9,000 MILLION YEARS AGO

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

4,500 MILLION YEARS AGO

All the planets in the early solar system grew into round hot ball of red, steaming molten rock around a heavy iron-rich and dense core with smaller amounts of silicon, magnesium, oxygen, and other elements. When the mass of the planets reached a minimum level, an atmosphere formed around the molten rock.

On Earth, the percentage of each element used to build the planet's molten rocky core is roughly 32 per cent iron, 30 per cent oxygen, 16 per cent silicon, and 15 per cent magnesium. The remaining 7 per cent are all the other elements such as hydrogen, carbon, phosphorus, nitrogen, zinc, titanium, uranium etc.

Surrounding the molten rock of the Earth was a gaseous atmosphere formed predominantly by icy comets colliding on the surface and to a lesser extent by gas emanating from the planet's interior. This resulted in an initial composition in the atmosphere of around 5 billion years ago of carbon dioxide, nitrogen, water vapour and, to a lesser extent, methane, ammonia, and the noble gas neon. Researchers have estimated that CO₂ made up a significant proportion of the ancient atmosphere, with computer models suggesting that this gas could have made up anywhere from 6% to over 70% of the early atmosphere. Analysis of iron micrometeorites found in ancient soils suggest that around 2.7 billion years ago, CO₂ comprised between 25% to 50% of the Earth’s atmosphere. Before 2.7 billion years ago, this figure was probably higher. Apart from that, it is no surprise to the scientific community to see that the early atmosphere at this time was nearly devoid of oxygen mainly because life had not yet established a foot hold on Earth. As for atmospheric density, there are no accurate measurements for the early atmosphere for this time frame. Some studies have calculated that the Archean atmosphere (4 to 2.5 billion years ago) was probably almost ten times denser than today. However, this density estimate is indirect and not universally agreed upon.

The bringing together of these elements in the ancient interstellar dust and gas clouds to form the planets began as electrostatic forces, in which radiation pushes charges together. Variations in the number of electrons orbiting the different atoms in various materials can vary the electrostatic force being applied, which can either push matter together (an attractive force) or push it apart (a repulsive force). This is because of the energy density of the radiation is either reduced or increased, respectively, by constructive or destructive interference of the electromagnetic energy by like (i.e. + +, or - -) or unlike (i.e., - +) charges. But for matter to come together, a minimum amount of mass is needed to help make the attractive force more dominant, not by increasing the size of the charges in atoms, but the way matter can shield radiation from one side. nature. Over time, as more mass gets added, the electrostatic forces become less important and soon the electromagnetic shielding effect of the mass creates an imbalance in the radiation pressure causing a reduction in the radiation energy density between the matter. Then the matter is pushed together by radiation from the universe. For 20th century physicists, however, it is more a case of sticking to the original concept they are familiar with and want to remember the great man who first suggested it — Sir Isaac Newton. Therefore, this force that brings matter together naturally is described as the gravitational force. So as the electric charge on the surfaces of matter balances itself out on a larger scale, the gravitational field takes over to "pull" matter together.

As a result of these forces, the planets of our solar system came to exist within the first few million years after a portion of this massive interstellar gas and dust had already swirled around a much heavier object, which we now understand it to be the Sun.

Is there evidence to support this "red hot ball" view of the early Earth at this time? Most certainly. It all lies with certain long-lived radioactive elements. Due to the incredibly long-lived nature of a select range of radioactive elements, such as tungsten, we know that the persistent nature of the radiation emitted by these elements is capable of heating other materials around them. Clearly there must have been a lot of heat in the early Earth. So, it stands to reason that at the beginning of the formation of the planets, we should expect to see this heating up effect on rocks to have occurred to a significant degree in the core of the planets, and probably extended to near or on the surface, as the concentration of these and other elements increased during the age when materials were coming together. Well, fortunately today, even after several billion years have passed, scientists can confidently say that beneath the solid and cool rock and dust of the Earth's crust, we have materials that remain in a molten (i.e., very hot) state. Although this heat is caused by radiation, the scientific approach is simply to say that the radioactive elements are responsible for the heating and these are prevalent in the iron core of the Earth (and all the other planets). Of course, if you need more direct evidence of this, scientists have taken samples of the lava flows coming out of various volcanic eruptions.

A peak was reached roughly about 100 million years after the solar system came into existence when the Earth's size stabilised. However, the Earth was either slightly larger or smaller than it is today. Something else had to affect the mass of the Earth to bring it into line with what we see today.

