Early “Fossils” Formed by Tectonics, not Life

The 3.7-billion-year-old structures were considered the first evidence for life on the planet; new evidence suggests differently.

Image courtesy of Abigail Allwood, Jet Propulsion Laboratory, California Institute of Technology (see “Publications”)

The Science

Scientists re-examined early “fossils.” They found the structures to be of geological, not biological, origin.

The Impact

Dating the beginnings of life on Earth has major implications for understanding how life emerged and evolved. Also, it has implications for the search for life on Mars and other planets.

Summary

Scientists re-evaluated evidence of life in 3.7-billion-year-old rock structures and found that the structures were of geological origin and not—as previously thought—of biological origin. Until this study, the structures were considered the earliest evidence for life on Earth. Previous studies on these rock samples employed millimeter-scale information using laser ablation analysis to determine the origin of the formations. For this study, the team of scientists used micrometer X-ray florescence analysis at the National Synchrotron Light Source II. Using the Submicron Resolution X-ray Beamline, they revealed crucial new evidence based on the elemental make-up of the rock structures. This evidence supported the conclusion that the rock formations are of non-biological origin. Finding evidence and dating the beginnings of life on Earth has important implications for our understanding on how life emerged and evolved. This knowledge can also help scientists in the search for life on other planets.

Contact

Abigail C. Allwood
Jet Propulsion Laboratory, California Institute of Technology
[email protected]

Joel A. Hurowitz
Stony Brook University
[email protected]

Funding

Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Funding for the work was provided by the NASA Mars 2020 PIXL flight project. Additional funding was provided through the Stony Brook University-Brookhaven National Laboratory Seed Grant program. This research used the Submicron Resolution X-Ray Spectroscopy Beamline 5-ID of the National Synchrotron Light Source II, a Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Brookhaven National Laboratory.

Publications

A. Allwood, M.T. Rosing, D.T. Flannery, J.A. Hurowitz, and C.M. Heirwegh,“Reassessing evidence of life in 3,700-million-year-old rocks of Greenland.” Nature 563, 241 (2018). [DOI: 10.1038/s41586-018-0610-4]