. They are extreme places for various reasons, the researchers reported in October in the journal "Nature Ecology & Evolution":
However, scientists have recently reported that microorganisms can live there.
Protozoa blown on the sea surface
The researchers around López-García again took samples from the lakes and the surrounding area and examined them under the scanning electron microscope. Chemical and genetic analyzes were also part of the study.
According to López-García, the scientists found isolated genetic traces. However, these are probably contaminants. Based on the composition of the DNA, the team assumes that unicellular organisms were blown onto the surface of the lake or, despite numerous precautionary measures, entered the sample in the laboratory.
The researchers also found tiny mineral fragments that look like biological cells under the microscope, so-called biomorphs. "These mineral particles may have been interpreted in other studies as fossilized cells," said López-García, according to the news portal Plataforma SINC. In fact, it is dead material that forms spontaneously in saline solutions.
Extremophile life forms around the lakes
The environment of the lakes, on the other hand, presented itself to researchers as the habitat of surprisingly many single-celled organisms. Most of them were archaea or bacteria. All species were among the extremophiles, a group of living things that thrive under extreme conditions. Whether there are waters with similar conditions elsewhere on Earth leaves the scientists open.
"Our analysis shows that there are places on the earth's surface that are sterile, even though they contain liquid water," says López-García. "We would not expect to find life forms in a similar environment on other planets, at least not if their biochemistry is similar to that known on Earth."
