Various alternate theories and other such hypotheses have arisen to speculate about the origins of HIV/AIDS. These alternative ideas range from suggestions that AIDS was the inadvertent result of experiments in the development of vaccines, to claims that human immunodeficiency virus was developed by scientists working for the U.S. government. While a few reputable mainstream scientists once investigated some of these theories as reasonable hypotheses, this is no longer the case, as continuing research has invalidated the alternative ideas. The current scientific consensus is that AIDS originated in Africa in the mid-1930s from the closely related Simian Immunodeficiency Virus.