London: A new study has revealed that the woolly mammoths died out because of dwindling grasslands - rather than being hunted to extinction by humans.
There was a severe decline in the pasture on which the mammoths fed after the ice age 21,000 years ago.
"What our results have suggested is that the changing climate - through the effect it had on vegetation - was the key thing that caused the reduction in the population and ultimate extinction of mammoths and many other large herbivores," the BBC quoted Brian Huntley of Durham University as saying.
Professor Huntley and his colleagues created a computer simulation of vegetation in Europe, Asia and North America over the last 42,000 years.
The researchers combined the estimates of climatic condition during this period with models of how various plants grow under different conditions.
They discovered that the cold and dry conditions during the ice age, with low levels of carbon dioxide, didn’t support the growth of trees.
So, instead of forests there were vast areas of pasture, which was ideal for large herbivores, such as woolly mammoths.
However, at the end of ice age, warmer and wetter climate and higher level of carbon dioxide helped in the growth of tress at the expense of pastures.
"During the height of the ice age, mammoths and other large herbivores would have had more food to eat," said Huntley.
"But as we shifted into the post-glacial stage, trees gradually displaced those herbaceous ecosystems and that much reduced their grazing area," he added.