Name: どうやってここに来たの？ (How Did You Get Here?)
Uploaded: 2021-01-14T10:37:51.000Z
Duration: 5 min 56 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

You just clicked on this video, so you're alive

and interestingly in order to understand exactly where you came from

reproduction and evolution. It's important to

remember this as we go way back in history to figure out exactly how you got here.

Astronomers believe our solar system began

to form 4.6 billion years ago, when a star exploded

and around 500 smaller planets collided with each other

to from the inner planets we know today, including your home, Earth.

Earth was too hot for life, most of the water was

evaporating into space, and even if some simple chemical

reactions began to take place creating life,

the comets and meteorites hitting Earth at the time

would have brought enough heat to make the developing oceans boil,

destroying all potential life. As comets and meteorites subsided

Earth cooled and it became possible for water to remain on the surface.

about 3.7 billion years ago. There are many theories about how

exactly it began, some believe simple life

arrived from a meteorite, while others think chemical evolution

or perhaps they were struck by lightning. And while the exact date

is difficult to pinpoint, a new study claims to have found

years old. An ancient microbe that flourished

around a hydro-thermal vent on the ocean floor. It's around

this time that the first simple cells began to evolve

on Earth, they were able to capture energy, replicate themselves

on which all life will be built, including you.

For 2 billion years, all organisms on Earth are

unicellular, and they likely lived in the oceans,

shielded from the hard ultraviolet (UV) light of the sun

but then something remarkable happened...

Around 2.5 billion years ago, a random mutation occurred that was

advantageous to cells, and they began using the energy of the sun to power their metabolism.

is the product of photosynthesis, our atmosphere changed

eventually creating the ozone layer which acted to shield the Earth

from the sun's deadly light. Of course at this point

but over time, cells evolve to tolerate it, and because metabolic

reactions using O₂ were more efficient, cells could grow larger.

cells begin to engulf and co-opt smaller cells,

increasing their abilities to live in diverse environments. This

selective advantage led to cells sticking together in a coordinated manner

even after dividing, and these cells eventually

AKA, they had sex. Single celled organisms would divide by mitosis

meiosis evolved, genetic reorganisation began to occur

and the rate of evolution increased as offspring

were now more genetically variable and some of these offspring

were more likely to survive and reproduce, and so the tree of life

began to explode. First there were plants

and then fungi, coral then protosomes like crabs,

echinoderms like sea urchins and then fish like sharks

and began adapting to living outside of the water part-time,

initially gulping air and absorbing oxygen in the gut.

As time passes, species would evolve lungs separate

from the gut for absorbing air as well as a new way to walk

dinosaurs and finally, mammals. In fact our entire

ancestry stems from a cute, furry tailed, rat-like mammal

which survived and thrived around 66 million years ago

just after an asteroid wiped out the dinosaurs.

And after tens of millions of years of evolution

and new species emerging, one branch of the Protungulatum family tree

evolved into our ape and monkey ancestors. And nearly 4 millions years ago, one of the first

human-like creatures arrive, Australopithecus Afarensus,

the most famous discovered remains being that of Lucy, who stood upright.

or 2-3 millions years ago, the species group

and started using their hands for more complex activities like creating and

wealding tools. This was the first step of transforming

our environment to improve our lives. It was also

a catalyst to switching from a vegetarian diet

to one containing meat which is a more concentrated

form of nutrition, and less effected by seasonal shortages.

These simple stone tools allowed us to rip through meat

and would become the tool of choice for 2 million

years. And around 1.8 million years ago, homo erectus

emerged, the direct ancestor to our species.

Finally, a few hundred thousand years ago, modern humans,

or homo sapiens, step into the light. Larger,

smarter and more capable than their predecessors.

A climate change event around 140 thousand years ago

plummeted the human population to only hundreds of people,

three different species of the 'homo' family co-exist.