Take swine flu. When the frightening influenza strain H1N1 began sweeping the nation last year, Rabadan and his team at Columbia University's Center for Computational Biology designed algorithms to search massive data sets for clues as to its origin. Whereas most other flu experts limited their search for genetic mutations to the past few months, Rabadan compared H1N1 with the DNA of tens of thousands of influenza samples dating back to 1918. In this way he was able to confirm swine flu's origin in pigs, not birds or humans, as other scientists had theorized. More important, his work revealed swine to be a dangerous yet underestimated breeding ground for new influenza strains. H1N1, the data showed, had been circulating in swine for 10 years. As a result, public health officials are now tightening surveillance for disease among pigs.