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				Noah’s Snowball Researchers find evidence that a massive ice age gave birth to a whole new type of animal - a multicellular one.
		Select text to jump ahead in the clip: and perhaps more significant. Astonishingly, we didn't even know about it until a year or two ago when geologists Paul Hoffman and Dan Schrag came up with the extraordinary idea that the Earth was once frozen solid like a snowball. These rocks on the New England coast were formed when the snowball began melting 600 million years ago. In what was then the ocean floor a stone fell from the melting ice and plopped gently into the mud. Here's a moment, many millions of years ago where that ice started to melt just enough for that rock to fall out of the ice through the ocean and down into that sediment and we're looking at a specific moment in time there. That moment, you can put your finger on it and say "This is the moment of the biggest climate change in Earth history"-- where it flipped from being incredibly cold to incredibly warm and we now can tell the story of that. Alda: It's a story that's breathtaking enough by itself but it may also unlock the answer to a really big question: How did life become interesting enough eventually to produce us? But let's start with the rocks. What we're walking on may be near Boston now but once, 600 million years ago it was in what later became Africa. There were glaciers all over Africa at that time. Is that what you're saying? That's right, 600 million years ago every continent in the world was covered by ice. Alda: And according to my companion's startling hypothesis it wasn't just the continents that were ice bound. We see here the sea ice that formed in the last few weeks but 600 million years ago, the sea ice was a mile thick. Mile thick? The ocean... The oceans were frozen over. And so, the whole Earth was in fact this giant snow... That's why we call it a snowball. Snowballs-- sounds more like an ice ball. I mean, it was really impenetrable. It's extraordinary. The idea that this happened makes you rethink everything you think you know about life on this planet about the chemistry of the Earth and about the geology of the Earth. Alda: Here's what Hoffman and Schrag think happened. For reasons they don't fully understand 600 million years or so ago the Earth cooled by a few degrees and the polar ice caps began expanding slowly toward the equator. As more and more of the Earth's surface became covered with the highly reflective ice more and more of the sunlight falling on the Earth was radiated away into space. When you get to about half the Earth's surface covered-- that is, the ice lines down to about 30 degrees north and south of the equator-- then the effect is unstoppable and the whole thing just freezes over instantly all the way to the equator. Schrag: Once the whole planet's surface is white because it's snow and ice, the temperature plummets. It goes down to about minus 50 degrees C. Alda: And there the Earth might have remained forever a brilliant, white, cloudless snowball floating in space. What saved it were its volcanoes poking through the ice and spewing into the atmosphere the gas that today we fear may be leading to global warming-- carbon dioxide. Eventually, carbon dioxide built up to levels where the greenhouse effect kicked in with a vengeance. Temperatures started to rise. The equatorial ice began to retreat and the snowball melted as suddenly as it was formed. When the snowball ended and you started to melt the ice at the equator you could say literally all hell broke loose where in 100 years you go from a completely frozen planet to the warmest state the Earth's ever been. Alda: This cataclysmic climate change must have been devastating for life on Earth or so you'd think. But life today is very different from life 600 million years ago when it was quite literally stuck in the mud-- boiling mud. Alda: Is this whole park on a crater... a volcanic crater? Woman: That's what Yellowstone is is the remnants of a massive volcano that occurred on the order of 800,000 years ago. Blew ash all over the western United States and this is what's left of it, and it's still pretty active. Is this as active as it's ever going to get now? Ever? No, there's a very thin crust here. It's going to blow again, you're telling me? It could... We're standing on one of the places... It's going to come up first. Bubbling already. That's right. Alda: Whenever they visit here biologists Sue Barnes and Norman Pace first measure the water temperatures which seem way too high for the sort of life that occupies most of the planet today. So this is going to be all water temps now, Sue. Barnes: Okay, that's fine. Pace: Okay, read them off. Alda: Okay, 109, 157. Whoa. Whoa! Let's wrap around down here. I'm sorry. Oh, no, it's okay. Barnes: It's not fatal. Have you lost many microbiologists here? I saw a bleached bone up there. Alda: But in fact, there is life here. Even where it's boiling the mud is teeming with microscopic creatures. ( bubbling and gurgling ) All my life, I've been taught that if you boil the water you'll kill anything nasty in it. And if you boil the medical instruments, you'll make them sterile. That's certainly true for the sorts of organisms that would infect us. They would not survive the boiling. But if you evolved capable of... you're in fat city if you're in such a hot environment then it doesn't matter. Alda: We brought along a microscope to take a look at these heat-loving creatures. Should be in focus. Can I look? Alda: I'm looking at