"For most of human history, people turn to religion or myth in Mali, they believe the world was molded out of Clay by the one god." "This mask represents earth and sky connected by water." "This mask represents earth and sky connected by water." "earthquakes were said to be caused by warring gods until, that is, christianity arrived in the middle ages and earthquakes and volcanoes became the work of the devil originating in hell." "Beliefs also differed widely about the earth's age." "In 1650, an enterprising cleric in Ireland even tried to calculate the exact moment of creation." "By following the chronology of the Bible archbishop ussher declared that the blessed event occurred on October 23, 4004 b.C. At precisely 9:00 A.M.-- only 6,000 years ago." "But increasingly, science has its own say." "How could just 6,000 years possibly account for the earth's natural features or its proliferation of life?" "As for the origins of earthquakes and volcanoes they might well lie beneath our feet but hell seems an unlikely place." "And so as the 20th century dawns scientists have a good idea of what isn't true but few hard facts about what is." "Osgood:" "At the t the earth is still a mystery to the scientists who study it." "Its age and origins lie at the center of a great controversy." "Most scientists of the time believed that the earth was formed from material torn from the sun." "Then, as the earth cooled, its crust contracted buckling, cracking and collapsing." "Geologists thought the parts that were left higher became the continents..." "And the parts that were lower filled with water and became the oceans." "Lord Kelvin, the great British physicist, is determined to settle the matter of the earth's age once and for all by using this theory of a cooling planet." "Man:" "Kelvin tried to provide a numerical estimate of how long it would have taken the earth to cool from this red-hot phase down to a temperature where animals could walk around and he came up with an estimate of around 100 million years." "Osgood:" "Lord Kelvin's name is synonymous with science." "The now-80-year-old physicist has been at the forefront of scientific discovery in Europe for over 50 years." "At the age of 23 he became the youngest professor ever appointed at Glasgow university and devised the absolute temperature scale that still bears his name." "But geologists rejected Kelvin's calculations." "Huge rock faces made from sediment surely took much more than 100 million years to form." "People were looking at these enormous thicknesses of sediment." "They would go out to the beach and see that these things must have been laid down a millimeter at a time or less and that the amount of sediment increasing in, say, a bay or a river over people's lifetimes was minuscule." "The only possible answer to the dichotomy here between huge thicknesses of sediment and very, very small deposition rates was enormous quantities of time." "So when lord Kelvin said definitively that the earth could only be 98 million years old what he was doing, in fact was ignoring hundreds of years of work by geologists and, in fact, even when they protested" "that his number was based on pure theoretical considerations without any observational tie, he basically said" ""I'm lord Kelvin," and stuck with it that way." "Osgood:" "In 1902, in an increasingly confident Chicago an American geologist prepares a counterattack." "T.C. Chamberlin of the university of Chicago a scientist of great dignity and authority rejects Kelvin's most basic assumption that the earth was hot when it formed." "And he developed what he called the imal hypothesis which is that the earth had accreted from small bits of dust, rock and small planets in the solar system..." "In the early history of the solar system that had come together collapsed under gravitational attraction to form a solid, cold earth." "The other issue that chamberlin raised was Kelvin's assumption that the only source of heat in the earth was the original heat from when the earth first formed and maybe, but maybe not." """ "If there were other sources of heat within the earth besides simply that original heat then all of lord Kelvin's calculations would be questionable;" "They'd be incomplete." "He wouldn't be looking another heat sourceisfound.D:" "It's one of the great discoveries of science:" "Radioactivity." "In London in 1904 at the royal institution of Great Britain a physicist is about to suggest that radioactive minerals exist throughout the earth's crust." "The physicist, Ernest rutherford, plans to say that the heat from such radioactivity throws off all of Kelvin's calculations." "Now, as he was about to say this-- and that's why physicists love to tell this story-- he looked up and saw that lord Kelvin was sitting in the back of the room and he said, "oh, god, what am I going to do?"" "And he remembered at the last moment in's estimate and he remembered for the age of the earthkelv" ""need no longer be attended, vered" ""as Kelvin pointed out" ""that his estimates were only good" ""if there were no additional source of heat and there is such an additional source of heat."" "And having seen Kelvin's eyes snap open as he mentioned the word "Kelvin"" "he saw Kelvin beam from ear to ear as he established that the earth was old, but that Kelvin had been correct." "Osgood:" "But how old is old?" "Once again, radioactivity provides an answer with a new technique-- radiometric dating." "Now, normal background radiation sounds like this." "(High-pitched series of beeps)" "But this rock... (Beeping intensifies)" "Is a little more interesting." "(Beeps come together in a high-pitched whine)" "And it's this rock which turned out to be the clock which allowed us to date the earth." "(Beeping stops)" "Osgood:" "The rock contains uranium an element that loses subatomic particles over time." "Those losses change uranium into other elements with fewer particles." "It's a process known as radioactive decay." "Greene:" "If you leave uranium around for years it all turns into lead but it turns into lead a little bit at a time so you can measure the rate at which it turns into lead." "Once you know this rate which is not hard to figure out physically by watchin real time you can go to a rock sample, break it open and measure the relative amounts of different kinds of lead and uranium in it" "and determine from this how long it's been since the rock cooled." "This was a phenomenal discovery and in the very earliest, most simple attempts at it it was discovered that, in fact the earth had to be an order of magnitude older than previous estimates had argued for and the average looked like it was" "about two and a half billion years at that time." "Osgood:" "Ultimately, rocks are found that are four and a half billion years old." "That's 45 times older than lord Kelvin's earth and 750,000 times older than the earth of archbishop ussher." "In turn-of-the-century Berlin the mysteries of the earth begin to intrigue another scientist." "His name is Alfred lothar wegener." "The son of a strict protestant minister he forsakes family tradition to become a professor of meteorology." "One Christmas, he receives an atlas and begins to study a map of the Atlantic region." "Greene:" "Wegener later told this story himself." "He said, "I started looking at it, and it was really odd." ""I'd always noticed, like everybody over the age of 12 has that Africa and south America fit together."" "He said, "but this map had information" ""from deep down in the Atlantic ocean" ""and what it showed is" ""that that match between south America and Africa" ""goes all the way along the continental shelf" ""all the way down to the foot of Africa." "Now, if this is the case," he said-- he thought immediately and pointed it out to his office mate" ""thist an accident of sea level" ""that these things look alike." "These things look alike because they're connected in some way."" "Osgood:" "Almost as a hobby, wegener develops a theory that the continents, once connected drifted apart over time." "But he's an experimental meteorologist, not a geologist so he spends the next two years in Greenland gathering weather data." "He also sets a European endurance record for ballooning and even proposes marriage in a balloon to else koppen the daughter of his mentor at marburg university." "But his theory of drifting continents keeps gnawing at him." "Greene:" "Wegener's original idea about continental drift was a momentary intuition." "For it to get to be science, you have to make the idea real." "There were particular kinds of fossils found only in certain parts of the world which wegener found very puzzling to explain how they got where they were." "This one comes from Brazil." "It's got a long, fish-eating skull a long swimming body and legs that look quite like paddles." "But the only other place in the world where these animals had been found was in South Africa." "And here is a specimen belonging to the very same species which was found in western South Africa." "See, here it's got the same long, thin skull paddlelike limbs and big, thick ribs." "How could this be?" "These two areas are noways 5,000 miles apart with the Atlantic ocean between