Land Bridge Theory: Lesson for Kids

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  • 0:03 What Is a Land Bridge?
  • 0:59 The Land Bridge Theory
  • 1:23 Why Did People Cross?
  • 1:53 How We Know About the…
  • 2:43 Lesson Summary
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Lesson Transcript
Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Expert Contributor
Will Welch

Will has a doctorate in chemistry from the University of Wyoming and has experience in a broad selection of chemical disciplines and college-level teaching.

Many years ago, large glaciers locked up much of the seawater, which exposed big stretches of land. In this lesson, you'll learn about the land bridge theory, which may explain how the first people made their way to North America.

What Is a Land Bridge?

Did past civilizations walk on water? Scientists think people used to walk from Siberia to Alaska, but there's one problem. These two lands are separated by a stretch of water called the Bering Strait. Those early humans didn't have any special skills that allowed them to walk on water, but they did have some help from the environment.

About 10,000 to 25,000 years ago, much of the land that makes up the continents of Asia and North America was covered with ice. This ice sucked a lot of the seawater into huge glaciers, which caused the sea level to drop so low that it exposed the land under the water.

Imagine standing on an island beach and suddenly the water turns into a giant ice cube. The water moves into the ice cube, leaving a strip of land that you can walk on to a nearby island. That land is called a land bridge, because it's a piece of land that connects two separate areas.

The Land Bridge Theory

Because of the exposed land between Siberia and Alaska, scientists developed a theory called the land bridge theory, which states that early animals and people traveled from Siberia to Alaska across a land bridge. Siberia is in Russia, and Alaska is part of North America, so this theory describes a possible way that the first people made their way to North America.

Why Did People Cross?

People who crossed the land bridge weren't looking for a new home - they were trying to survive by following their food supply.

When the land bridge was exposed, plants started to grow on it. The plants attracted all types of animals, including woolly mammoths, big wild cats, Arctic camels, bears, moose, and horses. People who lived during this time couldn't run to the grocery store for food. Instead, they had to follow herds of animals and hunt for their food, so as the animals moved across the land bridge, people followed.

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Additional Activities

Essay Questions on Ancient and Modern Migration

1. Look at a map or globe and locate Siberia.

  • What type of climate do you think Siberia has today?
  • What other places are close to Siberia and what do the people there look like?
  • Write a few sentences about what it would have been like to live in Siberia during an Ice Age.

2. The land bridge lasted for thousands of years and it opened and closed more than once in human history.

  • If the land bridge was above water at one time for 5000 years, how many generations of people may have crossed then?
  • Did everyone cross, or did people stay and settle on the land bridge?
  • Did animals only cross the land bridge in one direction? What about humans?

3. The land bridge is all the way in Alaska, but people have been living all over the western hemisphere for millennia.

  • How did people get all the way from Alaska to the tip of South America?
  • How long do you think it took for people to migrate that far?
  • How did people travel? Did they use animals? Did they use boats?

4. People still migrate to other places all over the world.

  • Why might ancient people have chosen to cross the land bridge rather than stay in Siberia?
  • What kinds of things cause groups of people to travel together to different parts of the world today? Are the reasons similar?
  • Can you think of examples of groups of people today who are migrating? How do they travel?

Possible Responses (Welcome students' creative responses):

1. Siberia is in the far northeastern part of Russia

  • Siberia is usually very cold
  • Siberia is in Asia; near Korea, Mongolia and China

2. The Land Bridge

  • A generation is about 20 years, so 250 generations.
  • While it was above water, people probably lived on the land bridge.
  • Scientists believe that during some periods, people did cross back to Asia.

3. Ancient Migration

  • People mostly walked.
  • Technically unknown ~1000 years?
  • The first migrants are not thought to have used boats, but eventually people started using them.

4. Reasons for migration

  • Survival is a major reason for migration; they were probably following food.
  • People migrate for similar reasons today; to escape danger, famine etc.
  • People who migrate today include: Syrian refugees, Central Americans, Africans. They travel by boat, plane, car, and still by foot.

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