A new discovery by researchers at Australia’s University of Wollongong points to what could be the earliest existence of life on Earth.
Researchers uncovered fossils that date as far back as 3.7 billion years—the world’s oldest—in the rocks of the remote Isua Greenstone Belt in Greenland.
If confirmed, these fossils will outdate what was once considered the earliest evidence of life on Earth by about 220 million years.
The structures, which range between one and four centimeters tall, are believed to have been formed by stramolites, which are layered formations that are created through microbes typically found within shallow waters. The discovery came as a shock to researchers, since Isua’s rocks typically undergo intense heat and pressure conditions, often destroying any evidence of fossils or sedimentary layers.
The researchers were able to spot an outcrop within the area that was visible after a snow patch had melted, revealing the structures.
The Isua Greenstone Belt is a crucial region for geoscience, as it is hosts the oldest surviving surface of Earth. It is situated along the edge of Greenland’s ice cap, and has been the sight of a rich geological history, hosting evidence of tectonic plate processes.
The researchers are still in the process of studying the nature of the structures, but if their discovery does point to microbes, it could provide crucial information for understanding not just life on Earth, but also on other planets. According to Professor Martin Van Kranendonk, director of the Australian Center for Astrobiology, the discovery could point to similar life structures on Mars considering the damp environment it hosted 3.7 billion years ago.
However, while researchers are pointing to microbes as the cause of formation for these structures, there are critics who doubt that this may be the case.
“It is completely plausible that we could find stromatolites in rocks of Isua age, and perhaps even older, because available evidence suggests that the Earth’s surface at that time already had conditions suitable for microbial life,” said Robert Riding of the University of Tennessee in an interview with The Guardian. “We just need to find well-preserved sediments of that age to really be sure.”
Talia Avakian is a digital reporter at Travel + Leisure. Follow her on Twitter at @TaliaAvak.