Friday, May 29, 2009

Eating The Sun


Here's what happened today. What really happened...


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Dawn broke first over the Pacific. Because the international dateline bisects the largest ocean that's where the dawn always breaks first - planting its first kiss over the Pacific and perhaps on the prows of a few container ships. Then the dawn made landfall in the north a few hours later, sweeping a fiery multi-hued arc over the icy tundra, and at the end of the world to the south, it broke like a wave crashing against the mountains of New Zealand. Soon, effortlessly, it glided westwards; filling the rice paddies of the Philippines and the depths of the South China Sea. It touched-down in Thailand on the faces of the drivers sleeping in their tuk tuks. And everytime the sunlight hit something green - something truly green, not something painted green or dyed green: something with greenness that grew - the most amazing miracle on the planet began - anew

When the light of dawn shone on the greenness, the greenness smiled and welcomed it, and comprehended it, and put it to use. The greenness thrived and drank, nay gobbled up the dawn. The greenness was chlorophyll, a pigment. It was arranged such that the sunlight's energy bounced from one chlorophyll to the next like a frog across lily pads before reaching the subtle trap at the centre, the three billion year old trap where the light of the sun becomes the stuff of the earth. The stuff of life, the stuff of frogs, the stuff of you and me - even the stuff of love (if you want to stretch the metaphor to breaking point). As the trap's jaws snapped shut on the sunlight, the spring that powered those jaws pulled electrons from a nearby water molecule, breaking it up into hydrogen and oxygen. The hydrogen was used along with the stream of electrons to turn carbon dioxide into organic matter. The oxygen was discarded as waste into the air to be breathed in by us. In every plant reached by the dawn this extraordinary three billion year old mechanism came into life millions of times over. The carbon dioxide to which these electrons were channelled was turned first into sugar and then all sorts of other molecules. Some of these were used to thicken the plant stems, others to lengthen the leaves, to enrich the soil and to colour the flowers still held tight in their buds. Light made life: that is what photosynthesis means.

If the light was to stop, on this day or any other, so would everything you care about. It has happened before. The dawn stopped in the time of the dinosaurs ending their reign. It can happen again. The manufacture of life from light is not the only thing going on as our dawn sweeps over Asia. For every leaf that greets the dawn there's an ant that eyes the leaf; for the growing grass there are hungry calves, and for the fattening calves there are hungry men; for the sugar-swollen root there's a sugar-sucking fungus. For growth there's decay. For life, there is death. By the time the dawn has reached America, most of the people on the earth have woken and gone to work; some in the far east have retired for the night. During their working day, almost all of those who can see will have seen something green. In built up London (My World) I can count well over five hundred trees from my trip to Canary Wharf. We might not give a conscious thought to the omnipresent green, but at some level we will enjoy it. We will flock to it in parks on summer days and relax under its cool sun-dappled shade. The greenness of life is so important to us that our eyes are tuned to discriminate among its various hues more precisely than the shades of any other colour. The green, we know without thinking, is good.

But we don't just enjoy seeing the green. It shapes the possibilities of our lives. More than two billion of us will have tended to the eaters of the sun in some way today. We will have hoed the soil for them, fed the sun eaters fertilizer, cared for them, kept em warm, kept them watered. We will have picked their fruits, dug up their roots, fed them to our livestock and ourselves. We will have made their carcasses into fabrics and furniture and firewood. We will have tended to some of them for their beauty and for their smell. It is not We who rule the world. They do: the sun eaters are our true masters. How little we know it.

And even if we ignore these plants, these eaters of the sun completely, by locking ourselves away in concrete-steel jungles, we will still rely on yesterday's sun eaters. Everyday we burn thirty million tonnes of fossil fuel to generate our electricity and drive our cars and warm our homes. And all that power and warmth comes from sunlight eaten long ago - energy trapped in coal and oil. This planet is covered not in dust, or lava, or ice like the other lifeless planets in the solar system. It is covered in tiny photosynthetic machines, vibrant whirring electron transport chains embedded in membranes, that trap the sun and eat it. This is the most wonderful trick ever invented. And it was invented soon after life first emerged on earth. These machines are more numerous than the sands of the sea or the stars of the sky. But they are also short lived. The hard work of taking light and funnelling it into chemical reactions takes its toll on their bodies and mechanisms. Plants spend a significant amount of energy keeping their photosynthetic machinery in good repair, and in winter, when light levels drop, the factories in which photosynthesis takes place (the leaves) are no longer worth the repair bill and so are shed in their trillions. Cost cutting. You trample over these dead crispy factories in autumn. But the idea behind the machines, the idea written down in their DNA and broken out fresh each spring, is not so fragile. It is always there, the idea lives on. Bodies perish, but the idea and the design live forever.