them." "So what could be the explanation as to how they came to be in those two places?" "Osgood:" "Wegener then learns that certain geological formations occur in very unlikely places." "Far above the arctic circle in the frozen islands of spitsbergen there are large deposits of coal but scientists believe that coal is formed in tropical climates." "Wegener also discovers that great rock sheets-- lt of ancient glaciers-- wegener also discovers that great rock sheets--resu stretch for miles across tropical South Africa." "Man:" "You can have glaciers in tropical areas if you've got very high, alpine-type mountains but not great, extensive ice sheets and that's what the evidence seemed to show." "And so wegener argued that those continents couldn't have been there when those glaciations occurred and had to have been either further north or further south." "Osgood:" "Putting all the clues together wegener suggests that the continents were once joined in a massive supercontinent called pangaea, or "all earth."" "The continents must have moved throughout geological time drifting across the ocean floor." "Before wegener can publish, war breaks out in Europe." "As a reserve officer in the German army he's called up to fight on the western front." "Injured early in the war before the worst of the casualties he continues to work out his theory while his wounds heal." "The result isthe origin of continents and oceans his argument for continental drift." "Geologists are not impressed." "Many of them said this was a theory proposed by a weatherman who moved continents around the way clouds move but the earth is this big, solid thing." "Continents don't just get up and skate around like pats of hot butter on a skillet." "They were able to show that when there was a major earthquake the earth just rang like a bell." "It pulsated, and long waves traveled round the surface of the earth for hours and hours after a major earthquake." "Now, existing physical theory said that anything that was strong enough or rigid enough to behave that way when there was an earthquake had to be far too strong to allow continents to move round at the surface." "Ener's 1915 theory was the fact to allow continents to move round at the surface.Of weg that he did not have a force by which to split pangaea and then propel its pieces across the face of the globe to take up their positions as the modern continents." "Oreskes:" "Wegener didn't know what made the continents move and frankly, I don't think he thought that was his problem." "He felt that that was something that other people would have to work on." "Osgood:" "In 1930, Alfred wegener leads a new meteorological expedition to Greenland." "He's undaunted by the negative reaction to his theory and has updated his book several times writing in the 1929 edition that the odds of his theory being wrong are one in a million." "The new expedition is plagued from the start." "Ner the new expedition is plagued frand his team.Shes wege over a month behind schedule as they rush to establish three bases before winter." "On September 21, wegener sets out to resupply one of the bases." "The temperature is minus 60 degrees." "The 200-mile jouey is planned for 20 days;" "It takes 40." "Most of the supplies are lost in blizzards." "Greene:" "He said to his closest friend" ""this expedition is now nothing but a matter of life and death."" "And then the guy who told this story often said:" ""And then he did something" ""that I'd never heard him do before." ""He talked about how he felt about the world." ""All I'd ever heard him do" ""was sort of laugh and smoke and do science." ""And wegener said, 'look" ""'it doesn't matter what happens to individuals,' he said." ""'Science is a social process." ""'It happens on a time scale longer than a single human life." ""'If I die, someone takes my place." ""'You die, someone takes your place." "What's important is to get it done.'"" "osgood:" "After a day of rest wegener and his eskimo guide try to return to their own base." "They are never heard from again." "Alfred wegener died just after his 50th birthday his idea of floating continents still unproven even ridiculed as a theory without a cause." "The origins of earthquakes and volcanoes also remained a mystery." "Other scientists become intrigued enough with wegener's theory to take up his quest." "For the next 30 years they struggle to prove wegener was right and to find the mechanism that could move continents only this time they turn their attention away from the ground below to a place far more mysterious." "This is where scientists seek the ultimate answer-- the deep ocean floor, as alien as another planet." "In the 1930s, geologists use world war I submarines to learn as much as they can about this new frontier." "One of the pioneers is Harry Hammond hess a young graduate student, fresh from Princeton." "Hess had spent the late 1920s as a mineral prospector in Africa even though he had failed his first mineralogy course and was told he had no future in geology." "But despite that prediction hess eventually joins the Princeton faculty." "Oxburgh:" "Harry was a totally remarkable character, very quiet little toothbrush moustache, great sense of humor." "If you went into his office you'd see his desk literally piled that high with papers-- letters, minutes of this, minutes of that." "I was with him one occasion, and he was looking for something and he came across an unopened letter." "He said, "oh, sent that letter." "I should have sent that letter."" "And he opened it." "It was a letter to another graduate student three years earlier offering him a place." "Oh, I wondered why three years earlier we never heard from him."D, "" "this was Harry." "Osgood:" "In 1932, Harry hess joins a renowned Dutch geophysicist, Felix vening meinesz who is surveying the Caribbean." "Man:" "Vening meinesz had borrowed a world war I surplus submarine from the U.S. Navy for this purpose." "Well, these submarines were not theqe2." "They were small, cramped, not very competent things and dangerous." "Something went wrong and the submarine went way below its designed maximum depth..." "And only drastic action by the captain actually saved their lives." "In the mass or density of sea-floor crust by measuring the force of gravity with a specially created device." "The delicate pendulums are slightly more attracted by denser rocks-- rocks exerting a greater gravitational pull." "It's so sensitive, it can only be operated in deep, still water far beneath the turbulent surface of the sea." "The measurements reveal something surprising-- large areas along the margins of continents where the sea floor seems much less dense than expected." "Oreskes:" "It was as if ps of the ocean floor were missing as if the rocks just weren't even there and this meant that there were forces actively disturbing the crust, and if that were the case maybe those forces were also moving the crust." "Osgood:" "Harry hess is at Princeton in December 1941 when Pearl harbor is attacked." "An officer in the naval reserve he travels to next day to report for active duty." "By 1943, he's the captain of a transport ship in the pacific." "It's equipped with sounding devices and hess uses every opportunity to take depth measurements of the ocean floor." "Oxburgh:" "He ended up the war taking in marines onto some of those horrific landings on the western pacific islands." "Throughout the war, he ran his echo sounder and he came back with an enormous volume of soundings of the floor of the pacific." "It showed, for the first time, very clearly delineated the deep ocean trenches round the western margin of the pacific." "Very curious features." "Osgood:" "Then, in the early 1960s, another piece of the puzzle:" "Core samples of the ocean floor are taken in the middle of the Atlantic." "Analysis of the rock reveals that the earth's crust gets progressively older on either side of an undersea mountain range called the mid-Atlantic Ridge." "Greene:" "The mid-Atlantic Ridge has been known for a long time." "It caused trouble when people were laying telegraph cables to have a mountain range at the floor of the Atlantic." "So people knew about it." "Osgood:" "Researchers find that the mid-Atlantic Ridge is not only younger than surrounding ocean floor but it's made of volcanic material." "Greene:" "The mid-Atlantic Ridge seems to be a pile of cooled lava on top of a fissure or an opening in the earth's crust through which hot material is constantly coming up from the earth's interior." "Oreskes:" "Hess suggests that the mid-ocean Ridge is the site at which the continents are breaking apart." "The mid-ocean Ridge is formed when molten rock rises from inside the earth, and then pushes the crust apart." "Osgood:" "Hess suggests that the reason the ocean floor is young at mid-ocean ridges is that that's where new crust is being created." "And so hess argued that, in fact, not only was crust new crust in the oceans formed at the surface but it traveled along horizontally and then dipped down back into the interior of the earth again a process called subduction." "This was a pthe true significanceion.D of the ocean trenches which he'd spent so much of his earlier years