How many nails must be pounded into a coffin before it ceases to spring open? Find out now, in Science Advances!
Defenders of the biogenicity of the ~3.5 Ga Apex chert “microfossils” have been fighting a rearguard action since 2002, when Martin Brasier and colleagues published a damning reanalysis of the specimens and their geological context. These specimens were once thought to be the oldest known fossils in the fossil record. William Schopf, who described the specimens in a celebrated paper, claimed that they occurred in a sedimentary bedded chert, and more spectacularly (since they greatly predate evidence for significant oxygenation) that they may have been related to oxygen-producing cyanobacteria. But Brasier and colleagues showed that the specimens most likely originated in a hydrothermal setting, ruling out a cyanobacterial interpretation. They also showed, for example, that parts of the original specimens were cropped out of the published photographs (and not represented in the accompanying interpretive drawings), all of which led them to conclude that the putative fossils were in fact abiotic structures that formed around recrystallizing mineral grains during a series of hydrothermal events.
I am going to write about the Apex chert sometime, because what I have related is only the beginning of the story. But from my extreme outsider’s perspective, it seems that Brasier and friends gained the upper hand in 2002 and never relinquished it. (Martin Brasier died tragically in 2014, when a severely overtired man fell asleep at the wheel and collided with Brasier’s car. It is an extremely sad story, not least because it is impossible to read about the circumstances of the accident and not feel sorry for the man who caused the crash.) Anyway, this new publication is the latest chapter in the now thirty-year saga of these probably-not-actually-fossils. It argues that the carbon associated with the specimens is not biological in origin. But it also raises a question: where did the organic molecules in the chert come from? One possibility is from a reaction between water and rocks, an intriguing suggestion that nonetheless does not exclude the possibility that life existed during this time.
For the full story, follow the link above to the open-access article. A more accessible write-up can be found here.