The woolly mammoth appeared in the Pleistocene and survived into the Holocene, from about 400,000 to 4,000 years ago. It was adapted to Arctic climates, weighed up to 6 tonnes and stood nearly 3.5 metres tall at the shoulder. Its long curved tusks, up to 4 metres long, helped it dig up plants under the snow and fight. It probably died out because of a mix of warming after the Ice Age and heavy hunting by humans.