Timeline of history
In this module, we will use the following abbreviations.
B y a. Billion years ago.
K y a. Thousand years ago.
Y a. Years ago.
13.7 B y a. The Big Bang creates all the energy, that will ever exist in the universe.
After about 318 thousand years, the first atoms of hydrogen were born.
The hydrogen atoms spread out, but not evenly.
Some pockets have more atoms, then the rest.
Gravity plays a big role, in sculpting the early universe.
13.4 B y a. Clouds of hydrogen gas squeeze together.
This was the beginning of galaxies.
The temperature was 18 million degrees.
Hydrogen atoms collide, and create the first Helium atoms.
The first stars are born.
Millions of stars are born in one galaxy.
The universe has billions of galaxies.
Stars are the nuclear reactors which created other elements within it,
through nuclear fusion.
Hydrogen fused to form Helium.
Helium fused to form Lithium.
Twenty five of the most common elements,
like carbon, oxygen, nitrogen and iron,
was produced in this manner in stars.
Some stars grew and exploded.
They are called supernovas.
The explosion provided the extra energy,
required for heavier elements.
Copper, Gold, Uranium, and the rest of the naturally occurring elements,
in the periodic table, was created in the stars.
The element factory in the stars continue for 8 billion years.
Stars were born and reborn.
Each new generation of stars, produced more heavier elements, than the last.
The process continues.
4.6 B y a. Our sun is born.
Our sun is a relatively young star.
A cloud of gas, is left behind by the explosion of previous stars.
This cloud to coalesced to form the sun.
99.6% of the material goes to form the sun.
The rest of the material goes to form the planets.
4.5 B y a. The planet Earth is born.
When it was born, the Earth was spinning at a much faster rate.
It took about six hours to complete the revolution.
So, the Earth day, in those times was 6 hours.
Earth was a mix of rocks and Lava.
Gravity caused the lighter materials, to drift to the surface.
These materials hardened, to form the Earth's crust.
The core mostly contained molten, iron, and nickel.
The spinning iron, in the core, caused the Earth to have a magnetic field.
This magnetic field protects the Earth, from the charged particles,
coming from the sun.
Other planets collide with the Earth.
One of these planets, is the size of Mars.
These are high velocity collusions, involving speeds up to 40000 kilo meters per hour.
Much of the colliding mass, is swallowed up by Earth.
The left overs are gathered up by gravity.
The moon is formed.
The moon orbits the Earth.
The gravitational pull of the moon, stabilises the Earth.
It prevents it from wobbling.
This stable rotation, saves the Earth from wild climate swings,
The collation from a large planet, leaves the Earth in a tilted position.
The tilted position of the Earth, causes the seasons we experience.
The gravity of the moon slows down the rotation of the Earth.
From a 6 hour day, the Earth evolves into a 24 hour day rotation.
4.4 B y a. Initially the planet was very hot.
Water existed in the form of steam.
Over millions of years, the planet cooled down.
Water vapour condensed, and rained on the planet.
This water collected as lakes and other water bodies.
Eventually, the oceans were created from this rain water.
3.8 B y a. Water is a universal solvent.
Elements dissolved in water tended to interact, in chemical reactions.
Vents in the ocean, caused heat from the core of the Earth,
to escape into the ocean.
This heat probably aided the chemical reactions.
Carbon, hydrogen, nitrogen. oxygen, etc.. started to combine.
Somewhere along the way, it caused an interesting combination called DNA to form.
This was the beginning of Life.
2.5 B y a. Life emerges as different forms of bacteria.
Bacteria is able to harness, the sun's energy.
Oxygen combines with iron to form rust.
This collects on the sea floor.
Later they rise up.
Oxygen fills the oceans, and escapes into the atmosphere.
The atmosphere slowly becomes, rich in oxygen.
Bacteria adapts to live on oxygen.
Oxygen is 20 times more efficient.
This sets the tone for future life.
Organisms from now on will breathe oxygen to live.
550 M y a. Solid continents, have formed in the planet.
Oxygen levels in the atmosphere have increased from 1% to 13%.
Oxygen acts as a catalyst for the Cambrian explosion.
Earlier, life forms were simple cellular organisms.
The Cambrian explosion, resulted in a dramatic rise of diverse forms,
of more complex living organisms.
500 M y a. Bony fish started to appear.
This was the blue print of the body plan of many animals including humans.
The Ozone layer formed in the higher atmosphere.
This Ozone layer protects living organisms from dangerous radiation.
400 M y a. Plant life evolves in land.
Some life forms emerge from the sea, and test land life.
Some of them adapt.
This leads to the amphibians.
Amphibians could live on both land and sea.
