The solar system was born from a fraction of interstellar gas and dust after a large ancient star underwent a massive supernova explosion.

 
Like a tiny raindrop of water forming around a dust particle, the early solar system formed a round hot ball of red, steamy molten rock around a heavy and predominantly iron core through gravitational forces. The coming together of different metals and countless numbers of dust particles of the ancient interstellar cloud around a large solid iron core is how the Earth was formed.

Due to the long-lived radioactive elements still prevalent inside the iron core of the Earth, the rock below the Earth's crust remains molten and very hot. Evidence of this hot molten rock can be readily observed in lava flows coming out of volcanic eruptions around the planet and in other cracks in the Earth's crust.

 
The origin of the Moon is not quite as elegant and romantic as the Earth. Its existence probably came about from a more violent event.

After measuring the abundance of the isotope 182-tungsten in materials collected by Apollo astronauts in one of the solidified "magma" oceans on the Moon and checking to see whether there is a difference in its abundance compared to the Earth's own magma, scientists have discovered the Moon was created approximately 30 million years after the formation of the Earth even when taking into account errors in the measurement. Because the Moon does not have an iron core as the Earth does and yet both bodies have similar compositions, scientists are lending their scientific weight in support of the theory that the Moon was probably created when a Mars-sized body collided with the Earth at this time, shearing off a reasonable outer chunk of the Earth. Fortunately the speed of ejection of the material was not enough to escape Earth's gravity. As a result, the material quickly solidified and, together with various other much smaller collisions, eventually pushed it into a circular orbit around the Earth. Finally, the material's own gravity was sufficient to shape itself into a sphere but not enough to retain an atmosphere of its own. Since then, various meteorites would hit the Moon and mould its surface to create the patterns we see of this body today.(1)

Further interesting observations of the Moon could reveal yet another interesting story. Researchers from the University of California in Santa Cruz (UCSC) has revealed a new computer model suggesting the likelihood of another body roughly one third the size of the Moon may have circled the Earth in a stable orbit.

The latest story began when recent lunar probes exploring the far side of the Moon discovered something interesting. According to the observations, the topography on the far side of the Moon shows a thicker crust and an unusually elevated and highly mountainous terrain compared to the relatively low and flat lava plains of the Moon facing the Earth.

Why the difference? Or as the scientists put it, the asymmetrical nature of the Moon?

In order to find a reasonable explanation for this observation, a planetary scientist at UCSC named Erik Asphaug teamed up with a young talented UCSC postdoctoral researcher named Martin Jutzi where, during the course of their studies, discovered a new computer model that could explain the observations. According to the new theory, a second moon may have formed at the same time as the Moon we see today. The second moon managed to park itself in a stable position in the Moon's orbit known as the "Lagrangian" point. Mathematically there are two points, either 60 degrees in front or 60 degrees behind. The second moon stayed in one of these points. For roughly 80 million years, the two moons stayed in the same orbit as they moved around the Earth without influening each other until the gravitational interactions of the Earth caused the two moons to slowly drift farther away over a period of tens of millions of years. Eventually the Sun's gravitational tug contributed to the demise of the smaller moon when it managed to destabilise the smaller moon's position causing it to revolve around the Earth at a different speed within the same orbit. As Asphaung said:

'The Lagrange points become unstable and anything trapped there is adrift.' (Lovett, Richard. Early Earth may have had two moons: Nature. 3 August 2011.)

It was only a matter of time before the smaller moon would collide with the larger one. When it finally took place, the smaller moon crashed into its larger sibling in what the researchers claim was probably the slowest possible collision for two massive bodies of this kind, allowing the materials to be splattered and raised to form the mountainous regions on the far side of the Moon. As Asphaung said:

'This is the slowest possible collision the two massive bodies could have if they fell into each other's gravity.' (Than, Ker. Earth had two Moons, New Model Suggests: National Geographics. 3 August 2011.)

Despite the slow speed, there was enough energy to eject trillions of tons of lunar debris into space. For the next million years, Earth would be showered by some of this debris.

While the new theory looks convincing, it still does not explain the unusually high levels of aluminium found on the far side of the Moon. Until then, scientists can only speculate on what happened. For further details, check out the article from the Nature journal.