working on." "Oreskes:" "Hess writes this idea up in an article." "He calls this paper an "essay in geopoetry"" "because, of course, he knows that wegener was severely criticized 30 years before for an idea that was not that different." "So by calling it geopoetry he's taking a kind of moderate stance:" "don't get too upset, don't take this too seriously but I think it's clear that he believes the theory is true." "Osgood:" "Hess's theory suggests that the sea floor moves due to circulating currents deep inside the earth." "The material beneath the crust is kept hot by the constant decay of radioactive elements causing convection currents that move the ocean floor along." "New crust is created at mid-ocean ridges and destroyed at deep ocean trenches, hess suggests-- a never-ending conveyor belt moving at a snail's pace through the ages." "His paper is greeted skeptically by the geologi but at Cambridge university, in 1963 geophysicists Fred vine and drummond Matthews uncover new evidence that supports hess's theory-- evidence based on rock magnetism." "They, with a brilliant piece of lateral thinking looked at the ocean floor south of Iceland-- but in other places as well-- and south of Iceland you've got part of the mid-ocean Ridge in the Atlantic and there was a feature of the Ridge" "which had been known for a long time, but no one had understood and that was that there were curious magnetic stripes on the ocean floor, parallel to the Ridge crest." "Throughout geological history, here had been times when the earth's magnetic field had reversed meaning the north pole had become the south pole and the ad become the north pole." "Since rocks are like little magnets, they would point in the direction of the prevailing magnetic field and then, as the crust split apart if there had been a magnetic reversal in the meanwhile this next set of rocks would point in the opposite direction." "And they were able to show that the width of these magnetic stripes was proportional to the known durations of these noepochs in geological history." "Furthermore, the stripes were generally symmetrical on either side of the ocean Ridge as Harry hess's sea-floor spreading idea would have suggested." "Osgood:" "It's nuclear testing during the cold war that provides the clinching evidence." "In an effort to monitor the tests of other countries the United States and britain set up a worldwide network of seismometers which also detect earthquakes." "Now geologists can map the locations of earthquakes with unprecedented acacy." "Soon a pattern emerges with stunning clarity." "Oxburgh:" "The eartxceedingly narrow b ands and these red spots are shallow earthquakes and you can see them following the crest of the mid-Atlantic Ridge, all the way..." "All the way down." "If we look over here in the pacific, you can see that these necklaces of oceanic islands and the deep ocean trenches that lie against them are associated with earthquakes, too." "You put this all together and what you get is plate tectonics the idea that the earth's crust can be broken up into large pieces, or plates that consist of both continents and also pieces of oceanic crust moving together over the face of the earth." "Osgood:" "The movementf the plates is only a few centimeters a year." "But that's enough to reshape the earth, build mountains trigger earthquakes and create volcanoes." "Volcanoes erupt where the crust splits apart or where it subducts, and molten rock is forced up from below." "Mountains, like the himalayas, form where plates carrying continents collide, crumpling up the land over millions of years." "And earthquakes occur along the boundaries of tectonic plates like the San Andreas fault." "In 1906, the earth had suddenly snapped along the fault line releasing pressure that had been building up for years caused by the slow, steady movement of the tectonic plates." "Life." "Cour planet is not merelyy movement of the tectonic plates." "Although it appears placid from outer space the earth is dynamic..." "Violent..." "Unpredictable..." "Constantly reshaping itself d wegener had suggested 50 years earlier.Fre" "Alfred wegener wasn't the only scientist in the early 20th century whose work remained controversial for years." "Charles Darwin's theory of evolution was still being fiercely debated decades after his death in 1882." "Where wegener conceived a new theory about the evolution of the continents" "Darwin offered one about the evolution of life itself." "Many of Darwin's contemporaries denounced his notion that all living things evolved from simpler, more primitive forms of life over millions or billions of years." "Most of the western world believed instead" "at first, Darwin didn't deal specifically with hu except to say that:" ""Light will be thrown on the origin of man and his history."" "Then, in 1871, he published the descent of man leaving no doubt that he thought that man, too, had descended from more primitive animals." "Darwin expected the book to be denounced but even he would have been surprised by the depth of prejudice among scientists long after his death a prejudice that would shape the study of human origins through much of the 20th century." "Osgood:" "In 1900, we know precious little about our prehistoric ancestors." "Our best clues are in their ancient bones..." "But even these are few and far between." "Only one bone in a billion hardens into a fossil to await discovery through the millennia." "The fossils that turn-of- the-century scientists have to work with were all uncovered in Europe and Asia." "In Germany's neander valley human fossils were found in 1856." "The ancient ancestor who provided them was dubbed "neanderthal"" "and was thought to have lived a few hund years ago." "And was thought to have lived a few huthis skull was foundter, estimated to be 20,000 to 30,000 years old." "It was named for the cave in France where it was discovered:" "Cro-magnon." "And in 1891, java man was found by a Dutch anatomist in Indonesia and dated at half a million years or more." "But was any of these fossils the humanlike ancestor who first evolved from the apes on the road to modern man?" "In 1909, some amateur scientists believe they have found the answer." "In Sussex, england, near piltdown common in a gravel pit beside a farm road..." "A worker's pickax hits what looks like a coconut shell." "Solicitor and part-time geologist Charles Dawson examines the fragments and decides they are parts of a human skull." "By the summer of 1912, Dawson and a small team spend weekends digging for more fossils." "One day they find three pieces of a human skull and an apelike jawbone with two teeth that look human." "They share the evidence with Arthur Keith, a distinguished anatomist who is determined to trace the ancient origins of the British." "Dawson believes the skull held a brain as large as modern man and is the oldest human fossil ever found." "He dubs it "Dawson's dawn man."" "Sussex celebrates its native son." "Sussex man:" "Brates it was an instant hit." "It really resonated with all of the thinking about how we became human." "And it was immediately embraced by the English anthropological community." "Man:" "These people believed that the brain, being so critical in humanity's survival and adjustment to life must have been enlarged Ean while the teeth and the posture must have caught up later." "Johanson:" "The piltdown discovery was very eurocentric." "Not only was he the first englishman but he was older than anything that had been found in Europe." "Not only did the brain have preeminence but the English had preeminence." "Osgood:" "The crown knights Arthur Keith and two others for their work on piltdown and britain is proud to be seen as the birthplace of modern man." "But in 1924, the preeminence of the British is threatened by a surprise coming out of Africa." "Tobias:" "There was a lime works called the buxton lime works about 130 kilometers north of kimberley where the diamonds came from." "And there was a contaminated lime-- but the pink material had in it bones." "Osgood:" "A lime worker named debruyn had been collecting baboon skulls for some years." "One day he notices a strange skull, and sends it off to anatomist and new Dean of the medical school in Johannesburg professor Raymond dart." "On November 28, 1924 dart's closest friend is about to be married in dart's garden." "Dart is the best man." "As he's dressing, a curious crate arrives at his house." "Inside it he finds chunks of limestone and the fossil of a brain." "Johanson:" "The first thing he noticed was this endocast-- this is the infillings of the brain case that reflect some of the convolutions and some of the blood vessels in the side of the brain." "And because dart was so carefully schooled in brain anatomy, as he had studied in england he recognized that this could not be some kind of a monkey." "Osgood:" ""A thrill of excitement shot through me." "It was no ordinary anthropoidal brain," dart writes later." "Most people would have dismissed the fossil as a chimpanzee but dart is sure he's onto something." "Tobias:" "Dart was already something of a heretic in science and I think it appealed to something in his makeup that he was