Who would have thought this universe would give birth to creatures green and seemingly simple. Who would have thought life could be so creative. Who would have thought the nuclear-powered sun could be harnessed and subdued. Look! they are all around you. Do you not see? Pay a little more attention to these greens. Our bodies may be made of stardust but our lives are powered by starlight eaten by the sun eaters.

_____


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Friday, May 15, 2009

The Origin of Life (part III)



If there can be said to exist a single formula; like the age-old secret of alchemists, a formula that makes all of life possible, then it is the following:

C02 + H2O  ---------  C6H12O6 + O2

Carbon dioxide + Water -------- Glucose (organic molecule) + Oxygen

It doesn’t look like much does it? It's rather unimpressive isn't it? How can such a simple formula hold the key to life? But it does! It makes you feel like a god just knowing it. A god surveying creation before him (or her). But enough of the purple prose. Time for some real science. But before we begin: A plea. I implore you to be patient. The science that follows will be tricky. I have tried my best to strip away any superfluousness, any excess fat, to simplify, to distill, so that what remains is the essence. But to truly understand will require a wee effort on your part. But the rewards; if I may be so bold to say, will be worth it. At the end of it all, if I can make you feel like a genius, if I can make you feel like a crazy lord of time surveying his dominion, than I will have succeeded. Let there be light!

We've already discussed that plants carry out the above reaction by harnessing solar energy during photosynthesis. We mentioned that photosynthesis is a hugely complex process involving numerous enzymes, proteins, electron carriers and an intricate membrane network. To reiterate: the first life on earth could not possibly have photosynthesised. Photosynthesis evolved much later. So, the question remains: How did the first life combine hydrogen with carbon dioxide to build the organic molecules necessary for it to exist?

I hinted that the ocean floor holds the key. Deep down below the surface; projecting from the sea bed like chimneys are hot water vents. These are like fissures or pimples on the earth’s skin where newly exposed rock, from deep within the bowels of the earth, reacts with sea water. It must be understood that water doesn’t just mix and percolate with the rock; it chemically reacts with it. The amount of water bound chemically to the rock in this way is astonishing. It is believed that it is equivalent to the entire volume of water in the oceans. As the sea floor expands from the movements of plate tectonics; these rocks which contain bound water, are ultimately plunged beneath a colliding plate. In what is known in geological parlance as a subduction zone.


Eventually, on the other side of the conveyor belt that powers the movement of the continents these rocks reach the surface of the sea bed. This is where the vents come in. The sea water that was once bound with the rocks is released again through the vents; but not as water (H2O) but as bubbling hydrogen gas.

At the turn of the millennium, scientists aboard the submersible Atlantis stumbled across just one of these vent systems spewing forth hydrogen gas. This vent system was nicknamed the 'lost city' and it had delicate finger like projections made of carbonate that reached up into the inky blackness. These projections gave the lost city a Gothic church look.


The projecting fingers themselves are porous, containing a maze of microscopic compartments like a bee hive. The compartments are 1/12mm in diameter (the same size as an average cell) and are teeming with life. The compartments are the home to colonies of industrious bacteria. The bacteria themselves provide the food source for other larger organisms that thrive in the vents. They are the 'producers' in this underwater food chain but the the key thing is that the entire ecosystem is supported by the reaction of hydrogen gas (H2) with carbon dioxide (CO2). Whereas on the surface this reaction has an initial energy requiring step in which hydrogen first has to be torn from water, but here, the reaction requires no such initial stage. Raw hydrogen bubbling from the ground as a gas is a rare gift on our planet, and life is normally obliged to seek out occult supplies, bound in tight molecular grip to other atoms, as in water or hydrogen sulphide. The reaction occurs painfully slowly, but from the view of thermodynamics it is a free lunch. In fact is is better then a free lunch. You see, not only does the reaction of hydrogen and carbon dioxide occur spontaneously but it also releases energy as a result - energy that can be used to power other reactions. It's like walking into a restaurant, having a meal, and then being paid for it! - the ultimate free lunch. It takes such a free lunch to get life going on a planet. These vents fit the bill as a hatchery for life on earth. They generate organic molecules. They have porous compartments, which can concentrate any organic molecules formed, making the assembly of polymers (long chained molecules) like RNA (Ribonucleic acid - simpler cousin of the more famous Deoxyribonucleic acid DNA). The vents are long lived; the lost city itself has been venting for at least 40,000 years. The walls of the vents contain iron-sulphur minerals which can act as catalysts to speed up and promote the reactions further.

