Scientists have long wondered when life began on Earth. The oldest fossil evidence had previously been dated to around 3.5 billion years, but a more recent discovery could set that timeline back by another 220 million years.
A group of researchers led by Australia's University of Wollongong made the initial find about four years ago in an ancient section of Greenland rock called the Isua supracrustal belt.
According to New Scientist, the team eventually determined that the structures appear to indicate the prior existence of 3.7 billion-year-old marine microbes which they believe resemble modern stromatolites.
Clark Friend, one of the authors of a recently published paper on the fossils, argues that their research pushes "the discovery of life earlier in Earth's history." He also questions the implications for extraterrestrial life, as the approximate date aligns with a time when Mars may have been wet.
However, critics have pointed out that none of microbes themselves have been preserved and that additional research needs to be done to rule out interference from other geological processes.