the sort of microbes Sue and Norm believe were once and for a very, very long time, the only life on Earth. It's like looking through a time machine, in a way... In a very real way. ...to the earliest days. In a very real way. I think that these organisms the general properties of these organisms will be not at all too dissimilar from the nature of the earliest organisms. Alda: Even after two billion years of evolution this is all life had come up with. At least it was well-equipped to survive the snowball nursed through the deep freeze by the heat of the same volcanoes that eventually re-warmed Earth. But life not only survived the snowball it was about to be transformed. To see how, we've come to southwestern China. Our journey begins with a train ride on a rainy summer morning. On board the train is biologist Andy Knoll. Knoll: We've all heard of the Big Bang through which the universe is thought to have begun. But in biology, there's another kind of Big Bang-- a Big Bang of animal evolution. Life began at least 3½ billion years ago. But it wasn't until 580 to 570 million years ago that we see any kind of animal life and then, in just a few million years we have a tremendous diversification of different types of large and complicated animals. And here in China, we see one of the best available records of that biological Big Bang. Alda: It's in the Chun Jiang Hills of Yunan that you can see spectacular fossils of those first animals in rocks that formed out of mud on the bottom of an ancient ocean 550 million years ago. In rocks just a little older than these all fossils are still microscopic so this place marks the very beginning of animal life. There's been an excavation here for almost five years and today, Andy is meeting the man behind it paleontologist Chen Jun Yuan. It's in there that the event beds that really captured the fauna are found. Yeah. Alda: The real fossil hunting here takes place across the road where 30 local women split the newly excavated rocks into thin slices. They get paid about 50 cents per fossil found plus a bonus for unusual discoveries. The rocks are loaded with fossils. While the fossils come pouring in Professor Chen tries to figure out what they were. Okay, so there's two valves... Yeah. And then, the animal inside was a little bit shrimplike. Alda: This seems to have been a kind of combined clam and shrimp. It has almost like a fin on it which would help it to move through the water. Yes. Interesting. How about this? This looks like big pincers. Oh, yes... Alda: And this fossil has the familiar look of a lobster claw. Chen's never found a whole one, but he's got enough parts to know these animals could get huge. Oh, the largest one can be two meters long. Two meters long? Yeah, very large beak and mouth... a large mouth. So this could eat everything else in the whole Chun Jiang fauna. Alda: Many of the fossils don't look like anything alive today. But for the first time life had broken through the constraints imposed by being simple, single-celled creatures and had begun an explosive exploration of the possibilities of complexity. Animals had arrived. And that brings us right back to our snowball. Hoffman: The question ultimately is, were animals inevitable? Would biology have come up with animals in any case? Or did you have to hit biology over the head with a hammer? Or we'd hit them with a snowball. Alda: Hit them with a snowball, yeah. So it sounds like you feel that you had to hit it over the head with a hammer. Yeah, because the coincidence in timing. I mean, it's hard to ignore the fact that you have this explosion of multicellular animal life. Alda: I mean, what do you... Two billion years, you had algae and bacteria living and nothing happened. Just fine. And then all of a sudden after you had these repeated glaciations that's when multicellular life occurred. It's possible that it's a coincidence but I think it's unlikely. It's such an... Catastrophe! A giant event, I mean, it's such a clear marker in the history. Exactly. In some ways, it's like Noah's flood-- a catastrophe, and then a redemption that actually ends in a much more interesting world than you had before. Alda: It's a captivating idea that volcanoes saved both our planet and our ancestors from an icy coffin in a period of cataclysmic climate change that kick-started animal evolution and that eventually led to us. The whole Cambrian explosion can't be traced directly. Alda: While Paul Hoffman and Dan Schrag are very aware that the Snowball Earth hypothesis is just that, a hypothesis they're still savoring its invention. Alda: When this all came together for you was it a gradual process Hoffman: or was iIn my case,ion, a it was like a flash. All of a sudden, my world was transformed. What was that like? Because not only, you know, did I suddenly get this clue but I just knew in my bones, almost from the instant not only that it was right buit was a big thing, it was a big deal. We tend to... Paul and I are both night owls and and at about 1:00ate at or 2:00 in the morning we had a conversation that was sort of an epiphany for both of us and as a result, the next two months we were ng back and forth new ideas flying and that exciting discovery being able to go out in the field and know that you've forever changed the way people think about this... That moment of discovery was amazingly exciting. Billions of years of evolution has produced probably billions of different living things.

				Alien Worlds Astronomers look for and find worlds outside our solar system. Some of them just might be teeming with life.
