It was good to read Gao et al. 's report1 which now leaves little doubt that chimpanzees (Pan troglodytes troglodytes) from central Africa are the origin of the human HIV-1 pandemic. Two additional points seem worthy of comment.
Chimpanzees live in multi-male communities with a promiscuous mating system, quite unlike humans or the other great apes. This makes them particularly susceptible to the spread of sexually transmitted infections, so they might have evolved some novel defence mechanisms which have allowed them to come to terms with HIV-1. If only we knew how.
One of the consequences of the chimpanzees' promiscuous mating system is that they have developed extremely large testes in response to gamete selection2. Unfortunately, this made chimpanzees attractive subjects for Serge Voronoff, director of experimental surgery at the Collège de France in Paris. In the 1920s, Voronoff was the leading exponent of testicular transplantation for the rejuvenation of ageing men3,4. Lacking an adequate supply of fresh human testes courtesy of the guillotine, he resorted to chimpanzee testes, which had the added advantage that each was so large that it could provide scrotal transplants for a number of men. Since his chimpanzee donors could well have come from Francophone central Africa, it is quite possible that some of his elderly male patients, and maybe even their partners, might have acquired an HIV-1 infection and developed AIDS.
Perhaps it is just as well that they were suffering from impotence and could not have been cured by the treatment. Nevertheless, their case histories would now make fascinating reading with the wisdom of hindsight.
Gao, F. et al. Nature 397, 436–441 (1999).
Short, R. V. Acta Paediatr. Suppl. 422, 3–7 (1997).
Gosden, R. Cheating Time: Science, Sex and Ageing (Macmillan, London, 1996).
Voronoff, S. Scientific American, October, 226-227 (1925).