Transcripts

Judgment Day: Intelligent Design on Trial

PBS Airdate: November 13, 2007
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Chapter 5

WITOLD "VIC" WALCZAK (Dramatization): Dr. Miller, what is evolution?

KENNETH R. MILLER (Dramatization): Most biologists would describe evolution as "the process of change over time that characterizes the natural history of life on this planet."

WITOLD "VIC" WALCZAK (Dramatization): And what was Darwin's contribution to evolution?

KENNETH R. MILLER (Dramatization): Darwin pointed out there's a struggle for existence, whether we like to admit it or not. He realized that those organisms that had the characteristics that suited them best in that struggle, those were the ones that would hand those characteristics down to the next generation, and that, therefore, the average characteristics of a population could change in one direction or another and they could change quite dramatically. And that's the essential idea of natural selection.

NARRATOR: Starting with Ken Miller, the plaintiffs walked Judge Jones through the conflict at the heart of this case.

Miller testified how Darwin's theory pictures the history of life as a tree, with species gradually evolving into others over millions of years, producing new branches and twigs, a process that gives rise to all the variety of life, from bacteria to Darwin's finches to ourselves.

But intelligent design takes a different view, as the movement's own literature shows. Intelligent design teaches a history of life in which organisms appear abruptly, are unrelated, and linked only by their designer.

NICK MATZKE: What's really being advocated is the idea that organisms poofed into existence through the miraculous act of an intelligent designer, i.e., God. That's the view that intelligent design promotes.

NARRATOR: So how can scientists be so sure Darwin's tree accurately represents the history of life on Earth?

As it turned out, the latest in a large body of evidence to refute intelligent design and support evolution was coming to light just as this case was unfolding.

NEIL SHUBIN: I remember thinking to myself, when all this was going on, "Wait'll they get a look at this, because it's just so beautiful."

NARRATOR: Darwin believed that evidence for his idea of common ancestry would be unearthed in the form of transitional fossils. For example, if, over millions of years, fish gave rise to land animals, as evolutionary theory predicts, we should find fossils of extinct creatures that are part fish and part land animal.

In 1999, paleontologist Neil Shubin and his colleagues set out to find just such a creature.

NEIL SHUBIN: What evolution enables us to do is to make specific predictions about what we should find in the fossil record. The prediction in this case is clear-cut. That is, if we go to rocks of the right age, and the rocks of the right type, we should find transitions between two great forms of life, between fish and amphibian.

NARRATOR: Many scientists think life began in the water, at least three and a half billion years ago. More recently, about 375 million years ago, the tree of life branched as primitive fish evolved into amphibians, such as today's frogs and salamanders, which live part of their lives on land.

Armed with this prediction, Shubin and his colleagues organized an expedition to one of the most desolate places on Earth, the Canadian Arctic, about 500 miles from the North Pole, where rocks of just the right age are exposed. Here, they hoped to fill a gap in the branch of the evolutionary tree that leads from primitive fish to animals with four limbs, or "tetrapods," by finding a fossil of an animal that shared characteristics of both.

But after three summers of digging through hundreds of tons of rock in this harsh environment, they had found little of interest. They returned the next year for one last try.

NEIL SHUBIN: Money was running out. This was it. We were told this was our last year up there. And then, in 2004, in the third day of the season, a colleague of mine was removing rock and discovered a little snout sticking out the side of the cliff, just exactly like this. And he removed more rock and more rock and more rock, and it became clear this was a snout of a flat-headed animal. And that's when we knew. Flat-headed animal at 375-million years old? This is going to be something interesting.

NARRATOR: They called it Tiktaalik, which means "large, fresh water fish," in the language of the local Inuit people. And it's one of the most vivid transitional fossils ever discovered, showing how land animals evolved from primitive fish.

NEIL SHUBIN: Over here you have a fish of about 380-million years old. And, just like any good fish, it has scales on its back and fins. You compare that to an amphibian, and you find a creature that doesn't have scales, and it's modified the fins to become limbs, arms and legs. And the head's very different. It has a flat head with eyes on top and a neck.

What we see when we look at the fossil record, at rocks of just the right age, is a creature like Tiktaalik. Just like a fish, it has scales on its back, and fins. You can see the fin webbing here. Yet when we look at the head, you see something very different. You see a very amphibian-like thing, with a flat head, with eyes on top. It gets even better when we take the fin apart. When we look inside the fin, as in this cast here, what you'll see is bones that compare to our shoulder, elbow, even parts of the wrist—bone for bone. So you have a fish, at just the right time in the history of life, that has characteristics of amphibians and primitive fish. It's a mix.

NARRATOR: And just as evolutionary theory predicts, Tiktaalik suggests a tree of life, with one species giving rise to another over millions of years.

The discovery of Tiktaalik was still being written up at the time of the trial, so it couldn't be used as evidence. But Shubin's colleague, paleontologist Kevin Padian, showed the judge examples of other fossils with transitional features that support Darwin's tree of life.

KEVIN PADIAN: My testimony in the trial was basically taking a day and showing the judge how we do our work and what the evidence is.

NARRATOR: How dinosaurs evolved into birds, as seen in creatures like Archaeopteryx which has a long tail and teeth like a dinosaur, but feathers just like a modern bird. How ancestors of modern reptiles evolved into creatures now extinct that share a common ancestor with mammals. And, how, surprisingly, whales evolved from large land animals that returned to the water.

KEVIN PADIAN: And where the Pandas book says we can't go from A to B, there are no fossils and we don't know how to study them, actually, we've gone from A to B and to C, D, E, F and G. We have the fossils; we have the transitional features; we have the ways of analyzing them with many different lines of evidence. And we're looking for the picture that accounts for the most lines of objective evidence.

NARRATOR: With each fossil, Padian refuted Pandas claim that different life forms appear suddenly, by showing how fossils of extinct organisms bridge the gaps between species, resulting in a picture of gradual evolution, just as Darwin proposed.

KEVIN PADIAN: The reporters in the courtroom were just amazed that we knew all this stuff. And how come they hadn't learned about this stuff before? And the reason is it's not in textbooks because the creationists fight so hard to keep it out. That's been a big influence.

ERIC ROTHSCHILD: The court took a break. And I remember the judge saying something like, you know, "biology class adjourned," you know, "for lunch." And he was, you know, smiling. And it was clear that we had the judge interested in science.


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