Not wanting to find alien life invading Earth is not the same thing as not wanting to find evidence of life, and I for one really, really want to find fossilized life on Mars.

Unfortunately, for the smallest forms of life, it can get super hard to differentiate between minerals that grow chemically and structures that grow biologically. In a new study in the Journal of the Geological Society, researchers explore our Earth looking for the kinds of things that may one day confuse us on Mars. According to researcher Sean McMahon: At some stage a Mars rover will almost certainly find something that looks a lot like a fossil, so being able to confidently distinguish these from structures and substances made by chemical reactions is vital. For every type of fossil out there, there is at least one non-biological process that creates very similar things, so there is a real need to improve our understanding of how these form.

While it is relatively easy to find things that look identical, it can be trickstery to figure out how to say this one was formed by life and this one by other natural processes. Short of finding DNA, which isn’t something we can do with fossils, we’re going to have to be able to say “these structures require either life or this specific environment”. And when you find the structures in the wrong environment, well, here’s to hoping life is what found a way.

More Information

The University of Edinburgh press release

“False biosignatures on Mars: anticipating ambiguity,” Sean McMahon and Julie Cosmidis, 2021 November 17, Journal of the Geological Society