There are two HIV viruses that infect humans. One is HIV 1 and the other HIV 2. Concerning HIV 1 it is a totally human virus that is more than 400,000 years old in mankind. It is a cousin to SIV simian virus. HIV 2 in contrast is a simian virus recently acquired by man in west Africa, probably in the 1950s. Presently the strains of HIV 2 are running wild in the sooty mangaby monkey of West Africa.  One of these strains infected man. There are numberous ways this could have happened. One of the most common is that monkeys have been hunted in Africa for food  for tens of thousands of years. A bleeding monkey slung over the shoulder of a man as game taken would easily HIV infect a sore on the back of the man caused by an insect bite.                                                                                                                                                    HIV 1 is widespread throughout the United States. It has been in the United States a very long time. In contrast HIV 2 is rare in this nation and has been confined to the few U.S. states which are those states Africans since slavery have immigrated to.  By far N.Y.S. has the largest number of HIV 2 cases and most of the remainder of the cases are found in states bordering N.Y.S. (Recent African immigrants avoided the southern states). Eighty percent of the U.S. states have never had a case of HIV 2. Nearly all HIV in the U.S. is HIV 1 which mathmaticall in terms of its widespread distribution, its mathmatical calculus or function, has been in the U.S. since the beginning of slavery or before. It is not an HIV which arrived a few decades before HIV 2 as presented in some studies. And HIV 1 and HIV 2 both spread rapidly in heterosexual vaginal intercourse when the sores and tissue debilities of common venereal diseases are present providing a route for invasion. HIV 1 and HIV 2 generally do not spread in heterosexual vaginal intercourse when these tissue sore invasion routes are not present.                                                                                                                                              As of year 2003 there were slightly over 100 (one hundred) cases of HIV 2 in the U.S. and the number of cases of HIV 1 in the U.S. was about 800,000  (eight hundred thousand). Although HIV 2 is rare still in the U.S. having a hard time taking hold and spreading because it is recent and because of our excellent Medicine for the cure of common venereal diseases whose sores permit the route of HIV invasion, HIV 2 is not uncommon in west Africa with from tens of thousands to over a hundred thousand cases. Although recently caught from a monkey strain of HIV it has spread rapidly because of increased frequency of sex  with the sexual revolution, increase in marriage age and poor medical care for the common venereal diseases the sores and tissue debilities of which HIV 1 and HIV 2 invade to reiterate.  HIV I is wide spread over Africa  in terms of millions of HIV 1 infected people and this has been the case for hundreds of thousands of years. However although wide spread in terms of areas there formerly was probably never an epidemic in terms of numbers infected in ratio to the population numbers. These numbers were probably on the conservative side.                                                                                                                                               HIV 1 differented from the other primate forms of HIV  (such as HIV 2) hundreds of thousands of years ago. However other primate strains of HIV (called SIV), the strains of the great apes and simian monkeys, are still not that different and some may have potential to infect humans. However all HIV types found presently to infect humans are HIV 1 which has infected man hundreds of thousands of years and Sooty Mangaby monkey (simian) strain HIV 2 which has begun to infect humans since the end of the slave trade, probably not untill the past half century. Both human HIV 1and simian HIV 2(SIV) now additionally  a human HIV virus can be treated with the same HIV medicines.                                                                                                                                                   In the west Africa rain forests there are significant differences in the percentage of Sooty Mangaby monkeys infected by HIV 2 in accordance with area. One possiblity for this is that there are differences in these area in HIV inhibitor qualities of native wild food the monkeys eat.  It needs to be studied.