Japanese geologists have found deposits of organic rocks in the northeast of Canada, indicating that life should have existed on Earth at least four billion years ago, according to an article published in the journal Nature.
The first living organisms appeared on Earth during the Archaean era, and so far there is no generally accepted point of view about how and when life began. To date, there are several fossil evidence that microbes already existed in the primary ocean of the Earth about 3.4 billion years ago, but many scientists believe that life could have originated much earlier than this mark.
Three years ago, Japanese geologists found hints that life already existed on Earth about 3.7 billion years ago, studying samples of graphite from Greenland. Last year, scientists found the first unambiguous evidence of the existence of life in that era, and in 2015 they found in Australia the probable traces of life that inhabited the oceans of the Earth 4 billion years ago. Recently, British geologists have found hints of the existence of microbes living on Earth almost immediately after the birth of the planet, 4.28 billion years ago.
Akizumi Ishida from the University of Tokyo (Japan) and his colleagues, who discovered traces of life in Greenland, continued their excavations, trying to find other deposits of graphite, “molded” from the remains of the first living organisms on Earth.
These deposits scientists were looking for already well-developed technique, studying the structure, chemical and isotope composition of the oldest rocks of the Earth, formed on the most ancient continental platforms. As a rule, graphite of biogenic origin produces two things – a low proportion of “heavy” carbon-13 and a special structure of its grains, which includes many elements similar in shape and size to bacterial cells and archaea.
Such deposits of Isis and his supporters were found in the north-east of Canada, near the town of St. John’s, the capital of the island of Newfoundland. Inside the local rocks, formed about 3.95 billion years ago, scientists found many small voids containing graphite.
This discovery caused them to split about one hundred and fifty cobblestones from Newfoundland and to study in detail the isotopic composition of these inclusions and analyze their shape. In total, Japanese geologists found about three dozen graphite deposits, which corresponded to both, and their biological origin.
A large number of graphite samples allowed Isis and his colleagues to reveal some details of what the life that gave birth to them looked like and in what conditions it lived. For example, quite high proportions of yttrium and some other rare earth metals indicate that the first microbes of the Earth did not live in freshwater lakes, but in salt water. Today many scientists doubt this idea, pointing to the absence in the primary ocean of the Earth of many critical elements, such as boron or manganese, which were present in large numbers on land.
In addition, the low concentration of “heavy” carbon in these deposits indicates that these bacteria fed on hydrogen or pure organic matter, using their energy to convert carbon dioxide (CO2) molecules to carbon monoxide and use it to synthesize amino acids and other ” bricks of life. ”
This, in turn, confirms one of the popular theories today about what Luke (LUCA) looked like, a common ancestor of all living things living in the vicinity of underwater volcanoes or hydrothermal springs. Further excavation, as the Japanese researchers hope, will help to supplement his portrait with new details.