http://www.boston.com/ NEW YORK - The AIDS virus has been circulating among people for about 100 years, decades longer than scientists had thought, a new study suggests.
Genetic analysis pushed the estimated origin of HIV back to between 1884 and 1924, with a more focused estimate at 1908.
Previously, scientists had estimated the origin around 1930. AIDS wasn’t recognized formally until 1981, when it got the attention of US public health officials.
The results appear in today’s issue of the journal Nature. Researchers note that the newly calculated dates fall during the rise of cities in Africa, and they suggest urban development could have promoted HIV’s initial establishment and early spread.
Scientists say HIV descended from a chimpanzee virus that jumped to humans in Africa, probably when people butchered chimps. Many individuals were probably infected, but so few other people caught the virus that it failed to get a lasting foothold.
The new work used genetic data from two old HIV samples and more than 100 modern samples to create a family tree going back to these samples’ last common ancestor.
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