What killed the woolly mammoth during the Ice Age? It wasn't necessarily climate change by itself. It turns out that changing vegetation and food sources might have caused these massive beasts to go extinct.
The Ice Age ended about 10,000 years ago. While protein-rich forbs were abundant before then, though, they were soon replaced by grasslands. It turns out that these forbs were a huge food source for the large land mammals that once roamed the planet.
"We knew from our previous work that climate was driving fluctuations of the megafauna populations, but not how," said Eske Willerslev, one of the researchers, in a news release. "Now we know that the loss of protein-rich forbs was likely a key player in the loss of the ice age megafauna. Interestingly one can also see our results in the perspective of the present climate changes. Maybe we get a hold on the greenhouse gases in the future. But don't expect the good old well-known vegetation to come back when it becomes cooler again after the global warming."
In order to learn a bit more about the past Ice Age and the extinction of these giant mammals, the researchers looked to ancient DNA. More specifically, they found that permafrost contains a vast collection of frozen DNA, which they then used to reconstruct the past ecosystems.
"For the first time, ecologists have been able to piece together the characteristics of more complete plant communities occurring in the Arctic during the last 50,000 years," said Mari Moora and Martin Zobel, two of the researchers, in a news release. "The new information shows clearly that the vegetation of the Late Pleistocene was rich in forbs but lost considerable diversity at the peak of the ice age. Different plant communities, with graminoids and woody plants prevailing, then started to develop during the Holocene."
The findings reveal that with the lack of these protein-rich forbs, large mammals such as woolly mammoths and rhinoceroses went extinct. The findings reveal that it wasn't just changing temperature that caused the mass extinction. In contrast, it was the resulting vegetation change.
The findings are published in the journal Nature.