going to overturn some of the fixed ideas of the time." "One of the fixed ideas was that the discovery was oin the wrong continent.As" "johanson:" "There was this view that everything important that happened in human history had to have happened in Europe." "White European males thought that we must have evolved in Europe." "How could we have come out of Africa?" "Look at how primitive Africa is." "Tobias:" "And it was considered to be the most unlikely scenario for human origins to look at this great so-called dark continent of Africa." "Osgood:" "The box holds another surprise..." "A tiny skull embedded in the rock." ""No diamond cutter ever worked more lovingly or with such care on a priceless Jewel," he writes." "Tobias:" "Four weeks later when the skull face came out of the rock and he could look at the teeth, to his amazement, he saw that the canine tooth-- the eyetooth-- was small likeuman, not enlarged and fanglike" "like that of a chimpanzee or gorilla." "And here is the lovely little face of the child with its small canine." "We have a full house of deciduous teeth, baby teeth still busy erupting." "And he was able to fit in the brain case, or the... the endocast so that you had a little child's skull." "It was a remarkable moment of revelation for him." "Osgood:" "Dart declares, "I knew at a glance" ""that what lay in my hands was the replica of a brain three times as large as that of a baboon."" "But then dart the anatomist notices something unexpected." "Tobias:" "The base of the skull pointed to the head being poised on an upright spine not hanging forward on an oblique spine, as one finds in creatures that go on all fours instead of on two legs." "Johanson:" "It possessed that single important hallmark-- that it was walking upright." "Dart was suggesting, in a word that this creature was knocking on the door of humanity but hadn't quite crossed the threshold yet." "A staggering thing." "It was the very personification of a missing link a link between animals-- nonhuman animals-- and humans." "Johanson:" "And I think probably trickling through his mind was that statement made by Charles Darwin in the late 1800s when he predicted that Africa would prove to be the cradle of humankind." "Osgood:" "Dart names the fossil the "taung skull"" "after the district where it was found." "After he writes up his findings, he ships them off to england to the distinguished journalnature..." "But the editor is skeptical." "Because infant apes look more like humans than their parents do, it's easy to make a mistake." "Bias:" "Tthey felt that darto, ithad not proven the caseke.To nor that hecouldprove the case on a child." ""Give us an adult, and we might listen to your case."" "Osgood:" "Most see no need to upset the status quo." "Johanson:" "People said, "we have piltdown." ""We already have a fossil that's maybe a million years old and it's very modern looking, it's very advanced."" "Osgood:" "Piltdown man upholds British pride and racial stereotypes as well." "Dart's find threatens all of this." "The British are adamant that piltdown, not taung, is the missing link." "Although dart continues to believe he's right he admits, "it's no good being in front if you're going to be lonely."" "While scientists wrangle over whether humans originated in Europe or Africa with big brains or small, others are outraged by the idea that humans descended from apes at all." "Newsreel announcer:" "Dateline Dayton, Tennessee, July 11, 1925." "Charles Darwin's til mankind had descended from a common ancestor had set off works." "John t." "Scopes, a Dayton biology teacher, had decided to test a new Tennessee law that forbade the teaching of any theory that denied the divine creation of man." "He was arrested and indicted." "A full house of avid spectators from all over the nation filed in to hear the debate." "The issue is no longer the innocence or guilt of scopes but rather the death struggle between two basic human philosophies-- fundamentalism versus modernism." "Osgood:" "Scopes is found guilty and loses his job but no one believes the public debate will end here." "The scientific debate also continues to rage." "It's not whether humans evolved from apes but how, where and when it happened." "An eccentric physician and zoologist-turned- fossil-hunter, Robert broom." "On his first visit to dart broom kneels before the taung skull to pay homage." "Widely recognized for his work classifying mammals in South Africa broom likes to flaunt authority." "He has already tarnished his reputation by selling fossils abroad." "Determined to validate dart's find, he sets out in search of an adult to match the taung child now known as us africanus." "Guided by dart's students, broom visits the sterkfontein lime deposits near his home." "Within days, he finds fossil fragments and shows them off during a lecture." "Tobias:" ""By the way," he would say, after two hours of lecturing and out would come what he described as two of the most marvelous teeth that have ever been discovered in the history of the world and these were australopithecus teeth." "D:" "After ten more years of persistent searchingosgoo the 80-year-old broom finally finds a complete skull." "It had a small, apelike brain but it walked like a human being." "Dart's taung skull is no longer an isolated find." "Tobias:" "It came to be realized that there was not one freakish little skull but that there was a whole community, a population." "It was the accumulation of new evidence that turned the tide." "Osgood:" "Then in London, in November 1953 one of the greatest scientific hoaxes of the 20th century is uncovered." "Newsreel announcer:" "Britain's August natural history museum is all a dither over a scandal concerning the piltdown man." "One of the most famous fossil skulls in the world is declared to be in part a hoax." "40 years ago, its discovery was a sensation." "Today comes the shocking news that this is skullduggery." "Johanson:" "Piltdown was guarded, I think even more closely than the crown jewels." "There wasn't an opportunity to really study the specimen in depth until the early 1950s, when the piltdown was on display." "A fellow by the name of weiner had an opportunity to see it." "And he thought that there was something wrong here that this specimen didn't really fit together." "Osgood:" "When Kenneth oakley, curator of the British museum osgood:" "Uses fluorine dating, curator ohe discoversh museum the skull is 10,000 years older than the jawbone!" "Johanson:" "A devastating publication came out and showed that this was in fact the lower jaw of an orangutan that had been doctored to look like a hominid jaw." "We don't know who actually perpetrated this or for what reason." "Some people think it was to embarrass other English scientists into believing that this was a bona fide human ancestor." "Osgood:" "With piltdown discredited, the taung child is now embraced as our rightful ancestor." "Africa appears to be the cra of humanity after all." "Over the following years, its terrain offers ever more clues to the mysteries of human origins." "Johanson:" "It's because of the geology that we have such good fossil remains in places like eastern and Southern Africa." "The development of the great rift valley, for example that's been going on for tens of millions of years has formed a series of collection places..." "Lakes and basins and rivers for animals to fall into and become fossilized..." "Osgood:" "In 1972, Richard leakey following in the footsteps of his mother and father adds to the growing trove of African fossils with the discovery ofhomo habilis almost two million years old." "Then in 1974, don johanson's research team sets out for east Africa." "Johanson:" "I was co-leading an expedition to the afar triangle and I had just finished my ph.D." "At the university of Chicago that year." "And my great hope was to make a major discovery something important that wouls fill in this picture of our earliest origins." "I was out surveying." "I happened to glance over my shoulder and spotted a piece of elbow and recognized it immediately as coming from a human ancestor." "This wasn't a baboon or an antelope or any other kind of animal." "It had to come from us." "And as I kneeled down to pick it up, and look at it more closely" "I saw other pieces." "I saw pieces of..." "For example, here is a leg bone." "The black portions are reconstructed parts." "But we had most of the femur or thighbone." "And as we continued to collect fragments from this hillside and piece them together we came to realize that we had most of a single skeleton." "And there were some astonishing discoveries." "The length of her legs, for example, suggested that she was only about three and a half feet tall much shorter than we are today." "The immediate question was, are we dealing with a child like dart was with the taung baby?" "Well, when you look at the teeth, you see that the permanent molars, the adult molars, have erupted." "So this Walt creature." "And because of its small size, we surmise that it was a female." "Osgood:" "They call her Lucy, after the Beatles song they played the night they found her." "When she lived, she was about the size of a chimpanzee and like