Welcome to The Nature of Things, I'm David Suzuki. Out of the Big Bang, matter was created. Stars and galaxes were formed. So was our planet. Out of the prebiolic soup,the molecules of life bulit simple,then more compex creatuers. Tonight, Natural Connections are new perspective on revolution.
Science is a way of learning how nature works. But science has grown so explosively that the individual scientist has to specialize more and more. This means that scientific knowledge has become highly fragmented.
But there is another approach,one that searches for unity within the vast diversity of nature,one that seeks to define our place in the overall scheme of things,that looks beyond the triumphs of techmology which seems so often to cut us off from our natural surroundings.
We enclose ourselves in cities,and see no further than our own reflections. Our traffic in the worlds resources,often in places far removed from where we live,is distorting environmental balances on a global scale. It is becoming more and more important to look beyond the many isolated fragments of our technological world to try to see nature as a single integrated whole.
The return of spring-birds,insects,plants,mammals-each intent on the perpetuation of its kind. Darwin saw these rituals of procreation as a process of evolution-all life descending from previous life. No species,not even our own,can be separated from its past. Since Darwin's time science has probed deeper into the ties that bind us to the past-exploring the very origins of life itself,making connections between living and non-living nature.
Microbes and people alike are made of atoms that originated in the stars. By analyzing light from the glowing nebulae,astronomers can identify the atoms adrift in space. These atoms are the ashes of burnt out stars,accumulated during the fifteen billion years since the universe began.
Five billion years ago a new star called "the sun" was born-on the surface of its planet earch atoms from space have become these living rituals of spring. But the story goes back even further. Physicists at the Fermi Lab pariticle accelerator,near Chicago,are retracing the whole incredible journey back to a time before the stars began to shine-back to the very moment of creation.
In the four mile circle of the accelerator ring particle collisions break open one of the oldest objects in nature-the proton,the nucleus of the hydrogen atom-scatterin a shower of sub-nuclear particles. These existed as separate particles only at the unimaginable temperature of the big bang-that flash of cosmic energy that marked the beginnings of the universe.
In some sense you can look at our machinery here as a kind of a time machine-it allows us to travel backwards in time to the very beginning. If you want to look at it this way the particle accelerators we have at Fermi Lab create temperatures,high temperatures during particle collisions.
And those temperatures just don't exist anywhere in the universe at present time,not in the sun,not in the supernova. The only times in the history of the universe that these temperatures existed is in the first minutest fractions of a second after creation,after the big bang.
What we have here at Fermi Lab is the biggest microscope in the world and what you see behind me is the eye that looks into that microscope. The microscope in our case is a large proton accelerator,about four miles in circumference,inside which proton and anti-proton bunches make head-on collisions almost at the speed of light.
Under the accelerator ring a tunnel houses a liquid helium cooled popeline around which pulsing magnetic fields prople protons and anti-protons in opposite directions.
The proton bunch in other words is coming from this direction moving very rapidly,almost at the speed of light,that way. The anti-protons meanwhile are coming in the opposite direction and the two bunches come together to make their collisions right at the center of the detector.
Disintegrating fragments leave ionization trails,much like a jet airplane's condensation trails. From these fleeting traces scientists can recreate a time of primal energy when the universe was first coming into being.
The detector is a massive technological achievement,its four thousand five hundred tons are packed with sophisticated elecrtonic sensors. When assembled it lies behind the yellow safety door in precise alignment with the proton anti-proton beams.
Why are we so interested in these particles that are not really very important in everyday life? I think the answer is that we're not terribly interested in the particles themselves;particles are not like people,people are interesting in themselves. The individuals that we meet,every individual is an interesting person.
The particles are not interesting,what's interesting is the underlying laws. Although these particles are not present in the universe today,they were abundant in the very,very early universe.
And so we are not only getting at that the underlying laws of nature,which in a logical sense determine why everything is the way it is,were also getting at the phenomenon which occured at the very beginning of the universe which in a historical sense have determined why everything thats followed has become the way it has become.
