Program 1: The Tree of Life

The Quest (Part 1 of 10)

Join Dr. Karl Stetter on a mission to find the closest living relative of the first life on Earth as he discovers a strain of bacteria he names "Thermatoga."



Narrator, Lillian Lehman: According to the myths of the ancient Greeks, Zeus in the beginning ruled over an empty world. From his home on Mount Olympus he looked out over oceans, and islands, and saw nothing moving. Nothing alive. Then Zeus gave Prometheus, and his brother Epimetheus the task of making living creatures. Epithimius made plants, and birds, and animals, but it was Pomethius who made the last creature, from soil, and water he made mud, and from the mud he molded the first human being. As long as we've lived on Earth, we have sought to understand how we've come to be here. Our origins. In recent years, advances in genetics have given us new insight into the question of origin. He can for instance, tell whether this man fathered this child, by comparing their DNA, the chain of chemicals that exist inside every every living cell. We can even trace family trees, back many generations by comparing the DNA of relatives both living and dead. Many of us are intrigued by the idea of family trees, knowing who our great, great, grandparents were, enriches our sense of who we are. Now, scientist are using DNA to construct a new kind of family tree. It will reveal not just the relationships of a few generations of human beings, but the exact genetic relationship of all living things on Earth. It is the Tree of Life. And it offers us a understanding of the roots of each and every one of us. That reaches all the way back to the birth of life, on this planet.

{Title: The Quest}

Narrator, Lillian Lehman: German scientist Karl Stetter is returning for the tenth time to the tiny island of Vulcano, off the coast of Italy. In ancient times, this active volcano was believed to be the gateway to Hades, land of the dead.

Scientist, Karl Stetter: I love these guys, these volcanoes, and there are only two ways, either you like them or you hate them. I like even the sulfur smell. So, this is an environment which really makes me excited thinking, and dreaming of the primitive Earth. It's very stimulating for me.

Narrator, Lillian Lehman: At the age of fifty-eight Karl Stetter is focusing his considerable energy on a monumental task, unraveling the mystery of early life on Earth. But Stetter is not searching for fossils. He is searching for microbes, what most of us casually dismiss as germs, but are really tiny fellow residents of the planet. Who inhabit a world that is even more complex and diverse than the world we can see.

Scientist, Karl Stetter: When I was a little child already, my parents donated {to} me for Christmas a little microscope, and I looked in it, and I saw all these many shapes of things, of amoeba, and bacteria, and so I became so excited, that I must work on this. Now I'm so happy that I, even can, search for the deep organisms in the Tree of Life.

Narrator, Lillian Lehman: The Tree of Life. For thousands of years, human beings have thought of life as being divided into just two branches one for plants, and one for animals. Now, through breakthroughs in the understanding of DNA, scientists are painting a very different picture of the Tree of Life. Their most amazing discoveries are about the evolutionary relationship between human beings, and microbes.

Scientist, Karl Stetter: Microbes are everywhere, and for example, even on my skin there are hundreds of thousands per square inch, and they are growing there, and they're protecting the skin, from organisms which are harmful to us.

Narrator, Lillian Lehman: On your skin there is a world in which hair follicles tower like redwoods, and dust mites are the largest animal, and far smaller still there are microbes living by the trillions. For those of us that think of microbes as germs, its hard to believe that tiny life forms like these might have a place on our family tree. Yet that is exactly what Karl Stetter is out to prove. How? Just as any one of us might learn more about the history of our own family, by tracking down our oldest living relative. Stetter searches for the hottest spots he can find, hoping to locate the modern life forms, most closely related to the first life on Earth. But why hot spots? From studying microbe fossils, scientists are convinced that life on Earth began before three, and a half billion years ago. But from studying rocks, they've discovered that before three, and a half billion years ago, our planet was still steaming hot, and covered by oceans that regularly reached the boiling point. All of which made for a riddle. What can live in boiling water? Microbes that thrive in boiling water, first discovered by Karl Stetter, on the island of Vulcano. These amazing microbes live in an environment very much like that of the early Earth.

Scientist, Karl Stetter: Some of these microbes, especially the ones which grow in this high temperature, one would say, are very different from our way of living. We are for example, we like to have roast pork, and on the other hand, we need oxygen to do our respiration. And these guys, instead of pork, they like hydrogen gas, and instead of oxygen, they like sulfur. And you see it all here, yellow. That's a stinky gas of stink bombs.

Narrator, Lillian Lehman: These heat loving microbes inhabit such remarkable homes as the boiling mud on the ocean floor, near Vulcano.

Scientist, Karl Stetter: The temperature is about Ninety to Ninety-five centigrade, so it's really damned hot, this sediment.

