NationalGeographicembarksonanexpeditionintothemysteriousworldofancientAmericanhistorytoshedadifferentlightonthehistoryoftheAmericas.　　Historybookstraditionallydepictthepre-ColumbusAmericasasapristinewildernesswheresmallnativevillageslivedinharmonywithnature.Butscientificevidencetellsaverydifferentstory:WhenColumbussteppedash...