That's the conclusion of a new study which likely will trigger a new debate within scientific circles.
The study points to a sharp decline in the amount of habitat available for grazing after the last ice age. There are several theories about what triggered the extinction of mega-species - including the emergence and spread of Homo sapiens, But according to Professor Brian Huntley, from the School of Biological and Biomedical Sciences at Durham University which led the research, a change in the climate produced a moister climate and higher levels of carbon dioxide. And that, they say, led to a decline in the amount of available grasslands.
"The change from productive grasslands across large areas of northern Eurasia, Alaska and Yukon to less productive tundra-like habitats had a huge effect on many species, particularly on the large herbivores like the woolly rhinoceros and woolly mammoth. Mammoths and other mega-mammals found it increasingly difficult to find food. We believe that the loss of food supplies from productive grasslands was the major contributing factor to the extinction of these mega-mammals."
Along with the woolly mammoth, other species that disappeared included the cave lion, the giant deer, the wooly rhino and the cave bear.