4,470 MILLION YEARS AGO

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

By measuring the abundance of the isotope 182-tungsten in material collected by the Apollo astronauts from one of the Moon's solidified "magma" oceans on the Moon and seeing if there was a difference in its abundance compared to the Earth's own magma, scientists have discovered that the Moon was created approximately 30 million years after the formation of the Earth even when errors in the measurement are taken into account. Because the Moon does not have an iron core like the Earth, and yet both bodies have an unusually similar composition, scientists are lending their scientific weight to the theory that the Moon was probably formed when a Mars-sized body collided with the Earth around this time, shearing off a reasonable outer chunk of the Earth. Fortunately, the speed at which the material was ejected was insufficient to escape the Earth's gravity. As a result, the ejected material quickly solidified and, together with various other much smaller collisions, was eventually pushed into a circular orbit around the Earth. Finally, the material's own gravity (or, more precisely, the electromagnetic radiation from space exerting pressure through the radiation shielding effect) was sufficient to shape it into a sphere, but not enough to retain its own atmosphere (i.e., too small). Since then, various meteorites have struck the Moon and sculpted its surface, creating the complex patterns we see on this body today.(2)

As for the Mars-sized body (scientists call this theoretical planet Theia) responsible for the geological carnage, it probably came back and got swallowed by the Earth to reach its present size. Or did it travel fast enough to escape the Earth's gravitational pull? Nobody knows for sure.

As soon as the Moon was created and re-shaped itself into a smooth, molten sphere, it appeared much closer to the Earth than it does today. Current calculations suggest that the Moon was 15 times larger in the Earth's sky.

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

The interesting story began when recent lunar probes exploring the topography of the far side of the Moon discovered a thicker crust and an unusually elevated and 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, why does the Moon look asymmetrical?

To find a reasonable explanation for this observation, Norwegian-American planetary scientist Erik Ian Asphaug of UCSC (now at Arizona State University) teamed up with a young, talented UCSC postdoctoral researcher named Martin Jutzi, where during the course of their studies they discovered an interesting new computer model that could explain the observations. According to the new theory, a second moon could have formed around the same time as the one 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 ahead or 60 degrees behind. The second moon stayed in one of these points. For about 80 million years, the two moons stayed in the same orbit, moving around the Earth without influencing each other. Then, after 80 million years, the two moons began to drift away from the Earth, and with the influence of the Sun's gravitational pull, these two factors alone were enough to destabilize the position of the smaller moon and eventually cause it to revolve around the Earth at different speeds within the same orbit. As Asphaug 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 collided with the larger one. When it finally happened, the smaller moon slammed into its larger sibling in what the researchers claim was probably the slowest possible collision for two massive bodies of this type, allowing the material to be splattered and raised to form the mountainous regions on the far side of the Moon. As Asphaug 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 tonnes of lunar debris into space. Over the next million years, the 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 about what happened. For further details, check out the article from the Nature journal. (3)

4,500 to 4,350 MILLION YEARS AGO

Looking closer at 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 and reached its new peak size, gases trapped in the planet's interior and from considerable quantities of icy comets (5) crashing into the Earth were released and held in place gravitationally (or, more accurately, electromagnetically by the universal background radiation) to conceive the Earth's atmosphere consisting mainly of nitrogen, methane, ammonia, hydrogen sulphide and hot water vapour.

This view for the formation of the Earth's atmosphere is confirmed by Dr. Sten Odenwald (Raytheon STX) for the NASA IMAGE/POETRY Education and Public Outreach program:

"Nitrogen-rich and water-rich compounds are common in interstelar clouds which contain formaldehyde, ammonia, methane, water and other molecules. Comets are samples of this primitive matter, and the young earth accreted from a cloud that was very very rich in water and nitrogen-rich compounds just like interstellar 'molecular' clouds are known to be. So the early atmosphere was very rich in these molecules, however, after the sun went through its T-Tauri phase, it stripped the earth of these early molecules, so we think that the way nitrogen and water got back to the earth to form the second atmosphere is through comet bombardments when the earth was still less than 1 billion years old."

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

As for the density of the early Earth's atmosphere, this was maintained thanks to the rapidly moving iron core inside the Earth to generate a strong magnetosphere. If we didn't have a magnetosphere of any kind, radiation would strip away the atmosphere by knocking electrons off atoms, sending particles into space. This is why Mars has a very thin atmosphere. At around 4,500 billion years ago, Mars had a very similar atmosphere with a density only slightly less than the Earth. However, Mars is a smaller planet and, therefore, can cool more rapidly. As it cooled, its magnetic field became weaker as the molten iron core lost its ability to keep moving. Eventually the magnetosphere shut down. Despite the distance of Mars from the Sun, it just took longer for the Martian atmosphere to thin out to its current state we see today.

In terms of the great oceans of water on Earth, this would come principally from the countless impacts of icy comets and, to a lesser extent, from internal outgassing. Upon hitting the molten rock, the ice would turn to vapour. The gas then filled the atmosphere. As air pressure increased in the cooler atmosphere, the gas recombined mainly around any solid dust particles or large molecules floating in the air. A liquid drop formed as more water molecules were electrostatically held in place. Once the drops of water in the atmosphere were large enough with enough mass, they became heavy enough for "gravity" to pull it (or radiation from space to push it) back to the surface. We call this rain.

