Frogs and toads have lived on earth for more than 100 million years. They survived whatever extinguished the dinosaurs, yet in our age, they seem to be vanishing. In a three part series beginning today, Minnesota Public Radio's Mary Losure examines this scientific mystery. It's a detective story in which the victims are frogs, not people--but people may have a big stake in the mystery's solution. Amphibians are sensitive indicators of environmental problems. If we can find out what's killing frogs, we may also learn if it will someday harm us.