Bubonic plague. AIDS. Yellow fever. Some of the greatest scourges mankind has ever faced – and those that may yet spark a pandemic, such as bird flu – all originated as infectious agents in animals that then made the jump into human beings. It’s no accident that close contact between man and rats in medieval towns led to the Black Death, and that people hunting primates in the African bush provided an avenue for AIDS to spread throughout the world.

What if scientists could identify the next killer bacteria or virus before it struck humans? Nathan Wolfe writes about how this early detection may be possible in the April issue of Scientific American. Wolfe is a professor of biology at Stanford University and director of the Global Viral Forecasting Initiative, an effort to take stock of animal diseases in hotbeds of human-animal proximity – the jungles of Africa and southeast Asia, for example – and to monitor local people for what germs they carry that came from the wild.

In this video from February’s Technology, Entertainment, Design (TED) Conference, Wolfe explains how the hunting of primates in Africa for their bushmeat by the poverty-stricken represents a prime way for new diseases to cross over. After all, primates are humankind’s closest relative, so what infects an ape has a strong chance of also taking hold in a person.