The Tangled Tree: A Radical New History of Life. David Quammen

Scientists studying the evolution of primitive organisms reported today the existence of a separate form of life that is hard to find in nature. They described it as a “third kingdom” of living material, composed of ancestral cells that abhor oxygen, digest carbon dioxide and produce methane.

      That was relatively accurate compared with coverage in some other news outlets. The Washington Post did less well than the Times, reporting that Woese claimed to have found the “first form of life on earth,” which suggested that a dawn organism, the very earliest living creature, self-assembled somehow about four billion years ago, had survived to occupy sewage in twentieth-century Urbana. Wrong. The Chicago Tribune was worse still, proposing that Methanobacterium thermoautotrophicum (misspelled) had left no fossil record because it “evolved and went into hiding” at a time before rocks had yet formed. Which rocks? “Utter nonsense,” Wolfe said. The Tribune story even carried a dizzy headline asserting “Martianlike Bugs May Be Oldest Life.” And from there the coverage spooled outward, via United Press International and other echo chambers, to small-town papers such as the Lebanon Daily News in Pennsylvania, under similar headlines tooting about “Oldest Life Form” rather than the distinctness between methanogens and all (“typical”) bacteria. At very least, the stories bruiting “Oldest Life Form” were missing an essential point presented by Woese and Fox. A headline about “Weirdest Life Form” might have captured that better.

      The problem, according to Ralph Wolfe, was not just announcing scientific results by press release but also that Carl Woese himself lacked facility as a verbal explainer. He had never developed the skills to give a good lecture. He stood before audiences—when he did so at all, which wasn’t often—and thought deeply, groped for words, and started and stopped, generally failing to inspire or persuade. Then suddenly that November of 1977, for a very few days, he had the world’s attention.

      “When reporters called him up and tried to find out what this was all about,” Wolfe told me, “he couldn’t communicate with them. Because they didn’t understand his vocabulary. Finally, he said, ‘This is a third form of life.’ Well, wow! Rockets took off, and they wrote the most unscientific nonsense you can imagine.” The press-release approach backfired, the popular news accounts overshadowed the careful PNAS paper, and many scientists who didn’t know Woese concluded, according to Wolfe, that “he was a nut.”

      Wolfe himself heard from colleagues immediately. Among his phone calls on the morning of November 3, 1977, “the most civil and free of four-letter words” was from Salvador Luria, one of the early giants of molecular biology, a Nobel Prize winner in 1969 and a professor there at Illinois during Wolfe’s earlier years, who called now from the Massachusetts Institute of Technology (MIT), saying: “Ralph, you must dissociate yourself from this nonsense, or you’re going to ruin your career.” Luria had seen the newspaper coverage but not yet read the PNAS article, with the supporting data, to which Wolfe referred him. He never called back. But the broader damage was done. After Luria’s call and others, Wolfe recollected in his memoir, “I wanted to crawl under something and hide.”

      To me, he added: “We had a whole bunch of calls, all negative, people outraged at this nonsense. The scientific community just totally rejected the thing. As a result, this whole concept was set back by at least a decade or fifteen years.” Wolfe himself felt badly burned by the events, his professional reputation in peril. There arose a wall of resistance—cast up by visceral objection to science by press release—against recognizing the archaea as a separate form of life. “Of course, Carl was very bitter all through the eighties and well into the nineties,” Wolfe said. “He was bitter that the scientific community rejected his third form. His phylogeny and taxonomy.” As it had been for Stanier and van Niel, and still earlier for Ferdinand Cohn, bacterial taxonomy was a hot issue again. This time the evidence was molecular, and the deeper story was of evolution on its broadest scale.

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      It’s hard to know in retrospect, and perhaps tempting to overestimate, just how severely Carl Woese was doubted, dismissed, and ridiculed during the decade following 1977. Certainly there was some of that, especially in America. But the resistance to his big claim softened somewhat after still another article, coauthored again with Ralph Wolfe and Bill Balch, offered many kinds of evidence (in addition to the 16S rRNA data) for considering methanogens a separate form of life. And in Germany, on the other hand, his idea of the newfound kingdom met a warm reception.

      Researchers there—three in particular—had been developing some parallel observations. The first was Otto Kandler, a botanist and microbiologist from Munich, with an interest in cell walls, who happened to visit Urbana earlier in 1977, before the papers were published, and met Woese through Ralph Wolfe. “Ralph marched him into my office to hear the official word from George and myself,” according to Woese’s later memory of encountering Kandler. “I think he smiled.” With a smile or not, Otto Kandler easily accepted the premise that methanogens were profoundly unique, because he had suspected it himself. His own work had shown him something even Woese and Wolfe didn’t know: that the cell walls of at least one methanogen were starkly anomalous. They contained no peptidoglycan. Remember that stuff, peptidoglycan—the latticework molecule, a strengthener of cell walls, that Stanier and van Niel had cited as one of the defining characters of all prokaryotes? It didn’t exist, zero, in the cell walls of a certain methanogen Kandler was studying. Furthermore, he told Woese, it seemed absent also from some other untypical bacteria, which lived amid high concentrations of salt. They were known, for that affinity, as halophiles. Salt lovers.

      The tip from Kandler about anomalous cell walls triggered a memory in George Fox. He had once been taught, in a microbiology course, that all bacteria have peptidoglycan walls—all except the extreme halophiles. Reminded of that by the German, Fox went to the library to verify it, and, in the process, he found another clue to the defining characters for inclusion in this third kingdom. Here we get technical again, but I’ll keep it simple: weird lipids.

      Lipids are a group of molecules that includes fats, fatty acids, waxes, some vitamins, cholesterol, and other substances useful in living creatures for purposes such as energy storage, biochemical signaling, and as the structural basis of membranes. Fox, rummaging in his library, learned that halophiles contain lipids unlike those in other bacteria. They were structured differently, with radically different chemical bonds. Carl Woese now had another omigod moment: Omigod, these salt lovers are full of weird lipids, just like our methanogen. The fact of such weird lipids in halophiles had been reported by other researchers a dozen years earlier—as Fox found in the library—but no one had drawn any conclusions. It was merely a little anomaly. But for Woese, in his ferment of discovery, it clicked into the larger pattern. “In my whole career I had never paid attention to lipids, and here we were with lipids on the brain!”

      And not just the lipids he found in halophiles. Fox also turned up the fact that two other kinds of extremity-loving bugs, known by their genus names as Thermoplasma and Sulfolobus, also had weird lipids of the same sort. Those two groups preferred environments that were very hot and very acidic, such as hot springs in areas of volcanic activity. In the technical lingo, they were thermophilic and acidophilic. Perverse little beasts, by our standards. Both had recently been isolated—one from a coal refuse pile, the other from a hot spring in Yellowstone—and characterized in the lab of Thomas Brock, the codiscoverer of Thermus aquaticus. Alerted to the weird-lipids connection by Fox, Woese got hold of samples and began trying to grow them and catalog them.

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