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Approximately 4.6 Billion years ago,

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our planet earth formed through a series 
of astronomical phenomena that enabled life 
to form.

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This inconceivable amount of time enabled 
the formation of biological molecules,

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which in turn, evolved to what we know as 
“Life” today.

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Now, let us ask,where did life even come 
from?

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And how did it become this complex system 
that leave scientists in mystery?

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In this video, we will explain the timeline 
and evolution of life on earth.

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Approximately 4.6 billion years ago,

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the planet earth was not as “habitable” compared 
to our current setting.

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This part of the history of earth was called 
the Hadean Eon.

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Although, it would be interesting to observe 
this

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since we would be able to see how the earth 
that we live on today was formed,

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it is not a pleasant environment to live 
on.

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Earth was consistently bombarded by asteroids 
and comets

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which in turn, heated the earth causing all 
water to convert into water vapor,

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thus the earliest atmosphere formed.

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This eon lasted for about 700 million years,

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thus we can imagine that the existence of 
life is really not possible at this time

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since all organisms would die due to the 
extremely high temperature of the planet 
earth.

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However, some scientists believe that these 
bombardments of heavenly bodies

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sparked the chemical building blocks of life,

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deoxyribonucleic acid

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or most commonly known as the DNA.

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Moreover, during this eon,

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the constant bombardment of the asteroids 
and comets as mentioned earlier

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caused repeated melting of the earth’s crust.

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Thus, no earth rocks from this time have 
survived.

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It is also during the Hadean Eon that the 
believed “Great Impact Hypothesis” occurred.

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This hypothesis tentatively explains the 
formation of the moon through the collision 
of a Mars-sized object to the forming Earth

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thus ejecting particles that in time,

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formed the moon through accretion and gravitational 
pull.

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The moon stayed in orbit with the earth since 
then.

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In conclusion,

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due to the harsh conditions of the earth 
back then,

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the existence of life in our planet earth 
occurred in the succeeding eons after the 
Hadean eon.

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The existence of the moon significantly affected 
the climate, oceans, and life on earth.

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In fact, due to the presence of the moon, 
the rotation of the earth slowed down significantly.

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From the original 6-hour rotation, it became 
a good long 24 hours.

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In addition to this, the moon significantly 
helped the earth to stop wobbling.

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Moreover, the different seasons in our time 
is caused by the moon.

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Because of its presence, the earth has a 
tilted orientation,

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making its revolution around the sun produce 
different seasons.

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In line with this, scientist have proposed 
that the climate of the earth stabilized 
during the Archaeon eon.

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After millions of years from the molten state 
of the earth,

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which caused water to evaporate and become 
vapour,

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during this eon, the water vapour condensed 
and formed liquid water

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due to the gradual decrease in the Earth’s 
temperature.

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In accordance with this phenomenon,

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when the earth became more suitable for life,

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primitive organisms were believed to have 
existed.

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An example of which are cyanobacteria,

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single celled microorganisms which release 
oxygen into the ocean as a waste product 
during their photosynthesis process.

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These led to an increase in the oxygen level 
of iron-rich oceans

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that paved way to the formation of banded 
iron on the seafloor.

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When all of the iron present in the ocean 
are consumed,

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excess oxygen are then released to the atmosphere,

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thus, the great oxygenation phenomenon occurred,

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which in turn, contributed to the increasing 
diversity of life in our planet.

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With the great oxygenation event caused by 
photosynthesis in cyanobacteria,

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an oxygenated atmosphere now ruled the Earth

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leading to the poisoning and subsequent extinction 
of chiefly-anaerobic microbes

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in what was called an oxygen crisis.

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With the abundance of methane in the atmosphere,

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there was the presence of an efficient greenhouse 
effect that warmed the Earth despite the 
less luminous young sun.

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However, with the emergence of oxygen and 
its combination with methane,

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carbon dioxide was formed.

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The greenhouse effect became weaker

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leading to an ice age which was termed as 
the “Snowball Earth”

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which lasted for hundreds of millions of 
years.

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From the dominance of anaerobic organisms,

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now, with an abundantly oxygen-filled atmosphere 
came the first aerobic eukaryotes.

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However, persistence of carbon dioxide limited 
their diversification.

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Dioxygen in the atmosphere led to creation 
of ozone and the thickening of the ozone 
layer.

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The ozone layer shielded the Earth from the 
harmful UV radiation

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and therefore life was able to diversify 
from shallow waters to the land

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in the end of the Proterozoic Eon and the 
Precambrian.

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Now we enter the Phanerozoic Eon and the 
Paleozoic Era with its 6 major periods.

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542 million years ago there was a sudden 
increase in oxygen levels

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causing the greatest boom of diversification 
of life in Earth’s history – known as the 
Cambrian explosion.

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Beginning the Paleozoic is the Cambrian period, 
known as the age of invertebrates.

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This is when the simple multicellular organisms 
like sponges, worms, and mollusks appeared 
in the Cambrian seas.

