American and Australian researchers have discovered the most ancient objects of biological origin. They are petrified bacterial mats (biocenoses) up to 3.5 billion years old. The finds were made in the western part of Australia and in their structure resemble modern bacterial mats.
Discovered by specialists in geobiology, the layer formed by microorganisms in the rock mass is about 3.48 billion years old, which is more noticeable than the previous similar finding, which allowed us to state that life on the planet appeared no later than 3.2 billion years ago.
The area in western Australia where researchers worked, the Dresser geological formation, was previously known as the place with the most ancient sedimentary rocks. Even older rocks are exclusively volcanic in origin.
In addition to interlayers left by bacteria, scientists discovered a number of other structures. In his article for the journal Astrobiology, the researchers described films covering stones, petrified gas bubbles and multilayer deposits. A chemical analysis of the samples was also carried out, which, like the method of comparison with modern bacterial mats, proves the biological origin of the find.
A beam with a specific wavelength was transmitted through the samples, which scatters on contact with the test substance. This spectral analysis, performed by Raman spectroscopy, revealed the presence of carbon and hydrogen in samples in quantities that exclude the abiogenic (occurrence of life as a result of the interaction of non-living substances) the origin of the structures.
Researchers believe that geothermal sources, which operated 3.5 billion years ago, could resemble similar sources on Mars. For this reason, scientists write, the discovery is interesting in the context of studying not only the past of the Earth, but also the geological history of the red planet.
In paleontology, the definition of bacterial mats is commonly understood to be thick layers formed by microbes on the surface of a rock, and such structures often have several layers. In its upper part, aerobic organisms settle (organisms for which oxygen is needed), and at the bottom, where access to oxygen is limited, anaerobic bacteria live (organisms that receive energy in the absence of oxygen by substrate phosphorylation). More simple and thin layers are called biofilms; Biofilms (a multitude of microorganisms located on some surface, the cells of which are attached to each other) are formed not only on inorganic objects, but can also be formed by pathogenic microbes in the human body.
Based on materials from Lenta.ru
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