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Age of Mammals

Ice Ages

Our human ancestors lived through the Ice AgesOur human ancestors lived through the Ice AgesIce ages have occurred frequently throughout the Earth’s history. They are times when the climate cools down so much that ice caps form at the poles and spread out. The most recent, the Pleistocene Ice Ages, began around 2.6 million years ago. Since then, on at least four occasions, great ice sheets spread southwards and obliterated much of northern Europe, North America and Asia for tens of thousands of years. These events are known as glacial periods. In between, there were warmer periods called interglacials. The last glacial period ended only about 11,500 years ago. Today’s climates are cooler than many past eras, so it is likely that we are living through an interglacial. A fifth glacial period may one day grip the world.

Woolly mammoths and other Ice Age animalsWoolly mammoths and other Ice Age animals
The ice cap in Greenland todayThe ice cap in Greenland today

Possible causes

Various causes have been suggested for why ice ages occur. It may be that the Earth’s angle of rotation changes slightly, tipping the poles further away from the sun’s rays. Other possible causes include changes in the Earth’s orbit around the Sun, the position of the continents or the chemical composition of the atmosphere.


The Pleistocene Ice Ages were not the only ones in the history of the Earth. A major Ice Age occurred at the end of the Carboniferous Period, about 305–300 million years ago.

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