The Tangled Tree

by David Quammen

  Margulis defended the butterfly paper’s publication if not the hypothesis, saying, “We don’t ask anyone to accept Williamson’s ideas—only to evaluate them on the basis of science and scholarship, not knee-jerk prejudice.” Other scientists pointed out that genetic data already existed, before Williamson even published his monster-butterfly notion, to refute it.

  Margulis thrived in this context: the challenges to authority, the dustups among scientists, the tension between caution and daring. She loved going out on a limb and bouncing there while others warned that the limb was weak and might break. Her attitude: If it breaks, fine, that’s science too! She became famous and much admired among nonscientists, over a lifetime of such provocations, and infuriating to some of her colleagues. She gave interviews, organized meetings, traveled to lecture, and contended robustly in controversies. A profile in one serious journal called her “science’s unruly Earth Mother.” Throughout all this, she remained cheerily energetic, open to discussion, confident to a fault, generous with her time, and likable. “I quit my job as a wife twice,” she once said. “It’s not humanly possible to be a good wife, a good mother, and a first-class scientist.” Something had to go. She preferred to be a scientist and a mother, unruly or otherwise. And she mothered, to one degree or another, a lot more people than four.

  In 1986 she published Origins of Sex: Three Billion Years of Genetic Recombination, the first in a series of books coauthored with her eldest son, Dorion. It was characteristic of her reach, to write a book covering three billion years. A year later, she and Dorion produced Micro-Cosmos: Four Billion Years of Evolution from Our Microbial Ancestors. Their 2002 book was Acquiring Genomes: A Theory of the Origins of Species, proposing at length what she had claimed elsewhere: that neo-Darwinism (the twentieth-century school of thought merging Darwin’s theory with Mendel’s genetics) is wrong about the main source of genetic variation that drives evolutionary innovation. That crucial element, variation—it doesn’t, according to Margulis and Sagan, come mostly from the tiny random mutations that seem sufficient to neo-Darwinists. “Rather,” they wrote, “the important transmitted variation that leads to evolutionary novelty comes from the acquisition of genomes.” It comes from symbiosis, the real origin of species.

  Symbiosis in this sense includes endosymbiosis—those bacteria you’ve been reading about, captured and transformed into the first mitochondria, the first chloroplasts, within eukaryotic cells. But it also includes, as I’ve mentioned, a broader variety of cases—less drastic, less epochal—in which two organisms, two genomes, amalgamate into one living partnership. For instance, Margulis and Sagan described sea slugs of the species Elysia viridis, which feed on green algae during their immaturity and then, instead of digesting the algae completely, retain algal chloroplasts within their own cells. The acquired chloroplasts allow the slugs to photosynthesize like plants, gathering their energy from sunlight in the tidal shallows where they live. As adults, they become in effect “plant-animal hybrids.” That sort of dramatic combining, Margulis and Sagan claimed, and not the incremental mutations of the neo-Darwinists, is the main way (so far as presently known) new species originate.

  Margulis invoked the green sea slugs years later during an interview. “The evolutionary biologists believe the evolutionary pattern is a tree,” she told a writer from the magazine Discover. “It’s not. The evolutionary pattern is a web—the branches fuse, like when algae and slugs come together.” She was right: the tree of life is not a tree.

  Despite the peculiarity of her views and her reputation as a rebel, Margulis got showered with awards and honors—enough to belie the popular image of her (and her self-image) as a rejected outsider. Election to the National Academy of Sciences in 1983 was only a start. Then followed election to the Russian Academy of Natural Sciences, far more rare for an American, and to the American Academy of Arts and Sciences, another august body. Election to the World Academy of Art & Science, whatever and wherever that is. She accepted the Alexander von Humboldt Prize in Berlin, shared the Darwin-Wallace Medal in London, and accumulated sixteen honorary doctorates. President Bill Clinton, in 2000, hung the National Medal of Science around her neck. The list is long. In 2010 she flew to the small city of Bozeman, Montana, to receive an award (from a wonderful institution called the American Computer Museum) named in honor of, and presented by, the biologist Edward O. Wilson, another scientific pioneer. Wilson had also flown in for the event. There was a banquet. That’s where I met her.