Narrator, Lillian Lehman: Stetter is on a mission to gather another sample of these microbes he affectionately calls bugs. He is particularly interested in a species he named Thermatoga Maritima.

Scientist, Karl Stetter: A lot of high temperature bugs are already in, and this will be very interesting to look at in the lab.

Narrator, Lillian Lehman: This is Regensburg, Germany founded two thousand years ago by the Romans. For four hundred years, home to the kings of Bavaria. And today Home to Karl Stetter. As he returns to Regensburg. Stetter goal is to find out for certain, how closely related Thermatoga is to the first life on Earth. To do that he needs to isolate Thermatoga's DNA. {Sounds of Singing.} This is Regensburg's world famous boy's choir. One way to think of DNA is as the recipe for producing a particular kind of organism, in the same way that a musical score is the recipe for producing a particular piece of music. {Sounds of Singing.} In western music, hard as it is to believe, the instructions for all the wonderful and complex songs ever written are made up of a eight different notes. {Sounds of Singing.} In DNA, hard as it is to believe, the instructions for all the wonderful and complex organisms ever produced, including us human beings, are made up of just four different chemicals. {Sounds of Singing.} In music, the basic notes have been arranged and rearranged in an almost infinite number of combinations to produce a unique score for every song that has ever been sung. In DNA, the basic chemicals have been arranged, and rearranged in an almost infinite number of combinations to produce a unique score for every organism that has ever existed. From bacteria to boys. {Sounds of Singing.} Stetter knows that if scientists can study the score of Thermatoga's DNA they can find out, where it belongs on the Tree of Life. But for Stetter and his team in the University of Regensburg, to gather enough DNA to study, is just short of impossible. The sample from Vulcano contains just a few invisible microbes, with the tiniest imaginable amount of DNA inside them. To get more DNA Stetter has to get Thermatoga to live and multiply in the lab, and that means some how recreating the environment in which the microbes were living on the volcano, in doors.

Scientist, Karl Stetter: Nothing is impossible. You have to try to do it, and you have to use, all tools, and mainly your brain, to find out how to get it, and there are many things which are possible, and which can be made.

Narrator, Lillian Lehman: Stetter begins by putting the sample of Thermatoga into a high tech brewer's vat. Then he pumps in steaming hot water, at what he believes is just the right temperature, and adds what he thinks is just the right combination of hydrogen and sulfur. Then he lets his in door volcano go to work.

Scientist, Karl Stetter: I always say, I hope never it will erupt.

Narrator, Lillian Lehman: Stetter is driven by a determination to succeed, where many others have failed. So far only a minute fraction of the microbes that live in nature have been successfully grown in the lab. Growing microbes might be compared to a gardener trying to get a rare orchid from the heart of the rainforest to flourish in a greenhouse.

Scientist, Karl Stetter: If you look carefully, you'll find the requirement. It's very simple with the orchid, some you have to hang them up into the roof, otherwise they will not be happy. Some people say I have a green thumb, but you see, it's not so green.

Narrator, Lillian Lehman: In the lab Stetter has reached the moment of truth. Has his green thumb produced a happy multiplying population of Thermatoga, or is something wrong with his recipe, and the microbes have died?

Scientist, Karl Stetter: It looks excellent, before it was completely clear, but now the micro-organisms have been grown, and there are about a hundred million per cubic centimeter. And so, therefore it's turbid, and not clear anymore, and that's, that we know it was growing very well.

Narrator, Lillian Lehman: By morning the tiny sample of Thermatoga from Vulcano, has grown into trillions of cells of Thermatoga. Which have been collected on this special filter.

Scientist, Karl Stetter: Now that's a lot, that's about ten thousand billions of cells, and their all alive, and there, this is the real color of this stuff, it's almost like yeast.

Narrator, Lillian Lehman: Now, Stetter and his team have grown more then enough Thermatoga cells. Enabling them to extract more then enough DNA for scientists to work with.

Scientist, Karl Stetter: That's DNA from Thermatoga Maritima, and that's a lot.

Narrator, Lillian Lehman: It is gooey material like this, that contains the instructions for creating all life on Earth.

Scientist, Karl Stetter: Normally we work hard, but this evening, let's drink hard? Prosit, Cheers.

Narrator, Lillian Lehman: Karl Stetter harvesting of Thermatoga's DNA is a remarkable accomplishment.

Scientist, Karl Stetter: Prosit.

Narrator, Lillian Lehman: But for other scientists, harvesting the DNA of an organism is not an end, but a beginning.

Scientist, Karl Stetter: That's good stuff.

(Transcript provided by Tyler Anderson)



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