In which John Green teaches you about Vikings! That's right, one of our most requested subjects, the Vikings, right here on Crash Course. So what's the deal with Vikings? Well, the stuff you've heard about them may not be true. The...

European exploration had a lot of side effects. When the Old World and the New World began to interact, people, wealth, food, animals, and disease began to flow in both directions. In the New World, countless millions were killed by...

We've been talking a lot about kings, and queens, and wars, and religious upheaval for most of this series, but let's take a moment to zoom out, and look at the ways that individuals' lives were changing in the time span we've covered so...

The North American continent used to have deep roots extending far into the Earth's mantle. They melted. Here's how scientists think they disappeared.

If you’ve been around the internet long enough, you’ve probably heard of the “conspiracy” that birds aren’t real (It's not a real conspiracy theory; it was started as a joke). Well for decades, scientists have been using fake birds (even...

Mushroom foragers rejoice! Your lives just got a whole lot easier! Now, we can farm four mushrooms that used to only be found in the wild: morels, huitlacoche, chanterelles, and truffles. Here's why it took so long.

Most cultures who developed metalworking technology never let the skill go to waste. But in what's now Michigan, Native Americans started making metal tools well before anyone else did, and then stopped. And the reason why this happened...

Where does water come from? If you turn on the faucet, there's water. But it goes on an incredible journey to get there. Today, Jessi and Squeaks learn about all the places we can find water.

How did the "false horse," Thoatherium, and its relatives survive when their hoofed legs seemed to be adapted for an ecosystem that wouldn't exist for another 12 million years?

The rise of the Himalayas affected more than just the immediate area. Turns out, we may have them to thank for everything from the rise of giant flightless birds in Madagascar; to the disappearance of plants from Antarctica; to the...

Where are all the east coast dinosaurs? Why don’t we find famous species like Triceratops in Central Park? Turns out, evolution and geology came together to make the east coast into an ancient lost world of weird dinosaurs.

Mountains have a unique effect on diversity, messing with our understanding of animals through time, and pretty much just making evolution weird. And they would eventually reveal something even stranger about a group of mammals even...

How did a relative of the red panda end up in North America? What can this tell us about how long ago – and how many times – North America was connected to Europe and Asia?

This is the hundred-year tale of how an unlikely bunch of bottom-dwelling marine critters helped reveal that ocean basins are basically reincarnated every few hundred million years.

There are a lot of great debates in science, and a major one is when exactly humans reached the Americas. There's contentious footprints and wishy-washy stone tools, all of which has spurred some heated academic arguments. But the most...

Sometimes, one animal ends up in an evolutionary arms race with another for millions of years. Here are four fascinating examples, including our own showdown with snakes. <b<br/>r/>

Hosted by: Jaida Elcock (she/her)

Trilobites are one of the most iconic fossil animals out there. And people have loved them for centuries! Let's talk about the people across time and space who have loved collecting trilobites, from Elrathia to Calymene, going back...

It's not just your imagination. Turbulence on airplane flights is getting worse, including severe turbulence that could cause injuries. The reason is the climate crisis -- here's how.<b<br/>r/>

Hosted by: Tom Lum

Groundhogs are famous in North America for "predicting" when spring will come (and also that Bill Murray movie). But while they might make for terrible meteorologists, they actually play a valuable role in several other scientific...

When monarch butterflies migrate, they produce one of the most iconic wildlife spectacles in the world — and provide us with an important indicator of ecological health, says photographer Jaime Rojo. Telling a story about our...

Which Bear Is Best?

Join Squeaks and Jessi as they learn about a time when lots of animals switched places -- like bears, sloths, armadillos, and more.

Come with Jessi and Squeaks as they explore some of the animals that roamed the Earth during the ice age. And a lot of these animals had giant features, like teeth the size of bananas or mouths shaped like a shovel!

There's an eclipse coming up in April of 2024! You'd think it takes a lot of modern technology for us to know about it, but it turns out that humans have been able to predict eclipses for nearly three thousand years. And we've been...