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Humans in the Universe13 Billion – 200,000 Years Ago

Big Era One

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Welcome, fellow time travelers!Me llamo “Mundo!” Nice to

make your acquaintance. I don’t know how you found me, but I

think you’ll be glad you did. Since you’re here and so am I,

let’s take a little trip, huh?

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I’m glad you’re here!People have been kind of ignoring me lately, so I’ve

been thinking a lot and wanted to share this story

I’ve been writing. It’s about me, of course (it’s my story, right?), but it’s about you,

too...

Let me start with a coupleof questions I’ve been

thinking about...

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Where did our Earth come from?

How did the universe come to be?

How & when did we humans

appear on Earth?

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Deep questions, huh?

Yeah, but I’m not the onlyone asking them...

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All peoples have explanations of our origins.

The Maidu people, native to California, say that Earth Starter made the world from some green slime Turtle brought up from deep underwater. He made humans from red earth mixed with water.

… And the Chinese used to say that Phan Ku – no thing, not yet born – burst from a hen’s egg and became the Great Creator.

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Scientists offer a different explanation, based on evidence gathered from sources on earth and in space. Here’s what they might say:

Long ago, there was no time...

There was no space...

But 13 billion years ago...

things changed.

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BANG!

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Where there had been nothing, now there was everything. The whole universe – tiny, and fantastically hot.

For an instant, it expanded faster than the speed of light. Then it slowed down but kept expanding, as it still is.

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As the universe cooled down, clouds of hydrogen and helium gas began to gather together, their centers getting hotter and hotter.

Big

Ban

g13 b

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And when they were hot enough, the hydrogen atoms began to fuse together with the power of millions of hydrogen bombs.

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STARSWERE BORN!

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They clustered together in vast galaxies, each containing billions of these new stars.

I can’t see us yet...

Stars &Galaxies

12 bil yrs ago

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Four and a half billion years ago – when the universe was already two-thirds as old as it is today – a star was born near the edge of a galaxy we call the Milky Way:

OUR SUN!

Our Sun & Planets

4.6 bil yrs ago

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rs &

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Around the sun, wisps of matter were drawn together by theforces of gravity to create the planets of our solar system…

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…Including the third rock from the sun:

OUR EARTH!

What a What a cute baby, cute baby,

huh?huh?

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The early earth was incredibly HOT.

Heavier metals melted and sank to the center, lighter metals rose to the surface, and gases bubbled up to make the earth’s first atmosphere.

Anybody got something for

a stomach ache?

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By four billion years ago, the earth had cooled enough for water to condense into oceans. And so the earth turned blue.

The surface hardened into thin “plates” floating on the molten materials underneath. Those “plates” float on the surface to this day, constantly changing the landscapes and weather patterns on the earth’s surface.

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Where the plates collided, great mountains were formed...

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...and where they tore apart, melted rock poured out from under the surface.

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Deep within the newly formed oceans, complex chemicals were created using volcanic heat for energy.

Some of these chemicals became so highly organized that they formed cells – the first LIFE ON EARTH!

FirstLife

3.8 bilyrs ago

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Our

Sun

& P

lanet

s4.6

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Living organisms changed the atmosphere, adding oxygen. Cells developed that could “breathe” oxygen...

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...and, about 600 million years ago, the first multi-cellular organisms arose in the earth’s oceans.

Big Era 1

3.8

bil y

rs

ago

Firs

t Li

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bil

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Our

Sun

& P

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ts4.

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es

12 b

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Multi-CelledOrganisms

600myrs ago

BigEras2-9

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The first animals appeared not too long after!

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After a while, some animals moved out of the oceans and onto the land.

First Lifeon Land

400myrs ago

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fe3.8

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250k

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ago

Today

Scale of Life on Earth

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Multi-

Cel

led

Org

anis

ms

600m

yrs

ago

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Dinosaurs were the most successful of the early land animals...

First Dinosaurs

220m yrs ago

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and

400m

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250k

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Today

Scale of Life on Land

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...but about 65 million years ago, a giant meteor came crashing down to earth...

...and the dinosaurs were no more!

Dinosaurs Disappear

67m yrs ago

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tD

inosa

urs

220m

yrs

ago

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and

400m

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Today

Scale of Life on Land

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MAMMALS!

This left a new class of animals dominant on the land.

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Over time, a particular group of mammals emerged that lived in trees.

To survive in that environment, these mammals needed 3D vision and large brains to process visual information. They also needed hands that could grip with precision. (Imagine living in a tree without any of these. You’d fall out!)

These mammals were the first PRIMATES.

Then, about 7 million years ago in Africa, a branch of those primates became the first to stand upright.

These were the first HOMINIDS. Different hominids lived on earth over the next 7 million years, some at the same time as others, but only one survives to this day...

US!!!30

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FirstHominids

7m yrs ago

The earliest hominids lived in small, family-sized groups. They gathered plants, insects, and small animals, and they occasionally scavenged the meat of larger animals killed by predators.

Din

osa

urs

Dis

appea

r67m

yrs

ago

250k

yrs

ago

Today

Scale of Life after the Dinosaurs

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4 – 1.5m yrs ago

Australopithecines

7m

yrs

ago

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The first hominids had brains about the size of a modern chimp’s. Over time, new species developed ever-larger brains, and they began to make more and more complex tools. The Australopithecines likely used sharp sticks to dig for food...

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Homo habilis

2.4 – 1.6m yrs ago

250k

yrs

ago

Today

4m

yrs

ago

Australopithecines1.5

m y

rs a

go

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...while Homo habilis hominids, a later species, were able to make stone tools. They chipped ‘flakes’ of stone from large rocks and used those flakes as knives. They also used the leftover ‘core’ to scrape out hides and do other jobs.

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250k

yrs

ago

Today

4m

yrs

ago

Australopithecines1.5

m y

rs a

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Homo habilis

2.4

m y

rs a

go

1.6

m y

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Homo erectus hominids, which lived on Earth for almost two million years, were probably the first ones who could control and use fire. They were alsothe first to leave Africa. Their fossils have been found as far away as China and Java (inmodern Indonesia).

Homo erectus

1.8m – 27k yrs ago

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Social relationships among our ancestors were complex. Like modern chimpanzees, early hominids must have been quite clever, with a great deal of social cooperation and group politics. They cared for each other, especially their children.

WOW! These early ancestorsof ours sound a

lot like us!

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Well, in some ways that’s true – but this species was different in many other respects from our species. We have no evidence, for example, that they had art, religion, or language.

ART RELIGION LANGUAGE

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So, what’s so special about

us? What makes us

HUMAN, and how did we

BECOME human?

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End of Big Era One

Well, you’ll just have to wait for

BIG ERA TWO to get the answer to those questions!