		Select text to jump ahead in the clip: Are we alone in the universe? The telescope here is almost 70 years old and looks it. I can operate the telescope from here. Alda: With only a 61-inch mirror it's puny by the standards of today's telescopes located on far more exotic mountaintops but it's playing a key role in searching for alien worlds. Come on up and take a look at the instrument. It seems hard to believe that with a relatively small telescope you can find something so tiny as a planet. Well, we don't find the planet. We only see the motions that the planet makes on its parent stars. In fact we have a model over here that might help you see how that works a little bit better. Here we have our model of an extra-solar planet. There's a star like the sun and then out there swinging around in its orbit is a planet. Of course, planets are much fainter than their parent stars because they only shine by reflected light. So it's almost impossible to take a picture of a planet. Instead we look for the motion of the parent star. The star is much more massive than the planet so its motion is much smaller. The planet swings in a wide orbit and then the star swings in a small orbit in response to the pull of the planet. Now, when you're looking with the telescope are you seeing the star move from side to side the way it appears to me or are you looking at something that goes away from you and toward you? Well, right now it's going away from you and that's the motion that we're measuring back and forth along the line of sight. Alda: My hosts point the telescope at a favorite star. Alda: What is it you like about this? I like it because it looks a lot like the sun. Has it gone behind a cloud now? Yes, the star's gone behind a cloud now. Alda: The clouds part long enough for the star's spectrum to be recorded and it's these lines that reveal the star's wobble back and forth. As the star moves these lines will shift their position depending upon what the velocity is. Alda: The telescope here is old but it's cheap and that's why it's useful. Some of them, like this one, are really quite interesting... Alda: With it, David and Robert can sift through hundreds of stars looking for just the ones that wobble and so are candidates for those much more powerful telescopes on much more imposing mountains. Over 13,000 feet up at the top of Mauna Kea in Hawaii, for instance is the Keck telescope. The mirror here is almost 400 inches across. Its ability to collect far more light means it can see far more details in the wobbles of stars. And in the last few years, the Keck and other huge telescopes have produced a cornucopia of likely planets-- over 30 in all. Almost all these other possible worlds are huge and orbiting much too close to their parent stars to support anything like life as we know it. The most dramatic discovery made by analyzing stellar wobbles has been of three planets orbiting a star in the constellation Andromeda. But looking for wobbles has its limitations. At best it says only that something is tugging on a star. Latham: But there's another way that you might deduce that there's a planet in an orbit around this star and that's if it happens to go between the observer and the star. You'll see the light of the star blocked a little bit. Right now that planet is not passing across the plane that the camera's looking at, I don't think. It wouldn't see any dimming. Yeah, too bad. So you have to look at a lot of stars to find the ones that are lined up just right to see a transit. Alda: And as it turns out, only days before my visit the patience of the Harvard team had paid off with the first-ever observation of a planet passing in front of another star. Alda: Oh, there... there it is. That's the one, huh? Stefanik and Latham: That's it. Latham: This is a star that's in our catalogs because we've been observing it for seven years. So, in August, we gave this star to one of the graduate students at Harvard and suggested he go look for a transit. And we told him when to look because, of course, we know the orbit so we know when the planet is going in front of the star if it goes in front. We had no idea it would go in front. It might go above it or below it and he'd never see anything. But he's a graduate student, you know. He has time to go do things like that. ( laughter ) And damned if he didn't find it, in September on the eighth of September and the 15th of September-- a very exciting way to begin a Ph. D. research program for Mr. Charbonneau, I can tell you. Alda: From an observatory in Colorado the graduate student measured the star's slight dimming exactly when David Latham had predicted it. The amount of light blocked gave the diameter of the planet-- the first time this has ever been possible. The planet turns out to be a little bigger than Jupiter and far lighter than the Earth still an unlikely spot for life, but unquestionably a planet. This is big stuff, isn't it? Both: This is very exciting. Something this exciting only comes along once or twice in your career. And you caught us! And here we were. And tonight's the night! And not only that, the clouds parted for us-- that's the great thing. What's drawing you on like this? What personally is making you look for those planets? It's one of the big questions: Is there life elsewhere out there? And if there's life, does it live on a planet? And are there planets where they might live? And we have an opportunity in this age to make a contribution to the answers to those questions. Alda: Meanwhile, the contribution of this elderly little telescope doesn't stop with simply screening stars for wobbles. This is the apparatus that we built at the Harvard Physics Labs and you can see it's sort of a parasite. It's screwed onto the side of the spectrograph which, as you know, is looking for planets around other stars. And we're also looking for planets but in a slightly different way. We take