by Arpita Myles Acquired immunodeficiency syndrome or AIDS is a global health problem that has terrified and intrigued scientists and laypeople alike for decades. AIDS is caused by the Human Immunodeficiency Virus, or HIV, which is transmitted through blood, semen, vaginal fluid, and from an infected mother to her child [1] . Infection leads to failure of the immune system, increasing susceptibility to secondary infections and cancer, which are mostly fatal. Considerable efforts are being put into developing prophylactic and therapeutic approaches to tackle HIV-AIDS, but there is also interest in understanding how the disease became so wide-spread. With the advent of the Ebola and Zika viruses in the last couple of years, there is a renewed urgency in understanding the emergence and spread of viruses in the past in order to prevent those in the future. The narrative surrounding the spread of HIV has been somewhat convoluted, but a new paper in Nature by Worobey et. al , hopes to se