Looking closer to our planet, we can see how as the surface cooled to form the Earth's crust over the next 150 million years since the Earth had formed, gases trapped in the planet's interior and from considerable quantities of icy comets (2) crashing to the Earth were released and held gravitationally in place to conceive the Earth's atmosphere consisting mainly of nitrogen, methane, ammonia, hydrogen sulphide and hot water vapour.

The process of outgassing from Earth's interior has persisted to this day but in much lesser quantities, known as volcanism.

The great oceans of water would rapidly come from all this extensive outgassing and countless numbers of impacts from icy comets being turned into vapour by the molten rock. All that is required for this to happen is for the molten rock to cool down sufficiently to permit water vapour to turn into the liquid state.

 
Oldest known rocks on Earth had been found from Greenland. Now scientists believe the oldest rocks in the world are to be found in Western Australia.

The essential technique for dating rocks has been done by taking a sample of rock and measuring the proportion of radioactive rubidium-87/potassium-40 and non-radioactive strontium-87/argon-40 elements (ie. the final products in the long radioactive decay process), respectively.

 
When the surface cooled sufficiently to allow water to remain in the liquid state, all it took was for water vapour in the atmosphere to condense and fall as rain for at least 60,000 years to form the great oceans of the world.

As the rains poured from the heavens to create the biggest and permanent flood in Earth's history known as the oceans, the highly penetrating and disruptive ultraviolet rays from the early Sun and the great electrical storms in the early hazy atmosphere of Earth assisted in the dissemination of methane, ammonia and water into smaller and highly reactive molecular fragments called free radicals. As the energy briefly dissipated, these energised fragments would quickly reassemble near the surface of pools or inside tiny water droplets in the primitive atmosphere to form a variety of new, interesting and potentially more stable chemical molecules of increasing complexity.

On can imagine a similar event occurring not far from the hot hydrothermal vents peppering the floor of the great early oceans and the numerous shallow seas and lakes scattered generously throughout the ancient muddy, hot and humid desert-like continents of the world. Under these extreme conditions of hot and cool and dry and wet, high water temperatures would break molecules apart and the cooler waters and around protected regions near the surface of clays nearby would permit the energised fragments to reassemble into various kinds of molecules, some of which would be crucial to the development of life.

Then as the water in some pools began to evaporate between major rains, the concentration of these molecules would increase in a smaller volume of water, and so increasing the probability of new and more complex molecules being formed.

Add to this the fourth complicating factor of icy comets surviving the fall to Earth and releasing their frozen cargo and it is possible another means of transferring vital chemicals or possibly primitive "alien" life by way of bacteria to Earth could also have started the process of life on Earth. Scientists are not certain how much contribution this "extraterrestrial influence" could have. It assumes that extraterrestrial life exists in the universe, that life can survive the long journey to Earth, and that certain catastrophic events will cause some bacteria from other planets to be suddenly trapped in ice and shot into space until through incredible luck the comet manages to reach and survive the plunge to the surface of an Earth-like planet. NASA scientists are currently investigating this possibility by understanding how long bacteria can potentially survive in extreme conditions such as ice and radiation. So far the evidence suggests there is no limit to how long bacteria can remain in suspended animation inside icy. They could potentially remain this way for billions of years.

Could very primitive extraterrestrial life exist in a state of suspended animation inside icy comets? Whether or not this is true, one thing is certain. Bacteria can survive in ice for a very long time. As we will learn later, the biggest ice age to hit the Earth was definitely not enough to wipe out all life on Earth. If anything, it just slowed things down. The single-cell bacteria would remain in suspended animation for at least 25 million years before being revived. Just a quick sleep and a sudden wake up and life continued potentially unabated.

So how did life begin on Earth?

In an attempt to resolve this mystery once and for all, scientists at NASA are considering the possibility that alien bacteria could be found in some icy comets floating through space.

To find direct observational evidence to support this claim, NASA has sent a probe into space to collect some icy material from a comet. The analysis of the materials so far has not turned up the necessary evidence. Perhaps it takes a vast number of icy comets to find the one lonely alien bacteria lying dormant and frozen in the material? Or maybe the alien bacteria lies deeper inside the comet? So the next best thing is to check a place in the solar system where a vast liquid ocean of water may exist. One possibility is perhaps beneath one of the moons of Jupiter where an ocean of liquid water appears to exist beneath a solid icy surface. If so, NASA is excited by the prospects that it could find evidence of alien bacteria trying to survive in this vast ocean in another corner of our solar system.