about a third of their light and we look instead for a different kind of signal. We look for a sudden flash of light from an alien civilization's laser sent in our direction to establish contact with us civilization to civilization. Alda: You heard right: Paul Horowitz is looking for laser beams sent our way by aliens who've detected our planet and are looking to open a dialogue. And if that isn't amazing enough he sees what could be a laser flash every couple of nights or so. Horowitz: We have spent extra time observing many of these objects because, you know, it's kind of fun. You see a flash in the data in the morning and you'd have to have rocks in your head to say "Well, on to the next object. " It sounds like it would be a semi-eureka to get a second flash from an object. Well, I think I'd like to see two... well, you know, how about three or four, equally spaced... Well, yeah, that would be a big eureka. x But I mean, if you got a second flash wouldn't your hair start to stand up on the back of your neck? Yeah, we probably have an object with two flashes so I'd better be cautious about hair standing on end. You do really have an... you think you have one in your... You do really have an... you think you have one in your... Well, we have to look at the data. But I think we've seen objects with a couple of flashes. I should say that the fuzziness in my statements here have a little bit to do with the fact that in the summer, when humidity is high these detectors start to show artifacts and in the summer, we definitely have multiple hits on objects. But we don't take it seriously. We hope that aliens will communicate with us wintertime, North America. Alda: Paul Horowitz is the first to acknowledge that his way of looking for planets is a long shot. But astronomers have growing confidence not only that planets are commonplace but that methods for detecting them will soon allow us to look for planets like our own and even for signs of life. Then we'll know where to point our laser beams if we decide to say hello. Alda: To end our show on Life's Really Big Questions we've come to a man whose job it is to wonder about such things--

				Robot Independence Natural selection is at work in the artificial world, as robots learn to reproduce without us.
		Select text to jump ahead in the clip: billions of different living things but it hasn't stopped there. Thanks to our invention of the computer evolution is now producing a whole new generation of creatures. Man: Evolution by itself has led to the creation of incredible complexity-- ourselves, all the organisms in the world. This process happened on its own, at least in my opinion. There is nobody that assembled all of these wonderful things in the world. On computers we can simulate the same process and we can get these very complicated, very interesting things without having to understand them and assemble them. Alda: Karl Sims was one of the first researchers in what is now a burgeoning field: artificial life. He started by giving his computer the instructions for a set of basic parts. Sims: The bodies of these creatures are fairly simple. They're just made of some number of blocks. The blocks are connected by joints which can bend or twist. The creatures also have a nervous system. They have sensors which can sense the angle of the joints or sense contact. And the nervous system processes the signals from the sensors and tells the muscles when to move which generates some kind of behavior. I've given it the capabilities to include all these elements but the computer actually decides how they're assembled and how they're used in specific creatures. Alda: Numbers chosen randomly by the computer-- a synthetic genetic code-- described how the first simple creature would look and how its nervous system would be wired. Then it was put into a simulated lake and told to swim. It twitched but it didn't get anywhere so now the computer went to work. Using the original numbers as its base the computer made a few random changes-- the equivalent of mutations. It did this again and again creating a new generation of 300 different offspring. Then all the offspring got a swimming test with the best swimmers selected as the basis for the next generation. Sims: When the computer makes mutations in the genes of these creatures it has no idea what these mutations are going to do. Sometimes the mutations might knock out a piece of the nervous system and perhaps cause the muscles not to move anymore. But other mutations might actually improve the motion. Alda: So from the original creature increasingly better swimmers evolved over generations all without any human intervention. In the end, this was the best swimmer of all. But when Karl Sims put it on simulated land it was like a fish out of water. So over subsequent generations the mutation and selection process had a new goal: to walk. After 15 generations, this was the champion. Other computer runs have produced even better walkers. Sims: Sometimes these evolving creatures would think of solutions to their goal which were completely different than I expected. In this one example the creatures got taller and taller and taller and would simply fall over. Instead of figuring out some clever way of walking they would fall to generate horizontal velocity. What I was telling them to do was to just move. And falling was a perfectly good solution as far as they were concerned. So this creature specialized in falling for as long as it possibly could including doing a complete somersault. Alda: Karl Sims' creatures may have evolved some very clever tricks but they're confined to the virtual world of the computer screen. All right, so what do I do? I take a piece and put it next to this? Alda: But here in Jordan Pollack's lab at Brandeis University artificially evolved creatures have already taken the first steps into the real world. Alda: You know, you should have