How AIDS first spread: Journey into night

RAILWAYS are one of humanity's most important inventions. But they can transport bad things as well as good, and one of those bad things is disease. In particular, suggests a paper just published in Science by a team led by Oliver Pybus of Oxford University and Philippe Lemey of the University of Leuven, in Belgium, they had a crucial role in the early dissemination of HIV, the virus that causes AIDS.Dr Pybus and Dr Lemey have been investigating the origin of this infection. Most cases are cause...