dart and broom's finds she walked upright, and had a small brain." "Johanson:" "We think Lucy's skull might have looked something like this with a receding forehead and a prominent face." "And with a brain case no larger than a chimp's this was no smart ape." "Osgood:" "In 1974" "Lucy is the most complete hominid fossil yet found." "She is more than three million years old." "But the path through those years, from Lucy to us was, like the rest of evolution, far from straight." "Johanson:" "As we look back and explore and discover fragments of our ancestry..." "We see that it wasn't a direct line from dart's taung child or from Lucy or whatever directly to us..." "That there were many false starts that there were branches, there were extinctions." "Every single one of these fossils we findisa link." "It's a link to our past, but even more importantly it's a link to the natural world." "And this is a tremendous blow to people who think of themselves as theinnacle of evolution, the chosen species..." "That we are not necessarily here because of some preordained idea..." "That we have gotten here through the same process as all other life." "20th-century paleoanthropologists got more than they bargained for but it was even harder for science to uncover the fundamental rules that govern the evolution of life itself." "How could ancient animals and plants like these fossilized ones evolve into the incredible variety of species we see today?" "What mechanism could explain an individual's characteristics being passed down to future generations?" "How could an entirely new species be created?" "The first breakthrough occurred in 1900 when the work of an obscure augustinian monk named Gregor mendel was rediscovered 35 years after his death." "Mendel demonstrated that the physical characteristics of pea plants like this one were inherited according to certain rules." "Eventually, he could even predict which offspring would be short or tall darker or lighter in color depending on the characteristics of previous generations." "But mendel had no idea how these traits were carried from one generation to another." "What told the pea to be wrinkled or smooth?" "For Darwin's theory of evolution to be fully accepted someone had to find the mysterious something that makes it all work." "According to Darwin species evolve through a process called natural selection." "When traits-- like the size of a fin-- are passed down from one generation to the next ariation, are passed down from oor mutation, may occur.Xtm v when this mutation helps an organism adapt to its environment" "the organism is more likely to survive and pass the altered trait on to its offspring." "It's through this process that a species changes, or evolves." "And if the accumulated variations are large enough a whole new species can arise." "As the 20th century dawns, many scientists find it hard to accept the randomness of natural selection." "And no one understands how mutations actually work or how traits are passed down through the generations." "In 1904, a biologist named Thomas hunt Morgan begins a series of experiments he hopes will uncover evolution's secrets." "Man:" "Morgan believed the modern-day species had descended with modification from previously existing species so in that sense, he was very much alongside of Darwin." "What he had trouble with, as did many of his contemporaries was the question of how you could get two species by selecting small, minute variations from one original parental population." "The experience of practical animal and plant breeders like dog breeders or horse breeders which he was familiar with from Kentucky and so on suggested that though you could make many improvements in these organisms by selection no one had ever produced a new species that way." "Osgood:" "Morgan grew up in Kentucky right after the civil war." "His uncle was brigadier general John hunt Morgan called the "thunderbolt of the confederacy"" "who had commanded the daring band of guerrilla soldiers known as Morgan's raiders." "As a boy, Morgan felt a strong attraction to the countryside around Lexington." "He saw the great swaths cut into the hills to prepare for the coming railroads and was fascinated by the exposed layers of sedimentary rock and the abundance of fossils." "Woman:" "My grandfather was always a little different." "He liked to go out collecting things in the woods-- stones, feathers, fossils, skeletons of animals." "Stones, feathers, fossils, skeletons of animals.Ct thi ngs and have his own little world." "Osgood:" "Morgan's love of nature leads to a ph.D. In biology." "Then in 1903, while teaching at Bryn mawr college" "Morgan hears enews." "Hugo de vries, a Dutch biologist discovers what appears to be a new species of plant growing right alongside its parent originally thought to be produced by a single large mutation." "When Morgan read de vries's work he felt that might be the answer to the problem that he didn't think Darwin had solved which is how you get from one species to a second very different species and so he became very interested in de vries's work." "But de vries had worked with plants." "Morgan was a zoologist and he decided he was going to try to generate and find those kind of mutations in animals." "Osgood:" "Morgan chooses the common fruit fly-- known as drosophila-- for his experiments." "It's a perfect choice." "Man:" "A female fly will produce 200, 300 progeny easily." "Secondly, they're easy to raise." "You could grow them on mashed bananas." "Third-- you could separate males from females easily." "The life cycle was short so that in a matter of 10, 12, 13 days depending upon the temperature you had a generation of flies." "So he started out just looking for mutations." "Osgood:" "The work of sorting through thousands of tiny insects in search of mutations is extremely laborious." "And, it seems, futile." "Allen:" "For several years, he didn't get any fruit flies that looked substantially different from their parents and he was just about to give up the experiment." "In fact, he wrote to a colleague in Europe and said, "I've just about had it with these fruit flies." ""It's been several years of work and I'm just going to abandon it and go on to something else."" "And just shortly after that he discovered in his culture one white-eyed male fruit fly." "Osgood:" "Finally, a mutation." "Not a new ies, but Morgan is intrigued." "Instead of looking for large-scale, de vries-like mutations that might drive evolution he decides to investigate small variations like the white eye." "He breeds the white-eyed male to a normal red-eyed female." "Will the mutation be passed on to the next generation making the offspring white-eyed?" "Or will they have normal red eyes?" "Or even show a blend of red and white and have pink eyes?" "Allen:" "There was no consensus about how inheritance worked." "No one really knew how traits were passed on whether there were any patterns or laws." "It was clear that like begets like that offspring look somewhat like their parents but sometimes they look like their grandparents or sometimes their great-grandparents or sometimes like no one in the family." "And there were about as many theories, as one author said of heredity, as there were people proposing them." "Osgood:" "The work of Gregor mendel, however, stands out." "Mendel had found that when he bred tall plants with short the first generation, the f-1's, all turned out tall." "But some short plants reappeared in the next generation in a ratio of about three tall to one short." "Mendel concluded that among those three-quarters that were tall two contained both tall and short characteristics but the tall was masking the short." "Mendel believed that all the plants' characteristics were controlled by some "factor" from each parent that was passed on to the next generation and that these factors, later called "genes"" "never blended together to form new ones." "They remained discrete determining the characteristics of offspring by their different combinations." "Man:" "Although mendel laid out genetics very clearly in 1865 it really didn't catch on." "I think the paper was largely ignored for the next 35 years." "I think the reason is that although this abstract concept was an interesting one hard-headed biologists would say" ""well, where are the genes, can you show them to me?"" "There was nothing physical to see about genes." "Osgood:" "Morgan is aware of mendel's work, but remains skeptical." "Green:" "He asked a very simple question." "What are these things that mendel called "factors"?" "Hownsmitted from one generation to the next?" "What's the basis for all of this?" "Are these units?" "Are they single?" "Are there multiples?" "What's going on here?" "Osgood:" "By 1910, Morgan and his wife Lillian also a notable biologist have produced a new generation of morgans." "They call them their f-1's." "They spend their summers in woods hole, Massachusetts where Morgan builds a big house half a mile from the ocean." "The morgans will summer at woods hole for the next 40 years." "Allen:" "Every summer, they would pack up these milk bottles full of fruit flies and bring them up to the marine biological laboratory in woods