From the first moment of creation,to the lighting of the stars to the forming of planet earth step by step-to the emergence of life-science confirms what ancient philosophers knew by intuition,that these is a seamless web uniting biological and cosmic evolution. Look at the universe today,we see relics of an earlier period in the history of the universe,when the universe was much hotter and denser than it is now.
The very chemical abundances with which the stars started their life,the basic recipe for making stars that we see throughout the universe:seventy-five percent hydrogen,twenty-five percent helium,seems to be just what would be produced in a very hot early universe when the temperature was something like a billion degrees when the universe was about three minutes old.
As it expanded this intensely hot incadescent universe of hydrogen and helium began to cool and grow dark and so it could have continued to a frozen lifeless infinity. But in the turbulence of the expansion local volumes increased in density and began to exert a gravitational attraction on surrounding matter.
Wherever this attraction began,in the dark clouds of gas,it became irreversible-the denser core pulling in more and more hydrogen and helium. As this concentration increased in mass,so did the pull of gravity,a cumulative process,feeding on itself.
A star begins to shine when pressures and temperatures at the core become so high that atomic fusion reactions turn hydrogen into helium. In the intense heat of the core billions of hydrogen nuclei,or protons,and free electrons continually collide. Some are converted into neutrons. Finally pairs of neutrons and protons fuse into helium nuclei with a tremendous release of energy.
Balancing with outward explosive force the crushing weight of gravity. But when the supply of hydrogen is exhausted,gravity continues to exert pressure,fusing three helium nuclei into a nucleus of carbon-again,with a release of explosive energy.
But here,in a star of average size,the process ends. The weight of gravity is not strong enough to force the fusion of heavier nuclei,and so the star cools to a compact cinder of carbon-seeding the universe with one of the main elements necessary for life.
Heavier elements,such as iron,are built up in more massive stars. But even the most crushing weight of gravity cannot fuse protons into a nucleus bigger than iron.
Without fusion reactions to hold up the weight of the star,gravity forces protons,neutrons and electrons into a single dense neutron ball. And the star continues to collapse on itself until finally it explodes with a brightness more intense than its whole parent galaxy-a supernova. Spreading its incandescent debris through interstellar space.
The Crab Nebula is the remnant of a supernova that exploded nine hundred years ago-the glowing atoms betray their presence by the colours they emit when seen through a prism. At the Dunlap observatory,near Toronto,a sophisticated light splitting apparatus is an integral part of the telescope.
Each atom emits light at specific wave lengths-a thumb print of spectral lines that can be used to identify the chemical elements in space.
We've just taken a spectrum of one particular piece,a filament of the Crab Nebula. This narrow band of light here is due to hydrogen,and these whopping strong emissions here,due to oxygen. And over here we see some helium-and here,some evidence for nitrogen. These lines here,there's a pair of lines here due to sulphur.
By making studies such as this,we can learn about the way in which supernovae contribute to the chemical evolution of galaxies. Because we believe that supernovae are the primary sources of everything which we know is fundamental to life.
Some of the atoms drifting in space coalesce around particles of dust,to form simple molecules-This is a computer model of oxygen with two hydrogens-a molecule of water. And this is carbon with four hydrogens attached-or methane-a gas that was part of the atmosphere of the earth when it first began to form.
This dust of atoms and molecules adrift in space was the raw material from which the earth was made-pulled together by the sun's gravity some five billion years ago. On the planet's cooling surface a creature has appeared,able to look back through evolutionary time and imagine how the simple chemical elements from space first joined together and began to stir with life.
In the deep winter round Fermi Lab,life is dormant,waiting for the warmth of the sun to bring forth all its teeming diversity. Scientists are beginning to piece together the steps by which the random elements of the early earth first organized themselves to become,in time,this multitude of living things.
