Woolly mammoths died out because climate change caused a massive decline in their grassland habitat, scientists reported last week.
Warming temperatures and the spread of forests after the last ice age 21,000 years ago, turned the mammoths’ grassland into less productive tundra-like habitat.
This reduced the food available to large mammals like the woolly mammoth, woolly rhino and cave lion and eventually led to their extinction, the team led by scientists at Durham University, and Lund University and Bristol University, says.
These changes coincided with an increase in the number and distribution of modern humans, Homo sapiens. A popular theory is that hunting and competition for land by humans caused the extinction of the mammoth. The team doesn’t rule out human influences but says that the changes in vegetation would have had the greatest effect.
‘We believe that the loss of food supplies from productive grasslands was the major contributing factor to the extinction of these mega-mammals,’ says Professor Brian Huntley, from the School of Biological and Biomedical Sciences at Durham University.
‘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.’
The team are carrying out a large study into how vegetation and climate changed in the Northern hemisphere during and after the last ice age.
They created computer simulations to show what would have happened to vegetation and habitat when the climate changed.
They found that the warming of the planet and a change to a moister climate with increased levels of carbon dioxide in the atmosphere resulted in the proliferation of trees and the subsequent decline in grasslands – the staple diet and fodder of large herbivores.
As well as a decline in the area covered by grassland, the research also showed that grassland productivity, which is key to the survival of grazing mammals, dropped.
A decline in herbivores would have affected other animals in the food chain, for example there would be less food for carnivores like the cave lion.
The team says that this research could be applied to the climate change problems we face today.
‘This is a model for what may happen as a result of rapid climate change over the next century linked to human activity,’ Prof Huntley says.
‘It is food for thought in these times of global warming and human-induced habitat change. There may well be a lesson to learn.’
Big species such as elephants and rhinoceros are the most likely to be the first affected by climate change and habitat pressure today.
This research along with research at the Natural History Museum is part of a broader collaboration of organisations looking at what caused the extinctions of the large ice age animals or megafauna.
Museum scientists are studying these mammals and will now be able to use the vegetation data from the results of this research to look more closely at how the vegetation changes affected the mammals.