There is a scientific theory that the origin of the Earth's oceans occurred after a Mars-sized planet collided with the Earth to form the Moon. If this is true, a considerable amount of water vapour would have escaped from the interior of the planet. A question still hangs over this theory as to whether there was enough water vapour internally to create the oceans. It is either that, or we may need to combine this theory with the knowledge that millions of icy comets have already collided with the planet. Once we do this, scientists have quickly realised how easy it is to explain the origin of all the water on the surface of the Earth (a rather simple and quick scientific calculation, we hear). However, there is still one tiny problem with all this deductive work: water as we know it in the liquid state was not even visible just before 3.8 billion years ago. The Earth's surface remained too hot to allow water to stay in the liquid state. Until liquid water became a reality, scientists are fairly certain that the Earth's surface was covered by a hellishly thick atmosphere of hot water vapour and other gaseous elements (the ultimate and largest Swedish sauna the world has ever seen).

Meanwhile, in those ancient days, the Moon could still be seen showing signs of lava flows in various low-lying valleys. Today, the remnants of these great lava flows can be seen in the darker and softer regions of the Moon, after they have cooled and been reduced to smaller rocks and dust by meteorite impacts.

3,800 - 3,700 MILLION YEARS AGO

The surface of the Earth was cooling down, forming rocks out of lava.

Some of the oldest known rocks on Earth were originally found in early samples from Greenland. However, scientists now believe the world's oldest rocks are in Western Australia. The essential technique for dating rocks has been to take a sample of rock and measure the proportion of radioactive rubidium-87/potassium-40 and non-radioactive strontium-87/argon-40 elements (i.e., the end products in the incredibly long radioactive decay process), respectively.

When the Earth's surface finally cooled sufficiently for water to become liquid and stay that way on the ground, all that was needed was for the 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 generously poured from the heavens to form the permanent global flood in Earth's history, the highly penetrating and disruptive ultraviolet rays from the early Sun and the great electrical storms in the early hazy atmosphere of the 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.

Or one could imagine a similar event taking place not far from hot hydrothermal vents and over certain clay surfaces that covered the floor of the early oceans and numerous shallow seas and lakes scattered across the ancient muddy, hot and humid desert-like continents of the world (remember, there were no plants growing anywhere). In these extreme hot and cool, dry and wet conditions, and the occasional lightning strikes on the surface and penetrating the atmosphere, there would be moments when molecules break apart into energised (or charged) fragments called free radicals. In other areas, especially where the water cooled and near protected regions of certain clay surfaces (most probably containing zinc), the energised fragments would reassemble into various kinds of molecules. From recent experiments, including the famous Stanley Miller's experiment, scientists have discovered that some of these molecules were crucial to the development of life on Earth.

Then as the water in some pools began to evaporate between major rains, the concentration of these molecules increased, and so raising the probability that new and more complex molecules forming under the right conditions.

Or, there could be another complicating factor in the formation of life on Earth: an icy comet surviving the fall to Earth could release their frozen cargo, including possibly a primitive "alien" life by way of bacteria, could also have started the process of life on Earth. Scientists are not entirely sure how much of a contribution this "extraterrestrial influence" could have made (4). 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 ejected into space until, by 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 that there is no limit to how long bacteria can remain in suspended animation inside icy materials. They could potentially remain in this state for literally billions of years.

Does this mean that primitive extraterrestrial life in a state of suspended animation inside icy comets had seeded the Earth with life? It is possible, but not proven at this stage. One thing is certain: bacteria can survive in ice for a very long time. In fact, there is no reason bacteria can be kept in suspended animation for billions of years. As we will learn later, not even the biggest ice age to hit the Earth for at least 25 million years was not enough to wipe out all life on Earth. If anything, it just slowed things down, keeping everything in a giant freezer until the right moment came when the ice melted and life could resume at its usual pace. Just a short sleep and a sudden awakening, and life continued virtually unabated.

So how did life actually begin on Earth?

In an attempt to resolve this mystery, scientists at NASA have been looking for evidence of alien bacteria inside some icy comets floating through space.

To find direct observational evidence for this claim, NASA has sent a probe into space to collect some icy material from a comet. Analysis of the material so far has been inconclusive. Perhaps it will take a vast number of icy comets (or a deeper examination of the comet's interior) to find that one lonely alien bacteria in the icy cosmic haystack lying dormant and frozen, waiting for its moment to come alive? So the next best thing scientists have at their disposal is to look for a place in the solar system where there might be a vast liquid ocean of water may exist. We can cross Earth off the list. It is too contaminated with bacteria. One possibility is perhaps under one of Jupiter's moons, where an ocean of liquid water appears to exist beneath a solid icy surface. If so, NASA is excited by the prospect of finding evidence of alien bacteria surviving in this vast ocean. Who knows? Perhaps many millions of years of evolution may have seen some this bacteria evolved into something larger. Would it be enough to see Hollywood producers consider this location as the scene for the next nasty alien sci-fi movie to emerge from Europa's icy surface by one of our exploratory probes or a spacecraft of humans visiting this corner of the solar system?