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These more complex organisms came about due 
to the presence of sufficient oxygen to maintain 
their energy needs

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when it came to evolving more complex structures 
such as shells and skeletons.

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As life continued to get diverse,

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485 million years ago entered the Ordovician 
period,

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when most of the world’s land was collect 
in the supercontinent Gondwana.

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Marine invertebrates and early vertebrates 
flourished in this period.

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The appearance of the first life that can 
thrive in land came in the transition to 
the next period 443 million years ago,

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the Silurian period.

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This is when the first simple land ecosystems 
appeared.

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In entering the Devonian period 419 million 
years ago,

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the first fish with jaws and backbones appeared.

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With the huge diversity of fish that sprung 
in this period,

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it was fittingly named as the Age of Fish.

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359 million years ago, large forests grew 
which also led to extreme oxygen levels

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an ideal environment for arthropods or large 
insects was created.

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Amphibians also flourished around this time.

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The evolution of some organisms to produce 
amniotic eggs

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made possible birthing on land and a rapid 
expansion of diversity.

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The large forests in the Carboniferous ended 
up as the coal deposits we use today.

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299 million years ago then came the last 
period of the Paleozoic, the Permian period.

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This is when the first large vertebrates 
dominated the land.

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The richness of plants in the surroundings 
and the evolution of stomachs capable of 
digesting such plants

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allowed herbivores to prosper in this age.

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With the Paleozoic beginning with the Cambrian 
explosion,

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similarly it ended with a magnificent explosion.

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However, in the process it took with it most 
of the life created in the Paleozoic.

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The Permian-Triassic Extinction is the largest 
mass extinction in Earth’s history

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killing 96% of all marine species and 70% 
of all terrestrial vertebrates.

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This event is also known as “The Great Dying”

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which was probably caused by an explosion 
of huge volcanic plume or perhaps the cataclysmic 
impact of a major asteroid.

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As Earth's climate continues to shift from 
cold to dry,

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amphibians that reside on rainforest lands 
die as the temperature rises and the rainforest 
collapses.

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This event is known as Carboniferous Rainforest 
collapse.

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Reptiles on the other hand were able to adapt 
and dominate the cool and drier land.

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They eventually evolved and increased in 
number.

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The Mesozoic, or "Middle Life" Era.

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Life diversified rapidly and giant reptiles, 
dinosaurs and other monstrous beasts roamed 
the Earth.

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For the next 160 million years, dinosaurs 
were the dominant land vertebrates on Earth.

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The dinosaurs adapted to their ecosystems.

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Some adapted as herbivores and some as carnivores.

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The union of the dinosaurs produced hybridization 
of dinosaurs.

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Spread of seeded plants resulted in more 
oxygen and less carbon,

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providing a more suitable habitat.

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The supercontinent Pangea eventually tore 
apart into smaller continents and drifted 
the dinosaurs apart.

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This is evident to the dinosaur fossils found 
on separate continents.

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A Dark Nebula collided with our solar system, 
covering the heat from the sun.

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Global cooling damages the ecosystem and 
kills many of its inhabitants.

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Finally, a meteorite struck the earth's seabed

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Creating a massive explosion that produced 
intense heat and deadly wind of dust across 
the globe leading to dinosaurs' extinction.

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The start of the Cenozoic era signaled the 
end of the dinosaurs.

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A 6-mile wide asteroid fell from the sky 
and obliterated most of the reigning reptiles.

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The fall caused a massive dust cloud that 
resulted to the decrease of the Earth’s temperature.

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This change in the climate the dinosaurs 
were not used to ensured their total destruction.

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Mammalian creatures were existent before 
the start of the Cenozoic Era.

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They were small and often hid from the dinosaurs 
that roamed the earth.

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The extinction of the dinosaurs let them 
emerge from their hiding and grew bigger 
to now dominate the land.

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Early Primates who emerged from the line 
of mammalian creatures stayed near their 
primary food sources, the trees.

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As time passed, trees became scarcer while 
grass grew more prolifically.

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They were forced to walk and look for new 
food sources.

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It is theorized that to see beyond the tall 
grass, ancient apes slowly evolved to walk 
on two legs and stand tall.

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They slowly mastered how to use their now 
hands from walking on four legs.

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Hominids or the early proto human learned 
how to wield objects in the form of sharpened 
silicon rocks.

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They wielded tools and by the Stone Age fire 
was discovered.

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This enabled humans to cook their food and 
gain more energy from their hunts.

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We slowly learned how to make complex sounds 
and reach the point of communication.

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The discovery of farming resulted into a 
shift from nomadic and slowly to community 
building.

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Through the social structures we were able 
to progress as a race and reach the modern 
man.

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The life on earth has come a long way.

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From a simple single-celled organism to the 
complex structures found in each living being.

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We have come a long way.

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Throughout the years we slowly developed 
our technology to reach this modern era of 
science and advancement.

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In the years to come, what developments could 
the modern man encounter that could drive 
humanity to a new era?