3.5 billion-year-old rock structures are one of the oldest signs of life on Earth, Scientists discover in a New Study

Layered rocks located in Western Australia have been discovered to be one of the earliest known signs of life on Earth. These rocks contained fossils known as stromatolites which were formed as a result of the excretions of photosynthetic microbes. Scientists were amazed by the existence of these fossils in the layered rocks.

The older stromatolites discovered in the rocks were traced back to 3.43 billion years ago. However, further studies enabled scientists to discover the oldest fossils which were traced back to around 3.48 billion years. These rocks located in western Australia have most traces of organic matter in older stromatolites erased due to billions of years of existence.

However, the absence of organic matter in these oldest stromatolites made scientists wonder if they were truly formed by microbes or by other geological means. These stromatolites were discovered to be in the Dresser Formation of the layered rocks. After conducting this recent study, scientists concluded that the presence of stromatolites is evidence of ancient life. Keyron Hickman-Lewis, who served as a paleontologist at the Natural History Museum in London led other scientists to arrive at a satisfactory conclusion after conducting the research.

“We were able to find certain specific microstructures within particular layers of these rocks that are strongly indicative of biological processes,” said Keyron Hickman-Lewis.

During an interview session with Live Science, Hickman-Lewis reveals that the recent discovery could help scientists in advancing the way we search for life on Mars. Scientists closely analyzed the rock samples and discovered that the Stromatolites are encrusted in iron oxide due to the reaction of iron with oxygen in the atmosphere. Based on our martian exploration, scientists have discovered that Mars’ terrain has similar oxidation. 

“Mars’ surface is similarly oxidized — thus the rusty orange color — but its rocks could hold similar structures left behind by ancient Martian life,” Hickman-Lewis said. 

How the scientists conducted the research

Hickman-Lewis and his team of scientists used rock samples containing stromatolites to conduct their study at the National Center for Scientific Research (CNRS) in France. These rocks samples were first discovered in 2000 in Western Australia. However, scientists had to wait until recently to find more fascinating stuff from the rocks.

Hickman-Lewis, co-author Frances Westall and other scientists used different high-resolution 2D and 3D imaging techniques to look closely into the layers of the stromatolite at a fine scale. Their observation unveiled the biological growth on the rocks samples. They also studied the uneven layers such as the little dome shapes that serve as evidence of photosynthesis.

Their further observation enabled them to see columnar structures that are present in modern stromatolites. These columnar structures are also discovered in a few spots around the world. Linda Kah, a sedimentologist and geochemist at the University of Tennessee who did not participate in the new study added all the structural clues together before sharing her thought with Live Science.

“Microbial mats give you layers that are uneven in their thickness and tend to be wrinkly or crinkly or go up and down on very small spatial scales,” Linda Kah told Live Science, “you end up with what looks like the characteristics of a microbial mat.” 

Scientists used the minerals contained in the stromatolites to conclude that the microbial mats may have been formed in a shallow lagoon fed by hydrothermal vents possibly linked to the ocean. The researchers published the outcome of this study in the journal Geology on Nov. 4.

Hickman-Lewis strongly believed that scientists could use the techniques deployed in this recent study to find evidence of life on Mars from the rock samples that will be transported back home from Mars in the future. What do you think about this scientific discovery?

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