While some scientists search for evidence of frozen alien bacteria in space and inside one of Jupiter's moons (e.g., Europa), a NASA scientist has boldly suggested the likelihood that microbial life could be embedded in some extraterrestrial rocks rather than ice or a distant extraterrestrial ocean, albeit fossilized, after discovering what looks like microscopic tubular structures reminiscent of earthworms here on Earth. The one thing going for the scientists in this area is the fact that 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 for those interested, these are meteorites containing 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. However, 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.(6)

Interesting as all this may sound, the counter-argument is, of course, that life could have arisen here on Earth.

Among the important scientific work being done to support this latter argument is that of 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) may have played 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 clay containing the right metals to attract a multitude of amino acids and help them form long chains of macromolecules called proteins. If enough of these proteins can be produced, the bubble could be reinforced by a protective protein-like membrane and thus maintain the spherical structure for a longer period of time, especially between periods when the rain would stop. 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 been found that these clays can also form 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 could concentrate small chemical molecules in a hot "organic soup" and then act as a kind of prebiotic scaffolding for the production of 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 attract all the twenty amino acids found in living things on Earth and all the different nucleotides that make up DNA, but have been observed to form macromolecules of up to eight amino acids and several chains of nucleotides. Longer, protein-like chains and DNA-like structures seem likely given sufficient time for their synthesis.

Again, despite the fascinating in-roads made in this particular aspect of the origins of life on Earth, scientists are still aghast at exactly how long is required for nucleotide chains to be long enough to store useful genetic information and, at the same time, to 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 hitching a ride on an icy comet?

To be conservative at this stage, scientists must assume that life was somehow created here on Earth and not in the confines of space (especially since 20th century scientists had yet to see alien life with their own eyes as yet).

Therefore, an unimaginable amount of time would have had to elapse, during which time the process of dissemination and reassembling of molecules and access to the right surfaces, pressures and temperatures to form 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 the ancient clays that existed beneath the hot springs (6).

Why was the water hot? If you said the hot magma beneath the crust was doing this job, this is not entirely true. In fact, the real source of heat came from the collision of enough asteroids with the Earth's surface. As some British scientists studying the Houghton Crater on Devon Island, Canada, have found, there is evidence that asteroids hitting 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 from 1,000 years to 1 million years. It is these cracks, together with the heat from the rocks, that some scientists believe may have allowed life on Earth to begin.

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." (7)

Then, suddenly and without warning (perhaps with the help of hydrothermal vents and a host of new and interesting catalysts in the clays and water to speed up the chemical reactions, 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 vital self-replicating macromolecule is the ancestor of Deoxyribonucleic Acid (DNA).

Because scientists have not yet recreated the exact events and conditions, obtained all the right materials in the laboratory, and allowed enough time for the experiment to see this important moment of the creation of self-replicating DNA take place, there is still considerable controversy about how likely this event can occur. Even the Nobel laureate and discoverer of DNA, Sir Francis Crick, thought the chances of this happening were extremely low. So much so that he was prepared to consider a more extraterrestrial origin for the first DNA molecule to appear on Earth. He said:

"Life did not evolve first on Earth, a highly advanced civilization became threatened so they devised a way to pass on their existence. They genetically-modified their DNA and sent it out from their planet on bacteria or meteorites with the hope that it would collide with another planet. It did, and that’s why we’re here."

Nevertheless, as we will discover in the Future Epoch page, the Universe seems to be a much bigger and older place than anyone had imagined. This means that if anything is not quite impossible (even if it seems extremely unlikely), then no matter how small the probability may seem, there is more than enough time in the Universe for even the random events to create the near-impossible outcome most scientists would not expect. Yet these random events are probably not so random after all. We see this in the way rocky planets concentrate these molecules on their surfaces, clays with zinc concentrating molecules to improve the chances of aligning and combining molecules together. Add whatever catalysts are naturally present and dissolved in water or the clays and it seems we are conspired to appear on an Earth-like planets under the right conditions to appear, even if the odds seem stacked against us. But even if one such planet in the Universe could create this supposedly random and unlikely event of producing life without outside help, all it takes is for the planet to be broken apart in a future supernova explosion or big enough asteroid impact, and this DNA could travel through space to potentially reach another new Earth-like planet. What all this tells us is that while certain events are not described by scientists as absolutely impossible with a zero likelihood of success, there is always the possibility that the event could still happen in a universe. Well, let's face it, we are here. So somehow it is possible. If the universe is large enough and old enough, it will happen. The only issue is, can it happen again and again elsewhere in the universe?

