How did the first AIDS occur?

For the first AIDS patients from where to show, at this stage and there is no affirmative statement, but AIDS is caused by HIV infection as an infectious disease, according to current speculation, AIDS is estimated to originate in Africa, the earliest may be out of the current animals, such as apes and apes. However, these viruses may not cause disease in animals, but after spreading to humans, they will quickly attack the immune system of the human body, resulting in opportunistic infections after the function of the human immune system declines, which is more likely to increase the expression of tumors and ultimately deprive patients of their lives.