Discovered in the mountains of Australia fragments of graphite, whose age is estimated at more than 3.5 billion years, are the remains of ancient archaea. Thus, scientists have new evidence that life existed on Earth from very ancient times.
Three and a half billion years ago the Earth was not as it is now — in particular, its atmosphere was not rich in oxygen and would be unsuitable for many modern creatures. However, it is assumed that then, and probably even earlier the planet was inhabited by microorganisms. However, to find evidence to prove the existence of such ancient forms of life quite difficult.
In the new study a team of scientists led by John Whalley of the University of Wisconsin in Madison have thoroughly studied the isotopic and chemical composition orogeny graphite in Australian sediments. As it turned out, the proportion of certain isotopes of carbon in them is typical for graphite, having a biological origin. We are talking about atoms of carbon-12 and carbon-13.
Continuing to compare inorganic sediments and the presumed remains of ancient microbes, scientists have managed to restore a picture of course of their metabolism. Apparently, the main source of energy for them was the methane, which is the period of Earth’s history were present in the atmosphere in abundance.
According to scientists, the results of their study suggest the presence of ancient archaea, that is living beings that are neither bacteria nor eukaryotes (this domain includes, including animals and plants). If the existence of such ancient bacteria experts suspected before, but archaea, as was supposed, until recently, appeared on Earth 2.7 billion years ago.
The study was published in the journal Proceedings of the National Academy of Sciences.
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