1. The History of Planet Earth

2. The History of Planet Earth: Sections
How the Earth was Born
An Unrecognizable Planet: The 1st Billion Years
Setting the stage for Life as We Know It
The Rise of Eukaryotes and Multicellular Life on Planet Earth
The Last 500 Million Years: A Surge in Variation and Complexity
The Rise of Humanity: Where we’ve been, Where we are, and Where we’re going…

3. How the Earth was Born
Every object in our solar system, large and small, was born from an exploding star approximately 4.6 billion years ago.
Over time the planets formed as gravity pulled together bits of matter into larger and larger bodies. This process is called “planetesimal Accretion.”

4. Did you Know?...
Every atom in your body was once part of an exploding star!

5. An Unrecognizable Planet: The 1st Billion Years
With its surface composed of molten rock, the early Earth was extremely hot & inhospitable . It had a poisonous atmosphere, no liquid water, and was constantly being bombarded by planetesimals from space.

6. The Formation of the Moon: The Collision Theory
In a violent collision of incredible magnitude, a large body from space collided with Earth in its infancy. Nearly 30% of the matter making up the molten surface of our planet was dislodged and became much of what our moon is today.

7. The Earth Cools
After a few hundred thousand years, the outer portion of the planet cooled as the constant bombardment diminished. Liquid water (courtesy of volcanic outgasing and delivery from comets) condensed into our oceans, and the planet began looking somewhat like Earth as we know it.

8. Early Earth’s Atmosphere
Earth atmosphere during the 1st billion years was much different than today. A mixture of poisonous ammonia (NH3), carbon dioxide (CO2), water vapor (H2O), methane (CH4), and nitrogen (N2).

9. The Miller-Urey Experiment
This landmark experiment yielded amino acids from the atmospheric components present in the primordial atmosphere.

10. Challenge Question!...
What did the spark in the Miller-Urey experiment represent?

11. The ‘Primordial Soup’ and the Origin of Life
Many scientists believe life originated in a warm shallow pool about 3.8 billion years ago.
The first life forms would have been anaerobic prokaryotes much like the archebacteria found on earth today.

12. New Theories About the Origin of Life
Although the ‘primordial soup’ hypothesis is still viable, many scientists believe life originated in a ‘reducing’ environment on crystalline and/or clay surfaces.

13. Precursor to the first cell: The “Ribozyme”

14. Setting the stage for Life as We Know It: Cyanobacteria
About billion years ago, the evolution of a specific prokaryote began primitive photosynthesis, setting the stage for the advancement of life by producing oxygen gas.
For over a billion years, these bacteria continued to ‘pump’ oxygen into the atmosphere, changing the face of the planet.

15. The 1st Eukaryotes and the Endosymbiotic Theory
DNA evidence shows that mitochondria and chloroplasts were actually once free-living prokaryotes.
The Endosymbiotic theory states that an ancestral prokaryote engulfed and initiated a symbiotic relationship with these specialized bacteria, resulting in the 1st single celled eukaryotes.
Link:

16. The Endosymbiotic Theory

17. The Evolution of Multicellular Life: 650 Million Years Ago
As eukaryotes evolved into increasingly varied and complex forms, they began working together, developing into the first multicellular organisms.

18. Multicellular Life
It is thought that multicellularity evolved many times independently, meaning plants, animals, and fungi had independent evolution paths.

19. Did You Know?...
Some of the first multicellular organisms, the Ediacaran fauna were soft bodied creatures which thrived about 570 million years ago.

20. The Last 500 Million Years: A Surge in Variation and Complexity
As life proliferated in the ancient oceans (and eventually on land) plants and animals became more varied and complex.
Here are some of the highlights…
What landmark events can you pick out?

21. The Cambrian Explosion: 550-500 mya

22. The Ordovician and Silurian Periods: 510-440 mya

23. The Devonian and Carboniferous Periods 415-360 mya

24. The Pennsylvanian and Permian Periods: 360-245 mya

25. The Triassic, Jurassic, and Cretaceous: 245-65 mya

26. Mass Extinction Events and the Evolution of Life on Earth
An Mass extinction event is marked by a sharp decrease in the diversity and abundance of life on Earth. (examples include Ice ages and asteroid impacts)
There have been anywhere from mass extinctions on our planet in the last 500 million years, each time ‘cleaning the slate’ for the evolution of new forms.

27. The Cenozoic/Tertiary Period 65 mya-present

28. Earth’s Timeline 3.8 billion years of simple cells (prokaryotes),
3 billion years of photosynthesis,
2 billion years of complex cells (eukaryotes),
1 billion years of multicellular life,
600 million years of simple animals,
570 million years of arthropods
550 million years of complex animals,
500 million years of fish and proto-amphibians,
475 million years of land plants,
400 million years of insects and seeds,
360 million years of amphibians,
300 million years of reptiles,
200 million years of mammals,
150 million years of birds,
130 million years of flowers,
65 million years since the non-avian dinosaurs died out,
2.5 million years since the appearance of the genus Homo,
200,000 years since humans started looking like they do today,
25,000 years since Neanderthals died out.
Taken from:

30. The Rise of Humanity: Where we’ve been, Where we are, and Where we’re going…
Humans and their ancestors have only evolved in the last 2.5 million years. Geologically speaking, our entire existence spans a mere ‘blink of an eye’ in the Earths long history.

31. The Rise of Humanity: Where we’ve been, Where we are, and Where we’re going…
Modern humans (existing for approx. the last 40,000 years) have accomplished unimaginable feats in an incredibly a short period of time.
Can humans use their intelligence and technology to survive vast expanses of time like the dinosaurs? Or will we succumb to our own self destructive behavior?
What about a mass extinction event?

32. That’s All Folks!