hole and work with them and do their breeding and do their cataloguing experiments here." "Roberts:" "We loved this place." "We'd run off down to the eel pond and see what was going on there." "We'd go out collecting in tide pools and make slides and study." "It was a very close and informal community." "The scientists that my grandfather knew were always in and out of the house." "Allen:" "Morgan would take his group out on the lawn outside of one of the laboratories at the marine biological lab and they would simply lie on the grass and talk about their day's results or the week's breeding figures and so on." "Osgood:" "Back in New York City" "Morgan's breeding experiments with his white-eyed fly begin to show the kind of results mendel's theories predict." "Allen:" "Yed fly to a red-eyed fly ag." "Now, all the offspring were red-eyed." "But then he asked-- being familiar with mendel's work, he thought" ""well, now, mendel observed that with his peas" ""that all the offspring of the first cross looked alike so what happens if you cross those with each other?"" "He did that, and lo and behold, he got about 25% white-eyed." "Every one of those flies" "why not females?" "Then he did a little thinking and he said, "what in a fly or what in any animal" ""starting from the grandfather will end up in a grandson?" "What's the only thing?"" "Osgood:" "A clue lay in a discovery of the late 19th century when biologists had seen pairs of long, threadlike structures in the nuclei of cells." "Omosomes" after the Greek word for colorr since these structures absorbed dye readily and stood out clearly under the microscope." "They found that a particular configuration of chromosomes seems to have a role in determining sex and since the white eye only shows up in males" "Morgan suggests that perhaps a mendelian factor for eye color is associated with the chromosome configuration that determines maleness." "Allen:" "Morgan did not go as far as to say that this factor for eye color was actually physically a part of the chromosome just that it always appeared with it in the offspring." "Within a year, Morgan had found several other characteristics that also seemed to be sex-linked and at that point he was willing to say that the factors determining these particular traits were actually physically part of the chromosome itself." "So he published a paper and he postulated that the white-eye gene, if there is such a thing must be on the chromosome-- t was the big step." "Must be on the chromosome--tha" "osgood:" "Morgan continues searching for more traits that are linked to convince himself that factors of inheritance-- genes-- are physically located on chromosomes." "It is tedious, exacting work that could only be done with a devoted team of researchers." "Green:" "In the Morgan lab there was a congeniality, a give-and-take." "It generated the kind of thinking which was necessary to do these crucial experiments and Morgan let people, you know, gave them free license." "Very few research projects at that time were done in groups and Morgan's group of young undergraduates d then, later, and Morgan's group of graduate studentstes an became the prototype of a whole new way of doing science." "Compared to the European tradition where the professor in charge of a lab was very austere, very stand-offish would maybe come through the lab once a day and talk to a few people about what they were doing." "Morgan was just the opposite." "He sat at his own desk in the fly room." "He had his own microscope." "He would count flies along with everybody else." "There was a tremendous amount of informality." "Osgood:" "Morgan and his team study over 13 million flies." "Gradually, during the early 1920s a genetic map of drosophila starts to emerge." "They begin to understand where on the chromosome genes for particular traits are located." "Man:" "And they became convinced now that you were dealing with a material particle that was indeed passed on from generation to generation during the period of cell division." "This gave them a sense that now they were gaining an understanding and in such fashion that you could alter it in the laboratory and predict the outcomes." "Something that was very, very difficult to do with evolution itself." "Osgood:" "Morgan's work convinces him that evolutionary change does not require large-scale mutations." "He has observed so many small variations in drosophila over the years that he comes to believe, like Darwin lander:" "Morgan gave rise, in his lab at Columbia to a whole school of geneticists that laid down all of the fundamental rules of heredity that shaped the rest of the century including all the fundamental rules we apply today in human genetics." "But what the genetic material was how it was organized in the chromosome precisely how the chromosomes replicated and how you replicated the genetic material and what it actually does in the developmental process-- that was a black box." "Osgood:" "Scientists knew that what was in the black box could in some way be called the secret of life." "The beauty and wonder of life itself..." "The incredible diversity that had puzzled and intrigued Darwin and Morgan..." "Could this be reduced to chemistry?" "Understanding the chemical basis of life had become the ultimate challenge for many scientists." "Man:" "The fascination was can you put together the ordinary atoms that chemists know-- carbon, phosphorous, hydrogen and others-- and make something that's alive?" "What is the physical basis by which something can reproduce itself?" "How does chemistry and physics explain that?" "Maybe there's something new a new principle that we don't know." "Is it like that Michelangelo-- is it a spark that has to go from one finger to another or what is it that makes something alive?" "Osgood:" "To be alive and grow the cells in an organism must be able to reproduce and pass along their genetic information to the next generation whether it's a human embs." "Whmorgan showed that genes transmit information from parents to offspring." "But how?" "By the 1940s, scientists know that genes contain DNA short for deoxyribonucleic acid." "Either proteins, which do most of the work of the cell or DNA must contain the secret of heredity." "But which one?" "Lander:" "All smart, right-thinking people at that time knew that DNA was an utterly boring structural molecule that couldn't possibly contain heredity." "Proteins had to be the stuff that contained heredity because proteins were very variable and very interesting." "Yet the experiments kept pointing to the fact that it was DNA, which when transferred to a new organism contained the secret of heredity." "Osgood:" "In 1951, at king's college in London researcher rosalind Franklin takes X-ray photographs of DNA molecules." "At 33, her scientific accomplishment is testament to her determination." "She defied her father, a London banker who thought education was unhealthy for women and had wanted her to be a social worker." "Instead, Franklin has become an expert X-ray crystallographer and her latest photograph of DNA suggests a helical, or spiral shape." "Cautious by nature, she decides she needs more evidence before sharing her findings." "She tucks the photo into a drawer." "60 miles away at Cambridge university" "James Watson, a brash 24-year-old American geneticist is also consumed by the study of DNA." "As a boy, he starred onthe quiz kids a Chicago radio show and by age 22 he'd earned his ph.D." "Working with Watson is British physicist Francis crick of whom Watson will write" ""I have never seen Francis crick in a modest mood." "He talked louder and faster than anyone else."" "Crick had studied physics at university college, London but at 35 has yet to complete his doctorate." "As they recall 20 years later somehow it's a match made in heaven." "Watson:" "He thought like I did." "Neither of us had sort of preconceptions." "Neither of us were trained for what really interested us." "As you've said, we had the same point of view." "I mean, of course, I found the same reaction to you as you found to me." "I was self-taught, I was stuck in Cambridge." "There weren't that number of people who I could communicate with." "Osgood:" "Later that year, on a trip to London" "Franklin is not ready to share publicly." ""My heart began to race," he says later." "He rushes back to Cambridge to tell crick that the shape of the DNA molecule may well be a helix." "They then began the task of literally constructing a model." "Back in Cambridge at the cavendish they took pieces and they tried putting them together in different ways." "Certainly they were working at fever pitch." "Lander:" "Was it a race?" "Of course it was a race." "Who wants to discover one of the secrets of the universe second?" "And they went after it with full force." "Osgood:" "They come up with a model that looks promising." "Watson:" "I was very excited probably because Francis was." "It was our first DNA model." "It did look like a sort of cylinder of things didn't it, Jim?" "A solid cylinder..." "With things sticking out." "Watson:" "It wasn't very pretty." "Crick:" "We were completely on the wrong track." "When you have an idea and you've been enthusiastic