Such an outcome was not necessarily mysterious. The early days of African exploration were incredibly hazardous. Even carefully managed expeditions lost half of their party or more. Those who did not succumb to malaria, sleeping sickness, and blackwater fever faced rivers teeming with crocodiles and hippos, jungles with leopards and suspicious, cannibalistic natives. And, for all its luxuriant growth, the rain forest provided little edible food; a number of expeditions had starved to death.
