A TEN-YEAR SEARCH UNCOVERS A NEW "TREE OF LIFE"

by Dan Sanders

                                                    — Microbiologist Carl Woese

The first chapters of Genesis mention two great trees in the center of the Garden of Eden. One is the Tree of Knowledge, whose fruit Eve takes against her Maker’s orders; the other is the Tree of Life. In the twelve millennia since someone wrote of Eden, countless scientists and philosophers have struggled to understand life’s origins and development. Yet it would take the long, lonely quest of an Illinois biologist named Carl Woese to truly define how life on earth began and evolved. His triumph is profiled in "Tree of Life" -- the premiere episode of INTIMATE STRANGERS: UNSEEN LIFE ON EARTH, airing on PBS on Tuesday, November 9, 1999, 8:00 - 9:00 PM (ET).

The discovery of life forms has always been a haphazard and patchwork affair. A new type of plant or animal is discovered and classified, with limited thought given to just how they fit into the ecosystem’s grand scheme. Carl Woese, however, wanted the whole story of life -- a record of all living things, what species came first, what they evolved into, and how they did it. He wanted this for the same reason the FBI wants the fingerprints of all its potential customers: if you know of everyone out there, who they work with and where they’re from, you can solve mysteries much more quickly. "I knew that, to really understand biology, you had to understand where everything came from," he says.

It was the advent of DNA research that made Woese’s epic mission a possibility. All life springs from four chemicals in intricately arranged DNA strands; Woese took x-ray film of each species’ strand, then compared one species’ sequence with another. Similar strands indicated that two species had common evolutionary ancestors, while new DNA sequences meant new branches in the tree. Bit by bit, he began to completely reconstruct science’s concept of the Tree of Life. But it became one of the great struggles in the history of recent science. Day after day, year after year for more than a decade, Woese worked largely alone, without research assistants, meticulously mapping out the countless forms of life on earth. The process was exhausting, punishing, and thankless. Like a lonely religious crusade, it was a task for an obsessed soul. Carl Woese got obsessed and he stayed obsessed. "I’m not sure that anybody but Woese could have pulled off the articulation of the Big Tree," says colleague Norman Pace in awe. "It required withdrawing himself from scientific society."

For Carl Woese, assembling this Whole Earth-Life Catalogue was like a titanic jigsaw puzzle. "To feel the thing growing... the islands became joined, being bigger islands, then all of a sudden you say ‘ah, this is what the picture is gonna be about,’ then you gleefully throw in all the other pieces, as fast as you can," recalls the now-celebrated Yale alumnus.

So what did the puzzle’s picture reveal? Science’s old tree -- with its great branches for Plant and Animal Kingdoms, and the assumption that never the twain shall meet — must be utterly rethought. Woese’s research revealed astonishing genetic similarities between wildly dissimilar species that offer startling new clues toward unknotting both the mystery and the history of life on this planet.

For Woese, what his work says about humanity’s true place on the Tree of Life is humbling. "It’s difficult to see this tree here as your relative, but ever since recorded history, almost, mankind has distinguished between animals and plants. These were the two great forms of life, and they were as different as different could be," he says. "But yet, scientists began to find out that there was a lot of commonality between plants and us. And that is the thing that has sort of shocked even me — to find out not how much different they are, but how much alike they are."

In short, Woese took evolutionist theory and made it proven, scientific fact. This allowed Pace and others to clone microbial species so they could be studied without the need to grow them. Suddenly, the entire world of microbes was open to study. "My belief is that Carl Woese has done more for biology than anybody since Darwin," Pace says of his tireless colleague.

Yet there was an even greater breakthrough. Life began in the roiling, sulphurous waters of ancient earth. In a volcanic vent like one might find at today’s Yellowstone, there is life not in spite of such hostile conditions, but because of it, an ecosystem so complex, thriving and different it merited its very own branch, which Woese named the Archaea. The Archaea completely changed science’s conception of just what life is, and proved life far more numerous and omnipresent on earth than previously believed. It is in water boiling at 100E centigrade, in Antarctic ice, in rock miles beneath us, and everywhere in between.

