The Pleistocene Epoch, also referred to as the Ice Age, began around 2.6 million years ago, although the Earth had been cooling for much longer than this. This period saw vast glaciers, known as ice sheets, expand across the Earth’s surface and take up large swathes of land. The ice sheets extended beyond the North and South Poles, where they still exist today, and reached as far as the Midlands in England and across what is now Canada and the northern United States of America.

These ice sheets could be up to 3km thick and nearly all animal and plant life were excluded from the areas they covered. Contrary to popular opinion, the large mammals known as megafauna that lived during the Pleistocene Epoch did not live on these glaciers but rather in the southerly areas next to them, where plant life thrived and supported an abundance of life.

With a vast quantity of the world’s water frozen in these ice sheets, sea levels fell that resulted in animals roaming between different areas of land and species spreading to new habitats that had previously been separated by water.