Maybe it's a big shocker-biochemistry and molecular biology-certainly of this current century,is that commonalty of the chemistry,the chemical basis of all life,whether we're discussing a bacterium or an elephant,a hippopotamus,or a oak tree-the same elements are there:carbon,hydrogen,oxygen,phosphorus,and sulphur.
And not only are the ellements there but they are arranged is just the same in all life. That's what tells us that Darwin is fundamentally right in one of his major contentions-and that is that all life came from pre-existing life,came from pre-existing life,came from common ancestry.
It's an ancestry that goes back at least three and a half billion years. The traces of life's first chemistry lie fossilized in rock,preserved from a time when the earth was still young. Minute shadows from which all life descends.
Four billion years ago,before life appeared,the atoms and molecules from space made up the earth's molten core,provided its atmosphere and were dissolved in its oceans.
To retrace how life might have emerged,two chemists,Urey and Miller,recreated the likely mix of chemicals dissolved in the primitive ocean and subjected it to electrical discharges to simulate lightning. Their hope was that the more complex molecules from which living organisms are made might form spontaneously by the joining together of the small molecules in this prebiotic soup.
I think it's true to say it came as a great surprise to chemists at the time,that they found what they were looking for. Instead of getting a completely random mixture of thousands and thousands of different organic compounds,they found a relatively small number of molecules. Now their most spectacular finding was the finding of amino acids.
These are computer models of typical amino acids-green is carbon,red is oxygen and blue is nitrogen. It came as a revelation that these amino acids could have formed so readily in the prebiotic soup-amino acids are the building blocks of life-linking them together makes protein,and protein is the stuff that life is made of.
Proteins in all the main working molecules of modern living organisms,are made up by stringing amino acids together,and there are just twenty different amino acids that get strung together in different orders to make all the different proteins and all organisms in the world.
On planet earth the random elements from the stars seemed to be organizing themselves spontaneously towards life. Meanwhile biochemist Sidney Fox was contemplating a further experimental step.
Chemically everything is very much alike. It might be a pineapple it might be an elephant,it might be a snake-but chemically they're very similar-similar and what we were looking at was a similarity of amino acid composition.
It occurred to Sidney Fox that the amino acids themselves might group together in interesting combinations under the volcanic conditions of the early earth. With this in mind he set up an experiment to heat,on a block of lava,a mixture of amino acids known to be in modern living organisms,and to wash off the molten liquid,as a rainstorm or the waves on the shores of a lake might have done billions of years ago.
Astonishingly it turned out that,under these simple conditions the amino acids formed small cell like structures made of protein. Thess cells or microspheres were enclosed by a double layered membrane-much like a living cell.
And furthermore,these microspheres would reproduce-a small bud forming on the surface would grow,by simple chemical addition,to the size of the parent and split off. Some would divide in the middle,like a modern cell. But the most dramatic results came from testing for electrical activity within the cell.
If you put a microelectrode into this like you do into a never cell or any other excitable cell-and if you shine light on that-or if there's light present,it's very hard to get away from a little bit of light. Then there are patterns of spikes-action potentials.
These are much like the action potentials in a nerve cell. In this experiment,the bottom trace is from an electrode inserted into a microshpere. Compared to a control,it shows electrical activity the instant it is illuminated-suggesting some form of primitive metabolism,stimulated by light.
Perhaps these almost living organisms were governed by the diurnal rhythms of the earth,waking by day and sleeping by night,billions of years ago. But they were without one essential ingredient for the emergence of life itself. In life it is DNA that directs the grouping together of amino acids into all the diverse proteins that make up even the simplest living organism-and Sidney Fox's microsheres did not contain DNA.
The appearance of amino acids and microspheres from the prebiotic soup was astonishing enough,but later experiments produced,in addition,the four bases of DNA that make up the genetic code.
When one considers that there are thousand of compounds of this complexity,it really is aremarkable face-not a coincidence I believe,a remarkable face-that such a simple procedure priduces so many of the most important molecules needed to make a living organism.
Leslie Orgel's aim has been to recreate the spontaneous formation of the genetic apparatus of life. Each base is attached to a nucleotide:these have to link together,lining up the bases in spiral strands.
