The "Descent" of Man

If human beings descended from chimpanzees or the ancestors of chimpanzees that produced both man and chimps and nothing else, how could HIV come from someone having intercourse with a chimpanzee when the predecessors of human beings would have had intercourse with the predecessors of the chimpanzee since they were the same species? Why would the virus not already have infected all human beings before that point?

Interesting - you can go many different directions on this.

Some says AIDs does not really exist or is not a Virus, anybody can get aids if conditions are right. I've also heard that the AIDs virus is a man made virus, some secret project that escaped the lab and has been covered up with a fictitous story.

TBG24601 : To answer your question.

HIV/AIDs is a virus. It has been confirmed that the two stains of HIV each originated from cross-species transmission from other primates. The killing of primates as "bushmeat" for human consumption allowed the virus to transmit to human hunters when thery handled infected carcassess with cuts or other open wounds on their hands. It didn't originally transmit through reproduction in humans. When it transmitted to humans it was through blood.

I don't believe in the other theories such as The Oral Polio Vaccine (OPV) theory (transmitted from medical experiments) and the 'conspiracy theory' or that it is 'man-made'. Those theories aren't very credible. They fail to take into consideration the lack of genetic-engineering technology available to 'create' the virus at the time that AIDS first appeared.