Woese understands how many might shrug about his findings. "Why should we care? We can’t see these things. Well, let’s do a thought experiment," he says. "If we take these things away, you know what’s going to happen? All the life that we can see with the naked eye, all that life, is going to disappear in short order. The microbial world is the basis upon which our whole ecosystem rests, and without them, there is no multicellular life." With an amazing feat of perseverance, Carl Woese has given humankind a better look at Eden’s Tree of Life.

                            — Dr. C.J. Peters of the Centers for Disease Control

Hosting countless microbes, the human body is an ecosystem unto itself, and its balance of nature is just as vital as with any collection of species; when that balance is upset and one organism asserts an excessive presence in the body, catastrophe can result -- HIV, cholera, Legionnaire’s Disease, Ebola.

When Navaho habitants of the desolate "Four Corners" region of the American Southwest began to sicken and die in 1993, scientists had to solve a biological mystery. Just what organism was killing these people? The usually peaceful, sometime deadly dance between microbes and their human hosts is profiled in "Dangerous Friends & Friendly Enemies," the third episode of the four-part series INTIMATE STRANGERS: UNSEEN LIFE ON EARTH, resuming on PBS on Tuesday, November 23, 1999, 8:00 - 9:00 PM (ET). The series will continue on subsequent Tuesdays through April 30.

"We looked for absolutely everything . . . all the bacterial agents, the viral agents, you name it," remembers Dr. C.J. Peters of the Centers for Disease Control of the first terrifying days of the 1993 outbreak. Within three weeks, CDC researchers pegged a strain of microbe known only in Europe and Asia, called the Hanta Virus, as the culprit. The cause, however, only led to another mystery — what was the medium of the Hanta’s transmission to humans? The case was broken in an astounding way. CDC researcher Dr. Ben Muneta, a Navaho, began to hear uncannily accurate descriptions of the disease from medicine men of his tribe — descriptions based on ancient tribal legends blaming a tiny rodent called the deer mouse. "The traditional healers told me that the way the deer mouse will take a human life is through their urine and their droppings," recalls Muneta. Research proved the medicine men exactly right.

In Great Britain, the Four Corners outbreak intrigued a medical student named Guy Thwaites, and he approached an infectious-disease expert, Dr. Vanya Gant with historical accounts of "The Sweating Disease," a malady that had ravaged the English countryside five centuries before. "I said, ‘this sounds exactly like the Hanta Virus,’" says Gant. Similar accounts place the disease’s symptoms in Asia before the time of Christ.

While Hanta’s ancient history is unsettling, and its recent resurgence disturbing, its future may give even greater cause for alarm. In Argentina, Dr. Delia Enria connected CDC accounts of the disease with recent, baffling illnesses near Buenos Aires. But this strain of Hanta had evolved, as microbes always do, and added a terrifying twist: it was not transmitted by rodents, but by other people. "I am completely sure this is the tip of the iceberg," says Dr. Enria of the new breed of microorganism. "We will find that they are causing diseases that we are not able to recognize yet." Humans -- mobilized by the airplane and increasingly invasive into previously untouched lands -- may well encounter steep challenges to their biological hegemony in the years to come.

INTIMATE STRANGERS: UNSEEN LIFE ON EARTH is a production of Baker & Simon Associates in association with Oregon Public Broadcasting and the American Society for Microbiology. The series, which is presented on PBS by Oregon Public Broadcasting, is made possible through major funding from the National Science Foundation, the Department of Energy, the American Society for Microbiology, and the Annenberg/CPB Project. Additional funding is provided by the Arthur Vining Davis Foundation, the Corporation for Public Broadcasting, and the Foundation for Microbiology.

The executive producer of INTIMATE STRANGERS: UNSEEN LIFE ON EARTH is Peter Baker.

Next week, INTIMATE STRANGERS: UNSEEN LIFE ON EARTH will look at ways in which science may soon deploy microbes to eradicate human disease, pollution and hunger as "Creators of the Future" airs on Tuesday, November 30, 8:00 - 9:00 PM (ET).