The Puzzling Origins of AIDS
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How did HIV originate? Four ideas are under serious consideration.
One is quite controversial—the notion that the progenitor
virus (which in the case of HIV-1 is found in chimpanzees) crossed
into humans through a large-scale trial of an experimental oral
polio vaccine carried out in the Belgian Congo between 1957 and
1960. The main competing theory is that the simian progenitor virus
passed to humans through cuts as someone was hunting or butchering a
chimpanzee (or, in the case of HIV-2, a type of West African monkey
called the sooty mangabey). The difficulty with the cut-hunter
concept is that, taken alone, it does not explain why the simian
progenitor virus did not make the jump to humans before the middle
of the 20th century (and then, why it did so multiple times). To
answer that riddle, two modifications have been proposed. Both
suggest that accidental blood-to-blood contact accounts for how
these simian viruses first infected people and that specific human
actions allowed them to spread in the population and eventually
mutate to HIV, sparking the current pandemic. One hypothesis
implicates the widespread reuse of disposable syringes, which were
introduced during the 1950s. The other focuses on the disruptions of
the colonial era, a time when Europeans brutalized the natives of
Central Africa, resulting in the deaths of millions and forcing
large-scale population shifts—all the while subjecting many
Africans to medical treatments that probably involved the reuse of
unsterilized syringes. Moore, an anthropologist and an author of the
last of these theories, gives a balanced account of the various possibilities.