about it and it's clear it's wrong, you must just push it away and get rid of it." "Osgood:" "DNA has four chemical components, or bases called adenine, thymine, cytosine and guanine or "a," "t," "c" and "g."" "The bases seem to occur in pairs so Watson decides to try something else." "Watson:" "I cut some things out of cardboard and made the right shapes and then pasted things on which would indicate hydrogen atoms." "Then I think I went off and played tennis and it wasn't until the following morning I came in and I started to put them together in pairs." "Osgood:" "When Watson makes models of the base molecules he realizes that when they're combined, "a" with "t"" "and "g" with "c," each pair has the same overall shape." "Lander:" "It all fell together and when it fell together, it was so obviously right that they had to have known that they had cracked one of the major secrets of the universe." "Osgood:" "Watson and crick suddenly realize that the structure of DNA is a double helix with the a-t and g-c bases on the inside of the molecule..." "Shown here as red and green, yellow and blue." "The base pairs connect to each other between two ladder-like chains of sugars on the outside all of it twisted like a double corkscrew." "Watson and crick publish their findings innaturein may 1953 sending shock waves throughout the scientific world." "Meselson:" "I was in the department of chemistry at Caltech and Max delbert was in the department of biology." "He asked, "what do you think of the paper by Watson and crick?"" "I said I'd never heard of these papers so he reached behind to a stack of reprints he had on a shelf behind his desk and he threw the whole heap of reprints-- because Jim Watson had sent him a bunch of reprints" "of the two papers-- at me and his floor is covered with these neat little reprints and he said, "read it carefully." "The most important discovery in biology in ten years"-- later I wondered why he didn't make it 50 years" ""and you don't know about it."" "Osgood:" "In 1962, the nobel prize goes to Watson and crick for discovering the structure of the DNA molecule." "But rosalind Franklin does not share it." "She had died of cancer several years earlier at the age of 37." "With the discovery of the structure of DNA comes an understanding of how chemical molecules can pass on the code of heredity." "Lander:" "The real significance of the discovery of the structure of DNA, was that heredity-- which you could imagine to be infinitely complicated-- was, in fact, very simple." "Osgood:" "DNA's double helix can unzip to make copies of itself." "Each half becomes a template that attracts matching bases to complete a new molecule." "Lander:" "And this was the great secret." "Any one strand-- because it was a perfect match for the other strand-- contained all the information." "You could take away one of the two strands of the double helix and you'd still have all the information left on the other." "Why was that the secret of life?" "Because it explained how organisms replicate how they pass on genes." "Osgood:" "Normally, the copy is exact and parental characteristics are passed on." "But with billions of pairs to duplicate the occasional error is inevitable." "The result is a misspelling, or mutation like Morgan's white-eyed fruit fly." "Lander:" "It's a slow and steady accretion of misspellings maybe at a rate of only one letter in a million..." "But then selected upon by natural selection." "But then selected upon to all the variationse that change the simplest plant cell to a sequoia tree." "And that is the basis of all the diversity on the planet earth." "Osgood:" "This extracted DNA is a virtual window on evolution-- a path to our past and to the past of all living things." "DNA change is a clock mechanism that allows us to date things-- to date when two species had a common ancestor" "osgood:" "Our DNA is only one percent different from that of a chimpanzee." "In fact, we're closer to chimps than chimps are to apes." "It is now believed that humans and chimpanzees diverged from a common ancestor only five to eight million years ago." "Through DNA analysis we can even trace our ancestry back two billion years to bacteria and yeasts." "Human DNA and yeast DNA are still so similar that human DNA can repair yeast cells which can no longer divide." "When human DNA is implanted in them the defective yeast cells begin dividing again." "That tells us better than any fossil record ever could that we must have a common evolutionary ancestor a common great-great-great- great-great-grandparent with a yeast cell that goes back all those billions of years." "A measly three billion letters of DNA-- just the amount of information you could put on a single c.D. Rom-- contains enough to specify all of the remarkable diversity within a human body and amongst humans." "The structure of the DNA molecule explained everything." "It laid bare the secrets of life..." "Of reproduction..." "Of mutation, of natural selection." "It shows us that the fundamental processes underlying all of life are the same in all living organisms." "It is an absolutely stunning unity of life." "In the latter half of the 20th century we come to understand that the arrangement of molecules in strands of DNA provides the information that tells cells what to do in a person's hand..." "Or in a turtle's shell." "That's a discovery that would have astounded biologists only a few decades earlier." "But there's still the question of how life started but tin the first place.Estion the Bible suggests that life sprang fully formed from the hands of god." "The ancient greeks, on the other hand believed that when the earth was new, its surface fermented until parts of it swelled up." "Then thin membranes formed around the swellings" ""and when the membranes broke all kinds of animals were born."" "For centuries, scientists had few ideas of their own." "But that begins to change in the 1950s." "About the same time Watson and crick are working on DNA o explore the mystery of life's origins." "Many theories are proposed, but none is proved conclusively." "And yet, as the century winds to a close scientists are beginning to believe that we are only a few steps away from learning how it all began." "Osgood:" "The early earth was hardly a suitable place for life." "It was violent..." "Incredibly hot from the constant bombardment of meteors." "But in time, the meteors were less frequent the earth cooled, oceans formed and somehow, somewhere, life managed to gain a foothold." "Probably around three-and-a-half to four billion years ago the first step from non-life to life was taken." "Lander:" "So what's life and how did life ever get started?" "We have a pretty good understanding of how single-celled organism with DNA, with particular genes could evolve by slow mutation into complex organisms today." "But where did those simple, single-celled organisms come from?" "Osgood:" "What could have made atoms and molecules on the primordial earth combine in just the right way to make life?" "In the 19th century" "Charles Darwin suggested that the answer might lie in what he called "a warm little pond."" "He talked about a notion relatively common at the time and that is, life began in that warm little pond where you had a mix of chemicals where you had the coursing through it something like that, he said, out of which you would have" "the formation of some proto-form of life." "Osgood:" "In 1953, Stanley Miller a graduate student in chemistry, inplans an experimenter to see if the molecules necessary for life could have formed under conditions present on the early earth." "His advisor, nobel-prize-winning chemist Harold urey believes that instead of being rich in oxygen the atmosphere of the primordial earth was more like the outer planets of the solar system-- rich in hydrogen, ammonia and methane gas." "But could life have really begun under these conditions?" "Man:" "This was a first-class scientific problem." "I don't see how one can think about anything without asking where we came from, where life came from and questions of that sort." "Osgood:" "Miller and urey build an apparatus to model the primitive earth-- a system of glass tubes and flasks in which water and atmospheric gases can circulate subjected to jolts of electrical energy." "Miller:" "The water is like the ocean." "(Crackling)" "The spark is somewhat like lightning." "And the gas flask of about five liters corresponds to the gases in the atmosphere." "Osgood:" "After about 24 hours the once-clear water becomes yellow." "After a week, it's nearly brown." "Miller's analysis of the liquid reveals have formed where none had existed before." "Miller:" "The amount of amino acids produced was far larger than what we had even hoped we could get." "We were confident that we'd get lots of organic compounds but that we should get one so closely connected to biology was the big surprise of the experiment." "Osgood:" "Amino acids make up proteins which, along with DNA, make life possible." "Lander:" "What Miller's experiment showed us was at least some of the basic building blocks clearly could arise on their own by chance and it led to an exploration of what else could arise