  Next day, very early on a blustery October morning, she and I and twenty other people, including Ed Wilson, boarded a bus for a field trip through Yellowstone National Park. Lynn and I sat together for much of eight hours while the vehicle rolled amid lodgepole pine forest, steaming hydrothermal vents, geyser basins, multicolored mineral springs, trout-filled rivers winding through meadows grazed by bison and elk, and other Yellowstone scenery. We talked about endosymbiosis, she and I, and the origin of species, the events of 9/11, the etiology of AIDS, and Lyme disease, while the others talked about—I’m just guessing—bison and bears and elk. Lyme disease especially engaged me, because I was writing a book on infectious diseases. We talked about much else too, probably including the local wildlife; she was interested in everything. Come to my seminar in Amherst, she said. Although I made no notes of our conversation during or after the bus ride—not foreseeing that I would ever write about her—there is a photo in my files to serve as a memento. It shows Lynn, myself, one other scientist, and Ed Wilson, posing with linked arms at an overlook into the Grand Canyon of the Yellowstone River. In the background is a great waterfall. Lynn wears a bulky gray sweater. Ed sports a park ranger hat—a Smokey Bear, with a flat brim—borrowed for this larky shot, and a smirk. He had suffered some of the punishments of voicing heterodox theories himself. He liked being out in the woods with Lynn Margulis, what the hell.

  Two weeks later, I did go to her seminar at the University of Massachusetts. Driving out to Amherst after other business in Boston, I kibitzed the class and then returned to her house for dinner, a hearty and simple stew she had cooked herself. I met her dog. We found no time to sit down, just Lynn and I quietly, so that I could interview her about Lyme disease, as I had hoped; but it didn’t seem to matter. There were other guests, there was far-ranging conversation. As always, Lynn stirred the pot. I drove back to Boston and never saw her again. She died a year later after a massive stroke. She was seventy-three.

  “There’s a role in science for iconoclasts,” Ford Doolittle said of Lynn, not in eulogy after her death but years earlier, when she was so tempestuously alive. “It would be a great mistake to jump on her with both feet.” Iconoclasts such as Lynn Margulis, he added, “raise questions even when they’re wrong. And, of course, they’re occasionally right, as she was.” Right about endosymbiosis, he meant, on two of the three cardinal assertions she had made: mitochondria, yes; chloroplasts, yes; undulipodia (those little tails), apparently no. While the bacterial origin of mitochondria and chloroplasts had been confirmed by molecular evidence—the genes were still there, linking them to bacteria—no molecular evidence matching undulipodia with spirochetes had ever been found. The only evidence was from microscopy, such as that notable similarity of the nine-tubule cross sections. But in the molecular age, microscopical synonymy wasn’t enough.

  Doolittle himself had gotten to know her in Boston, during a sabbatical he spent at Harvard through the 1977–78 academic year, while she was still at Boston University. He couldn’t recall, when I asked, just how he met Lynn, but they would have had a congenial starting point: his 1975 paper with Bonen, confirming the chloroplast postulate of her endosymbiosis theory. Lynn was still married to Nick Margulis then, living just west of the city. One thing Doolittle did remember: “She had a lot of good parties at her place.” For which, read: she lived life.

  Her openness to ideas, her personal confidence, and her love of intellectual stew pots gave her a knack for maintaining friendships, or at least amicab
ility, across deep divides of scientific disagreement, as reflected in her relations with some of the more strongly opinionated biologists of her era. She disagreed on important points with Ernst Mayr, one of the founding neo-Darwinists, but he was happy to write a foreword to one of her books, and she was happy to let him say in that foreword just where he felt the book went wrong. Stephen Jay Gould performed a similar service, vouching for another of her books; so did Joshua Lederberg, Lewis Thomas, and G. Evelyn Hutchinson. These are big names. Although she differed strongly with Richard Dawkins on neo-Darwinism and once debated him at Oxford, he said: “I greatly admire Lynn Margulis’s sheer courage and stamina in sticking by the endosymbiosis theory, and carrying it through from being an unorthodoxy to an orthodoxy.” That was nicely, and carefully, put. Ed Wilson handed her an award and, as mentioned, so did Bill Clinton.