had a five-year-old come and do this. What am I making here? Man: We call it the lamp. We don't really know what it is. It's a structure that the computer evolved or designed through evolution. Alda: The Brandeis computer is told the basic facts about Lego bricks: their weight, how firmly they stick together and so on. Then through hundreds of generations the computer uses its virtual Legos to evolve structures selected for how well they perform a certain task; in this case, to hold a 20-gram weight as high and as far to the left as possible. This is the computer's best current solution. A human-- in this case, me-- gets involved only to build it. This design was evolved to reach out as far as possible without breaking. And this crane was evolved in the computer to lift a 100-gram weight. The point of actually building the structures is to see how well a design evolved in the virtual world-- where everything is perfect-- holds up when it meets the real world where almost nothing is perfect. Man: Put it down gently, sir. All right, all right, let's see. Whoa! ( laughter ) Funes: It broke! Uh, was that me or was that the computer? Funes: I think... I think that was the gap on the table. Funes: I think that the books moved. The book moved? Yeah, I think that the books slipped. Oh, these books slipped. Now, there's an example of the real world, right? That thing worked in the computer. Had you ever put that catalogue on top of it? No. Yes. Oh, yeah, actually, before. Yeah, we have tried it. Okay, well, there's another example of the real world. I mean, sometimes the real world works one way and sometimes it works the other way. Pollack: Well, why don't we see if we have more success standing up today's new structure? Betsy and Greg have finished it. Now, this one's never been tested before. Never been tested before. Funes: The other one had been tested before. A lot of help that was. Alda: Now, it might seem odd in a show about life's really big questions to be worrying about whether a computer-designed Lego lamp is going to stand up. But Jordan and Pablo see this as the first step toward something far more ambitious: machines that are not only designed without humans but are built without humans-- in other words, robots that don't need us at all. So, there it is, it stands. Alda: But first things first. It's holding its own weight. It's holding its own weight. And now the question is, sir, do you want to... You have a real way with robots. I have a touch for this. Funes: No, not again! So put it between the last two knobs. Right between these two knobs. Alda: Okay, drum roll, please. I'm not going to jerk it. I'm just going to let it go... Look at that! Alda: Mission accomplished. Now, about those robots that can do without us... This artificially evolved creature is one of several the Brandeis computer has come up with that are very similar to the ones Karl Sims' computer created except that these creatures, with only minimal human help are already making the leap into reality. Man: The idea is that not only do we want the robots to be autonomous in terms of behavior and in terms of power but we also want them to be autonomous in terms of their own design and manufacture. Alda: Hod Lipson has written a program that allows the computer's design to be directly printed out in plastic. We've speeded up the time it takes but the remarkable fact is that between telling the computer what the robot should do and actually taking the robot out of its miniature factory no human was involved. There are still a few tricky steps that haven't yet been automated like plugging a motor into... well, at this point I'm not quite sure what. The computer came up with this loose, hanging-down piece in the evolution of this thing. What was it told to do? What was it told to make? The only thing that the computer was told to do is to make something that moves. As we will see this floppy thing is very important for its motion. Okay, this is great. Because, you know, if you just... I come up to this table and I look at this and you say the computer invented this great thing... ( laughing ): This great thing. and it moves and it uses this to move. And I'm thinking, "I don't think so. " The computer knows more than I do in this case. I can't wait to see this move around the table. That's the nice thing. You get creative, surprising sometimes, solutions. Yeah, there. Oh, look at that. There's something especially weird and interesting about the fact that the computer thought it up and then it told another computer to make it. Lipson: This is automation. And then you just have to help a little bit by plugging things in. Pollack: Plug in the motors. Alda: It's possible, of course, to see these awkward machines as the innocent forerunners of a sinister robot race that evolves beyond our control. But Jordan Pollack sees them rather as prototypes for cheap, disposable robots for everyday use. Pollack: You might have a meta-robot in your home and you say, "Gee, I want something to clean the front gutter of my house. " And you generate a robot and out it comes and you throw it up on the roof and it cleans the gutter of your house. And when you're done, you throw it in the recycling bin. This little robot-making machine... depending on what I need that week. Exactly. Alda: But as our little robot gets recycled in the laboratory toaster it's hard not to wonder if one day robots that can evolve and manufacture themselves will find humans unnecessary. These things might completely do without humans and surpass maybe human engineering capability and reach something that we can't think of today. How old is this telescope? Alda: The top of a modest mountain in MassachWusetts may seem an unlikely place to be asking our next big question:

				Handmade Humans What separates humans from the rest of the animal kingdom? It could be as simple, or as complex, as the way we pitch a baseball.
