Imagine if you could take in
all of human history
in the blink of an eye.
Well, from the first steps out of the slime
to the first steps on the Moon
that's exactly what we are in cosmic terms.
But in that short amount of time,
we have done quite a bit.
What would you see if you traveled
one billion years into the past?
In a sense, we're all time travelers.
We travel into the future at the rate
of one second per second.
But if you want to go backward in time,
you'll need to go faster
than the speed of light.
That's according to Einstein.
Or maybe your time machine
could jump through wormholes,
a hypothetical tunnel that connects
two different points in space-time.
However you decide to travel
through the jumbled mess of time,
you'll see the effects and then the causes
of the most powerful forces
that shaped our world.
As you watch history unfold, or refold,
or whatever,
you might be surprised at the toll
humanity has taken on this planet
in such a short amount of time.
If you start in 2021 and move backward,
you would watch the sixth
mass extinction event happening right now.
Known as the Holocene extinction,
we are currently living through
one of the most destructive periods
of our time,
caused by human activity.
As humans destroy coral reefs
and rain forests,
the numerous wildlife and plants
that depend on these ecosystems
die with them.
According to the International Union
for Conservation of Nature,
And since most of these extinctions
are undocumented,
we won't even know about what
we've lost until it's gone.
Maybe not even then.
Visit the 18th and 19th centuries,
and you could watch the pollution
created by the Industrial Revolution
reversed back into the smokestacks.
Cities would shrink down and return
to their roots as rural farmlands.
While this would let you see
the explosion of the human race
in terms of population and pollution,
if you want to retrace our first steps,
you'll need to go back farther.
Tour the planet 200,000 years ago,
and you would witness
the arrival of our species,
the homo sapiens.
Jump back 7 million years
to Northern Chad,
and the oldest known species of humans
could stroll right by you.
Known as the Sahelanthropus tchadensis,
this mysterious link in our chain
looked ape-like
but was the first to walk upright.
He seems friendly enough.
If you think you have challenges now,
imagine living during this age.
You would need the skills
this early human learned to survive,
and you would need them fast.
But if you sign up with The Great Courses Plus,
you can make this year,
whatever that is,
yours, by learning with a purpose.
With top experts in their fields
taking deep dives into a wide range of subjects,
there's something for everyone.
If you're spending time with our primitive ancestors,
you might want to take the Outdoor Fundamentals course
covering everything from
preparation to navigation.
Or maybe Introduction to Paleontology,
to mentally prepare you to meet the Spinosaurus,
the largest carnivore to ever walk the Earth.
Well, you can watch,
or listen to these lectures on any device,
anywhere, with the Great Courses Plus App.
Visit The Great Courses Plus dot com slash What If
to get a 14-day trial with unlimited access.
That's The Great Courses Plus dot com slash What If.
You won't have a chance
to go back in time to get this deal.
And if you don't study up,
you may not make it past the Jurassic era.
But travel to 60 million years ago,
and you'll see the first primates
emerge from the humid rain forests of Asia.
Okay, step back to 65 million years ago,
and you'd find yourself under
the giant asteroid that created
a global extinction event.
The impact caused a tsunami
and filled the air with dust
and debris.
The crash also set off
massive volcanic eruptions
across the world.
With the Sun blacked out
and the land flooding,
the last of the dinosaurs died out.
But without this event,
mammals like us may have never taken
over the planet.
Go back 130 million years,
and you'll see the first flowers bloom.
As you travel 200 million years
back in time,
you'll witness the breakup of Pangea,
the mass of land
that will become the continents.
As the land breaks apart,
the lava eruptions will be so massive
they kill almost
Keep going back another 20 million years,
and you could watch
the first early mammals,
small and nocturnal,
crawl around in the dark.
And if you go back
to 230 million years ago,
you could watch the early dinosaurs
walk for the first time on two legs.
Before that can happen, though,
the Earth has to go through
what would be known as the Great Dying,
also called the Permian extinction.
95% of all species on Earth died.
You could also watch the Earth's
landmasses come together
to form Pangea.
Now you could take a walk
from Argentina to China.
But things get interesting
around 375 million years ago.
You would watch marine animals walking
onto land for the first time.
Maybe you would see a Tiktaalik,
which looks like a salamander
mixed with a fish.
This strange creature would later
evolve into mammals and amphibians.
But just like every species
you saw before,
this growth doesn't happen
without a cost.
And now we're at the first extinction event.
The Ordovician extinction occurs
when ice sheets spread
from the polar caps into the oceans.
Almost 70% of all sea life died off
during this planet-wide freeze
over 460 million years ago.
Keep going back,
and you could see how
life started underwater.
Called the Cambrian Explosion,
the lineage of most of the species
on our planet today
can be traced back to this milestone.
But scientists are still unsure
how this unique event happened.
Between 635
and 850 million years ago,
the Earth froze over twice.
Once for almost 60 million years,
and the next time for 15 million years.
One theory suggests that
the Earth was only covered
in a thin film of ice,
allowing the Sun's rays
to seep through
and plant the seeds of life below.
But go back one billion years in history,
and you'll be surprised to find,
well, not a lot.
During this time,
red algae are forming
spores to reproduce.
Cells are coming together
to form larger organisms.
Life on Earth is microscopic
and not very threatening.
But nothing has been more vicious
to our planet in such a short amount
of time as humans.
But maybe humans will set things right,
eventually.
There could be a change in our planet,
or our hearts,
that might set our future
on a different path.
Or maybe, like the dinosaurs
and the neanderthals,
we would be replaced
by something else.
So let's take our time machine
and find out.
What if you traveled
one billion years into the future?
Well, that's a story for another WHAT IF.