While scientists search for evidence of frozen alien bacteria in space such as one of the moons of Jupiter, a NASA scientist has boldly suggested the likelihood that microbial life could be embedded in some extraterrestrial rocks rather than ice, albeit fossilized after discovering what looks like microscopic tubular structures reminiscent of earthworms here on Earth. Except the rock in which this structure was found had no opportunity to be contaminated by the Earth. The rock is known as a Carbonaceous Chondrite. A bit of a mouthful to pronounce, but these interesting meteorites contain about one percent by mass of organic matter that resembles the crude oil or tarry substances found on Earth. Although no extraterrestrial organism has been found trying to crawl out of these rocks, the total amount of organic matter in the interior of these rocks is too high to be considered entirely due to contamination with the Earth, and must show the ease by which molecules can form inside the protective confines of certain porous rocks in space. But does it mean we have found the first evidence of a fossilized extraterrestrial lifeform? Unless there are pockets of heated gases capable of pushing out the tarry material into tubular shapes before being fossilized, other scientists will need to study the evidence more carefully and determine whether it is possible for the same tubular structure to be replicated by natural means.(3)

As interesting as this may sound, the opposing argument is, of course, that life could have arisen here on Earth.

Among the important scientific work being conducted in support of this latter argument is one from Professor David Deamer of the University of California, Santa Cruz. He is currently working on the idea that bubbles (or vesicles as he calls them) could play a crucial role in the formation of the first single-celled organism on this planet. If he is right, bubbles could have formed regularly on the surface of certain types of clays containing the right metals to help attract a multitude of amino acids and help them form long chains of macromolecules called proteins. Because if enough of these proteins can be produced, the bubble could be reinforced by a protective protein-like membrane and so maintain the structure for a longer period of time. Then it is just a question of how long before the first DNA-like molecule is created to help replicate this first living single-celled organism. Already evidence has found that these clays can also create chains of nucleotides (the basis for building a DNA molecule).

For example, in 1977, while working at the National Aeronautics and Space Administration (NASA) Ames Research Center in California, USA, Dr James Lawless and a visiting scientist from Israel, Dr Nissim Levi, found evidence to support the 1947 claim made by British physicist Dr John Desmond Bernal (1901-1971) that ordinary clay can concentrate small chemical molecules in a hot "organic soup" and then act as a kind of prebiotic scaffolding for producing larger, more complex molecules at the very surface of the clay. Although most clays destroy a number of important amino acid structures, Lawless and Levi found that clays containing metals can attract certain amino acids and nucleotides without damage.

In particular, Lawless and Levi discovered two types of clays, one containing nickel and the other zinc, which not only attracts all the twenty amino acids found in living things on Earth and all the various nucleotides comprising DNA respectively, but which has been observed to form macromolecules of as many as eight amino acids and several chains of nucleotides. Longer, protein-like chains and DNA-like structures seem likely if given sufficient time for their synthesis.

Again, despite the fascinating in-roads made into this particular aspect of the origins of life on Earth, scientists still don't know exactly how long is required before the chains of nucleotides are long enough to store useful genetic information and, at the same time, be made to self-replicate in the right environment?

Or did life on Earth need a bit of a kickstart from a lonely little alien bacteria sitting inside an icy comet?

Never mind. Scientists must assume life was somehow created here on Earth and not in the confines of space (since scientists have not yet proven alien life exists). It is better to be conservative and assume life began on Earth. It would mean an unimaginable amount of time must have passed during which the process of dissemination and reassembling of molecules and the right surfaces, pressures and temperatures for making long chains of molecules continued unabated. Eventually, more and more complex molecules consisting mostly of fatty acids, sugars, tannins, amino acids and nucleic acid bases slowly accumulated near the surface of ancient clays existent beneath the hot springs (4).

Why was the water hot? The key to answering this question may lie not only in the Earth's hot magma heating up the water, but also in how asteroids achieve the same heating up effect. As some British scientists studying the Houghton crater on Devon Island, Canada, have found, there is evidence to suggest that asteroids crashing into the Earth can heat up the rocks, causing some rocks to vaporise while others develop tiny cracks as the rocks remain warm to hot for anywhere between 1,000 years and 1 million years. It is these cracks together with the heat of the rocks where some scientists believe life on Earth could have began.

