(Bloomberg Businessweek) -- The village of Ololosokwan sits in the Great Rift Valley adjacent to Tanzania’s Serengeti National Park, surrounded by thousands of square miles of savanna—grasslands spilling across low hills dotted with mimosa, jacaranda and umbrella-shaped acacia trees. The settlement consists of a few unpaved streets where sheep, goats, chickens and emaciated cows wander untended. A handful of shops in single-story, c...