titled "Panel Nixes Congo Vaccine as AIDS source", describing the findings of an independent panel which found each proposed step in the OPV-AIDS hypothesis "problematic". The story concluded: The oldest confirmed sample of human tissue that shows the presence of HIV-1 is an archival sample of plasma collected from an anonymous donor in the city of Leopoldville, Belgian Congo (now Kinshasa, Democratic Republic of the Congo) in 1959 and was found with retrospective genetic analysis to be most closely related to subtype D strains. In 2008, partial HIV viral sequences were identified from a specimen of lymph node collected from an adult female, also in Kinshasa, in 1960. This specimen, named DRC60, was around 88% similar to ZR59, but was found to be most closely related to subtype A HIV-1 strains. These specimens are significant not only because they are the oldest specimens of the virus known to cause AIDS, but because they show that the virus already had an extensive amount of genetic diversity in 1960. In 2000, the Royal Society held a meeting to discuss data on the origin of AIDS; the OPV AIDS hypothesis was a central topic of discussion. At this meeting, three independent labs released the results of tests on the remaining stocks of Koprowski's vaccine, which Edward Hooper had demanded in The River. The tests confirmed Koprowski's contention that his vaccine was made from monkey, rather than chimpanzee, kidney, and found no evidence of SIV or HIV contamination. Additional epidemiologic and phylogenetic data was presented at the conference which undermined other aspects of the OPV AIDS hypothesis. According to a report in Science, Hooper "did not challenge the results; he simply dismissed them." In 2001, three articles published in Nature examined various aspects of the OPV AIDS hypothesis, as did an article published in Science. In every case, the studies' findings argued strongly against any link between the polio vaccine and AIDS. The evidence cited included multiple independent studies that dated the introduction of HIV-1 to humans as occurring between 1915 and 1941, probably in the 1930s. These results were confirmed by a later study using samples from the 1960s that also found that the epidemic began between 1908 and 1930, and a study that showed that although recombination amongst viruses makes dating less precise, it does not significantly bias estimates in either direction (it does not introduce a systematic error). The author of