As Dr Charles Cockell of the British Antarctic Survey in Cambridge said:

'What we've discovered is that rocks inside the crater are more heavily colonised by microbes than the rocks outside the crater. So what we have here is an example of how impact events can create a habitat for life and not merely act as agents of destruction.' (5)

The world's biggest hot tubs to make those Norwegians truly jealous were literally bubbling away in many parts of the world.

Then suddenly, without warning (perhaps with the assistance of hydrothermal vents and a variety of new and interesting catalysts in the clays and in the water to help speed up chemical reactions; or as suggested by some scientists life may have already been controversially produced somewhere in the universe and was somehow frozen inside a comet until it hit one of the Earth's early warm ponds to release the microscopic life just like a human embryo being fertilised by a sperm (6)), a massive macromolecule made of proteins and nucleic acids was brought to life which was able to make crude copies of itself from the rest of the molecules in the organic soup. This vitally-important self-replicating macromolecule is the ancestor of Deoxyribonucleic Acid (DNA).

 
From the great turmoil of the early Earth came the first single cell organisms. The organisms, looking like tiny, perhaps semi-opaque bubbles floating around in the warm waters, consisted of a spherical-shaped protein membrane to protect the DNA molecule as it went about its incessant and rather important activity of replicating itself and crudely 'learning' from its environment on a regular basis.

The oldest direct evidence of life on Earth were these simple single cell bacteria fossilized inside rocks from Western Australia. The discovery was announced in 1993 by J. William Schopf of the University of California at Los Angeles, USA. (7)

 
Some of the earliest known fossilised evidence of ancient life on Earth appeared as nothing more than tiny single-celled microbes living around hot, deep sea hydrothermal vents. Dating techniques used at the time suggested these microbes were around 3,200 million years old. However, the suggested age of the oldest life on Earth has only been recently outdone by Dr Martin D. Brasier of Oxford University and a team led by David Wacey of the University of Western Australia after making an important discovery. As revealed in the study published in the journal Nature Geoscience on 22 August 2011, Brasier's team located the oldest sedimentary rock formation on the planet in a remote part of western Australia called Strelley Pool. On closer inspection of this formation considered the oldest shoreline in the world, scientists observed extraordinarily well-preserved tiny fossils of tubular microfossils lying between the quartz sand grains. As Wacey and his team put it:

'We therefore identify them as microfossils of spheroidal and ellipsoidal cells and tubular sheaths demonstrating the organization of multiple cells.'

The age of these little critters has been dated to 3,400 million years old and with great accuracy. As Brasier said:

'We can be very sure about the age as the rocks were formed between two volcanic successions that narrow the possible age down to a few tens of millions of years. That's very accurate indeed when the rocks are 3.4 billion years old.'

Brasier painted a hellish picture of the early Earth at this time. He thinks that as the microbes began to carve out an existence the sky was constantly cloudy and grey and acted as an effective heat trap despite the Sun being slightly smaller and weaker at the time than it is today. The oceans were like a giant hot bath with temperatures hovering around 40 to 50 degrees celsius both day and night.

And the extremely low levels of oxygen in the air made it likely these microbes relied heavily on sulfur compounds for food as well as the water for a good drink. Indeed, the presence of pyrite crystals in the sandstone are thought to be a metabolic sulphur reducing by-product of the living cells. Hence it is likely the oldest living things on Earth were sulfur metabolising bacteria. As the team state:

'We interpret the pyrite crystals as the metabolic by-products of these cells, which would have employed sulphate-reduction and sulphur-disproportionation pathways.'

 
The first microscopic single-cell organisms multiplied rapidly. Eventually, a time came when the food supply consisting of the freely-available organic molecules (including sulfur compounds) in the pools dwindled and the need for a more dependable source of food became increasingly more important for these tiny organisms.

At first, perhaps being situated close to an ocean or large shallow inland sea, a number of these single cells found their way from the pools into larger and deeper waters. This may have helped the cells to find more food and a reliable source of water.

