The topic of Martian fossils is a contentious one largely due to a somewhat premature conclusion
that came in the 1990’s that certain structures found in meteorites believed to have originated
on the surface Mars were in fact fossilized microorganisms or evidence thereof.
I made a video specifically on this topic on this channel, link in the description below
that gives the backstory.
But these findings, despite initially being backed with high confidence, ended up being
inconclusive as other researchers questioned them.
And, now, decades later, we still really don’t know if the structures found in the Martian
meteorites are fossils of bacteria, or merely chance geological features that do not indicate
life.
But meteorites from Mars are not the only potential indicators of past life on Mars,
or indeed a number of bodies in the solar system.
We might find them with rovers or even from orbit and a paper by Andrea Baucon and colleagues,
citation link in the description below, details just what we should look for as far as biogenic
structures on other worlds.
Finding traces left by an organism is a bit harder than finding the fossil of the organism
itself, which is hard enough.
You can find what appear to be dinosaur footprints in rocks, but in reality most things that
look like footprints are just chance formations in the wrong kind of rock.
But occasionally, the paleontologists do find dinosaur footprints where both the geology
and the circumstances of the fossils indicate that they are real.
But unambiguous trace fossils of this nature are rare, and indeed actual fossils can be
as well.
And they are often contested, purported fossil evidence recently found in both Canada and
Greenland over the last few years could represent fossils that date from the earliest ages of
life on earth.
Or, they may not.
And sometimes, we just don’t know what caused a rock to look like it does.
We know that sediments in water created by bacteria can produce fossilized structures
known as stromatolites.
We can see these forming even now, but we also see abiotic geologic processes that can
mimick the look of stromatolites and that whole issue has not been completely sorted
out.
This problem is much worse with Mars.
We know that life exists on earth and has been here for billions of years and has been
leaving fossils.
We have no idea if life was once present on Mars or any of the other bodies of the solar
system, or still is, or left evidence.
We only know that there is a possibility, and there have also been tantalizing clues.
But the bar is high as far as the evidence; this would be proof of life on another world
after all.
So while anything anyone finds will be subject to serious scrutiny, we should keep our eyes
out for biogenic traces of ancient life as we explore the solar system.
The authors of the paper lay out how we might do that, such as looking for traces of trails
and burrows that meander and look more like something trying to find food than an abiogenic
geologic process.
It’s worth noting that the researchers did search for biogenic signatures on Mars and
other worlds using open-access data.
They didn’t find anything conclusive.
But this brings us to an older paper where just such structures may potentially have
been detected, and it might be a pretty hefty coincidence if it wasn’t due to life.
In a 2015 paper by Norra Noffke potential structures are present in some of the images
returned by the curiosity rover, specifically in regards to a sedimentary outcrop known
as Gillespie lake, that may present fossil evidence of life in the form of microbial
mats, collections of microbes that we see here on earth that are still around but also
among the first fossils of life on earth.
Now, I should note that Noffke, a geobiologist with decades of experience looking at these
kinds of fossilized structures here on earth is very careful in the paper to not jump to
conclusions but to note that a further look at these structures is worthwhile and the
evidence that’s there is pretty tantalizing.
The paper also presents alternate processes that could have created the structures without
the presence of biology, but the coincidences of that happening here do seem to stack up.
Ultimately though, we won’t know the answer to the question of the potential Martian fossils
until we collect samples and take them to a lab, or perhaps find living survivors of
Martian microbial life on the red planet, or evidence of life elsewhere.
But I suspect it won’t be long, probably within the lifetimes of most of the viewers
of this channel, when we will have our answer.
And even if it is just a fossil of a microbe that lived billions of years ago, it’s still
evidence of life outside earth.
And, who knows what else we may find?
Thanks for listening!
I am futurist and science fiction author John Michael Godier and be sure to check out my
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explorations into the interesting, weird and unknown aspects of this amazing universe in
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