(ORDO NEWS) — Microbial life already existed on Earth no later than 3.75 million years ago, a new study indicates. These results challenge traditional ideas about the dating of the origin of life.
In this study, a team led by Dr. Dominic Papineau of University College London, United Kingdom, analyzed a fist-sized rock from Quebec, Canada, estimated to be between 3.75 and 4.28 billion years old.
In an early paper published in the journal Nature, the team found tiny fibers, knots and tubes in the rock that could have been formed by bacteria.
However, not all scientists agree that these structures – which are 300 million years older than the first ancient structures indicative of life – have a biological origin.
Now, after extensive and deeper analysis of the rocks, the team has discovered a much larger and more complex structure – a stem with parallel branches on one side, measuring about one centimeter in length – as well as hundreds of flattened spheres, or ellipsoids, in addition to tubes and fibers.
The researchers say that while some of the structures they discovered may indeed have been formed by random chemical reactions, this “stem with parallel branches” resembling a tree is likely biological in origin, as scientists have not yet encountered a similar structure formed as a result of the flow of only chemical processes.
The team also describes possible ways for bacteria to obtain energy. Researchers have found mineralized chemical by-products in this rock that are consistent with the metabolism of ancient microbes that produce iron, sulfur and possibly carbon dioxide and light in a process that is a form of photosynthesis that does not use light.
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