But after many more millions of years had passed, one of the single cells just happened to stumble across an important molecule called chlorophyll (8) which could trap the free and reliable energy from the sun and use it as a means of breaking down the highly abundant carbon dioxide in the Earth's atmosphere for food rather than depending entirely on basic chemical building blocks in the oceans. We call these chlorophyll-loving single-cell organisms the first plants to appear on Earth. The highly primitive plant life probably looked very much like blue-green algae which still exists today, but they were not blue-green algae at all. Rather, the first plant cells to appear on Earth were actually photosynthesizing bacteria (even more primitive than the algae we are familiar with today).

Scientists would call these primitive plant life by the more technical name cyano-bacteria.

When enough of these photosynthesizing bacteria filled the oceans of the world, another simple living cell evolved and, possibly after experiencing a moment of food shortage, discovered one day how it could consume or break-down this highly abundant 'plant-like' bacteria as a stable source of food, and so became the first animal to appear on Earth. An example of this is Protozoa, the oldest known animal fossil. Protozoa would swim or float around and consume smaller bacteria.

And why the need for the photosynthesizing and animal bacteria to "eat" carbon dioxide and other bacteria respectively? Because DNA needs the raw materials to rebuild itself as well as the cell structure for its survival. Also there is energy needed to achieve this aim, which means the energy has to be obtained or captured easily from some other source. Eating is about retaining a sense of balance in the internal physiology of the bacteria and their environment resulting in greater stability and a longer life as needed to feel "happy".

An example of a modern freshwater protozoa known as Stylonychia mytilus. Photograph by Hermilo Novelo. Image available from http://www.ucr.edu/pril/peten/images/el_eden/protozoa.jpg.

The concentration of carbon dioxide in Earth's atmosphere was at least 5 times higher than today with a density only about half that of present-day conditions.

 
Photosynthesising bacteria permeated every corner of the world where water was abundant.

This was an interesting time when many of the pools on land and some large shallow seas had turned a distinctly greenish colour (a striking contrast to the bluish oceans and possibly brown desert-like expanses of the great continents), showing the presence of countless millions of these ravenous photosynthesising bacteria.

The bacteria was also providing one other benefit for the single-celled animals emerging throughout the world. As a natural by-product of their photosynthesising work, the water was becoming oxygenated. In fact, so much oxygen was being produced by the bacteria that it slowly accumulated in the air, and so benefiting the development of more sophisticated animal life over the next 2,500 million years. Also the minerals and rocks of Earth containing iron, manganese, uranium and other elements progressively oxidized as levels of oxygen rose.

As these primitive photosynthesizing bacteria continued its ferocious appetite for carbon dioxide, the atmosphere of the Earth nearly 2,750 million years ago had increasingly fewer greenhouse gases by way of carbon dioxide molecules to effectively trap the heat from the sun. This meant that the Earth was getting cooler. But fortunately the orbit of Earth (in addition to the possibly high volcanic activity along regions where the thin, cool crust cracked) prevented the planet from heading towards an irreversible ice age during this epoch.

It is believed that clouds covering Earth finally broke-up sometime during the end of the epoch, and so benefiting the development of more sophisticated plant life the world has ever seen.

 
The Earth nearly 700 million years ago was warm and wet. An alien visitor looking intently at Earth at this time would notice through the break in the thick clouds a very large desert-like supercontinent lying north to south and across the equator as it drifted across the globe (assuming the planetary crust had tectonic plates). Nothing by way of a singular large plant or animal life could be observed. The only thing to suggest life might be appearing on this planet were the abundant photosynthesizing bacteria in the waters providing its greenish tinge.

As we know photosynthesizing bacteria are the equivalent to plants. What about animals? Where there any bacteria-sized animals floating in the water or attached to clay surfaces at this time? By animals, we mean creatures that would consume other bacteria, whether photosynthesizing or not. Well, it depends for what reason a bacteria would decide to become a proto-animal. Perhaps a deficiency in the amount of sunlight and carbon dioxide in the atmosphere would force some photosynthesising bacteria to become proto-animals. Is there evidence to support this? Given the size of these creatures, there is no direct evidence in the fossil record corresponding to this period. However, we do know today that some bacteria do consume other bacteria. It would seem natural to consider this possibility.