At the same time, something is telling scientists that not everything is totally random. There is a sense of the directed nature of things with the help of the right chemicals and conditions. It could well be the case that certain critical molecules needed in the formation of DNA and life in general had followed expected chemical pathways in a natural way here on Earth, and by implications so too for other similar Earth-like planets. The only evidence supporting this is the fact that scientists can observe the relative ease by which amino acids can be produced in a laboratory and in space and the ability of certain metal-rich clay surfaces to help assemble chains of nucleotides to form a crude non-replicating DNA-like molecule, and amino acids to form proteins. So not everything has to be totally random or based on pure luck.

Whether the origin of life follows the abiogenesis or panspermia process, there is much scientists have yet to understand in this great detective story

3,500 MILLION YEARS AGO

With a DNA molecule finally formed and able to direct the chemicals in the organic soup to assemble more copies of itself, and finding ways to achieve self-preservation in an unpredictable world with the help of other chemicals, we finally see out of the great turmoil of the early Earth the emergence of the first relatively stable single celled organisms. The organisms, which looked like tiny, perhaps semi-opaque bubbles attached to clay surfaces and eventually floating in warm water, consisted of a spherical 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.

The oldest direct evidence of single cell bacteria can be seen 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. (9)

3,400 MILLION YEARS AGO

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. In a study published in the journal Nature Geoscience on 22 August 2011, Brasier's team found 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 (a useful material to protect the delicate molecules from excess radiation in the environment thanks to its piezoelectric properties and the ability to reduce radiation energy density between opposite-charged quartz crystals under pressure from the weight of other materials on top). 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 with remarkable 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, of course, painted a hellish picture of the early Earth at this time. He believes that as the microbes began to carve out an existence the sky was constantly cloudy and grey and acted as an effective heat trap (and protection from excessive high-frequency UV radiation) 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°C both day and night.

And the extremely low levels of oxygen in the air made it likely that these microbes relied heavily on sulfur compounds for food as well as the water for a good drink; and why not a good bath too to get rid of those waste products (only to be turned into gold for another type of lifeform, as we shall soon discover). Indeed, the presence of pyrite crystals in the sandstone is thought to be a metabolic sulphur reducing by-product of the living cells. Hence it is likely that the oldest living things on Earth were sulfur metabolising bacteria. As the team stated:

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

3,200 to 3,400 MILLION YEARS AGO

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

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

However, after many more millions of years had passed, one of the single cells just happened to stumble across an important molecule called chlorophyll (10) which could trap the free and reliable energy from the sun and use it to break down the highly abundant carbon dioxide in the Earth's atmosphere for food rather than relying entirely on the basic chemical building blocks already formed and waiting to be collected in the oceans. We call these chlorophyll-loving unicellular 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 and shallow seas of the world, another simple living cell evolved and, perhaps after experiencing a moment of food shortage, discovered how it could survive by consuming these highly abundant "plant-like" bacteria as a stable food source. As soon as this living cell discovered an appetite for plant food, it became the first animal to appear on Earth. And not long after that, some cells discovered that there was no point in consuming plant cells for food. Why not consume the actual animal-like cells that do the plant eating, especially during times or locations of famine and limited plant foods? A reasonably reliable source of food, no doubt, as the number of "herbivore-like" animals increased. So maybe we have the origins of the first animal-consuming predator.

An example of an animal-like cell is protozoa, the oldest known animal fossil. Protozoa would swim or float around and consume smaller bacteria.

And why is it necessary for any bacteria to "eat" (or consume) carbon dioxide or other bacteria? Because DNA needs a constant supply of raw materials from the "food" to rebuild itself and its cell structure for its continued survival (until such time as radiation or something else damages the cell structure and/or DNA beyond repair and it must die). And it needs the energy to achieve these relatively selfish aims, which means the energy has to be easily obtained or captured easily from some source. Eating is about gaining this energy and materials as needed to repair and/or re-build the cell and to produce enough DNA molecules to help retain the genetic information it has acquired to adapt to its environment. In this way, the bacterium achieves a sense of balance (a term often used by religious leaders) in its internal physiology and be happy (a term often used by psychologists). In this way, the bacteria are more likely to achieve other goals in life, such as reproduction or whatever.

In psychology, we also call this sense of stability and living a longer life after consuming food as achieving "happiness" (or gaining feelings of love). To biologists, it simply means that life can relax and not have to spend time in the here-and-now moment of searching for more food to stay alive, and avoid that feeling of hunger. Otherwise, it is an innate and constantly striving activity to consume and reach the point of feeling happy again. The only question is, how much consuming do cells need to stay alive? And can highly consuming cells survive in the long term when periods of food shortage become a regular reality?

There have been observations of African tribes eating a lot at the right times of the year to gain weight and extra fat so that people can survive better and live long enough to get through periods of famine. Does this approach really lengthen lifespans of living organisms? Scientists are not sure what the answer is.

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.

