The Earth- a giant hunk of rock and water
that's home to the only known life in the universe. It's so vast and old that it seems unchanging,
yet it has in fact experienced cataclysmic upheavals and routine facelifts over the course
of its 4.5 billion year lifespan. Just like a human being, the earth ages, and
as it does it goes through major changes. Hello and welcome to another episode of The
Infographics Show- today we're taking a look at the most important events in the Earth's
history. 4.5 billion years ago the Earth and most of
the solar system was nothing more than a ring of protoplanetary dust circling the sun. However over time gravity gradually drew individual
particles of dust together, creating ever larger clumps. Eventually the clumps grew to the size of
boulders, then to the size of mountains, and over many millions of years the Earth was
formed. Yet this newborn earth was nothing like what
you see today, with little if any water and a surface that was perpetually molten. Over millions more years the outer layer cooled
however to form a crust, and planetary impacts of comets and asteroids brought all the water
that you see today to the Earth from space. Not long after the Earth's creation it's thought
that gravity put it on a collision course with another nascent planet roughly the size
of Mars. This planet, named Theia, slammed into the
Earth with 100 million times more energy than the impact that wiped out the dinosaurs, and
hurled vaporized chunks of both bodies out into space. Gravity eventually bound the ejecta together
and created our Moon. This impact gave our planet the tilt it has
today, which in turn gives us our four seasons, and helped stabilize its spin- two things
which scientists believe were critical for the evolution of advanced life. Sometime between 4 and 3.5 billion years ago
the first organisms evolved on earth. Scientists aren't exactly sure on when this
occurred as the oldest confirmed fossils of single-celled microorganisms are 3.5 billion
years old, but there could be undiscovered older fossils waiting to be dug up. What scientists do know is that life evolved
almost as soon as it possibly could, immediately after the heavy bombardment stage of our earth's
evolution when it was being periodically slammed by huge asteroids and comets. This gives many scientists hope that life
is actually abundant in the universe, and not just here on Earth. It's believed that the first life on earth
used chemical reactions to power itself, but it wasn't long after it first appeared- perhaps
as short as just 100 million years- that microorganisms evolved to use sunlight for energy. By capturing rays of sunshine these microorganisms
were able to make sugars from simple molecules, a vastly more efficient means of providing
energy than the chemical reactions employed by their ancestors. Photosynthesis, and the unlocking of exponentially
greater energy potential in organisms, may have been the key to life's diversity. About 3.5 to 3.2 billion years ago the first
continents began to form and plate tectonics began in earnest. Before this it's thought that giant plumes
of very hot magma shot new material straight to the surface and began to build landmasses,
but as heat-generating radioactive elements began to run low in the Earth's interior,
the mantle began to cool and less and less of these 'super plumes' were created. This allowed convection cells to become stable
in the mantle and start driving the movements of huge continental plates. If you like breathing oxygen- and we suspect
most of you do- then you should be grateful to tiny little bacteria that existed 2.4 billion
years ago. For half of the Earth's life there was very
little oxygen in the atmosphere, but then suddenly some bacteria evolved to use photosynthesis
to make sugar from carbon dioxide and water, much the same way as plants today. This was a huge leap forward in evolution,
as before then photosynthesizing microbes did not release oxygen as a waste product. Known as the Great Oxidation Event, this turning
point in earth's history is also known as The Great Oxygen Catastrophe, because the
introduction of this volatile gas was toxic to most pre-existing life. These tiny oxygen producing microbes would
go on to kill almost all life on earth as a consequence. Around 1.2 billion years ago life took another
significant leap forward when two microbes got together, put on some slow jazz music,
dimmed the lights, and invented sex. Scientists don't know why organisms simply
stopped dividing in two to reproduce, but they discovered fossils of red algae which
are thought to be the first organisms to develop specialized sex cells- in their case, spores-
indicate the change was relatively sudden. Shortly after the invention of sex, life took
its most significant leap forward, developing the first multicellular organisms about 1
billion years ago. Up until then life had consisted solely of
single-celled organisms living individually or in colonies, but now cells were working
together to form complex life and creating things like mouths, limbs, and sensory organs. Plants would beat animals to the punch though,
and secure a foothold in this brave new world first. Another mystery of science, the Cambrian explosion
took place 535 million years ago and gave us almost every group of modern animals alive
