FLICKR, BENNYResearchers once blamed human hunting for the disappearance of mammoths and other giant mammals more than 20,000 years ago, but a new study based on DNA extracted from ancient fossils suggests that a warming climate may be to blame. The results were published results in Science this week.
Paleogeneticist Alan Cooper of the University of Adelaide in Australia and his colleagues analyzed the genetic material from dozens of megafauna fossils from North America and Eurasia to determine how the populations changed over time. They found that “invisible extinctions”—in which the fossil record looks continuous but in fact species were dying out while being replaced by morphologically similar cousins—were relatively common: the steppe bison, the cave bear, and the giant short-faced bear were all replaced by genetically distinct populations.
“This all happened very abruptly,” Cooper told the National Geographic blog Not Exactly Rocket Science. “They’re weren’t all happening at the same time, but the patterns were there, and many of these changes were only detectable through DNA.”
The team then analyzed ice cores from ...