by chance and how could the things that were easiest to arise by chance" "give rise to more things and more things and how could you get a system that could sort of bootstrap itself up going?" "Miller's experiments didn't show us exactly how life arose but it pointed the way to how you could begin to tease apart that problem." "Osgood:" "And yet other scientists reject the experiment's most basic assumption." "What if Miller and urey are wrong about the conditions on earth four billion years ago?" "Man:" "In the '50s it was thought that the early earth had an atmosphere rich in methane and ammonia." "In that kind of atmosphere it's very easy to make organic molecules and it's easy to see how to get the ball rolling for the origin of life." "But the consensus opinion right now is that the early atmospheoxid e-rich not methane-rich, and in that kind of atmosphere it's much, much, much harder to make organics." "And that begins to push you to look at other possibilities." "Osgood:" "In 1977, at woods hole, Massachusetts another possibility for the origins of life is uncovered..." "Almost accidentally." "A miniature submarine, nicknamed Alvin sets out to explore an area of the Atlantic ocean where new, molten sea floor is pushing apart the earth's tectonic plates." "Alvin's crew discovers large plumes of super-heated water streaming from the ocean floor at nearly 700 degrees fahrenheit." "Volcano-like vents giving off black smoke." "And most amazing of all strange forms of life never before seen." "Chyba:" "There are whole communities of organisms ranging from bacteria to crabs to long tube worms that make their living out of harvesting the chemical energy from these vents." "Ght out of harvesting the chemical energy from these vents.Thou that the best source of energy at the beginning might be the sun but we now understand there are other sources of energy." "It's possible that the ear might have been the source y used by early life." "Whatever it was a reliable source of chemicals and a way to capture both of those efficiently." "Osgood:" "Yet another theory suggests that the precursors of life didn't originate on earth at all." "This theory gains credibility when a meteorite is recovered in Australia in the fall of 1969." "Announcer:" "Space scientists have discovered it contains amino acids-- the building blocks of life-- and found them in combinations that seemed to prove they were there before this tiny piece of asteroid hit the earth." "Chyba:" "So there's this possibility that the building blocks of life on earth didn't come from the earth itself but were imported." "The meteorites that actually would be big enough to see if you could look at them, burn up in the atmosphere." "But if you're smaller than that, if you're microscopic in size you can enter the earth's atmosphere and just get gently slowed down and not get burned to a crisp." "Organic molecules in those dust particles-- those micrcopic dust particles-- can make it intact to the surface of the earth." "Osgood:" "Could life have begun simply because a comet or meteoroid happened to approach the earth in just the right way at just the right time?" "The evolution of life is propelled by random events so why not life's origins?" "In the late 1970s a father-and-son team of American scientists proposes that another random meteor impact might be responsible for the massive destruction of life-- a chance event that also shaped the course of evolution." "Man:" "In the late '70s" "Walter and Luis Alvarez were doing things that geologists love to do." "They were simply measuring the rate of accumulation of material." "This was out in Italy, in gubbio, Italy and they were measuring the rate of deposition and they discovered something very unusual." "They discovered a layer-- a very thin zone-- that has an enormous amount of iridium." "Now, iridium is not a naturally occurring element." "It is usually brought to earth by the outside is brought to us by asteroids and comets colliding with the earth." "Osgood:" "Es of iridium the Alvarez team finds in Italy er 65-million-year-old come from rock strata 65 miridium layersld.On oth are found in other parts of the world like here in Southern Colorado." "This date happens to coincide with the time in earth's history when the dinosaurs went extinct after thriving for more than 150 million years." "This is the k.T. Boundary." "Below this horizon is the cretaceous period-- the time of the dinosaurs." "Above this white layer, they were gone." "The dinosaurs were simply gone." "Osgood:" "The alvarezes suggest that the impact of a giant meteor caused the dinosaurs' demise." "It's a daring idea with enormous implications for our own origins." "If the dinosaurs had not gone extinct we probably would not be here." "Dinosaurs were enormously successful organisms." "And if they hadn't been snuffed out the mammals may never have risen to be the dominant form of life on the planet and human beings might not be here." "So in a very immediate sense osgood:" "Earlier in the century, most scientists did not believe that the earth had ever been struck by large meteors." "Even craters like this one in Arizona now known as meteor crater were thought by geologists to be made by volcanic action." "Man:" "There was no consensus on whether the craters were volcanic or actually derived from impact." "When the tide shifted in the late '50s and '60s toward the belief that, indeed, almost all of these features toward the belief that, indeed, almost all of these featureshe result of meteorite impact it brought a phenomenal new understanding" "to the activity in the solar system." "Osgood:" "Manned exploration of the moon in 1969 confirmed that moon craters were not the result of volcanoes-- which had been widely believed since the time of Galileo-- but the result of frequent, often massive asteroid impacts." "And if the moon had been a target why not the earth?" "Why couldn't a random impact have wiped out the dinosaurs?" "Although the Alvarez theory is widely ridiculed at first a small group of scientists begins to find more evidence in the geological strata." "Man:" "There was shocked quartz grains which means deformation of quartz in a way that only happens in giant explosions." "There were little droplets of melted rock that is little spherals of rock that had been melted." "There was soot." "If you measure around the world and then add up the total amount of soot in this layer there's enough soot that you have to burn down something like the total amount of forests in the world today or twice that much, to generate that much soot." "Osgood:" "It's hard to conceive just how powerful a blast it must have been and what devastating effects it had." "Imagine the impact of a typical nuclear warhead multiplied a 100 million times." "Schultz:" "This firestorm came sweeping over this region-- a mass of incredible temperatures." "Dinosaurs would have been literally fried in their tracks." "Osgood:" "As the evidence grows, more scientists are swayed but many remain skeptical." "If such an impact occurred, they ask, then where is the crater?" "Schultz:" "We had the layer." "We had the iridium." "We had the hypothesis, but we didn't have the crater." "We did not have the smoking gun." "Osgood:" "By 1991, geologists think they have it." "In an area off Mexico's Yucatan peninsula circular, crater-like structures are discovered buried under thousands of feet of sediment." "Core samples taken from the area indicate the age and nature of the material found there which matches up with other material found all around the world." "Analysis shows it all to be 65 million years old." "It's hard to imagine any explanation other than the impact of a giant meteorite." "Lander:" "So what are we to make of the tremendous importance of random factors in evolution?" "Well, for one ths that things didn't have to work out the way they did that, for example, humans didn'thaveto evolve." "If that big meteorite 65 million years ago had missed, we might not be here at all." "That should give us a certain humility that our presence here is not a foregone conclusion." "I think that's the hardest thing to understand the hardest thing to appreciate about life about most of the forces shaping the origins of everything is that there are steady chemical and physical laws at work every day-- they come to work every morning" "these chemical laws, these physical laws-- and yet the outcomes of them are shaped in really mysterious ways by chance." "I think it should give us a lot of pause about what actions we take in the future." "Humans are now such an important force on this planet that we have the ability tobea random event to carry out extinctions, to greatly shape the earth and I think we are the first major random event that can actually think about the consequences of its actions." "I think we have a lot of responsibility to bring into the next century." "Osgood:" "In a universe so affected by chance we will always be surrounded by mystery." "No matter how great our discoveries there will always be something new..." "Something we can't decipher..." "Something unpredictable." "Our quest for understandingnti nue." "Our science odyssey will never end."