Another possibility is that a single-cell may not have stayed single for long. Perhaps in response to animal-like bacteria consuming other bacteria, it is likely a group of cells did come together to become the first multicellular life forms to exist on this planet. Again, it is not entirely clear whether any animals, single-celled or multicellular, had existed in the waters at this time. All that scientists know is that life wouldn't grow to a size visible to the naked eye.

There is a good reason why life remained microscopic in size. The smaller you are, the less energy you require. And energy requires oxygen to be used up. So any animal trying to grow to a larger size would require considerable amounts of oxygen to be extracted from the water. However, as scientists have determined at this time, oxygen levels in the water and those in the atmosphere remained inadequate to meet the extra energy demands of bigger organisms. As one wise person said, we all must learn to float first, then swim, followed by crawling, walking and eventually running in that specific order. And each action step in the mobility continuum would require an increasing amount of oxygen. We can therefore surmise that no animal would have dared got bigger while the oxygen levels in the water were low and in the atmosphere remained at around a measly 1 per cent.

As the photosynthesizing bacteria continued to have the upper hand so to speak with their veracious appetite for carbon dioxide, it was only a matter of time before the Earth began to cool down.

And eventually it did. In fact, the success of these little photosynthesizing bacterial critters, covering almost all parts of the world's shallow seas and on land as it feverishly consumed the carbon dioxide in the atmosphere, had probably caused the world's first and most massive glaciation ever seen in the history of the Earth around 650 million years ago. The world's greatest ice age saw great ice sheets of several kilometres thickness move across the temperate latitudes and started to encroach into the tropical latitudes where the ice sheets reduced in thickness to probably a few metres to several hundred metres in places. There is even a strong possibility the ice may have closed up at the equator right around the planet (although not yet proven at this stage) leaving the planet in a state known as Snowball Earth (a term coined by geobiologist Dr Joseph Kirschvink after spending 20 years gathering evidence to support his theory of what happened at this time). For example, boulder rocks identified as having been moved and shaped in a common and highly characteristic way as seen in the debris left behind by glaciers in the Flinders Ranges in Australia and in Death Valley in the United States at a time when analysis of the residue magnetism in the rocks at time of solidification showed these locations were at or very near to the equator is suggesting the glaciers had probably existed at the equator. Even if it didn't, ice entering the tropical regions would have made this the most severe Ice Age the Earth has ever experienced. There is no question the population of "carbon dioxide" loving bacteria were decimated (or simply put into a state of suspended animation). Nevertheless, such severe conditions was not enough to end life on Earth. The extremophile nature of these bacteria suggests there were places where the bacteria could survive. And even then, the bacteria can survive in suspended animation in the frozen ice for as long as is necessary until such time when the ice eventually melted.

As it turned out, the time needed to melt the ice in a significant way would begin 25 million years later. And it would be enough time to achieve one other important event. For a start, the Sun's intense ultraviolet light hitting the icy surface would convert a significant amount of the water molecules near the top of the ice sheets into a chemical called hydrogen peroxide. Don't be fooled by this seemingly innocent-looking chemical. We should not underestimate the importance of this chemical to life on Earth. Scientists are now firmly of the belief that this chemical had crucial implications for life on Earth. It is just a matter of time before we would see the full potential of the chemical.

The potential of this chemical for developing and expanding the range of different species in the life forming on this planet began around 625 million years ago when a global surge of massive volcanoes punched their way through the ice sheets. The volcanoes literally broke apart the great supercontinent in half along the equator. Over the next million years, the volcanoes spewed out vast quantities of the familiar carbon dioxide into the atmosphere.

Things were beginning to warm up again.

Give it another few more millions of years and the ice sheets and glaciers began to melt and retreat. As the ice turned into liquid water, hydrogen peroxide trapped in the ice would break down into hydrogen and oxygen gases. While the hydrogen gas escaped the Earth, it is the oxygen gas with its heavier weight that would end up in the water and atmosphere. Scientists are certain a vast amount of oxygen was released through this non-biological method.

 
As world temperatures warmed up to end the great Ice Age, oxygen levels in the atmosphere rose dramatically to probably around 21 per cent. The door of opportunity for life to evolve into larger and more diverse forms had finally arrived.

