The origins of HIV are something of a historical puzzle, but recent discoveries make that puzzle a lot easier to solve—and it looks a lot like European colonialism is a big piece of it. That's the thesis of a new book by Craig Timberg and Daniel Halperin called Tinderbox. In an excerpt in the Washington Post, the authors explain how scientists examined chimp feces across Cameroon to determine that HIV first sprang up earlier than previously believed—at the turn of the 20th century—in a remote Cameroon jungle.
Few human settlements ever graced the region; it was only when Europeans sent hordes of African porters through the region and set up trading posts that the virus had the chance to spread. HIV is hard to transmit; to grow it needed a place bustling with people on a scale not seen in Africa before colonialism. It found it in Kinshasa, a city founded by Belgian colonizers down the river from its probable birthplace. Every strand of HIV scientists have tracked eventually points to an explosion of the virus in Kinshasa—what the authors call the "big bang of the AIDS epidemic." (Read more HIV stories.)