today. Animals exploded in variety, sizes, and shapes,
and filled every available niche both on the seafloor and in the water column. This explosion of animal life also saw the
evolution of the first predators, and launched the predator/prey arms race of weapons and
defenses that persists to this day. Towards the end of the Cambrian Explosion,
about 465 million years ago, plants began to venture onto the land. Descendants of green algae, plants quickly
diversified into the descendants of today's modern plant life. Animals also made the trek to land, but only
briefly- most likely to lay eggs somewhere without predators. However these brief forays and the expansion
of plant life on land led animals to begin to evolve to exist on land. These first plant eaters were quickly followed
by their predators. About 460 to 430 million years ago though
things took a turn for the worse for Earth's budding animal and plant life. Though life had exploded during the Ordovician
period, towards the end the planet began to cool and ice sheets spread out from the poles. 85% of all marine species were wiped out,
and fish became much more common as a result. Evolving from newt-like amphibians, the first
reptiles appeared about 320 million years ago in the middle of the Late Paleozoic Ice
Age. Unlike their amphibian ancestors though reptiles
had tough, scaly skin and laid eggs with hard shells. These evolutionary adaptations allowed them
to leave their amphibious lifestyle behind and begin the colonization of the earth, eventually
leading to the age of the dinosaurs. Before dinosaurs could arrive on the scene
though, the earth threw a particularly violent temper tantrum lasting millions of years and
exploded with volcanic activity. Toxic gases in the atmosphere led to the acidification
of the oceans, killing up to 96% of all marine species and almost all land animals as well. Despite being nearly wiped out- again- life
would bounce back, and in the aftermath of what is now known as The Great Dying, the
first dinosaurs evolved. As dinosaurs began to rule the earth 220 million
years ago, a small group of them took a different evolutionary path. Descending from small reptiles called cynodonts
with faces like dogs and possibly even having fur or whiskers, the first mammals were the
size of a shrew and were almost certainly only active at night so they could avoid being
easy meals for their dinosaur overlords. Their nocturnal lifestyle may also have led
to their warm-bloodedness, and the ability to keep their body temperature constant regardless
of the environmental temperature- a key adaptation for surviving a future catastrophe... Sixty five million years ago a giant asteroid
larger than Mount Everest smashed into modern-day Mexico. The asteroid was so huge that just as the
tip was touching the surface of the earth, its uppermost edge was still high up in the
atmosphere. The initial explosion devastated a large area
of the earth and created tsunamis that wiped out coastal areas. As debris from the explosion was hurled up
into space and re-entered the atmosphere on the other side of the earth, it set off huge
forest fires around the world. Dust thrown into the upper atmosphere would
block out sunlight and bring about a miniature and sudden ice age that would be the fifth
and last mass extinction on our planet. You probably didn't know, but the first mammals
were actually egg layers just like their reptile brethren. In the aftermath of the global extinction
event that killed off the dinosaurs though many mammals began to nourish their young
inside their womb, which was safer than laying eggs in a cold, hostile world. About 60 to 55 million years ago, some of
these early mammals evolved into the very first primates, who would eventually give
rise to modern apes, monkeys, and of course humans. The first true apes appeared in Africa about
25 million years ago, then suddenly about 13 to 7 million years ago the ape family split
into the ancestors of modern humans and the ancestors of modern apes. The oldest known hominid was Sahelanthropus
tchadensis, and lived about 7 million years ago. Hominids proved to be so successful that their
evolution continued down through the ages until finally, 200,000 years ago we appeared
on the scene, irrevocably changing the earth forever. Our earth has a long and storied history of
death, rebirth, and constant change. It might seem static and unchanging to us
with our short life spans, but we've only existed for a blink of an eye in terms of
planetary history, and the processes that shape our world and the species within it
are constant and incessant, working every single day to create a new future. For the first time in the earth's history
though what that future may look like is largely dependent on one of its own species, and as
we face the threats of global warming and ever-more destructive wars, we will be largely
responsible for our own survival or extinction in a way no other species has ever been. If you could have been alive to see any event
in Earth's history, which would it be? What will the future of the Earth look like? Also, be sure to check out our other video
Days That Changed Mankind Forever! Thanks for watching, and as always, don’t
forget to like, share, and subscribe. See you next time!