With the extra oxygen loaded up in the oceans and seas and carbon dioxide in the atmosphere had reached reasonable quantities to maintain adequate warmth to keep much of the water in liquid form throughout most of the planet, not to mention the extra nutrients from pulverished rock entering the oceans after the glaciers had passed through, this was a remarkably vibrant and creative time when life suddenly diversified, got physically bigger from the extra food supplies, was able to detach from the bottom of the oceans or control the direction in which certain species could float with their appendages, began to crawl and eventually swim faster, and multiplied in great numbers as the first multi-cellular organisms made their appearance on the world stage. Among these organisms were the first large multicellular animals to appear.

A bigger and more mobile body was clearly the order of the day for these animals. We must presume this was a response to keeping predators at bay through shear size, showing techniques in greater mobility and speed through the water, and/or developing greater protection mechanisms for slower moving creatures such as a tough outer shell and hardened armour plates and protrusions running along the spines to protect vital organs. Or else learn to hide underneath the sands, or behind rocks and caves. There is no doubt the explosion of diversity in the type of animals that appeared near the coastal regions and later the rest of the oceans and shallow seas would have resulted in many extraordinarily ingenious survival techniques to bamboozle predators as well as to maximise the chances of finding food and reproduce with relatively ease.

As palaeontologist Dr Jim Gehling stated:

'After snowball Earth, we see a revolution in the history of life from the fossil record. Because for the first time, we see large creatures — creatures that anyone can see with the naked eye. They are the first [multicelled] animals on Earth.' (Quote taken from the documentary titled Catastrophe: Snowball Earth. Produced by Pioneer Productions for Discovery Channel and Channel 4 Television, ©2008).

Not only were these large animals multicellular, so were the new plants coming up from the ocean floor with the existence of large sponges and seaweed. Does this mean life was already multicellular before the great Ice Age? In which case, this incredible explosion of life after 625 million years ago was probably nothing more than an explosion of the body size and with the added advantage of mobility due to extra oxygen in the water. Still, it remains unclear.

At any rate, the success of these new multicellular creatures was made possible only because a new cell had suddenly arrived on the scene with the idea of working together (or "socialising") with other similar cells as a means of maximising its own survival. In return for working together with others cells, the cell would receive what it needs to survive, be better protected from the environment, and so physically live for longer without having to change significantly and constantly than if it was on its own.

As a general rule of thumb, the more independent the cell becomes, the more multifunctional and/or faster it has to change and adapt to a wider range of environmental conditions in order to survive. Stay socialised and protected in a group, and the cell won't need to change and can therefore potentially live for longer. But in exchange for this stability and longevity, and in receiving the things needed to stay alive, the social cells must learn to be happy to fit in like a cog in a giant biological machine doing a specific task very well and without complaint.

Already we start to see the benefits of why cells may want to work together with other similar cells.

Probably how it all happened is that in the early stages, a natural string-like protein called collagen (only found in animals) was produced by a new single-cell which is able to capture like a spider-web a group of other single-cell bacteria to form a conglometrate of cells. Why? Because, as the cell had learnt after many millions of years, being anchored to clay surfaces in deep enough water or underneath the clay would provide significant protection from the radiation and with less agitation of the chemicals in the water. But get a group of cells together and these can act in virtually the same way as ordinary clay.

Yet the cells have to get close enough to realise the benefit of communicating with other cells by sending chemicals to one another in order to perform certain tasks in a unified manner. This is especially true the deeper the cells live beneath the oceans where food is harder to obtain. So it is possible that during a moment when one of the cells was partially damaged that one of the single-cells had managed to physically enter another cell and remove its DNA so that the invading cell and its own DNA can become more better protected while directing the host cell to perform specific functions that made it easier to clump together at close range with other similar cells. In other words, the inner cell can continue its selfish individualistic aim of protecting and replicating DNA at all costs, while the outer cell can be directed to find, bind and come very close to other similar cells in order to give better protection and at the same time send chemical messengers of how to perform specific tasks.

For example, the very early forms of these animal-like cell conglomerates were initially anchored to the ocean floor with the fundamental aim of maximising the surface area in order to allow a reasonable amount of the food-laden water to make contact with as many cells as possible. We call these filter feeders. A classic example of this type of creature is the coral sponge. Later the cells learned to coordinate a number of cells to move in unison while anchored internally with other cells in order to achieve what scientists would call a rudimentary form of contraction as needed to "pump" and thereby increase the flow of the food-laden water through the conglomerate of cells.

