Fossils recently discovered in Greenland have the potential to revolutionize our knowledge of the earliest known forms of life on Earth. Disappointingly for some, the 3.7-billion-year-old fossils weren’t made by any strange proto-organisms themselves, but instead are impressions of mineral deposits created by some of the earliest known microorganisms on the planet.
According to new research published in Nature, these fossils confirm other genetics-based estimates made about the earliest life on Earth:
[The discovery of these fossils] demonstrates the establishment of shallow marine carbonate production with biotic CO2 sequestration by 3,700 million years ago (Ma), near the start of Earth’s sedimentary record. A sophistication of life by 3,700 Ma is in accord with genetic molecular clock studies placing life’s origin in the Hadean eon (>4,000 Ma)6.
The fossils were discovered by a team of archeologists based out of the University of Wollongong in Australia who were digging for fossils in the remote Isua Greenstone Belt region of Greenland close to the Arctic Circle.
According to a press release issued by the university, these fossils show that complex life existed long before scientists previously estimated, and much closer to the creation of our planet than was theorized:
This indicates that as long as 3.7 billion years ago microbial life was already diverse. 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.
The fossils were created by stromatolites, or tiny layers of mineral sediments created in shallow waters by film-like microorganisms like cyanobacteria. Stromatolites form in mineral-rich waters and are left behind as the microorganisms that formed them either die off or grow upwards, creating new layers. They are an interesting subject of study in that they are some of the only evidence of microorganisms that is visible with the naked eye.
According to the researchers behind this discovery, the presence of life in such ancient rocks could mean that similar evidence might be found in Mars rocks formed during the same time period. Current theories about Mars contend that the red planet was warmer and wetter around 3.7 billion years ago just like Earth was, meaning similar microorganisms might have thrived there around the same time.