==HIV is highly likely to have been a derivative of SIV. Zoonosis is not uncommon when you have a bunch of people hunting and eating monkeys.
Before I comment, could you please reveal where you are getting your information from? Sources please.
http://www.avert.org/origins.htm
http://www.avert.org/evidence.htm
http://www.cdc.gov/hiv/resources/qa/qa3.htm
http://depts.washington.edu/ceeh/News/mot1.html
http://www.ncbi.nlm.nih.gov/pubmed/9468138
http://news.bbc.co.uk/hi/english/static/in_depth/africa/2000/aids_in_africa/aids_facts.stm
http://en.wikipedia.org/wiki/AIDS_origin
http://www.sciencemag.org/cgi/content/full/279/5352/801
http://www.fasebj.org/cgi/reprint/15/2/276.pdf