And for genetic replication,the bases have to form bridges to a companion spiral-each base locking only with its opposite number,like pieces in a jig saw puzzle. This primitive encoding and copying of genetic inforation took place in conditions that could have occured in the prebiotic soup.
In the simplist of living organisms,the strands of nucleotides are about three million long and the organism successfully makes copies of this in ta most twenty minutes. It takes us several days to make a copy of something only fifteen long,and what's more,we can't do for all sequences fifteen long,so we still have a great deal to learn about this process.
But it is enough to suggest a beginning. The great leap from the non-living to the living probably took place when the first simple genes became incorporated into a cell,and began to direct the stringing together of amino acids into new varieties of protein.
In time,nurtured within a cell,short strings of bases could have evolved to become the millions-long chains of DNA. Genetic instructions are coded by the order of the bases strung along the double helix of DNA. They're translated into life by these separat twisted spirals of nucleotides which bind to an amino acid at one end and read the genetic code at the other.
A gene,or a single chain of bases is copied from a length of DNA and sent to the cell factory. Here the little translator molecules read the three base sequences of the genetic code,bringing in,one by one,the corresponding amino acids. In this way amino acids are joined together in the gene,to build the complex proteins,hundreds of units long that are necessary for life.
In every living cell it is DNA that co-ordinates the interactions of thousands of proteins such as these. The genetic system,once developed,presented evolution with limitless opportunity for diversity. Simple changes,or mutations,in the genes meant new proteins-organized into a host of new possibile creatures.
It was Darwin who first saw that every successful design arose from a previous design. One form evolving into another. And it was Darwin also who saw that each form of life was part of a larger scheme-an ecosystem that included both competition and mutual dependence. Within this context DNA developed forms that exploited every opportunity for survival.
Ancient success stories persisted,and new ones arose-different ages living side by side. Whether large or small,the criterion for sucess was to survive and to produce offspring. And to garner a living from every possible habitat the earth provided.
But this explosion of diversity began only a mere five hundred million years ago-the culmination of three billion years of previous experiments in genetic engineering by minute single-celled microbes in the oceans of the primitive earth.
Evidence of life that is two billion years old lies in these rocks on the shores of Lake Superior. These were boulders that stood in the shallow waters of an ancient lake and became covered with layers of bacteria. A thin transparent section from this fossil deposit discloses life as it then was-already well over a billion years old it is still a microcosm-a world of microbes.
You're in a micro world,you're in a micro world in which predation-that is,the really vicious capture of one organism by another is going on-in which sex lives so bizarre you can't imagine.
Or where organisms are coming together passing all sorts of genes without fusing their bodies-or other organisms that are fusing their bodies back to front and all sorts of bizarre postures that tou can't imagine. It's all going on,it's all going on in drops of water that are within a few millimeters of the surface.
Loose strands of DNA lie in the center of these modern microbes known as cyano-bacteria-their direct ancestors,two billion years ago,by the swapping and rearranging of genes,came up with a complex molecule that would change the face of the planet.
It was chlorophyll-when exposed to light it instantly generates a flow of electrons-energy directly from the sun to power the chemistry of life. As a byproduct of this process of photosynthesis,oxygen,essential to modern life,was first released into the atmosphere. At the time it was a deadly toxin-a nearly catastrophic challenge to life.
The microbes,separately,had developed a number of survival skills. In more than a billion years of genetic experiments in these munute laboratories some organisms like the cyano-bacteria,could process sunlight-a few could tolerate oxygen-and one had developed a thin tube-like protein that enabled it to move.
These separate skills came together in one larger cell-the mobile microbe may have been eaten,but the tubular protein inside it remained undigested-Perhaps oxygen breathing microbes attacked the cell,but found instead a safe place for reproduction,and contributed oxygen tolerance to the host. And the chloroghyll containing cyano-bacteria contributed energy from the sun.
