do [Music] [Music] so [Music] so [Music] an ancient mystery is etched upon these mountains a story of primordial oceans and prehistoric life of creatures stranger than fiction and the controversy that has surrounded them for more than a century buried among these majestic peaks are glimpses of an event that transformed the planet in a moment of geological time compelling evidence etched in stone that challenges long-held assumptions about the origin of animal life on earth so [Music] [Music] today most paleontologists think that complex animals first appeared on earth about 530 million years ago during a geological period known as the cambrian but early in the 19th century little was understood about this seminal event in the history of life [Music] in 1831 the renowned geologist adam sedgwick began to excavate the cambrian rock strata in northern wales he was assisted by charles darwin a recent graduate of cambridge university for the young darwin the fossils embedded in the cambrian shale were an intriguing curiosity but at 22 he lacked the perspective to appreciate their full significance natural selection the theory of evolution and the origin of species all lay years ahead so he couldn't imagine that the stones beneath him held a mystery he would never resolve it was a mystery darwin would ponder into old age and then pass on to future generations the mystery of the cambrian explosion the cameron geological interval is just great in terms of the fossil record because that's when animals effectively first colonize the earth it's a very exciting time and by and large scientists like to work in really you know vividly interesting areas you know where there's a hum about the whole thing and that's very much the case the cameron at the moment [Music] simon conway morris has devoted his career to the study of evolution and the early history of life morris has staged expeditions on four continents and surveyed the intervals of geological time while focusing his attention on the cambrian period and evidence for the sudden emergence of animals in a veritable explosion of life well a cameron explosion is exactly what it says it is it's an explosion now not explosion in terms of pieces of animal flying all over the place actually when biologists talk about an explosion what they mean is effectively an enormous diversification what we call a radiation so we have during the cambrian what appears to be the abrupt appearance of animals we're filling the barrel with lots of different types of organisms but we're also inventing nervous systems we're inventing eyes we're inventing how to move quickly so the whole world is speeding up it's an event where in many respects everything changes forever [Music] more than a century ago a stunning window to the cambrian explosion was opened by a series of discoveries made in western canada [Music] in 1886 the canadian pacific railroad reached british columbia and the kicking horse valley for the first time eastern and western canada were linked by a 2500 mile steel artery that opened the rocky mountains to tourists adventurers and men of science among them was the geologist r.g mcconnell [Music] earlier in the year mcconnell had heard reports of a shale bed on the flank of mount stephen just outside the town of field railroad carpenters who had explored the area said it was filled with stone bugs [Music] in september mcconnell climbed the mountain to his amazement he found unmistakable imprints of prehistoric life on most of the shields in the bed [Music] mcconnell was standing in an ocean of fossilized trilobites trilobites are icons to the cambrian and there are billions of trilobites high up on the shoulder of mount stephen one reason for that is that as they grew they periodically threw off their old skeleton and made a new skeleton so basically they made many fossils through their individual lives [Music] mcconnell collected hundreds of these fossils and sent many of them to other scientists for examination news of his work soon reached the offices of the united states geological survey and charles doolittle walcott a leading expert on cambrian paleontology [Music] walcott was fascinated by mcconnell's reports but had to wait almost 20 years for the opportunity to conduct his own research finally in 1907 as the newly appointed secretary of the smithsonian institution he boarded a train for western canada walcott spent two summers at mount stephen collecting fossils and surveying the geology of the area yet despite his success here he knew his exploration of these mountains was only beginning looking out across the kicking horse valley to the burgess pass walcott set his sights on a corner of the rockies untouched by the hammer and pick of any geologist this is where he would move his expedition on august 30th 1909 walcott led his team below this ridge 15 miles north of mount stephen there legend holds he stopped to examine a pile of shale that blocked the narrow horse trail as he picked up a slab the geologist noticed a faint but well-defined fossil he had never seen before a delicate lace crab he later named marella he knew plenty and plenty about the cambrian he was an expert on the camera he published many papers and when you see this little morella it's only about a centimeter in length you get out your hand lens and you suddenly see that this is you know shouldn't be there this is soft-bodied effectively and i'm sure he realized in seconds what it meant he must have in the summer of 1910 walcott found a fossiliferous band in the ridge [Music] after blasting a quarry the geologist and his family unearthed thousands of exquisitely preserved specimens from soft-bodied animals previously unknown to science he called the site the burgess shale there in burgess shale especially the lower level which walcott first exploited the preservation is miraculous it's astonishing we find trilobites of course but we find many many other sorts of arthropods almost none of which are ever found in a typical cambrian assemblage so we can treat them effectively as being soft-bodied they have almost no chance of being fossilized in normal circumstances geologists believe that the animals of the burgess shale were buried quickly and alive by an avalanche of sediment that created an air-tight tomb and prevented the decay of soft body parts like eyes legs and internal organs now in the animal marella very often there's a sort of what we call a dark stain and i find it's very intriguing because that dark stain evidently as the body