Climate change 'killed mammoths'
Climate change and spreading forests killed off the woolly mammoth and its big mammal cousins - not spear-wielding humans, a major new study has concluded.
The demise of the mammoth and other extinct "megafauna", such as the woolly rhino, giant deer and cave bear, is blamed on the loss of grassland across most of the northern hemisphere.
By 11,400 years ago, many of the large animals that once roamed across northern Eurasia and North America had vanished.
Some experts have argued that the rise of our Homo sapiens ancestors was largely responsible for their disappearance.
Human population exploded during this time, posing a new threat to many creatures that were hunted for their meat and skin, or because they were considered dangerous.
People also competed with the mammals for land, placing pressure on their habitats.
But these factors alone could not have led to the extinctions, argue scientists from the University of Durham.
Their findings are part of the most comprehensive study to date of northern hemisphere climate and vegetation during and after the height of the last Ice Age, 21,000 years ago.
The study concludes that a period of post-glacial global warming led to a massive loss of grassland over much of the Earth's surface.
As the prairies and steppes dwindled, spreading forests took their place. The changes made survival impossible for the big grazing herbivores and the predators that fed on them, it is claimed.