All life on Earth likely originated from a single spark in Earth’s early history. After some time, it diversified, branching into subspecies that helped it survive.
Exactly when these moments occurred was a point of contention in the scientific community, but it is new Research It indicates that both steps may have occurred earlier than we previously thought.
The studyled by researchers from University College London, is based on evidence of diverse microbial life inside a fist-sized piece of rock from Quebec in Canada, dating from about 3.75 billion to 4.28 billion years ago.
In 2017, the researchers who discovered it speculated that the structures in the rock — fine filaments, knobs and tubes — were left by ancient bacteria.
But not everyone was convinced that these structures – which would delay the date of the first signs of life on Earth by at least 300 million years – were biological in origin.
However, after more comprehensive analysis of the rock, the team discovered a structure that is larger and more complex than those previously identified. Within the rock was a stem-like structure with parallel branches on one side about a centimeter long, as well as hundreds of deformed balls, or ellipsoids, along with tubes and threads.
“This means that life could have started in as little as 300 million years after the Earth formed. Geologically speaking, that’s fast — about one rotation of the Sun around the galaxy,” Says the lead author of the studygeochemist Dominic Papineau of the University of California.
A key question posed by Papineau and colleagues was whether these structures could have formed through chemical reactions unrelated to living organisms.
According to the research paper, it was conceivable that some of the smaller structures were the product of abiotic reactions, however, the newly identified “tree-like” stem is likely biological in origin, as there is no such structure, created through chemical reactions alone. It has been found before.
In addition to the structures, the researchers identified mineral chemicals in the rocks that could be byproducts of different types of metabolic processes.
The chemicals are consistent with energy extraction processes in bacteria that would have included iron and sulfur; Depending on the interpretation of the chemical signatures, there could be hints of a version of photosynthesis.
This discovery points to the possibility that the early Earth – only 300 million years after its formation – was inhabited by an array of microbial life.
The rocks were analyzed by a combination of optical observations through Raman microscopes (which use light scattering to determine chemical structures), and digitally recreated sections of the rock using a supercomputer that processed thousands of images from two high-resolution imaging techniques.
The rock fragment in question was collected by Papineau in 2008 from the Nuvvuagittuq Supracrustal Belt (NSB) in Quebec, which was once part of the sea floor. The NSB contains some of the oldest known sedimentary rocks on Earth. The rocks laden with the fossils were also analyzed for levels of rare earth elements, as the researchers found that they did indeed contain the same levels as other ancient rock samples, confirming that they were as old as the surrounding igneous rocks.
Prior to this discovery, the oldest fossil evidence of life was found in Western Australia, dating back 3.46 billion years. However, there is similar disagreement as to whether these fossils were biological in origin.
Perhaps the most exciting implications of this discovery are what it means for the possible distribution of life in the universe. If life was able to evolve and evolve in the extreme conditions of the very early Earth, it could be more common throughout the universe than we think.
“This discovery means that only a few hundred million years are needed for life to evolve to an orderly level on a primitive, habitable planet.” Name the authors of the paper.
“We therefore conclude that such microbial ecosystems can exist on other planetary surfaces where liquid water interacts with igneous rocks, and that the oldest of these microfossils and double fossils reported here from the NSB suggest that extraterrestrial life may be more widespread than Previously thought.”
The study was published in the journal science progress.
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