• A video shows what Earth would look like after the oceans have been drained
  • Draining the oceans would reveal ancient land bridges that connected continents
  • The land bridges were used by early humans to migrate to different continents

A planetary scientist remade a video previously released by NASA to show Earth’s ancient features such as mountain ranges and land bridges that early humans used to cross continents. The video was made by simulating the disappearance of oceans and other bodies of water on the planet.

The original video was released in 2008 and was made by NASA physicist and animator Horace Mitchell. In December last year, scientist James O’Donoghue of the Japanese space agency, who previously worked for NASA, remade the video to add a few interesting details.

In his own version of the video, O’Donoghue added a tracker that shows how much water has been drained. He also slowed down the clip to clearly show the emerging land masses as they become visible following the disappearance of the oceans.

The planetary scientist noted that he decided to create a slow-motion version of the video to show how much underwater landscape will be instantly revealed once the water level drops by a few meters. Even though much of the world’s hidden landscape emerged after the water level dropped to around 7,000 meters below sea level, a lot of land masses can already be spotted after the oceans drained by just 10 meters.

“I slowed down the start since, rather surprisingly, there's a lot of undersea landscape instantly revealed in the first tens of meters,” he told Business Insider.

As the water disappeared, several natural features that have been hidden underwater for tens of thousands of years began to emerge. Some of these prominent features include the world’s longest mountain chains in the mid-ocean ridge. Around 90 percent of this natural feature, which in total stretches over 37,000 miles across the planet, is hidden underwater.

Other prominent features revealed in the video are the land bridges that connected continents. These bridges were mainly used by ancient humans to migrate from one continent to another, crossing from Europe to the U.K. and from Siberia to Alaska.

“When the last ice age occurred, a lot of ocean water was locked up as ice at the poles of the planet,” O’Donoghue explained. “That's why land bridges used to exist. Each of these links enabled humans to migrate, and when the ice age ended, the water sort of sealed them in.”

Earth photo
Photo of Earth taken from space in 2003. NASA