Feb 11, 2021 10:05 PM
https://www.sciencenews.org/article/fake...al-fossils
EXCERPTS: When it comes to finding fossils of very ancient microbial life — whether on Earth or on other worlds, such as Mars — the odds are just not in our favor. Actual microbial life-forms are much less likely to become safely fossilized in rocks compared with nonbiological structures that happen to mimic their shapes, new research finds. The finding suggests that Earth’s earliest rocks may contain abundant tiny fakers — minuscule objects masquerading as fossilized evidence of early life — researchers report online in Geology.
The finding is “at the very least a cautionary tale,” says study author Julie Cosmidis, a geomicrobiologist at the University of Oxford. [...] the farther back in time you go, the harder it is to interpret tiny squiggles, filaments and spheres in the rock. One reason is that the movements of Earth’s tectonic plates over time can squeeze and cook the rocks, deforming and chemically altering tiny fossils, perhaps beyond recognition.
But an even more pernicious and contentious problem is that such tiny filaments or spheres may not be biological in origin at all. Increasingly, scientists have found that nonbiological chemical processes can create similar shapes, suggesting the possibility of “false positives” in the biological record.
[...] In fact, scientists have known for centuries that certain chemical reactions can act as “gardens” that “grow” strange-shaped mineral objects, twisting into tubes or sprouting branches or otherwise mimicking the weirdness of life. “There’s a complacency about it, a misconception that we kind of know all this and it’s already been dealt with,” McMahon says.
Strategies to deal with this conundrum have included looking for particular structures — such as mound-shaped stromatolites — or chemical compounds in a potential fossil that are thought to be uniquely formed or modified by the presence of life. Those criteria are the product of decades of field studies, through which scientists have amassed a vast reference dataset of fossil structures, against which researchers can compare and evaluate any new discoveries.
“Anything we find, we can look at through that lens,” McMahon says. But what’s lacking is a similarly rich dataset for how such structures might form in the absence of life. This study, he says, highlights that attempts “to define criteria for recognizing true fossils in very ancient rocks are premature, because we don’t yet know enough about how nonbiological processes mimic true fossils.” (MORE - details)
EXCERPTS: When it comes to finding fossils of very ancient microbial life — whether on Earth or on other worlds, such as Mars — the odds are just not in our favor. Actual microbial life-forms are much less likely to become safely fossilized in rocks compared with nonbiological structures that happen to mimic their shapes, new research finds. The finding suggests that Earth’s earliest rocks may contain abundant tiny fakers — minuscule objects masquerading as fossilized evidence of early life — researchers report online in Geology.
The finding is “at the very least a cautionary tale,” says study author Julie Cosmidis, a geomicrobiologist at the University of Oxford. [...] the farther back in time you go, the harder it is to interpret tiny squiggles, filaments and spheres in the rock. One reason is that the movements of Earth’s tectonic plates over time can squeeze and cook the rocks, deforming and chemically altering tiny fossils, perhaps beyond recognition.
But an even more pernicious and contentious problem is that such tiny filaments or spheres may not be biological in origin at all. Increasingly, scientists have found that nonbiological chemical processes can create similar shapes, suggesting the possibility of “false positives” in the biological record.
[...] In fact, scientists have known for centuries that certain chemical reactions can act as “gardens” that “grow” strange-shaped mineral objects, twisting into tubes or sprouting branches or otherwise mimicking the weirdness of life. “There’s a complacency about it, a misconception that we kind of know all this and it’s already been dealt with,” McMahon says.
Strategies to deal with this conundrum have included looking for particular structures — such as mound-shaped stromatolites — or chemical compounds in a potential fossil that are thought to be uniquely formed or modified by the presence of life. Those criteria are the product of decades of field studies, through which scientists have amassed a vast reference dataset of fossil structures, against which researchers can compare and evaluate any new discoveries.
“Anything we find, we can look at through that lens,” McMahon says. But what’s lacking is a similarly rich dataset for how such structures might form in the absence of life. This study, he says, highlights that attempts “to define criteria for recognizing true fossils in very ancient rocks are premature, because we don’t yet know enough about how nonbiological processes mimic true fossils.” (MORE - details)