But I hear the whispers of naysayers. I know what you're thinking: such vents are all very well, but how did life progress from such natural reactors to the complex, marvelous tapestry of invention and ingenuity that we see around us? The answer, of course, is unknown but there are clues within all of us. A clue to the past. Yes, within each of us is a 'smoking gun', an ancient remnant of the origin of life itself. All life on earth without exception has within it a set of deeply conserved biochemical reactions, like a living fossil, but not a fossil of bones, nay a fossil of biochemistry. The same reactions that occured at the dawn of life, also occur in the underwater vents and also occur inside your body! Amazing huh? From Bacteria to Penguin. From woolly Mammoth to Chimpanzee we all contain a clue to our primordial past. Don't believe me? I'll show you. We now turn to these for the next step in our wonderful story.

All life on earth shares certain qualities. All living things are composed of cells (with the exception of viruses). All cells in all living things on earth have genes made of DNA; all DNA codes for proteins by means of a universal genetic code. All living things also share the same energy currency, known as ATP. This chemical is like a £10 note, used to 'pay' for all kinds of work that needs to be done to keep life alive. We can infer that all living things inherited these qualities from the first remote common ancestor. All life today also shares a common core of biochemical reactions, at the heart of which is a little cycle of reactions that is the bane of many a biochemistry student: the Krebs cycle! The Krebs cycle occupies hallowed ground in biochemistry - but for me it was something to be rote learned for exams and then quietly forgotten. Yet, within this ancient and dusty cycle of reactions lies the answer to the meaning of life - or, if not that, then at least how it got started!



(The Krebs Cycle - a pain in the ass for all biochemistry students)

I don’t expect you to understand the details. The main things to take are:

  • The main purpose of the Krebs cycle is respiration i.e. to generate energy
  • At the top you can see a chemical called Pyruvate which is shunted into our cycle
  • ATP (the cellular currency of energy) is generated as the wheel turns. The ATP is then used to power life.
  • Carbon dioxide and water are produced as waste products of this cycle.

What has any of this got to do with anything you're wondering? Let me explain. At the top of the cycle is a chemical called Pyruvate. Where does Pyruvate come from?



Don't worry about the details (!). All you need to do is look at the top left and read out the name of the first chemical you see...exactly, glucose. And the last chemical at the bottom...pyruvate.

So glucose is absorbed into the body and is converted into Pyruvate via the above series of reactions. Pyruvate in turn is shunted into the Krebs cycle thereby generating energy and releasing carbon dioxide and water as waste products. This is your basic respiration you learnt at school. But wait a minute! Isn’t this the opposite of the reaction we want? Aren’t we trying to combine carbon dioxide (CO2) and water (H20) to make glucose? Aren't these cycle of reactions breaking down glucose to generate C02 and H20. Yes, true but if you look at the cycle again you'll see double arrows between the reactants. This means that the Krebs cycle is reversible. It can run backwards.

Here is a simple version of the cycle to explain my point:




Glucose enters at the top to be broken down into water, carbon dioxide and ATP. If we run it in reverse we can combine water and carbon dioxide, and with the input of some energy, make glucose!

And he said: 'Let there be life, and life sprawled forth from the vents'

Normally the Krebs cycle is used in respiration to break down glucose. But it can also run in reverse to make glucose and other organic molecules. The reversal of this cycle is common in primitive bacteria - especially those found living in hydrothermal vents. It is clearly a primitive way of converting carbon dioxide and water into the building blocks of life. The other amazing thing about the cycle is that it can spin of its own accord. It is thermodynamically stable. In other words it was not invented by living things, it is chemistry that already existed before life emerged. Life simply took the naturally occurring reactions occurring in the ocean vents and made them its own. When life emerged it 'conducted' a score that already existed! Once the Krebs cycle got spinning, side reactions would have been inevitable, giving amino acids and proteins. How much of the core metabolism of life on earth arose spontaneously, and how much is a later product of genes and proteins is an interesting question and quite beyond the scope of this post. But I would hazard a guess that if you were to set up the Krebs cycle in a test tube, give it a spark of energy, and a wollop of inspiration, a whole bunch of proteins and nucleic acids would be synthesised spontaneously. It is a thermodynamic inevitability.

