Researchers are revealing the evolution of HIV, after recovering a near-complete HIV genome from tissue sliced from the lymph node of a man in the Democratic Republic of the Congo and encased in wax since 1966, STAT reports. HIV-1, one of the main viruses causing AIDS, was discovered in 1983. Older samples are scarce and their genetic material has degraded. This is the first HIV-1 genome from the 1960s and the oldest near-complete genome by a decade. The study, published on the preprint website bioRxiv, offers a more accurate “molecular clock” for the evolution of HIV. The virus’s genome does not show a different evolutionary timeline from more recent samples and supports the idea that the disease jumped from monkeys to humans in the early 1900s. The research was led by Michael Worobey, an evolutionary biologist at the University of Arizona in Tucson who studies the origin and evolution of HIV/AIDS through archival blood and tissue samples. His team has dispelled the myth of “patient zero”—that a flight attendant introduced the AIDS virus to the United States—and traced the virus’s spread across Africa.