Life on Earth could have originated not in the depths of the ocean, but in water bodies on land. This is evidenced by the traces of the vital activity of bacteria found by scientists in geyserite deposits aged 3.48 billion years.
Scientists have found the oldest traces of life on Earth in hot springs in Western Australia. The find will help answer one of the most important questions of evolutionary biology - whether life originated deep in the ocean or in water bodies on land. The research results were published in the journal Nature Communications.
The age of the found fossils is 3.48 billion years, which makes Darwin's assumption about the origin of life on the ground more weighty.
The find not only proves that microbes lived in hot springs much earlier than previously thought, but is also the oldest evidence of microbial life on land in general - previously found in Africa, their age was 2.7-2.9 billion years …
Tara Jokic of the University of New South Wales and her colleagues studied the surprisingly well-preserved deposits of the ancient Dresser Formation on the Pilbara Craton (an area of the earth's crust that has not changed since the Archean) in Western Australia. These deposits were previously classified as marine remains, but new evidence suggests these findings were incorrect.
“Our results not only shift the time when life appeared in hot springs by 3 billion years ago, but also show that life generally originated earlier than previously thought, by about 580 million years. This may influence hypotheses about the origin of life on Earth,”says the researcher.
The Dresser Formation contains geyserite, aka siliceous tuff, a hard, porous rock composed of opal, according to a study by Jokic and her team. Geyserite can be found at the outlets of hot springs and geysers containing dissolved silica.
Earlier, the oldest geyserite deposit was discovered in rocks 400 million years old. The age of the new find is 3.48 billion years.
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This means that life could have originated in ancient sources on land.
This version is also supported by the two types of stormatolites found in the sediments, the waste products of cyanobacteria. Also, the sediments retained traces of bubbles, which could have been previously filled with a substance produced by microorganisms.
American Association for the Advancement of Science (AAAS) / Eurekalert.org
All of the finds paint a picture of an ancient crater filled with hot mineral springs that provided the chemical and thermal conditions for primitive life forms billions of years ago. The results of the study can also be useful when looking for signs of life on other planets - for example, traces of hot springs are also preserved on Mars.
“The results suggest that at a very early stage in the development of life on Earth, there may have been a variety of life forms in fresh water,” explains team member Martin van Kranendok. "The deposits in Pilbara are similar in age to the crust of Mars, making the remains of the hot springs of the Red Planet an exciting target for the search for traces of life."
The evidence based on the study of such finds depends largely on interpretation, but if such signs of the origin of life in terrestrial reservoirs can be found, this will support the hypothesis of terrestrial origin of life.
Alla Salkova