		Select text to jump ahead in the clip: But of those billions, only one-- so far as we know-- wonders about how and even why it's here. Which poses, perhaps, the biggest of life's big questions: What happened some five million years ago that set us off on our unique journey and strode away on two legs, freeing its hands to become... Well, that's what our next story is going to explore. Man: Make a fist. Point at something. Alda: I'm returning to the Stone Age equipped with a cyberglove able to measure every subtle movement of my fingers and hand. the very latest in high tech , being used to study the oldest tech of all-- tools one. ( rocks clicking ) Mm-hmm... Ah, there, I got a nice piece there. Man: I think we have natural. Oh, now I have two. Here, you want to cut some? ( people laughing ) I'll go halves with you on that antelope. Well, how did I do with this? I think we're quite impressed with how you did with that. Very effective and, uh... removed a lot of flakes. Alda: So that must mean it must be innate, right? Alda: That's the idea we're exploring in this story: that our hands were designed for making stone tools-- that they were, in fact, designed by making stone tools. You've got quite a cutting edge here so you'd be quite competitive. So you can move up 100,000 years in evolution. ( chuckling ) Alda: Of course the hands of our ancestors got a great start. This is Tujo the orangutan, one of the stars of the Phoenix Zoo. Orangs and humans last shared a common ancestor about 12 million years ago. While we've both been evolving ever since Tujo's hands give us a glimpse of what ours may once have been-- extremely dexterous, but shaped by a life in the trees. Woman: You notice that he's carrying it in his foot. When they're moving around, they have two hands that they're moving on the branches with. the fruit with them And the onp is to carry it in the foot. And the feet act very much in coordination with the hands in manipulating foods. Alda: Tujo uses his feet not just to carry the grapefruit but to help eat it, too. And he needs at least both of his hands to help resist the pull of his teeth. Marzke: Possibly we would do that for a big piece of fruit but as it gets smaller we are able to get a good purchase on it by our thumb and fingers which adapt to the shape of the grapefruit. Alda: To Mary Marzke, this is an important clue as to what makes our hands different and far more capable. But before our hands could change they had to be free and that meant standing on our own two feet. Is that Lucy there? This is Lucy. This is actually a copy of her bones. Alda: Our most famous ancestor, Lucy lived about 3.2 million years ago in what is now Ethiopia. How do you know she was an adult? Well, we have her lower jaw. And we can see that the last molar tooth-- the so-called wisdom tooth-- is erupted and was being used for chewing. And we can actually see that because the tips of the little cusps on top of the teeth are polished and worn meaning that she was using them to chew. That's full adulthood. 3½ feet tall, however, which is, you know when down on the ground is not much bigger than a good-sized umbrella, you know when you put its tip on the ground. So she's very tiny. Her brain... Although we don't have too much of her skull, unfortunately what we do have suggests a bra Although we don't have not much bigger skull, And that really drives home one of the most important points about Lucy and that icontrast between her anatomy beneath the neck which is fully consistent with an upright, two-legged walking and the anatomy above the neck with a very primitive, apelike jaw and teeth and a very tiny brain. Alda: One of the below-the-neck features suggesting Lucy walked upright is her pelvis-- short and wide when compared to the pelvis of a chimp. Here we see, for example... Alda: Then there are the leg bones themselves. You can see, here's the hip and here is the knee. And there's a very pronounced angle as the thighbone runs from the hip joint to the knee with the knees being much closer together. Alan: Yeah, I can see that over here, too. Very obvious, very obvious in a human. And in a chimpanzee when it stands uprat's . The thighbone is more or less perpendicular to the ground. Alda: This combination of a tall pelvis and upright thighs gives chimps their characteristic waddle when they walk on two legs-- not an efficient way of getting around especially when you're in a hurry. But Lucy was probably quick on two legs and she had bipedalism's most useful spin-off-- genuine hands rather than modified feet. Is this Lucy's hand or one of her relatives'? This is a composite set of hand bones from Lucy's relatives-- beautifully preserved, very nice joint surfaces. And some of the interesting things are at the base of the index finger where there are three joint surfaces and these surfaces all are oriented in the way that they are in modern humans. And they are all different from the way they are oriented in chimpanzees. And the different orientation would have allowed a little bit of rotation of the index finger. "Rotation," meaning what? Rotation toward the thumb. And when you rotate the index finger toward the thumb this helps you to grasp. Alda: Lucy's ability to pick up and firmly grasp an object like a round stone opened up a whole new way of earning a living. Chimpanzees throw stones, but underhand and not very accurately. Lucy's ability to hurl a rock hard and on target brought her into a different league. Would Lucy have been able to pitch? She could have. She had the anatomy to do it. And if she had practiced she would have been able to pitch. She had a hand that could have grasped the ball and controlled it. And she had a pelvis that allowed for balance of the trunk on the hind limbs. So she could have used her trunk as