contents are oozing out so in other words the animal is beginning to decay and then something stops it on many of the arthropods we have the most delicate branches and you can see every single fine hair along them quite astonishing similarly antennae going out like that in particular instances we have some worms so we see the outside of the body we can see various things at the front which enable the worm to burrow through the sediment but then you look at the animal itself and you can see this sinuous reflective line and of course you say oh that's the gut that's the elementary canal and then in certain cases you actually look at one part of the elementary canal and you can actually see food inside it shellfish which is swallowed it is a remarkable insight into a fossa you'd never expect to be fossilized the burnished shale was once part of a massive reef in the pacific ocean a haven for a menagerie of life that thrived at the edge of what is now the north american continent [Music] throughout long periods of geologic upheaval tectonic forces elevated these rocks and the fossils they bear more than seven thousand feet above sea level [Music] here the basic body plans of major animal groups that still exist today and many others now extinct made their first appearance in the fossil record so suddenly that biologist richard dawkins noted it is as though they were just planted there without any evolutionary history these fossils gave science its first detailed look at the biology of the cambrian [Music] with seas animation we can now bring that world to life [Music] like something out of science fiction opa benia was a creature so bizarre it still eludes classification while its five eyes watched for predators the animal captured its prey with a grasping claw [Music] first described in 1899 from a fossil found on mount stephen huixia has also puzzled scientists this mysterious cambrian animal is covered with overlapping scales and may have fed by scraping microscopic particles off the sea floor [Music] the animal most frequently discovered at walcott's quarry was marilla [Music] more than 15 000 fossil specimens of this prehistoric crab have been excavated most revealing multiple pairs of jointed legs and feather-like gill branches used for swimming [Music] the anatomy of hallucigenia has baffled paleontologists since walcott first discovered its fossilized remains two rows of sharp spines on its back and more than a dozen needle thin legs gave the animal the appearance of being upside down even when it was right side up [Music] at the top of the food chain was anomalocaris the undisputed terror of the cambrian seas [Music] measuring up to three feet long this super predator used barb feeding arms to capture both hard and soft bodied animals [Music] it then devoured its prey with layers of razor-sharp teeth [Music] between 1910 and 1924 charles walcott collected more than 60 000 cambrian fossils many of which are still studied in museums and research centers around the world but the treasures of the burgess shale represent more than a wealth of information about ancient life they are also flashpoints in a controversy that began long before the great geologist ever set foot in the canadian rockies [Music] oh in 1859 this country estate 30 miles south of london was ground zero for a scientific revolution here in the solitude of his study charles darwin completed his landmark book on the origin of species in it darwin attempted to explain how every organism that had ever lived evolved from a single common ancestor as a result of natural selection acting on random variations the idea of evolution itself change over time was not novel with darwin what darwin did that was i think really revolutionary was to advance a hypothesis of common ancestry that all living things were related he would have a branching tree pattern and for a long time you would only have that one species and then it would eventually branch into two species and then more species and different families and orders and classes and darwin's thinking given enough time those differences accumulate especially under natural selection if the environment changes those differences accumulate to the point where a thousand or a million generations from now your great great great great great grandchildren will be a different species so it is both logically and almost aesthetically a unifying picture a unifying image that pulls together the whole of life on earth and for many biologists that kind of unification is very important common descent and natural selection became the twin pillars of modern biology and darwin's branching tree of life its foremost icon yet despite the clarity and detail of his argument darwin acknowledged a problem that defied explanation the cambrian fossil record the distinctness of specific forms and they're not being blended together by innumerable transitional links is a very obvious difficulty i allude to the manner in which species belonging to several of the main divisions of the animal kingdom suddenly appear in the lowest known fossiliferous rocks [Music] when darwin was writing the origin of species it was well known at the time that the first fossils of animals appeared suddenly without precursors in the geological record so there was a deep conflict between what his theory told them to expect to find namely an abundance of transitional forms going back to that common ancestor for the animals versus what was there in the fossil record darwin knew that if his theory was true the older rock strata directly beneath the cambrian layer should reveal a progression of fossils connecting simple earlier forms to complex animals like trilobites through a trail of incremental steps and failed biological experiments [Music] such evidence would document the trial and error process of natural selection but darwin says in the origin where are these transitional forms they're not there in the fossil record what we see instead are fully formed discrete groups now that's a world-class puzzle for someone like darwin and so it's very very striking and one can see why charles darwin was so puzzled by the camera explosion because he had enough knowledge even at that time to realize that deep in the earth history you just didn't find the animals if my theory be true it is indisputable that before the lowest cambrian stratum was deposited long periods elapsed and during these periods of time the world swarmed with living creatures to the question of why we do not find rich fossil forest