  But with Carl Woese, it was different. Woese had little patience for her more venturesome ideas, and she was scorned also by some of the scientists closest and most loyal to him, whom she called “Woese’s Army,” as though they were arrayed in battle against her. One of those loyalists, when I asked his opinion of Margulis, answered silently by miming expectoration. These feelings went deep. Woese disliked her, according to Jan Sapp, who knew them both well, and he resented the army metaphor. He told Sapp, “If I hear her say it again, I’m going to sue her.” Woese himself had moved away from militaristic and sovereign words such as empire, even kingdom, in choosing a categorical term for what he preferred to call the three great domains of life. Although he doesn’t seem to have been an especially pacific person, this point was important to him. Meanwhile, she coauthored a book titled Five Kingdoms, published in 1982, delineating five major divisions of life on Earth, which ignored and contradicted Woese’s own great discovery of a third form of life in 1977. Was it three domains? Was it five kingdoms? They couldn’t both be right.

  Woese expressed his considered view of Margulis, caustically, in a private communication written in 1991. It was his response to a request from the dean of the College at the University of Chicago, her alma mater, which was considering her for an honorary degree. (She never got this degree, for one reason or another, and had to content herself with the other sixteen.) Carl Woese may have seemed, to the Chicago dean, a logical choice for supportive words: another world-renowned biologist concerned with cell evolution and based there in Illinois. Woese preferred to be blunt. “If you wish merely a complimentary letter to support the case for Prof. Margulis’ receiving an honorary degree, you have come to the wrong individual,” Woese wrote.

  “I have fairly deep scientific disagreements with her,” he added. He might have left it there, but he didn’t.

  Granted, she was a good teacher, Woese told the dean. Her reputation in that regard was deserved. By his lights, she was “primarily a teacher,” only secondarily a contributor of new science. She had done “more than anyone to promulgate the idea” of endosymbiosis in the origin of eukaryotic organelles, “and for this she deserves great credit.” But, of course, that idea wasn’t uniquely hers. In fact, the correct parts of the theory weren’t original with her, he noted, and the parts original with her weren’t correct. She was wrong about flagella (her undulipodia). She was wrong about the primordial host cell—within which captured bacteria became embedded—having been a bacterium itself. Woese acknowledged that her efforts at “spreading the word” about cellular evolution, through teaching and popular writing, had been very effective. “Unfortunately,” he added, “that word itself has been somewhat defective.” She was sowing confusion.

  He disapproved in particular of her book Five Kingdoms. The first edition was bad enough, but its mistakes were “excusable,” he told the dean. The revised edition, published in 1988, annoyed him still more. This one was inexcusable because, in the six years between printings, she and her publisher had been advised (presumably by him) about its deficiencies regarding “the newer findings in microbial evolution,” and they had done almost nothing to fix the problem. The problem, for Woese, was that Margulis and her coauthor had persisted in treating his great discovery of 1977, his separate form of life, as something not separate at all. The problem was five kingdoms versus three domains, and none of those five labeled Archaea. The problem, which Carl Woese couldn’t forgive or ignore, was that her tree of life differed so fundamentally from his.

  PART  IV

  Big Tree

  37

  In late February 1864 Charles Darwin received an unusual package in the mail—unusual even for him, to whom the faithful postman in his little village routinely lugged correspondence and natural-history specimens (dead pigeons, French peas, pickled barnacles, and so forth) from contacts all over the world. This package weighed more than seven pounds. It contained two big folio volumes: one filled with stunning copperplate engravings, one of text, comprising a work titled Die Radiolarien. It was a monograph on the radiolaria, a group of single-celled planktonic marine creatures that produce elaborate silica skeletons, varying species by species like a gallery of crystal chandeliers. Darwin had seen the book—so erudite, yet so decorative—sometime a year or so earlier during a visit to London, probably at the home of his friend Thomas H. Huxley. Now he had his own copy, sent with courtesies by its author, a young German zoologist and artist named Ernst Haeckel.

