Scientists have discovered fossils in the Isua Greenstone Belt in Southwestern Greenland that they claim could be the oldest signs of life on Earth.
At 3.7 billion years old, the fossils could support the theory that life on Earth started immediately after the birth of the planet.
"Here we report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in the ISB that contain 1–4-cm-high stromatolites — macroscopically layered structures produced by microbial communities," the researchers reported in their study, which was published in the journal Nature on Aug. 31.
The ancient remains contain evidence of stromatolite, a mineral structure formed by a number of microorganisms. The Isua stromatolites have tiny cones and were just between 1 and 4 centimeters tall. The structures and internal layering of the fossils also look like other ancient and modern stromatolites.
The texture of the surrounding rocks hints that the stromatolites were laid down at the bottom of a shallow sea, providing the first evidence of an environment where early life thrived.
If its age is confirmed, the newfound remains could push back the origins of life by 220 million years. Prior to this discovery, the oldest evidence of life were fossil stromatolites that were discovered in Western Australia and were dated to be 3.48 billion years old.
The current estimated age of the newfound fossils suggests that they formed toward the end of the Late Heavy Bombardment, the period when the newly formed Earth was continually pounded by asteroids and comets. Scientists still debate if it would have been possible for life to form on Earth during this period.
It is also possible that the microorganisms crept in just after the bombardment ended. If this is true, it suggests that life may have evolved in just 100 million years, which is much faster than previously believed.
The age of the fossils suggests that a planetary neighbor may have also supported life at some point because planet Mars is believed to have been very similar to our planet during the Late Heavy Bombardment period, which could mean that the Red Planet may have also generated life during this time.
"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," said study researcher Martin Van Kranendonk, from the University of Wollongong in Australia.