deposits belonging to these assumed earlier periods prior to the cambrian i can give no satisfactory answer darwin was deeply troubled by the cambrian explosion he called it an inexplicable mystery but he wasn't about to abandon his theory and instead proposed that the animals just looked like they appeared suddenly because he thought that the fossil record was incomplete i look at the natural geological record as a history of the world imperfectly kept and written in a changing dialect of this history we possess the last volume alone relating only to two or three countries of this volume only here and there a short chapter has been preserved and of each page only here and there a few lines so darwin argued well perhaps paleontological discovery digging through the rocks needed more time that the transitions were out there that not enough collecting had occurred not enough sampling if you will of the fossil record on earth and given time those transitions would turn up three decades after darwin's death charles walcott's historic work in the canadian rockies did nothing to fill the gaps in the tree of life or the fossil record while caught uncovered the remains of cambrian animals unknown to darwin and each demanded its own unique progression of evolutionary ancestors a trail of evidence that did not exist in the burgess shale walcott realized that the cambrian explosion of life was an even bigger problem than darwin imagined so in an attempt to defend evolution he reached back to darwin's explanation of an incomplete fossil record like darwin walcott thought that the cambrian explosion was an illusion he was convinced that the fossils were there they were just inaccessible to scientific discovery and he expected that they would eventually be found someplace buried deep beneath the oceans for decades walcott's hypothesis was widely accepted but untestable however later in the 20th century new technologies led to empirical conclusions once the oil company started to drill offshore they brought up what are called drill cores and inside the core were hunks of sedimentary rock and some of those rocks contained fossils but none of them were made by animals that lived before the cambrian explosion [Applause] since the 1960s scientists have also used radioactive minerals and evidence of changes in the earth's magnetic field to analyze and date undersea sediments from extensive surveys they have created this digital map that defines the age of the sea floor we now know that the oldest rocks on the bottom of the seafloor only date back to the jurassic period which means that on the standard geologic time scale there are hundreds of millions of years younger than the rocks below the cambrian strata if you're looking for the ancestors to the cambrian groups the last place you would expect to find them is out somewhere on the seafloor those rocks are much too young [Music] so how did the cambrian animals emerge and where are the signs of their evolutionary past darwin and walcott both confronted and failed to solve this mystery and today the plot has thickened as science looks back to what the planet was like before trilobites and morales first inhabited the ancient seas [Music] [Music] according to standard estimates almost 90 percent of the earth's history took place during the pre-cambrian geological period while our knowledge of the pre-cambrian is far from comprehensive most textbook accounts include a similar chronology and chain of events about three and a half billion years ago primitive life first appeared on earth in the form of single-celled bacteria over time these cells gathered into clusters to form blue-green algae that floated on the surface of the oceans [Music] life changed very little for more than 3 billion years then on the threshold of the cambrian period evidence of multi-celled organisms first appears in the fossil record in the late pre-cambrian and at the cambrian boundary we're seeing the rise of larger organisms that had fluid skeletons and strong muscles and they could burrow and they could crawl around and as time goes by we began to see on the ancient seafloor sediments trails little squiggles where a small worm was crawling along and they looked like squiggles left by little tiny worms today so from near 600 million years to 543 million years more or less 50 or 60 million years what we mostly see as far as living kinds of animals are are these little squiggles there is also evidence that near the end of the precambrian the oceans were inhabited by jellyfish sponges and the mysterious ediacaran fauna if you go to immediately before the cambrian then actually you find something extremely puzzling because you get large organisms large fossils and these are called the ediacaran assemblages and they have been one of the great headaches for paleobiology and also for evolutionary biology why well because basically some look like animals but other ones don't look like animals at all some of them look like air mattresses quilted air mattresses others look like a frond they're not plants but they kind of have that appearance so these ediacaran assemblages are bag-like what we call sessile most of them didn't move or if they did they probably moved pretty slowly it looks a rather sleepy a rather dozy world [Music] whether the ediacarans were actually animals or plants is still uncertain but late in the pre-cambrian they disappeared from the earth then long after their extinction everything changed in a geological instant in a spectacular burst of creativity the basic blueprints for most of the animal kingdom exploded into being and for the first time biologically complex structures like compound eyes spinal cords articulated limbs and skeletons appeared on earth [Music] to understand the speed of the cambrian explosion imagine the history of life compressed into a single day if we imagine the whole history of life on earth taking place in one 24-hour period the current standard estimates for the origin of life put it at about 3.8 billion years ago let's say 4 billion so if we start the clock then our 24-hour clock six hours nothing but these simple single celled organisms appear the same sort that we saw in the beginning 12 hours same thing 18 hours same thing three quarters of the day has passed and all we have are these simple single-celled organisms then at about the 21st hour in the space of about two minutes boom most of the major animal forms appear in the form that they currently have in the present and many of them persist to