The giant sable bull arrived dangling beneath a sunny-yellow helicopter, its four-foot-long horns curving back toward its flanks like the bucket of a backhoe. As it came into view, the hundreds of people who had been waiting to greet the massive antelope at the dry, grassy edge of Angola’s Luanda Strict Nature Reserve broke into tears, song, laughter, dancing. For the Angolan people, the giant sable is a national symbol, adorning everything from soccer jerseys to postage stamps. But this giant sable represented something even greater—hope. After the helicopter pilot…