We’re so good at spotting life that we see it even when it isn’t there.
There is a strong probability that any fossils discovered on Mars are fakes, experts warn in a new report published last week in the Journal of the Geological Society.
And, while it’s easy to see how this may occur in the alien atmosphere of space, the researchers point out that there have been centuries of false fossil discoveries on Earth as well. It turns out that it is rather simple to notice something and form incorrect conclusions—so will we get fooled again?
The report, which is a review of previous studies, examines the evidence for all known processes that could have resulted in the formation of life on Mars.
“It is often acknowledged that the search for life on Mars might produce false positive results, particularly via the detection of objects, patterns or substances that resemble the products of life in some way but are not biogenic,” said the authors of the study.
“The success of major current and forthcoming rover missions now calls for significant efforts to mitigate this risk.”
To minimize the possibility of false positives, sometimes known as “false biosignatures,” we must examine the various processes that can result in deposits that appear to be fossils. These types of samples date all the way back to the beginning of the human discovery of geological artifacts on Earth.
“In the nineteenth century, intricate layered and tubular structures found in rocks from the Canadian shield were interpreted as ancient forams, designated the ‘dawn animal of Canada,'” the paper noted.
Following that, experts determined that the samples were inorganic, or non-living. This is a frequent occurrence. Throughout the twentieth century, paleontologists in other parts of the world confused drag marks for “worm trails” and natural pyrite crystallizations for “medusae” animals.
All of these cases show that we should be careful while dealing with Mars samples.
“[T]he return of samples from Mars will not necessarily solve once and for all the problem of the existence of (ancient) life on that planet,” the researchers explained.
“Although we must hope for definitive results, candidate biosignatures are likely to be at least somewhat ambiguous.”
Indeed, Mars has already hosted examples of ambiguous evidence, and Occam’s razor—a logical principle stating that the simplest explanation is usually the best—suggests that these should be interpreted as ambiguous rather than suggestive.
It’s difficult to live with ambiguity, especially when one plausible answer, such as life on Mars, is so fascinating. However, the scientists advise caution and encourage other studies to continue in the ambiguous zone if the evidence supports it.
“To give an extreme example from Earth, the biogenicity of the filamentous mineral networks found in ‘moss agates’ has been unclear for more than 200 years,” they explained.
So, what could be the red flags on Mars? Space programs are already planning a more in-depth examination of Mars than we’ve seen from even the most successful space probes and surface rovers, so fresh examples will almost certainly emerge in the future. However, there are a few well-known examples to date:
“These included carbonate globules and magnetite crystals resembling bacteriogenic precipitates, polyaromatic hydrocarbon compounds, and worm-like microstructures interpreted as morphological fossils.”
All are still uncertain, according to the experts, with life being just one of many plausible explanations.
“Environments conducive to the origin and maintenance of life may also, by their very nature, be conducive to the formation of false biosignatures,” they added.
Indeed, it makes obvious that exercising care initially could result in more credible and definitive conclusions later on.
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