How the Bering Land Bridge Shaped Human Migration

by Camila Cruz, age 17

Thousands of years ago, humans used the Bering Land Bridge, a large strip of land connecting Siberia and Alaska, to cross from Asia to North America. During this time, sea levels were significantly lower, since much of the Earth's water was contained in massive glaciers. Due to this, land that is now underwater used to be above water, including this bridge of land stretching between two continents.

For roughly 25,000 years, this bridge served as a route for human migration into North America. The Bering Land Bridge, which allowed humans to move between continents, opened about 35,700 years ago. This information is supported by new research from Princeton University. A study suggests the time of the bridge’s appearance aligns with genetic evidence showing that ancestral Native American populations began separating from Asian populations. This suggests humans may have crossed the bridge as soon as it appeared.

The bridge emerged during the Last Glacial Maximum, a peak of the last ice age when ice sheets were at their largest and sea levels were at their lowest. Scientists previously believed sea levels had dropped steadily, but new data reveal that this drop and the growth of ice sheets happened much more abruptly. Surprisingly, these changes occurred even when global temperatures were relatively stable. Scientists started linking other factors, like changes in sunlight intensity, to ice sheet behavior.

As the Earth warmed up, glaciers began to melt and the ice age came to an end. Sea levels rose about 11,000 years ago, submerging the land bridge.

The Bering Land Bridge played a crucial role in the early migration of humans from Asia to North America, as it connected the two continents for 25,000 years. Appearing at a time of frigid temperatures, the bridge allowed people to cross into modern-day Canada from Russia across what is now the Bearing Strait. As the temperature rose, glaciers melted and sea levels rose, once more covering the land bridge. This shows the connections between climate, geography, and migration, and how fast humans can adapt to the world.

[Sources: National Science Foundation; National Parks Service; Princeton University]