THE AMERICAN MASTODON may not have been hunted to extinction. Northern mastodons may have died off as forests disappeared in the last glacial period. Meat-hungry humanity has long been suspected of hunting North American megafauna to extinction, but new research suggests that Homo sapiens may have gotten a bum rap — at least when it comes to the demise of the American mastodon. Research published last week in the Proceedings of the National Academy of Sciences argues that the ancient beast started to disappear from what is now Alaska and Canada’s Yukon Territory long before humans ever set foot on the continent. One key reason for the confusion, authors say, is that specimen contamination has rendered decades of carbon-14 dating research potentially inaccurate. “It’s a concern,” said Yukon paleontologist Grant Zazula, lead author of the study. “A lot of the radiocarbon dates that are out there in the literature are probably problematic.” Although it is still