This has to be the beginning of what will become for certain conglomerate cells the gut of a living animal.

As this energy-intensive pumping action was taking place, more oxygen would be needed. Soon other cells in the conglomerate learned to specialise their function to perform the task of extracting and distributing enough oxygen to all the cells in the conglomerate. These cells would form the beginnings of a cardiovascular system.

And in order to coordinate the multitude of contractions at the right times, other cells came together to send electrical impulses and other chemicals to various cells throughout the conglomerate. It is clear the beginnings of a nervous system would have to take place.

Yet more changes would be needed.

Indeed, the next stage would have to be for this conglometrate of cells to free itself from the ocean floor or clay surfaces and let the ocean currents take the cells to places where the food supply was likely to be plentiful. But if the body size is too great as some animals discovered, the creatures had to develop a way to move about. Therefore the ability of these cells to contract muscles inside external appendages would be crucial to developing independent movement of the entire conglomerate of cells without needing to be totally influenced by ocean currents or gravity. And finally, these creatures would have to move off the surface and swim in the oceans. Thus the need to constantly change in order to adapt to a changing environment would diminish significantly after each major evolutionary step.

Before making this ambitious leap so to speak from the ancient ocean floor, animals crawling or wriggling across the ocean floor would develop the basic body plan of a head, a tail and a symmetrical body known as bilateral symmetry.

However, what would drive these "social" cells to continue changing and developing increasingly complex tasks inside the body of a living organism? What would drive these cells to make changes and increase the number of different function to be performed in order to make the conglometrate of cells we call the organism look like it is adapting (eg. getting bigger, developing appendages, a more complex nervous system and eventually a bigger brain etc) to the environment? It was probably the presence of other living organisms competing for the same sorts of food, not to mention the impact predators (9) may have had on some living organisms to change and adapt. By pushing animals to their limits almost constantly and hopefully less so over time through evolutionary improvements, the cells would be forced to adapt to new environmental conditions, be more efficient and better handle the attacks from the marauding predators and eventually make microevolutionary yet significant changes as needed for better adaptation and survival. We are pushed to change and survive merely because we do not want to be eaten by predators.

As for the size of the organism, growing bigger does have a significant benefit in terms of dealing with a multitude of predators now making an impact in the environment. Furthermore, the development of any self-directed movement through the water using external biological appendages means more food can be consumed and this in turn helps to increase the physical size of the organism.

Despite the great success of these social cells, the highly independent single-cell organisms would not disappear overnight. They would continue to flourish side-by-side with the new "social" cells to the present day because of their ability to evolve more quickly to handle the diverse, extreme and changing environmental conditions much better than the social cells. We can see evidence of the power of these single-cell organisms to adapt quickly in those resilient bacteria which become resistant to human-made antibiotics. We have to remember that single celled organisms are just as successful in surviving on this planet as multi-celled organisms. Neither has a greater advantage over the other. But if advanced and intelligent life is to evolve and be capable of asking questions about its environment, only multicellular organisms would achieve it.

At any rate, these new 'social' cells were more complex than their predecessors. Apparently, the cells grew in complexity with the advancement of a nucleus (the control centre of the cell) which contain additional structures needed to help master the art of socialising with its own kind of living cells while still maintaining some aspect of its individualism necessary to keep itself alive.

Soon countless numbers of these highly successful 'social' cells came together to produce simple 'animals without backbones', such as worms and jellyfish. As for the plant-like cells, they combined to produce seaweeds and sponges to name a few.

The eventual evolutionary progression from single-celled microbes to many-celled organisms may have taken a very long time — at least two billion years to accomplish this next biological feat — but once certain cells learned how to come together without eating each other and could specialise their functions to minimise change while benefiting from the extra food and oxygen, the progression to multi-celled organisms took off at a very rapid pace. (10)

At the same time as the animals were evolving into larger and more sophisticated forms, many of the multicellular animal life that existed after 625 million years ago developed a primitive nervous system of the level at least of present-day jellyfish. The development of a nervous system would become necessary to coordinate and handle the increasing amount of diverse and sophisticated functions that had to be performed by the multicellular organism as it adapted to new environmental conditions in the oceans, including other advanced life.

 
Two large supercontinents drifted across the globe. They would later join-up in another 400 million years to once again form another great land mass.