Mars Life Is a Mirage
It’s an ongoing fault of astrobiologists to stampede
on life claims. Two geologists want to yank the reins.
“Whoa up there, pardner. Ain’t no water there; it’s a mirage.”
Two geologists would like to find cool water but they ain’t foolin’ for no mirage. Keep-a movin’ Dan / Don’t you listen to him, Dan / He’s the devil not a man / and he spreads the burning sand with water. So wrote old cowboy singer Bob Nolan in the classic “Cool Water” in the TV western era. New lyrics are needed for the freezing sands of Mars, where astrobiologists like thirsty hoss Dan stare at “false biosignatures” and feel the urge to gallop ahead, only to be disappointed again (13 Jan 2022).
Sean McMahon and Julie Cosmidis, “False biosignatures on Mars: anticipating ambiguity.” Journal of the Geological Society, Volume 179, Issue 2 March 2022.
Dr Bergman tells of false positives in the search for evolution since the time of Darwin himself, including Eozoon mentioned at left.
McMahon and Cosmidis have a message for astrobiologists: Hold yer horses. “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,” they caution. “The success of major current and forthcoming rover missions now calls for significant efforts to mitigate this risk” [of galloping toward mirages]. It’s true these are “exciting times for astrobiology,” they continue, but they worry about adding to the difficulties of finding life that have continued to “plague paleontology” for many years.
One reason for concern is that such errors have been frequent in the history of palaeobiology and astrobiology down to the present day. In the nineteenth century, intricate layered and tubular structures found in serpentine-rich metacarbonate rocks from the Canadian shield were interpreted as the fossilized tests of ancient forams, designated Eozoon canadense, the ‘dawn animal of Canada’; it took much heated debate, and some decades of careful work, to show that these were abiotic textures (Adelman 2007). Palaeontologists in the twentieth century repeatedly made similar misdiagnoses; examples listed by Cloud (1973) include spurious ‘worm tracks’ (drag marks), ‘medusae’ (pyrite rosettes), ‘arthropods’ (mud curls around desiccation cracks) and numerous Proterozoic ‘microfossils’ (crystallites, contaminating spores and preparation artefacts).
There are numerous abiotic processes, warn McMahon and Cosmides, that can mimic biosignatures. For instance, stromatolites are often claimed to be formed by bacterial mats, but abiotic processes have been known to create conical structures that mimic them. The authors list a number of other physical processes that can produce biological mimics that are ambiguous at best, and misleading or completely false at worst. In conclusion of their open-access paper, they warn that life detection is futureware.
If we are lucky, plain and unequivocal biosignatures will be discovered on Mars in the coming decades. But in light of the many cautionary tales in the history of palaeontology and astrobiology, it seems prudent to anticipate more ambiguous results. In interpreting these, it will be important to understand how misleadingly life-like objects and substances might have formed abiotically on Mars.
False positive “biosignature” in Martian rock ALH 84001, reported 1996.
It’s important to realize that the authors are evolutionists who believe that Earth life formed by chance. And yet realism about the complexity of life tugs at the conscience:
Because life itself is presumed to be the product of self-organization in abiotic geochemical reactions, the complexity of abiotic natural products should not be underestimated.
McMahon and Cosmidis advise that astrobiologists should add systematic searches for abiotic processes to their optimistic searches for biosignatures so as not to be fooled by false positives.
Further work on the physics and chemistry of far-from-equilibrium systems will ultimately reveal the limits of abiotic self-organization and may even lead to new discoveries on the organizing principles at the origin of life on Earth.
By implication, astrobiologists have not demonstrated the feasibility of a biotic system (e.g., a living cell), forming by self-organization, or by far-from-equilibrium systems, or by any other process. If they had, the press would gallop and never stop whinnying about it.
Everybody sing the new Rover’s lament, OOL Fodder!
[OOL= origin of life; Pers=Perseverance Rover; Dan=a PhD student]
All day I’ve faced the barren waste without the taste of fodder: OOL Fodder.
Old Dan ‘n’ I, with ink bone dry, and souls that cry for fodder—
OOL, OOL, fodder.
Keep a-movin’ Pers, don’t ya listen to him Pers,
My advisor is perverse, and he makes me curse my Alma Mater.
NASA, can’t you see that PhD where the funding’s runnin’ free
And it’s waitin’ there for me and you!
“Blueberries” concretions on Mars (natural) next to drill cores (designed).
The nights are cool, and I’m a fool,
Each core’s a jewel of fodder: OOL fodder.
But with the sol I’ll wake and roll and sadly stroll
For fodder: OOL, OOL fodder.
Keep a-movin’ Pers, don’t ya listen to him Pers,
My advisor is perverse, and he makes me curse my Alma Mater.
NASA, can’t you see that PhD where the funding’s runnin’ free
And it’s waitin’ there for me and you!
OOL, OOL, fodder. [Background voice: “False positive again.”]