The Origins of Aids, by Jacques Pepin

If you think that the AIDS pandemic began with a promiscuous French airline attendant in the early 1980's you would be wrong.  Though our cultural awareness begins here I think.  HIV, the causative agent of AIDS, has been around quite a long time in humans (at least as far back as the first decades of the 20th century - well documented by analysis of archival specimens and DNA analysis of mutation rates of existing strains of HIV) and in chimps as nearly genetically identical SIV for many thousands of years before that.  Pepin, a microbiologist and researcher, does an exhausting job outlining the origins of AIDS from its beginnings in the jungles of central Africa to its global spread.  His theory, and I would argue that the preponderance of evidence moves it out of the hypothesis stage to theory, is that the virus jumped to humans from chimps (the common chimp, pan troglodytes) from incidental contact during hunting (a human hunter butchers a chimp with a machete and gets contaminated by chimp blood).  This hunter either makes his way to a city that rapidly urbanized during 20th century colonization (e.g. Leopoldville), sleeps with a prostitute and disseminates the virus in this manner, exponentially, for the prostitute sleeps with many others, or remains in the rural areas of the Congo and gets treated parenterally (e.g. intravenously) for Yaws, sleeping sickness or another tropical disease, contaminates the syringes, which are reused frequently without proper sterilization, and launches the exponential spread of the virus in this manner.  Either way, the exponential spread of the virus was enabled by colonization and subsequently spread globally by international trade and travel.  Pepin's work is scholarly and exhaustive in detail, documenting epidemiological data for central Africa mind numbingly at times.  Too much for the lay reader and sometimes even for me (I'm a pathologist).  Nevertheless, if you are interested in the true origins of HIV, or even certain aspects of 20th century central African colonization by Belgium and France, it is well worth your time.