New research describes the complex structures of rocks from Quebec, Canada, which are estimated to be between 3.75 and 4.28 billion years old and of possible organic origin.
The structures found in Canada are more than 200 to 700 million years older than the oldest pre-fossils of microbes found in Australia, where they formed only 100 to 300 million years after conditions on Earth became favorable for life.
Finding the oldest fossils on Earth
Researchers discovered the structures in iron-rich and silica-rich sediments deposited near hydrothermal vents on the former sea floor, and as the ocean closed, the oceanic crust was lifted, merging with the continental core of what is now the Canadian Shield.
While some structures can be formed through chemical reactions by chance, their general complexity indicates that they are likely biological in origin, as no structure created by chemistry alone has been found.
The most complex of microfossils consists of a stem with parallel branches on one side about one centimeter long, others resembling deformed tubes and filaments. These new findings suggest that a variety of microbial life may have existed on the primitive Earth.
Interpreting the structures as the remains of past life forms is not new, but the study provides new geological evidence to support this hypothesis. The sulfur and carbon dioxide helped maintain growth and reproduction, and the microbial waste formed small nodules of hematite, the iron oxide that gives rocks their red colour, in the sediments, and hematite nodules are very similar to the concrete materials that are still formed to this day by Iron-eating microbes live on the sea floor, and they still contain traces of organic carbon.
Is there life outside Earth?
“Using many different evidence, our study strongly suggests that a number of different bacteria species existed on Earth between 3.75 and 4.28 billion years ago,” said study lead author Dr. Dominique Papineau.
“This means that life may have started in less than 300 million years after the formation of the Earth, and geologically speaking, that’s fast, about one rotation of the sun around the galaxy.”
“These findings have implications for the possibility of extraterrestrial life. If life is relatively fast, under the right conditions, this increases the chance of life on other planets.”
Source: Forbes