Courtesy of E. Grosch/Univ. of Bergen
Some of Earth's earliest life-forms were thought to have left their mark roughly 3.45 billion years ago in minerals found in what is now the Barberton greenstone belt of South Africa. However, the minerals formed closer to 2.9 billion years ago, and the microstructures within them were not created by early microorganisms, scientists argue May 26 in the Proceedings of the National Academy of Sciences. The results suggest that scientists will have to search for a different set of signatures of early life on Earth and also on other planets.