2,500 MILLION YEARS AGO

Researchers at the University of Waterloo have discovered evidence of ancient life trapped inside a 2.5‑billion‑year‑old ruby from Greenland. While studying some of the world’s oldest ruby deposits, the team found a graphite inclusion—pure carbon—within the gemstone. Analysis of the carbon’s isotopic composition indicates that it most likely originated from early microbial life, dating to a period long before multicellular organisms existed on Earth.

"The graphite inside this ruby is really unique. It’s the first time we’ve seen evidence of ancient life in ruby‑bearing rocks,” said geologist Chris Yakymchuk involved in the ruby's analysis.

The graphite not only provides a rare biological signature but also offers insight into how rubies formed in the Archean era. Its presence suggests that fluids once moved through the rock, removing silicon dioxide and creating the chemical conditions necessary for corundum — the mineral that forms rubies — to develop.

The discovery emerged during a study of corundum formation in the Archean North Atlantic Craton of southern West Greenland, home to some of the oldest known ruby deposits.

2,750 to 2,000 MILLION YEARS AGO

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

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

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

As these primitive photosynthesizing bacteria continued converting carbon dioxide into food and emitting oxygen, 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 heat from the Sun. This meant that the Earth was getting cooler. 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 sliding into an irreversible ice age during this epoch.

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

700 to 650 MILLION YEARS AGO

The Earth nearly 700 million years ago was warm and wet. An alien visitor looking intently at the 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). The only indication that life might exist on this planet were the abundant photosynthesizing bacteria in the water, which gave it its greenish tinge.

As for the bacteria-sized animals floating in the water, these little creatures probably didn't stay single-celled for very long. Perhaps in response to other animal-like bacteria consuming other bacteria, it is likely a group of cells came together in what may be 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 water at this time. They were too small to be visible to the naked eye, making it extremely difficult for scientists to find fossilized evidence of their existence.

However, there is a good reason why animal-like bacteria did not become very large creatures by grouping together a multitude of these cells. No doubt the advantage in doing so is the fact that should a predator take a bite of a multi-celled organism, one or a few cells may get sacrificed, but not the entire multi-celled organism. Thus, there is potential to survive a deadly encounter with a predator and even continue on to reproduce and achieve other tasks. For multi-celled photosynthesizing plants, losing a few cells isn't a major blow. If anything, it could be beneficial. All the plant has to do is regenerate the lost cells and keep growing while the carbon dioxide and sunlight continues to be supplied. Easy. However, there is a limit to how much regeneration is possible. Some cells can be lost occasionally, but not too many. This is true for all plant and animal organisms. At the same time, there is also another good reason why individual cells should not get too large, or even the entire organism itself should not acquire too many cells. The smaller you are, the less energy you require. If you need too much energy, the environment may not be too forgiving in providing enough food to give you the energy to move around a lot as well as other nutrients to build new cells as needed to survive. Famine was still a regular and common event for life on Earth at this time. Furthermore, the benefits of eating less and using less energy is that you can live longer, either because you are less of a target for the predators (and later you can be nimble enough to evade certain predators), but also because being too large can attract more radiation to the "body". The presence of extra radiation means there is a heightened risk of developing more mutations. Or else you must stay close to the sea bed to use the water as an effective radiation shield to reduce the mutations. Yet another benefit of using less energy is that any energy you do expend requires oxygen to be used up in the metabolic process. This means that any animal trying to grow to a larger size would need to extract more oxygen from the water. However, as scientists have determined at the time, the oxygen levels in the water and those in the atmosphere remained rather paltry 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. With this in mind, we can naturally surmise that no animal would have dared to grow larger than a microscopic organism while the oxygen levels in the water remained relatively low and the atmosphere still had a measly 1 per cent oxygen content.

With the supply of carbon dioxide in the atmosphere looking rather plentiful, the world continued to be dominated by photosynthesizing bacteria (and possibly even plant-eating animal-like bacteria). As the photosynthesizing bacteria continued to have the upper hand so to speak with their veracious appetite for carbon dioxide in the early stages, it was only a matter of time before the Earth began to cool down even further.

And eventually it did. In fact, the success of these little photosynthesizing bacterial critters in feverishly consuming 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 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 (although not yet proven) that the ice closed in around the planet at the equator, 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 that there were places where they could survive. And even then, the bacteria could remain 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 needed for the development of more complex lifeforms. First, the Sun's intense ultraviolet light hitting the ice 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.

Indeed, the potential of this chemical to assist in the development of life was realised when, around 625 million years ago, there was a sudden and significant global upsurge of massive volcanoes punching their way through the ice sheets. The volcanoes literally split the great supercontinent in half along the equator (where the ice sheets were thinnest). Over the next million years, the volcanoes spewed out vast quantities of the familiar carbon dioxide into the atmosphere, not to mention the numerous minerals on the ground that were washed into the oceans by the melting glaciers and ice sheets.

Things were beginning to warm up again.

