WE ARE MARCHING single file on a mountain path, winding our way through a bamboo forest, tall spindles shooting to the sky. Sunlight splashes through the canopy, hitting the pale green of the bamboo sheaths and turning the light a refulgent green. It’s magical, and strenuous. About 2,000 feet up, the vegetation turns into a jungle of hairy plants with needles and nettles. My ankles and calves itch terribly, but I concentrate on the mission at hand: getting face-to-face with a mountain gorilla.