leverage in pitching. As we watch these pitchers, they're rotating their trunk and then they're putting on the brake with their gluteus maximus muscle so that their arm accelerates in a whiplike way. And she had both of those features both in the hip region and in the hand. So it takes a lot of practice but she could have done it. Alda: Of course, Lucy's strikes weren't on batters but small game and they could have significantly increased her food supply. We're back in the lab again where Mary has assembled a team of experts to delve more deeply into the link between anatomy and the technological breakthroughs that set our ancestors apart from everything that had lived before. Ouch. Alda: Dr. Ronald Linscheid is a retired hand surgeon. Nick Toth is an archaeologist. The needles in Nick's arm and hand are implanting thin wire electrodes into his muscles to measure how vigorously they contract. Linscheid: You're going to feel a little stick right about there. May have felt that hit the bone a little bit. Alda: Nick will also be wearing the cyberglove I was modeling earlier. And you'll understand now why my participation in the experiment ended right there. Marzke: All right, Nick, imagine there's an animal there and thatt. Alda: Mary's purpose in organizing this little party is to closely monitor the hand and its muscles then his wife, Kathy Schick , start behaving like Stone Agers. Our ancestors from the time of Lucy-- 3. 2 million years ago-- may have been hot on the mound. But they would have had problems at the plate. Here's a chimpanzee letting off steam with a stick. He's swinging it with great determination but his grip is quite different from that used by a baseball batter. Our old friend Tujo the orangutan uses the same grasp as the chimp with all four fingers curled into his palm. Neither modern orangs nor chimps or, it turns out, even Lucy can do what we can do-- rotate our little finger across the palm to touch the thumb. Marzke: Thxe advantage of having this rotation can be seen óp when you hold something cylindrical, like this bone where you grasp things in a trough, across the palm with the little finger and the thumb strongly opposed. And this allows you to bring the tool down in line with your arm. That's interesting. I was taught in tennis to squeeze these last two fingers as I hit the ball and that gives control. Yes, yes. And that's what they were able to do when they shifted over to this kind of a finger. Yes. Alda: It was a shift that didn't take place for a few hundred thousand years after Lucy's time. But when it did our ancestors would certainly have made the most of it. After stunning, say, an antelope with a well-aimed stone the tennis racquet grip would have made finishing it off much easier. Of course, not everything was easy to kill. So what did it take-- about a million years-- for people to find out you couldn't kill a pillow? ( people laughing ) Alda: But look at this: As Steve Shakley takes his turn with the glove and the electrodes while making a stone tool you can see he's relying on the flexibility of his hand to manipulate and grip the stone he's hitting. There's so much attention paid to the opposable thumb. But the opposable pinkie-- it turns out to be really valuable. I mean, if I hit this stone without that little finger giving me pressure this stone would just come right out of my hand, right? I can really manipulate it and keep it right where I need it with strength. Alda: So while Lucy could have gripped the hammer stone like a baseball only her descendants could have cradled the stone being struck firmly enough to have fashioned it into something useful. ÷ñ Mary Marzke plans to use the data she's getting from her volunteer Stone Agers to help her interpret the fossil bones that are all that remain of our ancestors. Kathy Schick, meanwhile, has rediscovered the one inescapable consequence of making stone tools. So, what have you left yourself with here? Tourniquet. ( laughing ) You don't want to see this. Oh, God! You know, this is heroic what you're doing for science. In all the years we've been doing this show I've never seen people bleed for science like this. It's only a flesh wound. Alda: From the time our still nonhuman ancestors started making stone tools 2½ million years ago until just a few thousand years ago this is how we fashioned the tools and weapons we used gradually to dominate our planet. With grips we use today to hold a bat and ball our hands helped make us human. Alan: I get the impression from talking to both of you that we can do amazing things with our hands now because of what these... these people did a couple of million years ago with stones. We can work the keys of a computer. But I also get the impression that the very invention of a computer-- the way we use our minds to come up with a computer-- is, in a way, an outgrowth of this stone work. Very much so. Trace that for me a little bit. You may not be able to document every step along the way but what's your thinking on that? Well, I think a lot of it has to do with we as humans' ability... And I think that really separates us much from the animal world-- ability to look into the future to build something today that will make our lives easier tomorrow. Now, some might argue that computers don't necessarily do that-- they make our lives more complicated. But I think in general that's why computers were invented was to make our lives easier in the future easier to get through the day. And stone tools were no different. And somebody 2. 5 million years ago must have discovered and thought and invented this piece, this flake to make his or her life easier in the future. Alda: Evolution may have created

				I, Robot Philosopher and author Dan Dennett marvels at the human machine and its unique ability to wonder.