the present and we have them with us today less than two minutes out of a 24-hour period that's how sudden the cambrian explosion was since darwin excavations on every continent have revealed the magnitude of the explosion of life an event that was clearly global in scope most recently several discoveries in southern china have fascinated science and deepened the cambrian mystery in 1984 one of the most important finds in the history of paleontology was made outside a small town in china's yunnan province while surveying this mountain near xinjiang ho cienguan unearthed cambrian fossils older more diverse and better preserved than any ever discovered the condition of the chenjeng fossils was so remarkable oh said it appeared as if the animals were alive on the wet surface of the mudstone the fossils they've collected i mean first of all they're stunning i mean they're really beautiful to look at they're brightly colored stained with iron and probably other kinds of minerals so they're kind of golden looking or kind of reddish and they really stand out from the rather tan colored background of the rocks and they're just beautiful so aesthetically they're wonderful many of them are soft bodied no hard parts no skeletons no shells just soft bodied and yet they're exquisitely preserved so you can see the cameron explosion in greater detail than you can anywhere else in the world [Music] in the early 1990s reports of the chinese fossils were released to the rest of the world at the university of san francisco marine biologist paul chen followed the news [Music] what drew my attention was in fact a couple articles published in people's daily the official paper from the communist party in china announced that the chung jiang fossils drew the attention of scientists worldwide people said he reported that this fine actually challenges the theory of darwin's evolution and then towards the end of 95 time magazine and december 4th has this front cover story about animal big bang which talk about chinese great leap forward in science then really solidify my interest i said this is something really big i want to get to the bottom of this one day i would stand in front of that fossil site myself and find out what's going on since 1996 paul chan has made several trips to southern china to conduct his own investigations when you talk about cambrian explosion lots of people find it fascinating and so forth but when you get into the topic generally there are two reactions uh people who loves it and people kind of avoid it the cameroon explosion does challenge the traditional idea of gradual evolution of animals because they all seem to appear all of a sudden and the problem is how do we explain it paleontologists have determined that the chinese fossils were older than those excavated at the burgess shale yet anatomically they were often even more complex this discovery also confirmed that previous estimates of an explosion lasting 20 to 40 million years were much too long the time period that we figured it took the animals to be established in the ocean in those days took probably 10 million 5 million years so this is truly an explosive event in the scientific terms what we are seeing is a quantum jump and this quantum jump has no explanation the cambrian explosion was so short that it is below the resolution of the fossil record it could have happened overnight so we don't know the duration of the camryn explosion we just know that it was very very fast as the interval of the cambrian explosion is compressed in other words as the time available shrinks the challenge to evolutionary theory grows because the differences in form that have to be constructed very rapidly are much more dramatic it's going to pose a real and i think fundamental challenge to evolutionary mechanisms from what i saw the chinese scientific community as a whole seem to be rather progressive around us they are convinced by the evidence that cambrian explosion is real and and they see it's a challenge due to the darwinian theory they're honest about it therefore they are thinking about how to explain this outside of the darwinian thoughts the qinjang fossils provide the most inclusive picture of the cambrian explosion yet documented and directly beneath them in pre-cambrian shales another chapter in the history of life is written in the rocks there's another amazing find that's been made in china paleobiologists have discovered little tiny microscopic sponge embryos in the layers of rock just beneath the layer that documents the cambrian explosion these embryos were soft-bodied animals some fossilized 60 million years before the cambrian explosion their eggs and embryos which are preserved in thin crusts of mineralized material phosphatic material on ancient seafloors which suggests that the chemistry of the seawater in those days was somewhat different than it is today because this method of preserving fossils disappears during the cambrian and it's not around today so we're lucky that we have these thin crusts with little tiny fossils in them this is highly significant because one of the most popular explanations for the missing pre-cambrian fossils is that the pre-cambrian animals were too soft and too small to have been preserved [Music] since 1999 paul chen has studied fossil embryos and helped develop techniques to analyze their structure by treating with acid you can actually remove the rock and isolate the embryos and then you get around pebbles like or sand grain like samples and then we look through some tiny little ones larger ones up to one millimeter in size and we found about the range between 500 and 800 micrometers we have mostly sponge and then i start breaking up these balls and and try to uh start looking inside and with the help of the electron microscope i was able to see the detailed subcell structure within these embryos jen's work on these fragile remnants of pre-cambrian life raises an important question if these lower strata can preserve an embryo if they can preserve a soft microscopic embryo then why couldn't they have preserved the larger ancestral forms that supposedly evolved into the cambrian animals in other words if you can preserve something as fragile as an embryo why couldn't you in the same strata of rock preserve the immediate ancestor of a hard shell trilobite so the idea that the fossil record is too damaged to provide us with at least a general picture that idea just doesn't wash during the past 150 years fossil hunters have searched the earth for the many transitional links darwin's theory requires if i set you on a treasure hunt and said what i really want is this you're gonna go out and look for this whatever it happens to be well if you come at the fossil record with a darwinian expectation of an abundance of transitionals that's what's going to get you a professorship you find those transitional forms so all over the world and countless outcrops people have been looking for those forms that would capture the major transitions in the history of life [Music] this search has extended from the walls of the grand canyon to the shores of the irish sea and as countless specimens have been excavated one question endures how complete is the cambrian fossil record i think the cambrian fossil record is surprisingly complete i think it may be more complete than we realize the reason for that is for instance if you look at the stratigraphy of the world if i go and collect cambrian rocks in wales and find turned fossils if i then go to china i don't find the same species but i find the same sorts of fossils if i go into carboniferous rocks i go to canada they're the same as what i find in this country so there is a clear set of faunas and floras which take us through geological time the overall framework is falling into position there's no question that if you dig and sample more you're going to find new kinds of fossils but generally speaking the fossils that we find fall into groups that we already knew about when you see that what i think nature is telling you is you've got a pretty good sample of the history of life on earth the groups that you already had established are the ones that capture the new fossils to the paleontologists the lack of intermediate fossils is well known some people still think that if you look long and hard enough you will eventually find them but i think most of the paleontologists that i have been in contact will not have that hope very high they simply feel that we have looked long and hard enough and they are not there they are not there [Music] the difficulty of assigning any good reason for the absence of vast piles of strata rich in fossils beneath the cambrian system is very great the case at present must remain inexplicable and may be truly urged as a valid argument against the views here entertained [Music] [Music] [Music] in 1831 three months after his first exposure to cambrian geology young charles darwin embarked on an expedition that would influence the development of his theory of evolution as naturalist aboard the hms beagle darwin sailed to the galapagos islands 600 miles off the coast of ecuador [Music] [Applause] for five weeks darwin explored this remote island chain home to an extraordinary assembly of animals here the idea for his tree of life was planted according to darwin as one form of life morphed into another new species arose and as they gradually branched apart larger differences in form emerge eventually evolution produced an even greater level of disparity the distinct body plans of new phyla phyla are abstract categories that bring together basic features that unite large groups of animals so you can think about a phylum as a group of organisms that all share a basic architecture based on the body plan of the animal we divide animals into these major groups there's vertebrates the backbone and soft bodies outside the bone structure there's arthropods which have a hard skeleton on the outside and a soft body on the inside these are the insects and the crabs there's the echinoderms which are the sea urchins and starfish sea stars are different from jellyfish different from worms and different from crabs and lobsters so each group has their unique teachers to make them very different from the next group the stability of these forms in the animals that exemplify the distinct phyla contradict darwin's vision of an interconnected tree of life the phyla don't blend imperceptibly one into another arthropods for example didn't evolve from chordates mollusks aren't the offspring of sponges instead a phylum is in effect as different as it can be from another phylum so how did these differences arise if one reads the origin of species it's clear that darwin's caught in a bind natura none fatchit sultan that was darwin's famous latin phrase which means nature takes no sudden leaps in fact darwin went on to say that if you found evidence of saltation of sudden appearance in the fossil record that would be something like evidence of of special creation one of the most striking examples of a sudden leap in nature is evident in the number and stability of new animal body plans that first appeared during the cambrian explosion one of the other remarkable things about the cambrian explosion is that a huge percentage of the total number of phyla that have ever existed on earth all appear within a very narrow window of time it's a defensible statement that most of the major animal body plans are present in the cambrian explosion that's where they first appear [Music] imagine a graph if you will of the appearance over time of phyla in darwin's picture you'd have one then two then four perhaps then eight a gradually increasing curve of the number of phyla growing over time what you actually have in the fossil record is a sudden spike in the number of phyla that appear during the cambrian and then a few that trickle in across the rest of geologic time this kind of discontinuity is radically at odds with the darwinian picture of the history of life the pattern we see is the major body plans present at the beginning and that the organisms that we know today fall into one or another of those major body plans they don't gradually increase over time [Music] the sudden appearance of animal body plans deepens the cambrian mystery in another way the darwinian model predicts that as new biological forms evolved simple to complex they developed gradually from the smallest differences in classification to the largest or from the bottom up darwin's idea was that given enough time evolution would lead to new species new families orders and eventually phyla and only after millions and millions of generations do you end up with you know the several dozen phyla that we see around us nowadays that would be the bottom-up pattern predicted by darwin's theory now the other picture is top-down the top-down picture says the primary differences are original they're there right at the start when you find molecules in the fossil record or the arthropods boom there they are with the