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GENERAL KNOWLEDGE 5
ICE AGES

The Pleistocene era (beginning 2.58 million years ago) saw several phases in which Earth’s mean temperature dropped and the polar icecaps expanded towards the tropics. These are clustered into four broad ice ages- periods with cool temperatures and a significant continental ice sheet (at times, up to one-third of Earth’s land surface was covered), separated by interglacial periods of 10-15 millennia.
Nomadic humans, with fire, weapons and language, were able to hunt across the tundra and secure caves in which to shelter. Their prey needed larger areas to forage, causing humanity to spread widely in pursuit. Falling sea levels opened up land bridges across today’s oceans -most significantly, the Americans were populated by humans spreading from Mongolia, while horses evolved in America but migrated east before becoming extinct in their native land. The last significant glaciation came to an end 10,000 years ago. The last significant glaciation came to an end 10,000 years ago, although a climatic cooling of about 500 years from century AD 1300 has been noted.

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