Divers exploring a southern Florida sinkhole have uncovered clues to what life was like for some of America's first residents.Led by University of Miami professor John Gifford, underwater archaeologists are exploring Little Salt Spring, 12 miles (19 kilometers) south of Sarasota.Earlier this year, students working about 30 feet (9 meters) below the surface found the remains of a gourd that probably was used as a canteen by an ancient hunter about 8,000 or 9,000 years ago, according to Gifford.Archaeologists have been recovering primitive relics from the spring since 1977, when divers found the remains of a large, now extinct tortoise...