Ancient fossils in Greenland suggest evidence for microbial life from 3.7 billion years ago

Melting snow in Greenland has unveiled what might be the world’s oldest fossils. On the newly exposed, 3.7 billion-year-old rock, researchers led by Allen Nutman of the University of Wollongong found conical geological formations called stromatolites (see dotted lines), deposits made by ancient microbial life (Nature 2016, DOI: 10.1038/nature19355). If confirmed, this finding—characterized by trace element, mineral chemistry, and other analyses—pushes back the geological evidence for life by 200 million years. At the time, our planet was being bombarded by asteroids and comets—not particularly hospitable for life. Yet, Nutman tells C&EN, this work confirms what geneticists have long argued: that life did exist during that era.