The ancient tools and bone are 14,550 years old, they reported Friday in the journal Science Advances, making them the most ancient human remnants ever found in the southeastern United States. The researchers say the find is unequivocal proof that people were in Florida more than 1,000 years earlier than anyone had imagined — a discovery that could help rewrite the history of humans on the continent. . . The age given for the tusk didn't fit that paradigm, other scientists said — the ice-free corridor wouldn't even have been open yet. . . and since the ice free corridor wasn't open yet, obviously there are a lot implications for getting people down from the interior of Alaska," Jenkins said. . . It seems likely that the first Americans sailed down the Pacific coast . . . From there, they may have followed America's river systems to the other side of the continent, or trekked across Central America at its narrowest point and sailed up into the Gulf of Mexico.