  Darwin had never met Haeckel and knew him only through the exchange of a few polite letters. It was a difficult time for Darwin; in addition to the new crush of fame and controversy brought by On the Origin of Species, he had suffered a recurrence of the mysterious illness that punished him for much of his adult life. Haeckel knew Darwin from his Beagle journal, a best-selling travel book with no overt evolutionary message, published decades earlier, and more importantly from The Origin, recently made available in German (a bad translation, but good enough to be inspirational) promptly after its second edition in English. Haeckel’s life, vision, and sense of scientific purpose had been transformed by reading The Origin, and he wanted his hero to know that. Hence the gift, which also implied an expectation: Please read me.

  Darwin replied graciously just a week later, telling Haeckel that Die Radiolarien was “one of the most magnificent works which I have ever seen, & I am proud to possess a copy from the author.” This was the careful language of a polite but busy man, and while seeing and possessing could be reported easily, reading the thing was another matter. Darwin read German only slowly and painfully, so he may not yet have gotten far into the 570-page text, nor come across the footnote on page 232 in which Haeckel gushingly saluted him and his theory. But he had at least browsed the illustrations. “It is very interesting & instructive to study your admirably executed drawings,” Darwin told him, “for I had no idea that animals of such low organization could develope such extremely beautiful structures.” He had never studied the radiolaria himself, not even aboard the Beagle.

  Another thing of which Darwin had no idea—not in 1864, when he couldn’t have foreseen it—was the huge role that this effusive young German artist-scientist would play over the next fifty-five years in promoting his theory and depicting a Darwinian concept of the tree of life. By the early twentieth century, in fact, long after Darwin’s death, Haeckel would be the world’s most famous living Darwinian, and his trees would be well rooted in the popular understanding of life’s history.

  38

  Ernst Haeckel was born on February 16, 1834, making him almost precisely twenty-five years younger than Darwin, perfectly spaced to reach an age of fervid impressionability just as Darwin exploded into midcareer fame. Haeckel’s father was a jurist and a counselor to the Prussian court at Potsdam until the family moved to Merseburg, a smaller town in Saxony, where Ernst grew up. His parents exposed him to great literature and serious ideas—the poetry of Friedrich Schiller, the nature philosophy of Johann Wolfgang von Goethe—and as a boy, he read Alexander von Humboldt, and Matthias Schleiden’s vivid botanical book The Plant and Its Life, and Darwin’s Beagle journal, all wh
etting an appetite for adventurous scientific travel. From Humboldt and Schleiden, he learned that “proper evaluation of nature required aesthetic as well as theoretic judgment,” according to his biographer Robert J. Richards, a scholar of German Romantic thought. Haeckel leaned toward botany, but when he reached age eighteen, his father, concerned for the practicalities, pressured him to study medicine. He enrolled at the University of Würzburg and hated the medical curriculum but stayed with it, stealing time to read more Humboldt and Goethe amid his studies. Then came his clinical training, which by Richards’s account was devoted largely to “horrible worms, rickets, scrofula, and eye diseases” among the poor of Würzburg. Haeckel detested it. He wasn’t born to be Albert Schweitzer. The part of medicine that he did enjoy was autopsies—a grim exercise fitting his interest in anatomy. He also liked histology, studying the microscopic anatomy of cells and tissues, and he discovered an aptitude for drawing tiny structures in fine detail, one eye on the microscope eyepiece, the other on the page. That would later come in handy for the radiolaria.

  He passed his state medical examinations in March 1858 but never practiced, renouncing medicine at that point to do research in zoology. Haeckel was fascinated by morphology, which encompasses anatomy but goes beyond it—anatomy being the study of bodily structures, morphology being the study of relationships among and comparisons between bodily structures. Morphology led toward questions of whence and why, evolutionary questions, while anatomy remained descriptive. Haeckel followed that lead fairly soon, but at first, for him it was just nature study. In particular, he came to love marine creatures, including those radiolarians, which offered a universe of weird bodily structures.