		Select text to jump ahead in the clip: a philosopher. The old stereotype of philosophers, of course, is that they spend their time counting how many angels can dance on the head of a pin or just contemplating their navels. Dan Dennett isn't that kind of philosopher though as a graduate student he did once spend some time contemplating his arm. Dennett: Somebody raised the question of "What's going on when your arm falls asleep "and you can't move your arm "and it seems to be this sort of dead appendage and you're trying to move your arm and you can't? " I thought, "Well, that's a good question and I don't know the answer. " And I was amazed to see that the philosophers present not only didn't know the answer but didn't seem to want to know the answer or they thought maybe they should just think about it. ( laughing ) I thought, "Well, I don't think that's going to work. " Must be a bunch of angels in there. Yeah, well, something. But I thought, you know, I just took the fact that I didn't know the answer to that question-- even though it was my arm-- that maybe the best route to your own mind is through the minds of others. Find some science, see how the parts work. Alda: Dan Dennett has been trying to see how the parts work ever since. In particular he's fascinated by how simple parts can be put together to make complex things-- like people. I thought it was really interesting that you said in one of your books that we're descended from robots and composed of robots. Yeah. Uh... in what way? If you think of an individual, single cell as a sort of little robot like a bacterium is a robot... well, we're descended from bacteria. And there's a trillion and counting cells in your body and in mine. Each one of those is clueless. It's not conscious, it's just a little machine doing its job. And it's very myopic. It doesn't kno It just knows about its surface and very little about that: just a few inputs, a few outputs. So you have a trillion myopic robots with different powers, different jobs, different specialties. You put them all together just right and you get a human being... or an elephant... or an oak tree. Yeah. And before you got the human being at least in the course of the history of our planet you got a lot of other animals and we think we're distinguished from them. We keep trying to find ways in which we're distinguished from the other animals. How would you say we are, or are we? I think one of the really fascinating and also frustrating controversies that's been running for centuries concerns "Well, are we just animals or are we really different from animals? " And the answer is, "We are just animals, we're mammals but we really are different. " And primarily what makes us different is human culture. And primarily what makes that possible is language. What language and human culture let happen was just an explosive capacity to know. We have created this vantage point where we and we alone can sort of look back and say "Wait a minute. "I'm not so sure "that the highest good in life is "procreating and replicating more of my kind. "I think I'd rather be a poet "or I think I'd rather join a monastery or be a scientist or who knows what. " Alda: For Daniel Dennett, nature-- with its mindless little robots exquisitely assembled into trees or birds or people-- is a source of endless wonder. And nothing is more wonderful than the fact that we can wonder-- a human gift, he argues that's denied to even the most appealing of the creatures with whom we otherwise have so much in common. Alda: When you see a dog lying in the sun ? choosing that one little spot on the living room floor, you... there's this terrible urge to think the dog has chosen it the dog is aware of it or when the dog is looking out the car window, seeing sights... Really enjoying those smells... Yeah, there seems... looks like enjoyment. Sure, I think it is. So there's some kind of thought going on. Oh, yeah. Certainly. I think that more complicated, so-called higher animals-- mammals, birds-- do have many of the properties that we have in our minds. They also lack some. In particular, they lack the sort of elbow room to reflect on their own reactions to things so that they can feel pain and they can anticipate pain to some degree but they can't sort of dwell on it the way we can. ( chuckles ) And the same goes for pleasure. I think one of the prices that we pay for being capable of multiplying our suffering through reflection, reliving and anticipation is that we also get to have more joy. We get to think about our lives and our prospects in a way that no animal can. So that implies that we have some kind of freedom of choice. Indeed. And then do you feel we do? Yeah. I think that human freedom is as different from the sort of freedom that other species have as human language is from, say, birdsong. Yeah, the bird can fly wherever it wants but it doesn't have very expansive desires. It doesn't have a vision of what life could be that makes freedom like our freedom such a big deal. It's not such a big deal because it doesn't realize what the options are. It doesn't really have any way of grasping even the wonderfulness of what it's doing. But with us it's different. I mean, we could dream of flying for hundreds of years. For thousands of years we could dream of doing what the birds do. Now we can do it. Come visit us at PBS Online. Scientific American Frontiers can be found on the World Wide Web at: Brought to you by: