Scientists from Australia's University of Adelaide say the DNA was analyzed in a study of how special genetic modifications can turn genes on and off without altering the DNA sequence itself.
This kind of change, called "epigenic," can occur rapidly between generations without requiring the time for standard evolutionary processes and could explain how animal species are able to respond to rapid climate change, they said.
Researchers said it is possible to accurately measure epigenetic modifications in extinct animals and populations such as the bison found in permafrost in Canada's Yukon region.
"The climate record shows that very rapid change has been a persistent feature of the recent past, and organisms would need to adapt to these changes in their environment equally quickly," Adelaide researcher Alan Cooper said. "Standard mutation and selection processes are likely to be too slow in many of these situations."
"Epigenetics is challenging some of our standard views of evolutionary adaptation, and the way we think about how animals use and inherit their DNA," he said.