In 1771 Joseph Banks and other wealthy collectors sent a talented, self-taught naturalist to Sierra Leone to collect all things rare and curious, from moths to monkeys. Henry Smeathman's expedition to the West African coast, which coincided with a steep rise in British slave trading in this area, lasted four years during which time he built a house on the Banana Islands, married into the coast's ruling dynasties, and managed to negotiate the tricky...