They form natural boundaries, dictate how we spread around the planet, create natural defenses, and control our weather. From the World War that began with a gunshot in the Balkans to the feuds of the Appalachians, mountains have also been flashpoints for violence. They provide minerals and metals that make civilization possible, and the water that feeds billions, yet we were never designed to live in their extreme environments. Without mountains earth would be desolate and uninhabitable, and scientists now believe that an invisible mountain range made life possible ...

Humans have small teeth and no claws or armor, so how do we project our power? Warfare has defined traditional history, but Big History digs deeper to reveal how it all began. We see how bat poop and ancient trees shaped the history of weapons, and link the gun all the way back to a change in our bodies that turned us into throwing machines.

Behind that cup of coffee or tea is a global story that goes back to the collision that created the Moon and the evolution of plant and animal life. The key is the molecule that gives your morning cup its kick: caffeine, the most popular drug in history. This is the story of how a plant poison became our drug of choice, and stimulated revolutions around the planet.

Flight takes more than wings. We need the right kind of air, the perfect materials cooked up over billions of years, and cosmic forces that are just right for us to leave the ground without tumbling off into space. Big History reveals how planet Earth is the perfect planet for flight.

From the Great Pyramid at Giza to the towering skyscrapers of today, humans have engineered massive constructions for at least 5,000 years. But why? How do biology and human emotions affect our desire to build gigantic structures? Why were the earliest mega-structures almost always pyramids? Why do people have the urge to build tall, and how do mega-structures on earth echo a basic principle embedded in the very structure of the universe?

Reveals how cold has the power to turn men into Barbarians, spark history's longest running war, and create the concept of race. After the heat of the Big Bang, cold creates the Universe and the planet as we know it. For thousands of years on Earth, cold controls the fate of our species by changing our bodies, our skin, and even the metals we use to fight our wars. When we finally take control of the cold, we learn to dominate the planet.

This episode asks why mankind is gold crazy, and discovers there's a hard-wired reason we lust after it, and a microscopic explanation for why it shines. We reveal how the science behind our favorite metal drives men across oceans and continents, and how a difference in the way it's used in each hemisphere leads to a clash of civilizations.

The horse has been a revolutionary animal in unexpected ways. It has changed how we speak, what we wear, and sets the hidden limit for the size of our most massive empires. It's a story that spans the cosmos, from the Big Bang, to the Sun, to a changing planet that turned the horse into man's best friend in the animal kingdom.

We all know that mankind can't live without air, food and water...the same is true of salt. The salt on your table is a key to unlocking the story of our planet and the cosmos. Big History reveals how this simple molecule underpins our civilization, launched wars, built monuments like the Great Wall of China, sparked revolutions from India to France...and it's even the substance that makes up our thoughts.