Exploring a new area in New Guinea’s vast lowland jungles entails risk.  If another tribe already occupies a given region, the slightest intrusion by strangers may provoke conflict.  In “Sensing Danger,” the paddles these be-feathered warriors use, turned end-for-end, double as spears.  Plus!  The inner hull of each craft is lined with bows, arrows and war shields.  These explorers, aware that something has spooked that flight of squawking parrots overhead, decide to hold their war shields at the ready.  Does an ambush await them around the next bend?