Reindeer, horses, and woolly mammoths were some of the key megafaunal species of the Late Quaternary.
Credit: Mauricio Anton
Beringian megafauna in the Late Quaternary included muskoxen and woolly mammoths.
Credit: George Teichmann
DUBLIN: Humans are off the hook, it seems, for the extermination of large Ice Age mammals, according to a new study.
Climate change was the primary cause of population declines, according to a new study published in Nature today which looks at genetic data, climate data and the archaeology of six large herbivores.
"Finding a smoking gun is very difficult," said lead author Eline Lorenzen, researcher at the Centre for GeoGenetics in the University of Copenhagen in Denmark.
"The results are more complicated that we previously thought. Our study indicates that humans played no part in the extinction of the woolly rhinoceros or the musk ox in Eurasia and that their demise can be entirely explained by climate change," said co-author Simon Ho from the University of Sydney's School of Biological Sciences.
Quaternary extinctions
Towards the end of the Late Quaternary, beginning around 50,000 years ago, Eurasia and North America lost approximately 36% and 72% of their large bodied mammals, respectively. The role of humans in this has been contentious, but it seems our ancestors were not responsible, at least not for large herbivores.
The new picture that is emerging is complicated, with a mixture of climate change, environmental change and human impacts impacting on various species. And all species react differently to their changing world, which makes things even more complex.
The herbivores studied expanded their range, and their populations rose with the colder, drier conditions after 30,000 years ago (Last Glacial Maximum), which favoured an expanse of steppe tundra. But they did not expand at the same time - it was over a space of thousands of years, said Lorenzen.
Although the researchers set out to find similarities among six large herbivores, this proved impossible. "The surprise was how difficult it was to find a common story because they all showed such different patterns," Lorenzen said.
Woolly rhinos
There is no evidence that there was a human factor in the extinction of the woolly rhino around 14,000 years ago in Siberia. Climate change was to blame, according to the study. The Eurasian Musk oxen also went extinct 2,500 years ago due to climate change, with no evidence of human pressure for the last 20,000 years.
A combination of climatic and human impacts appears to have been responsible for the extinction of the Eurasian steppe bison and wild horse. Lorenzen believes humans had a hand in the horse's decline; the species had a huge potential range 6,000 years ago, yet it dwindled in number. At the same time, it is very common in human archaeological sites. "Humans likely played a role in the extinction of bison in Siberia," she said.
