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Posted at 10:44 AM ET, 08/22/2011

The great microfossil debate

Of the five biggest unknowns in science, the origin of life is number 3 (personal ranking; your mileage may differ). We don’t know how nonlife became life, whether it was in a small, warm pond, or at the edge of a deep-sea hydrothermal vent, or in the back of someone’s refrigerator, or whatever. Maybe it showed up on a meteorite (which enables us to outsource the annoying origin-of-life problem to some other world and never think about it again).

What we do know — or what we think we know — or what we know with sufficient confidence that we put it in textbooks as though it’s an actual fact — is that by about three and a half billion years ago, early in the Earth’s theoretically habitable existence, the planet was in fact inhabited. There was life. It wasn’t very exciting life, but it was better than the alternative.

The precise origin of life on Earth probably will never be known, since it is highly unlikely that there is any fossil remnant of the first organisms. However, if you hunt around long enough among the oldest rocks on Earth, you do find stuff. Therein lies one of the most enduring scientific feuds of our time.

The Post and the Times have stories about a new discovery of ancient fossils in Western Australia. This is the latest salvo, as the Times explains, in a running battle over who has claim to being the discoverer of the oldest fossils on the planet.

In 1992 and 1993, William J. Schopf of UCLA published papers saying that he’d found cyanobacteria fossils in a formation known as the Apex Chert. Thin sections showed squiggly shapes with cell-like elements. This became the stuff of textbooks.

Schopf is, I should note, a wonderful character. He’s bombastic, arrogant, funny. One of my favorite lectures of all time is Schopf describing how an alien scientist on a distant world, given a container of earthlife, could deduce almost everything about our solar system. Schopf was the guy at NASA headquarters in 1996 who dumped cold water all over the dramatic claim by scientists that they’d found Martian life in a meteorite.

But in 2002, a scientist from Oxford, Martin Brasier, launched an attack on Schopf’s Apex Chert fossils and by extension on Schopf’s otherwise sterling scientific reputation. Brasier said Schopf’s microfossils were just crud — pretty much what Schopf had said about the Martian microfossils! As Brasier put it (more scientifically) in the journal Nature: “We reinterpret the purported microfossil-like structure as secondary artifacts.”

Robert Hazen lays out this story in juicy detail in his book “Genesis: The Scientific Quest for Life’s Origin” (here’s my 2006 Style story on Hazen and the origin-of-life debate). Hazen reports on the bizarre face-off between Brasier and Schopf at Moffett Field, Calif., in 2002, when they shared a stage and took turns saying the other was full of beans. Here’s Hazen, describing Schopf looming over Brasier as Brasier made his presentation:

“...an agitated Schopf stood up and began to pace distractingly a dozen feet behind the podium. Back and forth he walked, hunched over, hands clasped firmly behind his back — a tense backdrop to Brasier’s staid delivery....

“As Brasier calmly outlined his arguments, the scene on stage shifted from awkwardly tense to utterly bizarre. We watched amazed as Schoft paced forward to a position just a few feet to the right of the speaker’s podium. He leaned sharply toward Brasier and seemed to glare, his eyes boring holes in the unperturbed speaker...”

But that’s as far as it went, and everyone went home to figure out who won the debate. Hard to say — but now Brasier is the co-author on the new paper claiming to have found microfossils in rocks 3.4 billion years old. The paper, published in Nature Geoscience, was submitted with a claim that these were the oldest fossils ever found. But as the Times reports, lead author David Wacey backed down when the paper’s reviewers questioned the “advisability” of making such a claim. So the paper doesn’t go that far (even though an Oxford press release does).

Schopf hasn’t responded. I imagine we’ll be hearing from him.

Although in no position to referee such things, I think the Wacey/Brasier paper may offer a kind of subtle support for Schopf’s original claim. The Wacey/Brasier microfossils were found in rocks only slightly younger (by 65 million years) than Schopf’s rocks (though the dating of those rocks remains in dispute). And the two sites are only 20 miles apart. Thus Wacey/Brasier say they’ve found ancient squiggly critters very close to similarly aged rocks where Schopf has found (they say) only a bunch of stuff that looks like ancient squiggly critters.

To be continued, no doubt.

By  |  10:44 AM ET, 08/22/2011

 
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