The first Indian prime minister to serve two consecutive terms since Nehru, it’s been Singh, a 77-year-old economist, who has kept India’s tiger economy growling. Responsible for leading one of every six people on earth, Singh has done so as a Sikh, a minority in India. His ability to avoid the stain of corruption has also earned him praise. An professor with a knack for politics—think India’s Josiah Bartlet—Singh has thrived on the world stage. “Anyone who can obtain a Ph.D. in economics from Oxford and successfully manage the world’s largest democracy has to be the smartest person in the world,” says one of our MacArthur voters, Loren H. Riesenberg of Indiana University.