What If We Traveled  One Billion Years Into The Past?

 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 further. 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.