A LOW FOG ENVELOPES the steep and remote valleys of southwestern Uganda most mornings, as birds found only in this small corner of the continent rise in chorus and the great apes drink from clear streams. Days in the dense montane forest are quiet and steamy. Nights are an exaltation of insects and primate howling. For thousands of years the Batwa people thrived in this soundscape, in such close harmony with the forest that early-twentieth-century wildlife biologists who studied the flora and fauna of the region barely noticed their existence.