[Intro plays]

When people talk about the environment, they're usually talking about what we generally call the "natural environment." You know, the outdoors. Nature! The wild. But for most of us, our everyday environment looks a lot like where I am, in this room. 

My environment is the space around me. My home, the CrashCourse studio, and the city I live in. And even when I'm outside, I'm in a space that has been engineered by other people.

Obviously, these spaces aren't exactly natural. I mean, the grocery store didn't pop out of the ground like a spring daisy. No, the grocery store, my home, this room, these places are made by people.

To make our human environment, we've taken resources from other parts of the world, and, in the process, we've altered the environment that used to be there. These are examples of humans changing the space around them.

So today, let's explore the many ways that humans change their environment.

[text: Big Question]

Our effects on the environment are almost so obvious that we might actually miss them. But they're important to consider. Think about your life; What pieces of it are a result of human intervention?

Let's walk through your day. In the morning, you wake up in bed in a home that's made from natural resources, like wood taken from other parts of the world and shaped by people.

You go to brush your teeth, and the water coming out of your tap is a result of humans changing the water flow. Your water probably came from a river, or an aquifer a few miles away. Trust me, that water didn't naturally flow into your home. It was directed there by people.

Now it's time for breakfast. That food was grown on land that was altered by human hands. Maybe some forest was cleared to make space for the farmland. Wild animals were pushed off of that land and some new ones probably came in. The crops were probably watered by irrigation, again, the action of moving water from one place to another. And the plants themselves wouldn't be there if it weren't for people.

Then you ride your bike to school on the sidewalk. The pavement is an alteration of the environment. When it rains, water slides across it's surface and down into drains instead of sinking into the ground, where it would replenish aquifers and water plants that once grew there.

Wow! You haven't even really started your day and already you've totally changed the world. Here's the thing, though. People change the environment that they live in, definitely, but everything that's alive changes its environment.

[text: Investigation]

All of the plants, animals, even tiny bacteria, have an effect on their environment, too. It's just that people do it in a particularly intense way. Wherever there are people, there are changes in the environment. For an extreme example, let's take a look at a familiar place. Do you recognize it? Probably not. This is what scientists think this place looked like over 400 years ago. What does it look like today? That's right. It's New York City, baby. About 9 million people now live here. But it wasn't always this way.

Before 1609, the island of Manhattan was inhabited by the Lenape, a Native American tribe. The Lenape ate oysters and clams and burned parts of the forest to clear space for crops. They changed the environment, too, of course. Remember, every living thing has an impact on its environment.

But when Europeans first came to New York in the 1600s, it began an incredible transformation. At first, the settlers carved roads into the landscape. Then they built farms and fortifications. These seemingly small changes to the geosphere affected the ranges of animals in the area and changed the plants that grew there. And eventually, after a couple hundred years, and a whole lot of development, what was once mostly wilderness; forests, wetlands, grasslands, and beaches, became paved with over 9,600 kilometers of streets.

Once a habitat for beavers, elk, turkeys, and black bears has become home to people, rats, cats, dogs, and pigeons. People didn't just change the landscape, by altering the landscape they changed what animals could survive there. 

More than 160 kilometers of streams once flowed through Manhattan. Today, New York City's water supply system, delivered to the city through a network of tunnels and aqueducts, stretches over 200 kilometers, delivering more than three and half billion liters of drinking water every single day.

Wanna think about something crazy? Time Square was once a swamp, but we changed that.

[text: Conclusion]

New York City is an extreme example of human's ability to change an environment. But you don't have to travel to the Big Apple to see it. The changes are all around you. Almost everything you touch is a result of human innovation acting on the world's natural resources. It's a lot to take in, but remember, we're living things and we're part of the natural world and every living thing changes its environment. 

Next time, we'll look at ways that other living things make their own kind of changes.