As the ice turned into liquid water, the second stage in the development of life would begin when hydrogen peroxide trapped in the ice would break down into hydrogen and oxygen gases. While the hydrogen gas would escape the Earth, it is the oxygen gas with its heavier chemical weight that would end up in the water and atmosphere. Scientists are certain that this non-biological method released a huge amount of oxygen, so much so that up to 20 per cent of the atmosphere probably contained oxygen.

625 MILLION YEARS AGO

As global temperatures warmed up to end the greatest ice age in Earth's history, oxygen levels in the atmosphere rose further to around 21 per cent. As the ice and massive glaciers melted, fresh flowing water would have ran over the edge of massive cliffs and down mountains. The well-oxygenated water would have reached the oceans.

At the same time, pulverised rock from the movement of glaciers during the greatest ice age and the more recent lava flows from massive volcanoes would have washed into the oceans, providing additional trace elements. (11)

All this geological activity would have assisted life in the oceans in some way, whether to build and maintain healthy tissues or to keep the organisms alive through the extra oxygen in the water. Clearly the door of opportunity for life to evolve into larger and more diverse forms had finally arrived for those willing to take it.

And indeed life grabbed hold of the opportunity like never before.

With the extra oxygen and trace elements loading up in the oceans and seas, and carbon dioxide in the atmosphere having reached reasonable quantities to maintain adequate warmth and thus keep much of the water in liquid form over most of the planet, this was a remarkably vibrant and creative time when life suddenly diversified, grew physically bigger from the extra food supplies and oxygen, and began to detach from the bottom of the oceans or control the direction in which certain species could float with their primitive appendages (but not designed for speed and agility as yet). This was a time when organisms could crawl and eventually swim a little faster, and multiplied in great numbers as the first multi-cellular organisms made their appearance on the world stage. Among these new organisms were the first large multi-cellular animals to appear as the plant life grew.

A bigger and more mobile body was clearly the order of the day for these animals. We must presume this was in response to predators and the need to evade them, and/or develop greater protection mechanisms against these predators for the slower-moving creatures, such as a tough outer shell and hardened armour plates and protrusions along the spines to protect vital organs. Or else they learn to hide under the sand, or behind rocks and caves. There is no doubt that the explosion of diversity in the types of animals that appeared near the coastal regions, and later in the rest of the oceans and shallow seas, would have resulted in many extraordinarily ingenious survival techniques to bamboozle, outwit, or out manoeuvre the predators and so maximising the chances of surviving, finding more food, and ultimately achieve the one important goal iof not just being happy and balanced, but later to reproduce when the predators were not around to spoil the party.

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 [multi-celled] 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, but so were the new plants that came up from the ocean floor with the existence of large sponges and seaweed. Does this mean that life was already multicellular before the great Ice Age? It is possible. 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 some mobility due to the extra oxygen in the water. Still, it remains unclear.

In any case, the success of these new multi-cellular creatures was only made possible 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 with other cells, the cell would get what it needed to survive, be better protected from the environment, and so physically live for longer without having to change significantly and constantly than if it were on its own.

Of course, that does not mean that a single cell organism could not survive on its own, or that it didn't have its own advantages over the more social cells. Bacteria today is an example of a single-cell organism that has survived perfectly fine to this day and are among the most successful creatures on this planet. It is just that the more social cells had other advantages.

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. In other words, you had to change quickly and often constantly, or die and hopefully have reproduced a new cell before then to be able to better adapt to the new conditions. Stay socialised and protected in a group, the cell does not have to change (or at least not as it would if it were on its own) and can, therefore, potentially live for longer. But in exchange for this stability and longevity, and for receiving the things they need 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. The perfect soldier is designed to follow the orders of its superior (i.e., DNA), a nd the DNA-like messengers that translate the genetic information into specific proteins for controlling the cells.

Already we start to see the benefits of why some cells may want to work together with other similar cells. Basically it is to be a little bit more lazy and doing a specific job being asked of it very well and in return receive better protection from the environment in order to live longer. Otherwise, the only other benefit in having multiple cells is as a form of protection for the organism in the event a predator decides to take a bite. A loss of some cells is usually not likely to be fatal. Painful? Yes. But you will probably survive to see another day as they say.

The process from single-called and multi-cellular clearly didn't happen overnight. It would appear that a natural string-like protein called collagen (found only in animals) was produced by a new single-cell to help capture, like a spider-web, a group of other single-cell bacteria to form a conglomerate 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 (and potentially less likelihood of being eaten by predators). But if predators get smart and learn how these cells protect themselves, it is better to get a group of cells together and these can act in virtually the same way as ordinary clay, except this socialising of the cells has at least one major benefit: the cells don't have to stay in one spot. The cells can finally move off from the clay surfaces or wherever it is attached and start to move around more freely, initially with the help of the oceans currents, and later with the evolutionary growth of appendages to allow the cells to move where they want to (usually to where the food is and away from predators).

