I gave up on Edward Hooper's tome The River: A Journey to the Source of HIV and AIDS after reading 380 out of its 1000+ pages. It's a well-written and exhaustively researched book, but it goes into excessive detail.

The fundamental hypothesis is fascinating. Hooper argues that early applications of the polio vaccine in Africa may have introduced AIDS into the human population. Certain monkeys and chimpanzees have simian immunodeficiency viruses (SIV's), which are genetically similar to HIV. Some oral polio vaccines were generated by passaging the polio virus through primate kidneys. Hooper investigates whether a polio vaccine, contaminated with SIV's, may have transferred the virus to humanity.

The theory sounds plausible, though the evidence supporting it is circumstantial. For example, the geographic region and time period where AIDS first appeared coincides with the large-scale testing of one variety of the polio vaccine.

However, the scientific and medical establishment attacks the theory vehemently. As an outsider, it's difficult to tell whether the criticisms are justified.