STATE COLLEGE, Pa., March 8 (UPI) -- U.S. scientists say they've determined the sharp decline in Arctic musk oxen that began about 12,000 years ago was due to a warming climate and not hunting.
"This is the first study to use ancient musk oxen DNA collected from across the animal's former geographic range to test for human impacts on musk ox populations," said Penn State Assistant Professor Beth Shapiro, one of the team's leaders. "We found that, although human and musk ox populations overlapped in many regions across the globe, humans probably were not responsible for the decline and eventual extinction of musk oxen across much of their former range."
Musk oxen once were plentiful across the Northern Hemisphere, but they now exist almost solely in Greenland and number only about 80,000 to 125,000.
To conduct its research, the team collected DNA from musk ox bones and other remains of animals that lived during different times -- up to 60,000 years ago -- and from musk oxen that are alive today.
"It is becoming clear that each species is following its own population trajectory," Shapiro said. "This is a strong argument that it is changes in habitat that are driving these population dynamics, and not a single factor such as the introduction of human hunters.
The study that included scientists at the University of Copenhagen in Denmark appears in the early online edition of the Proceedings of the National Academy of Sciences.