major differences present right at the beginning so the upper level architecture is top-down present right there [Music] this top-down pattern of biological development can be compared to the development of human technology if you look at any major invention like the automobile for example the basic body design is set in place from the very beginning [Music] you've got four wheels a chassis a drive shaft two axles there are certain basic features of all automobiles that have persisted since ford and benz got the whole thing going over a century ago [Music] in the decades it followed the introduction of the automobile's basic framework designers and engineers have created thousands of variations on the original theme but regardless of differences in size color and chassis design the foundational body plan remains consistent to its original form and an interesting thing about the fossil record is that there's a similar top-down pattern evident in the history of life the basic body plan of the arthropod phylum has a segmented torso jointed legs and an exoskeleton all of which arose suddenly at the beginning of the cambrian explosion and today we still see the continuity of this original plan this foundational idea in over a million species of animals this top-down pattern looks nothing like the predictions of darwin's theory darwin's theory is that there's a tree of life where you have one organism diverging into many other organisms and big differences appearing at the top what we really see is from here up this does not exist in the fossil record if i were using a botanical illustration it would be a lawn with separate blades of grass sprouting independently of each other and those would be the phyla now within each phylum there is subsequent diversification but even there i don't see the branches connecting that would make them a tree of life darwin was caught in the grip of a deep dilemma the fossil record showed him one thing his theory told him something else he comes to an impasse at this point and he says if this pattern holds it is a genuine argument against my view and i think 150 years later we've added a great deal more detail to the picture but i think the basic problem is still unsolved how did these new animal body plans and fundamentally new forms of life come into existence this was the mystery that darwin set out to solve but everything we've learned in biology over the last 50 years has brought this mystery back with a vengeance how do you explain the origin of the cambrian animal seemingly out of nowhere this isn't just a problem of explaining the absence of evidence in the fossil record it's also a problem of explaining everything we know about life right down to the level of molecules and cells the biological structure of a cambrian trilobite was as complex and sophisticated as a modern crab its organs included a brain gut heart and compound eyes each organ was constructed from specific types of cells each cell type was made from dozens of specialized protein molecules and each protein was assembled from a four-letter chemical code in a section of dna called a gene now for the evolutionary process to transform a simple pre-cambrian organism like a sponge with four or five cell types into a cambrian trilobite with at least 10 times that many different types of cells that's a huge leap in complexity and to make that leap you need a vast amount of new genetic information where does that information come from that's the central mystery of the cambrian explosion [Music] according to neo-darwinism new proteins are constructed by the dual mechanisms of genetic mutations and natural selection as the genetic instructions for building proteins are copied an occasional error can alter their contents if these accidental revisions prove beneficial to survival they are selected or preserved and passed on to future generations over eons these small changes accumulate and new proteins cell types and even cambrian carnivores gradually evolve into existence [Music] richard dawkins the famous oxford evolutionary biologist has illustrated how the darwinian mechanism works using a metaphor he calls climbing mount improbable from the front side the mountain is a sheer cliff that could never be scaled in one giant leap for dawkins this represents the impossibility of creating a complex animal by chance alone yet dawkins also envisioned an alternative route of the backside of mount improbable a long gradually sloping trail of small steps leading all the way to the summit according to dawkins that's how you'd climb the mountain and that's also how you'd build a cambrian animal one small step at a time what chance alone can accomplish in one blind leap natural selection can accomplish through the cumulative effect of many small incremental steps in theory each step corresponds to a small unit of biological change a new gene and its protein product but do mutations and natural selection have a reasonable chance of producing even one protein in the time available since 1992 molecular biologist doug x has examined this question there's a story that's being told and there's a appeal in in the case of darwinism to random mutation and natural selection as being in vague terms the mechanism but if you look at the detail what kind of mutation can accomplish these transitions and there it's important to realize that the one area where we can really nail this down is at the single protein level where you can actually measure it and if you look at protein structures to get a substantially new protein fold is prohibitively difficult each of the thousands of different proteins in nature is actually a chain made from a specific combination of 20 different amino acids the sequential order of these chemical building blocks is crucial for if they are arranged correctly the chain folds into a functioning three-dimensional molecule but if the amino acids are incorrectly assembled no protein will form if proteins are indeed rare among the possible sequences of amino acids what are the odds that mutations would stumble upon a functional combination of chemicals from the vast number of alternatives to find out acts randomly altered the structure of an enzyme protein comprised of 150 amino acids you've got the protein 150 amino acids long then you've got 20 to 150 power possible ways of arranging the amino acids out of all those possibilities how many are functional and how many are gibberish if you do the experiments and you analyze how much information is required to get say