This paints an extraordinary portrait of the first life on earth - our first ancestor. She wasn't some free living, pulsating, moving, throbbing cell but a rocky labyrinth of mineral cells, lined with catalytic walls of iron, sulphur and nickel. The first life was a porous rock that generated complex molecules and energy right up to the formation of proteins and DNA itself. If this doesn’t shake you and evaporate the anaesthetic of familiarity that hovers above you in your daily life, then I don’t know what will. Do you feel like a genius now?

We now turn to DNA and cells. How did they arise from this queer and wonderful ancestor of ours. This rocky labyrinth of mineral cells...


Open your eyes (Snow patrol)

Saturday, May 09, 2009

The Origin of Life (part II)


What was it about the early earth that first breathed life into lifeless matter? Are we unique, exceedingly rare, or was our planet but one in a million hatcheries scattered across the universe? These are questions to ponder, simmer and sin over. These are questions to discuss with good friends over good wine over good tasty dead life-forms in a good restaurant. These are questions to which we, for the first time in our history, now have sensible answers to. No longer is it deemed necessary, or even respectable, to invoke fantastical gods, talismans, shamens, and fairy tales for answers. We have a wonderful tool at our disposal -  a tool the ancients lacked, a tool which today is taught in all good schools throughout the world. A tool called chemistry.



The Origin of Life, as we shall see is a chemical problem. True, classroom chemistry, as taught today by boring dusty old teachers in dilapidated damp-cold laboratories, can extinguish (like blowing out a candle) the curiosity of many a bright and promising student. Students are told to memorise staid formulas, molarities and learn the Periodic Table - by rote. Hardly, an exciting endeavour to entice the curious amongst us into a world of science. But there are a few dedicated souls amongst us who do devote their lives to science, who look beyond the formulas and staid equations. Who breathe new life into the equations. Don't worry, I won't be throwing equations at you, but I will expect you to understand and appreciate the one's I do fling in your general direction.

But first before we begin, a little warning. We can never know for sure how life really started on earth. Even if we succeed in producing bacteria that crawl out of a test tube from a swirling soup of chemicals, we will never know if that is how life actually started on our planet. All we can say is that such things are possible. The quest for the Origin of Life is not about answers to what happened at a particular moment in the year 3,851 million BC, but it is a quest for the general rules that must govern the emergence of any life, anywhere in the universe, and especially on our planet, the only example we know of where life exists. I believe the rules that apply to our planet also apply to life elsewhere - wherever it may be found in the universe. The story we’ll trace is almost certainly not correct in every detail, but it is broadly accurate, and as we’ll see, perhaps almost inevitable once certain conditions are met. It is a story of chemistry and the ancient past. It is a story of many teenage years spent in angst mulling over lifes mysteries. It is a story of Life, the Universe and Everything. It is also very exciting. I'm excited. So let's begin!

There is a fundamental rule that governs all life on earth. All living things need to generate energy in order to build bodies and survive. Without energy life reverts back to the state of lifeless inanimate matter from whence it came. Most creatures on earth are consumers and get their energy from other living things - by eating them. Every time you eat a chicken drumstick a la KFC style, you are absorbing the energy stored by the chicken in its flesh. Where did the chicken gets its energy from? From seeds. It spent hours and hours converting seeds into chicken flesh. A chicken is a fascinating device. Through its mouth enter the seeds, and down its oesophagus they go into its tummy. Eventually via a complex cogwheel  of reactions called 'respiration' these seeds are converted  into tasty yummy chicken flesh. The chicken converts the seeds into feathers too, and muscles, and guts, and feet, and a brain and nervous system (albeit a very small one). And the seeds? Where did they get their energy from? Or to pose the question in another way: where does the energy trapped inside all living things ultimately come from? Answer: the sun. It is the green plants and other so called 'producers' that harvest the energy in the sun to build organic carbon molecules with which to build bodies. The equation is that of photosynthesis:

6 CO2 + 6 H2gives C6H12O6+ 6 O2

carbon dioxide + water ------ (energy from the sun absorbed by leaves) = glucose + oxygen

Let's stop and think what is happening here. Plants are effectively stripping away the hydrogen atoms in water, and then recombining them with the carbon and oxygen atoms in carbon dioxide to build glucose. From glucose they then make bodies and power their myriad functions (this is a little simplistic but it is essentially what is happening). The energy to power the combination of hydrogen with carbon dioxide comes from sunlight. The sunlight is trapped by the leaves by the green pigment chlorophyll.

