A few years ago, a group scientists claimed that rocks found in Greenland, which date back roughly 3.7 billion years, could hold the oldest evidence of life on the planet Earth. According to a new analysis, though, another group argues that these rocks are just that: rocks.
First of all, the initial study took place two years ago, at the University of Wollongong, in Australia. In this study, geologist Allen Nutman (and colleagues) managed to identify cone-like structures in this 3.7 billion-year-old rock, which was taken from southwest Greenland’s Isua formation. The researchers allege that these structures provide evidence of stromatolites, which are sedimentary formations that result from the layered growth of microbial organisms, in shallow water.
Upon identifying these formations, scientists rejoiced at what looks to be profound evidence of how quickly life emerged on Earth after it formed roughly 4 billion years ago. This, of course, leads to other similarly profound implications about Earth and the potential for other habitable planets within our solar system or, at least, our galaxy.
Published earlier this week in the journal Nature, the second group of experts describes how they examined structures within the rock which had originally believed to house several communities of single-celled microbes that grew out of the bottom of a salty and shallow sea. When looking at these structures up close, scientists found three-dimensional shapes that are dissimilar to the categorical upside-down ice-cream cone shape produced by most microorganisms. Instead, these structures appear more like shapes from a Toblerone candy bar.
Stony Brook University geochemist Joel Hurowitz explains that the shape is “hard to explain” in terms of typical biological structures. Alternately, it is easier to look at them as something which might have resulted from rocks that were squeezed and/or deformed as a result of tectonic pressure.
In addition, NASA Jet Propulsion Laboratory astrobiologist Abigail Allwood, who is also the lead author of the second study, argues that there is very little chance—if any at all—that these structures could have been created by ancient microbes.
It is important to note that the most widely accepted evidence of the earliest life on Earth can be found in Western Australia. This is where Allwood—and other researchers—found cone-shaped structures that were created by microbes in rocks dating back 3.5 billion years.