a new protein fold is just far beyond what you can get by random mutation and natural selection how far beyond tax published his findings in the journal of molecular biology he determined that among all the possible amino acid combinations the probability of generating just one short protein by mutation is roughly 1 in 10 to the 74th power or one chance in a hundred trillion trillion trillion trillion trillion trillion to put that in context there's only 10 to the 65 atoms in the entire galaxy so to build a new functional protein by selection and mutation within the time allowed for the cambrian explosion what you're essentially having to do is equivalent to a blindfolded man looking throughout the entire galaxy for one marked atom so what we're talking about is searching for a tiny tiny needle in an enormous haystack and and having a very limited time to search [Music] so on the question of something like the cambrian explosion there does not appear to be any way that unguided random mutations can accomplish what needs to be accomplished to explain new functional proteins and certainly by extension wherever in the history of life you would need to have multiple new protein folds the probabilities multiply so there's no reason to think that this is plausible but the inability of random mutations to generate new genes and proteins is only part of the problem for the origin of cambrian body plans demanded more than new genetic information a lot of the information for specifying an anomalocaris a trial by what have you uh does not reside at the dna level the body plan as far as we know is not in the dna while dna carries the instructions to manufacture proteins it cannot alone assemble them into cell types or arrange cell types into new tissues and organs or tissues and organs into body plans instead the formation of body plans ultimately requires another level of information stored somewhere in the three-dimensional structure of the egg cell and the embryo instructions that direct the development of complex animals from fertilized eggs with computer animation we can observe this intricate process [Music] as an egg cell begins to divide and differentiate a network of biological commands orchestrates the development of an arthropod [Music] after several stages of division dozens of new cells align against the outer membrane of the egg and then cued by a chemical signal they start their migration toward targeted areas in the embryo where they will gather and develop into a mature organism [Music] the cells steadily increase their numbers and align like members of a marching band into patterns that will form the tissues and organs head and legs of the growing embryo that happens by a process of cell specification and differentiation where cells are committed irreversibly to performing particular roles you're going to give them different jobs to do you're going to be part of the locomotory system of this organism you'll be an eye you'll be a gut and so forth to me that's an absolutely astonishing process but it works and what it builds you is different kinds of organisms depending on the instruction set that's provided so there is an organismal blueprint an ultimate point that the embryo hones in on and is attracted to and eventually embodies that foresight that pre-ordained outcome is built into the embryo when you talk about these early developmental sequences and anomalocaris and hopi vineyard what have you you're talking about information in the broad sense codes specifications entailments implications that are orders of magnitude beyond anything that we can currently conceive it's so off-scale that you've left that line of impossible by chance a long time ago [Music] the volume and complexity of information that controls the development of a body plan is staggering and its location in the cell stands as perhaps the ultimate challenge to the neo-darwinian scenario of random mutation and natural selection we know that much of this higher level information that's required for building new tissues and organs and body plans isn't found in dna that means that you can mutate dna indefinitely without respect to probabilistic limits without respect to time and number of trials and you're never going to get the kind of form and structure you need to build a new organism dna is simply the wrong tool for the job and no amount of time is going to overcome that limitation that has a really devastating implication for the neo-darwinian mechanism [Music] if the darwinian mechanism cannot explain the origin of the information necessary to produce the cambrian animals is there any other cause that can for more than 20 years stephen meyer has explored this fundamental mystery in august 2004 meyer published several of his conclusions in a peer-reviewed journal affiliated with the smithsonian institution [Music] his essay triggered a firestorm of controversy that jeopardized the career of the journal's editor evolutionary biologist richard sternberg but why did a technical paper on the origin of animal body plans evoke such heated response for many people the problem with my paper was simply the conclusion i not only argued that the darwinian mechanism could not explain the origin of the new form and information that arises in the cambrian but i also argued that there were critical features of that explosion that pointed to the reality of a designing intelligence in the history of life since his years as a graduate student at cambridge university meyer has worked to develop a scientific case for intelligent design a case based on a standard method of reasoning used by both darwin and the famed 19th century geologist charles lyell lyell insisted that the best explanation for an event in the remote past was a cause known from our experience to produce it a presently acting cause one now in operation the present is the key to the past that was lyell's dictum it was it's standard historical scientific methodology if you're trying to reconstruct what happened in the remote past we should let our present experience of cause and effect guide our search for the best explanation this reasoning helped focus meyer's conclusions about the origin of information the light came on for me because i realize it's not that hard what you're looking for are causes which are known to produce the kinds of effects you're trying to explain i asked myself the question what is the cause now in operation that produces new information whether it's digital code or whether it's hierarchical