Fossils Dating Back 3.7 Billion Years Could Be Evidence For Oldest Life On Earth

When did life arise and impact Earth’s chemical cycles? This is a key question in the planet’s evolution as biological activity plays a major role in its hydrosphere, atmosphere and lithosphere. In what is being described as an “extraordinary find,” a team of Australian researchers has uncovered ancient fossils in a remote area of Greenland that could point to the earliest existence of life on Earth.

The researchers led by the University of Wollongong’s (UOW) professor Allen Nutman discovered 3.7 billion-year-old stromatolite fossils in the world’s oldest sedimentary rocks located in the Isua Greenstone Belt along the edge of Greenland’s ice cap. The latest findings, published in a study that appeared in the journal Nature on Wednesday, are also expected to help scientists better understand the possibility of life on Mars.

The Isua stromatolite fossils were exposed by the recent melting of a perennial snow patch. They were found lying down in shallow sea, which, according to researchers, could provide the first evidence of an environment where early life might have thrived near the start of Earth’s geological record.

Stromatolite fossils not only “provide obvious evidence of ancient life that is visible with the naked eye, but that they are complex ecosystems,” Nutman said in a statement, adding that the newly discovered fossils are about 220 million years older than the world’s previous oldest stromatolite fossils that were found in Western Australia in 2006.

The newly found structures, according to researchers, are tiny bumps with their shapes and internal layering strongly resembling both ancient and modern stromatolites. In addition, the surrounding rocks also contain carbonate minerals such as dolomite that are common in younger stromatolites.

The new findings indicate that “as long as 3.7 billion years ago microbial life was already diverse,” Nutman added. “This diversity shows that life emerged within the first few hundred millions years of Earth’s existence, which is in keeping with biologists’ calculations showing the great antiquity of life’s genetic code.”

In addition to providing a new perspective into the history of Earth, the discovery is also expected to provide significant insights into the study of planetary habitability. The researchers believe that the Isua stromatolite fossils could point to similar life structures on Mars, which had a damp environment 3.7 billion years ago.

“This discovery represents a new benchmark for the oldest preserved evidence of life on Earth. It points to a rapid emergence of life on Earth and supports the search for life in similarly ancient rocks on Mars,” Martin Van Kranendonk, a professor at the University of New South Wales and a co-author of the study, said in a statement.