And finally tonight, a new book explores the history and spread of AIDS in Africa. Ray Suarez has our conversation. Since AIDS was first identified in the West 30 years ago, its toll across the world has been vicious.It's killed 25 people since 1981. An estimated 34 million are living with the virus today. Just how the disease began and spread perplexed scientists for years. A new book tracks the emergence of the HIV virus out of a remote part of Cameroon to what is now Kinshasa in the former Belgian Congo. Tinderbox: How the West Sparked the AIDS Epidemic and How the World Can Finally Overcome It" connects the economies and atrocities of colonialism to that initial outbreak and to current medical approaches to the treatment and prevention of HIV in Africa. Craig Timberg and Daniel Halperin, welcome. Thank you. Thank you for having us. The book is about a great many things, but one of the conclusions that's gotten a lot of attention is the responsibility of colonialism for helping AIDS break out of the deepest rain forests into the rest of the world. How does that happen? Well, the virus that became HIV was infecting a community of chimpanzees for hundreds of years, probably thousands of years.