information in the form of a blueprint where does that kind of information come from well we know from our experience from our uniform and repeated experience which is the basis of all scientific reasoning about the past that information always comes from an intelligent source so when we find information in the cambrian animals when we realize that large infusions of new information are required to build those animals the most natural thing the most logical thing to conclude is that those animals owe their origin to an intelligent source that the information required to build them in turn must have come from an intelligence as i've reflected on this over the years i've realized that the same reasoning that applies to the origin of biological information also applies to the origin of the other key features of the cambrian explosion [Music] the sudden top-down appearance of the fire during the cambrian explosion defies the simple to complex pattern of development that darwin predicted in darwin's picture you'd have little differences accumulating to big differences the top-down picture turns that on its head you find first you get new phyla and then you have some variations on those themes over time but the new form the big differences appear right from the beginning in the fossil record if you consider the possibility of design you realize that that pattern makes perfect sense because we see in our own history of technology the same pattern of top-down appearance in new forms you're always working from your high level objective to your details in order to accomplish the high level objective only intelligence can visualize a complex endpoint and bring together everything that's needed to actualize that endpoint the body designs evident in the cambrian animals have continued to appear in different species throughout the history of life yet though these species share common body plans they are not connected by a continuous line of intermediate material forms the continuity that explains that consistency of form through time is the continuity of an idea so when we see in the fossil record the same basic idea popping up over and over again that suggests that a mind has played a role in the origin of that form of that body plan organization [Music] design systems also display another distinctive feature they are comprised of a network of complex and precisely organized component parts you could speak of these in terms of a nested hierarchy you have the very high level parameters that specify the whole project goal below that you have layers and layers of more detailed parameters that are needed in order to complete the whole project as an example resistors capacitors and transistors are each made from specifically arranged materials these components are then assembled to form integrated circuits circuits are arranged to build computers that are then arranged into networks of computers so each level there is a specificity of arrangement that's provided in turn by the intelligent designer the engineer that keeps the whole system working what you have in biology is something very similar in living systems genes code for proteins which are organized to form distinctive cell types which are arranged to form tissues and organs which are assembled into body plans including the plans that arose during the cambrian explosion we know of only one cause in the entire universe that can produce that kind of hierarchical arrangement of form and structure and information and that causes intelligence this is the kind of thing that minds do but natural undirected processes don't evolution works very slowly as darwin saw it with lots of failed experiments along the way and one would expect that over millions of years as sediment is being deposited that you would capture some of those experiments some of those blinking groups leading to the trilobites that he knew all about so the absence of those forms is profoundly mysterious but from the standpoint of intelligent design it's not mysterious at all because we know that intelligent agents can bring things into existence that didn't exist before because they had an idea they had a blueprint in their minds that they realized in their creative activity there's no need to tinker through millions of years of evolutionary history if you can actualize a plan at a discrete moment in time and that's exactly what appears to have occurred in the cambrian explosion [Music] if numerous species belonging to the same genera or families have really started into life all at once the fact would be fatal to the theory of descent with slow modification through natural selection no aspect of the natural world troubled charles darwin more than the cambrian fossil record and the explosion of life it revealed [Music] today many of the details of this remarkable chapter in the history of life still await resolution yet modern paleontology genetics and embryology have cast new light upon the cambrian mystery and the origin of complex life on earth if you have very different forms of life that appear in a very short and very brief time period with with respect to the earth's history it certainly has the appearance that design problems were solved and that they were solved elegantly and that they were solved in very many instances when these forms appeared it wasn't just one or two rickety hanging on the edge forms it was a panoply a manifold of different body types it does have an explanation if you regard in addition to matter and energy in the universe information as being just as important if not more important and that is where i think intelligent design theory comes into play i think to build an animal the kind of process that the evidence requires is a process that can look into the future and bring everything together to actualize something like a trilobite or a chordate or a mollusk or the other different forms that we see in the cambrian explosion it's going to be a process that has foresight it's going to be a process that can visualize complexity it's going to be a process indistinguishable from intelligence that's not natural selection that's design [Music] the postulation of intelligent design not only helps to resolve a long-standing scientific mystery but it also speaks to a larger question because what we see in the origin of complex life on earth is not evidence of just an undirected process instead we see evidence that life was designed that life was planned that it was intended [Applause] [Music] [Music] [Music] [Applause] [Music] you