And, of course, the other benefit is obviously to improve the chances of survival after an encounter with a predator or the ravages of high-frequency radiation on the DNA within the cells. If only a few cells are sacrificed to satisfy the food requirements of the predator, or have to be removed and new cells formed to replace them once the old cells fail to do their work or not in the proper way, then there is a good chance the organism will survive.

However, the cells need to get close enough to realise the benefit of communicating with other cells by sending chemicals to each other (in order to do their tasks properly and in a unified way for the likelihood of staying alive to be high). This is especially true the deeper the cells live under the oceans, where food and oxygen are harder to obtain (perhaps this is another mechanism for organisms to escape predators by moving into harsher environments?). Therefore, it is possible that a moment came when one of the cells was partially damaged, allowing another single-cell to physically enter the damaged 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 while still incessantly making copies of the cell. 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 communicate with 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 creating what we call an organism were initially anchored to the ocean floor with the fundamental aim of maximising the surface area in acquiring food from the water with as many cells as possible. We call these filter feeders. A classic example of this type of creature is the coral sponge.

Later these cells learned to co-ordinate a number of cells to move in unison in order to achieve what scientists 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.

As this energy-intensive pumping action was taking place, more oxygen would be needed. While cells did benefit from the extra oxygen in the water after the end of the great ice age and the extra food by staying together, there would be moments when food supplies would temporarily run low, forcing the cells to become more efficient and specialised in their functions. Those cells whose job was to extract and distribute oxygen to all other cells would form the beginnings of a cardiovascular system and quickly became very good at this task.

Later, in order to co-ordinate the multitude of contractions at the right time, other cells came together to send electrical impulses and other chemicals to various cells. It is clear that these cells would show the beginnings of a nervous system for the organism.

Yet more changes would be needed.

The next step would be for this conglomerate 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. However, if the body size is too great for any reason as some animals would discover when it needed extra oxygen and food, the creatures had to develop a way to move about independent of the ocean currents. Therefore, the ability of these cells to contract muscles inside external appendages would be crucial to the development of independent movement of the organism. By doing all these things, the need to constantly change in order to adapt to a changing environment and other animals after each major evolutionary step would be greatly reduced.

Before making the next ambitious leap so to speak from the ancient ocean floor to swim around in the water, 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.

Then came the first animals to swim in the water. We call them fish.

So what drove these "social" cells to continue changing and become more complex in the tasks performed even if coming together would have reduced the need for change? Apart from searching for food, it was probably the presence of other living organisms competing for the same sorts of food, not to mention the impact predators (12) may have had on some living organisms to change and adapt and so help to cope and handle the predators in their own special way. By pushing animals to do more than what they think they can, it helps to create micro-evolutionary improvements until the DNA makes sufficient changes cause a sudden evolutionary change in the next offspring for the better. Then the cells and the entire organism will find it much easier to adapt to the environmental conditions, such as being more efficient at a particular task, or to better handle the attacks from marauding predators. Apart from radiation forcing changes in the genetic code of DNA, we are constantly pushed to change and survive through our choices partly because we want to stay alive long enough and be stable in our environment (i.e., be happy and feel balanced). In other words, we do not want to be eaten by predators. This is a simple fact of life.

As for the size of the organism, growing bigger does have a further benefit. A bigger animal can keep predators at bay (until the predators grow large enough to handle the prey or work together in a group to bring down a larger prey).

Despite the great success of these social cells and their coming together in large numbers, the highly independent single-cell organisms would not disappear from the face of the earth. They would continue to flourish side-by-side with the new "social" cells to the present day because of their ability to find new solutions and evolve (often 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 rapidly in those bacteria that are resistant to human-made antibiotics. We have to remember that single celled organisms are just as successful at 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 able to ask questions about its environment and find alternative solutions to the age-old problem of how to survive, only multicellular organisms would achieve it.

At any rate, these new "social" cells were definitely more complex than their single-celled predecessors. Apparently, the cells grew in complexity with the advancement of a nucleus (the control centre of the cell, and a kind of secondary cell living inside another cell) which contained additional structures needed to help master the art of socialising with its own kind of living cells, while still retaining 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" known as the invertebrates. These included such things 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 finally learned how to come together without eating each other and could specialise their functions to minimise changes while benefiting from the extra food and oxygen, the progression to multi-celled organisms took off at a very rapid pace. (13)

At the same time as multicellular animals were evolving into larger and more sophisticated forms after 625 million years ago, the nervous systems of these animals had evolved to the level of present-day jellyfish. The development of a nervous system is considered necessary to properly coordinate and handle the increasing amount of diverse and sophisticated functions that multicellular organisms had to perform as they adapted to new environmental conditions in the oceans, including other advanced life that were carving out their own existence.

600 MILLION YEARS AGO

Two large supercontinents drifted across the globe. They would later reunite in another 400 million years to form another great land mass.