In this new composite cell the tightly packed nucleus of DNA is on the right. Inhabiting the same cell are the black sausage-like oxygen breathing mitochondria,once seoarate living microbes,and the larger shapes contain chloroghyll.
The dark areas to the left and right are threads of tubular protein,remnants of the invading mobile bacteris that now arrange and separate the chromosomes in cell division. These once competing microbes form the modern oxygen breathing cell;powered by sunlight. Evolution by co-operation.
So what was a dreadful aggression with time becomes an unholy alliance and with even more time becomes a confederation that works for all of the members,better together than when separate.
And I think that's the basic idea. It's not co-operation versus competition. It's not death versus life. It's the usual conciliation, reconciliation, struggle, aggressiveness conciliation that we're all very familiar with,that leads to an emergent entity with properties better and more adaptive than single units.
While the many independent microbed,like the cyano-bacteria of today,continued their separate existence in the oceans,the new composite cells conbined in a host of new and intricate designs. On the way to becoming plants they used the energy of the sun to build more and more complex structures.
Which are successful,the cyano-bacteria that are outside in nature,or the once that have been internalized and gotten into the large trees and the bushes,and so on,and you see that consortia pays off.
That in fact the once that get spread to the high alpine regions and to the tropical forests,are the cyano-bacteria that are trapped inside the leaves of the plants rather than the ones that have tried to make it on their own. The light processing microbes have become,in time,an integral part of these delicate platforms reaching to the sun;spreading out and greening the planet.
The animal cell unlike the plant cell does not contain chlorophyll,and can't precess sunlight,but in compersation it developed a separate skill. By making use of calcium extracted from the water it learned to build hard protective structures;a chemistry that would lead to the bony skeleton of animals. Electron micrographs show these intricate coats of armour once built by single celled organisms.
The modern animal skeleton is made by the same five hundred year old chemistry. Built around a jointed skeleton,animals are mobile and able to exploit the sun's energy stored in the plants.
What's so fascinating is that if you take a cell of a rhinoceros,or a fish,of a person,or a chicken,the cell componenents are so similar you could hand your friends electron micrographs from all those animals and not see any difference at all. In fact,you're looking at the way those cells are packaged that make the differences.
A common chemistry-a common history-means a deep and underlying unity in nature's diversity. Every stage of evolution exists within us and around us. A few cells in a single package. Single cells beginning to act in unison-in a mold called labyrinthula. Microbes digesting wood in the gut of a termite-each dependent on the other and ultimately on the trees reaching to the sun.
Whenever you have an ecosystem full of animals-deer,and a forest of trees,the microbes have not been replaced,they've just been augmented. The microbes are still there in the soil. They've on the surface of the trees. They're in the deer just as they're in our own bodies. And,so what you have to do is sort of close your eyes,and get rid of the large animal for a moment,and see this microbial shadow that makes an outline around him,inside him,and so on.
We think of ourselves as individuals,but in fact we are walking ecosystem. We are essentially walking microbial communities. Nature has made many uses of the little tubular protein that became part of our composite cells two billion years ago. It drives the sperm to its target in the womb. As cell whips,or cilia,it confers mobility on many small organisms.
The richest source of microtubules,it turns out,besides sperm tails and cilia,and cell whips in general,is the brain. Nervous tissue. When the never cells evolved,they evolved from a microtubule substructure that was already their in the microcosm.
Through the human brain-itself a product of evolution-we are able to look back to see the pathways by thich we have come;to imagine-and begin to piece together the stages in our cosmic journry.
Given the characters-the objects-and given an understanding of the structure of the forces-the rules by which you put these objects together-you can build-up the entire universe as we know it. First,the sub-nuclear particles,then the protons and neutrons,then the nuclei,then the atoms,the molecules,the genes,the people,and so on. All the way up-the galaxies and the stars.
The silent atoms from the immensity of space have come together to kindle the spark of life on planet earth. We come into the world carrying within us the history of the universe. Like all living things we're embraced by a nature that is whole and indivisible.