Animals evolved from amphibians.
Animals could lay eggs, which had water inside them.
These eggs could survive on land.
Animals lead purely land based life.
Plants were the primary source of food, for animals.
Animals who would evolve to colonise most of the land areas.
300 M y a. Some tropical forest die.
They get buried in land, possibly during earthquakes.
Over millions of years, they get compressed, and become coal and crude oil.
These are the fossil fuels that we currently mine, for our energy needs.
These fossil fuels are a limited resource of the planet.
250 M y a. Volcanic activity in the planet spikes.
Atmosphere is chocked with carbon dioxide.
70% of the species become extinct.
This was the worst mass extinction in the planet.
It is called as the Permian extinction.
New forms of life emerged.
The gravitational force of the moon, helps the Earth,
to stabilise its rotational speed.
Earth settles down to a 24 hour day.
Hard wood forests start to appear.
The era of dinosaurs starts middle 160 million years ago.
All the continents are clustered together,
in a single land mass, called Pangea.
Medium size animals are eaten up.
The planet is populated by small mammals,
which co-existed with giant dinosaurs.
Dinosaurs ruled the Earth.
65 M y a. A large asteroid, about 10 km wide, slams into the Earth.
The impact is massive.
It changes the direction of the evolution of life.
Dust clouds caused by the impact, envelop the Earth.
They block out the sun rays.
Most of the large creatures, weighing more than 14 kg, go extinct.
This marks the fall of the dinosaurs, which become extinct.
This gives opportunity for a variety of mammals to rise.
Mammals typically have eyes facing opposite sides.
Some species evolve with both eyes facing forward.
This in turn, leads to the brain perceiving depth of vision.
Some of these species develop hands with 5 digits.
This is the hint of the early appearance of primates.
50 M y a. Primates are evolving in the hot jungles.
Africa is separated from the American continents.
Egypt is buried in an ancient sea.
On this sea floor, lime stone forms, from sea shells.
50 Million years later, these lime stones are used by Egyptians to build pyramids.
10 M y a. Mountain ranges forms.
The weather patterns are disrupted.
The planet starts getting colder.
Panama in the American continent, separates the Pacific and Atlantic Ocean.
This affects the ocean currents.
The world moves towards an ice age.
Most of the planet is covered with ice.
Primates managed to survive in the warmer tropics.
7 M y a. Primates live in trees in the forests.
Climate change results in more grass land being formed.
There are fewer trees and more grass land separating them.
Primates have to move from one tree to another to find food.
They have to climb down from the trees and walk on four legs to the next tree.
Somewhere in this process, they learn to stand on 2 legs and walk.
Standing helps them to see above the tall grass.
After learning to walk, primates find that there hands are free.
The probably wonder what to do with there free hands.
2.6 M y a. Hominids evolve from the primates.
They are the prototypes of humans who will evolve later.
Silicon is the most abundant material on the surface of the Earth.
Silicon combines with oxygen to form rocks.
Hominids use free hands to shape stones with sharp edges.
They find that this stone is very useful tool for hunting.
The foundations for the industrial revolution, is laid by tool making hominids.
800 K y a. The making of fire requires some unique ingredients.
Dry trees and plants, require oxygen from the atmosphere, and a spark provided by lighting.
Earth is a unique planet which offers all these ingredients.
Hominids learn to make fire and use it.
They use it to cook food.
Many types of food, which was previously in edible, now become edible.
This increases the food supply.
It gives hominids an edge over other species.
Cooking also provided more calories.
Many animals spend a large portion of their waking hours, hunting for food.
With more food and calories being available, hominids had more time at their disposal.
They started to think.
It is possible, that this triggered a faster and better evolution of their brains.
Modern human beings, have the most highly evolved brain ,
among all species.
Free hands, fire, tools and food, could have been some of the factor, that helped humans,
develop a superior brain.
200 K y a. Modern humans belong to the homo sapiens species.
Homo sapiens begin to appear.
They have a more evolved brain.
Homo sapiens develop the capability for making more complex sounds.
Using this they are able to share information among themselves, and across generations.
100 K y a. Africa and Asia, called Eurasia, constitute the largest contiguous place on Earth.
Half the land on Earth, can be reached by foot.
Some migration of homo sapiens would have started during this time.
50000 Y a. Ice age advances.
Glaciers advance.
Major migration of homo sapiens out of Africa begins.
30000 Y a. First homo sapiens in Europe.
20000 Y a. Peak of ice age.
Freezing ice, leads to decrease in oceans levels.
Oceans levels decrease by 300 to 400 feet.
The Bering land bridge connects Siberia to the continent of North America.