The first life on earth had to be a producer. It couldn't have been a consumer; i.e. it couldn't have fed on other life, because there was no other life to feed on. At first the only producers that scientists knew of were green plants and photosynthetic bacteria. But this painted a paradox. You see the problem is that photosynthesis is a wonderful process. In fact it is too wonderful! And it is wonderful precisely because it is very efficient and very complicated (as any 1st year biochemistry student will attest to) - and therein lies the problem. It requires organelles (tiny spherical green bodies) inside cells called chloroplasts with an origami network of twisted internal membranes. It is inside chloroplasts that the reactions of photosynthesis take place and it is is an extremely complex biochemical process. It involves a chain of protein molecules embedded in the membranes. It involves a vast array of protein catalysts called enzymes to help and control these reactions. It requires a green pigment called chlorophyll to trap the light, and it requires molecules to shuttle electrons along the complexes at break neck speed. In short photosynthesis as we know it is far far too complicated to have arisen in the first life. It is way too complicated. See image below:



(Phosynthesis is far too complicated to have arisen in the first life forms)

The first life that arose, therefore had to be, by definition, very simple. It would have had to generate energy from a very simple process not involving enzymes and proteins and membranes. In short it couldn't have photosynthesised. So how did it generate it's energy? And more importantly: what did it look like? The answer as you'll see is a strange and wonderful one. In fact, the first life probably did not look like life as we understand it. It looked almost alien. To find it we must travel deep down into the ocean depths...far down, on the sea bed where strange things lurk...

It was in the early 1970s when the first pieces of the jigsaw puzzle were found. We've been putting them together ever since. The first clues to an answer to the origin of life came in the early 1970s, when rising plumes of hot water were noticed along the Galapagos Rift, not far from the Galapagos Islands. Little happened for a few years and then in 1977 a submarine descended to the rift seeking the source of the hot plume of water. What it found were hydrothermal vents; huge 80 metre tall chimneys at the bottom of the ocean venting black smoke and hot water into the cold salty sea water. What surprised everyone even more was the existence of giant tube worms, some of them eight feet long, mixed with clams and mussels, all living off the heat and minerals from the deep dark undersea vents many miles below the waters surface. The sheer abundance of life down below was astonishing; a veritable cornucopia of life approaching the exuberance of rainforest's and coral reefs; and all powered by the energy from the exhalations of underwater vents rather then sunlight. You see sunlight cannot penetrate these murky depths. These vents soon acquired the name ‘black smokers’ and since then over 200 ‘fields’ of black smokers; tottering as high as skyscrapers, have been found over the earths ridges, in the Atlantic, Pacific and Indian Oceans. But this is not smoke as we know it. The black stuff consists of broiling metal sulphides, hydrogen gas, ammonia, all seeping up from within the earth’s magma, reaching temperatures of 400 degrees centigrade in the crushing pressures of the ocean. The chimneys themselves are composed of sulphurous minerals, like iron pyrites, which settle out from the black smoke and amass as thick deposits over wide areas.


('black smokers' - deep sea hydrothermal vents - did life begin here?)

This bizarre and alien world seems like a vision of Hell itself and comes replete with hell fire, brimstone and the foul reek of hydrogen sulphide gas. And what lives in these conditions? Life. Large 8 foot worms with no mouths and no anuses, and eyeless shrimps swarming in countless multitudes on the ledges and cliffs below the smoking chimneys. Life
doesn’t just scrimp by and earn a living here; it positively thrives in these infernal conditions. It needs the hydrogen gas, hydrogen sulphide, and ammonia to survive! On the surface of our planet this stuff would be poisonous. But not here. How can life survive down here? What is going on?

The answer as we’ll see will tell us something about the Origins of Life itself.

Friday, May 01, 2009

The Origin of Life (part I)

Well actually I lied! Life didn't start with a tree...trees come much much later in our story. But before we begin our odyssey I have something to tell you. A little secret. I feel a little embarrassed telling you this. But the devil take it! You see, the reason I studied Biochemistry at university was because I wanted to discover...nothing other than...the origin of life! I know, I know, how childish! Unfortunately somewhere amidst the boring lectures on the Krebs cycle, glycolysis and gene transcription the question got lost and I became embroiled in the serious business of passing exams. It is sad how academic study, instead of becoming an exciting quest for new knowledge; an adventure into the unknown, can turn into a wearisome struggle to pass exams. But I am back with a vengeance! Oh yes! After a break of almost ten years. The good thing is that ten years is a long time in science. Entire world views can crumble and brand spanking new shiny edifices rise up in their place. The scientific landscape I see before me today is different to the one that existed when I was an undergraduate. Things have moved on - and in science that is always good.

Before we begin our journey to the Origin of Life we must first understand what it is we are trying to find the origin of. Or, put more bluntly: What exactly is life? Is it something that moves? something that grows? that eats? that reproduces? that breathes? that shits? Trees don't move yet they are living. Viruses don't breathe and they too are living. Flowers don't shit and they are definitely living. Is there a definition of life that encompasses all? Yes there is:

Life is something that can maintain a state of order via the expenditure of energy.

We are blobs of order in a chaotic universe. What is the difference between a bird and a mountain? (apart from the obvious). A bird is vastly vastly more complex than a mountain. It has intricate parts that work together to make it do 'birdy' things like fly, bob its head, eat, and make copies of itself in the form of baby birds. It looks as if it was designed. Nobody looks at a lump of rock and says: 'Hey, look at that! It must have been designed by someone' - but the same can't be said for birds, worms, insects and humans. Look at the different parts of a human - the muscles, the guts, the bones, the nervous system. Surely a human being couldn't have come about just like that? A human being has purpose written all over it. There is the famous story by William Paley about stumbling upon a watch in the heath. If you spotted a watch upon the heath it would be obvious it was designed by someone for a purpose - wouldn't it?

The complexity of the living world is crying out for an explanation. From bats to penguins - from flowers to bees - from spider webs to birds nests. Where did this complexity come from? Surely it was designed? By someone? For a purpose? Just like a car, a laptop, a TV. But living things are vastly more complex than any man made object. If you think that this bewildering complexity does not deserve an explanation than you've got issues. If you've never marvelled at the natural world and thought: 'Hey, wait a minute! Where did it come from?' - if you've never done that than you need to sort out your priorities and start getting down to some serious thinking. In short: you need to get a life!

But enough philistine bashing for now. I'll get plenty of chances to bash you later. There is another point I want to make: it is important to note beforehand, lest I furnish you with unrealistic notions, that we can never really know with certainty how life began. It was an event that occurred such a long time ago. 3.85 billion years is an unfathomably long time. Imagine the age of the earth can be represented on a 24 hour clock. The earth was formed 4.5 billion years ago at 12 midnight. Life emerged at 4am in the morning and remained single-cell bacteria like until 8pm the following evening. After 8pm in our 24 hour clock it became multi-celluler and grew bodies arms, legs, guts and heads. And humans? Humans appeared in the last second at 11:59 (59secs) (!). The fact that we can say anything about an event that occurred so long ago is astonishing in the least. But we can do more than that. We can make educated inferences, based on what we know about life today and in the past, about the kind of process that the origin of life was and had to be. We know it had to be a chemical process; because there was no biology at the time. Thanks to recent advances in gene technology, thermodynamics and the discovery of hitherto unknown branches of life - we can now say, with a high degree of confidence, how life is likely to have begun.

It's been a long time coming. Man has lived in a state of 'duh-duh I dunno' for far too long. It is about time the veil of ignorance was lifted and our minds opened to the weird and wonderful. So lets venture into the well of the long deep past. It is the year 3.85 billion BC. It has been 700 million years since the earth was formed out of a red hot ball of interstellar material. The oceans have cooled and land risen. The atmosphere is noxious with methane, ammonia and carbon dioxide. Something momentous is about to happen...the story begins deep in the chasms of the earths oceans, in the mid-ocean ridges, many miles down, where thanks to the forces of volcanism and plate tectonics, continents collide and slide beneath one another, creating earthquakes and raising mountains... weird and wonderful and wholly extraordinary conditions are being created. It is safe to say that life probably began on earth in an alien environment...