In industrialized countries, only one in six thousand people lives past the age of 100. Scientists say they have identified a group of genetic variants that can predict exceptional longevity in humans. The study, published online by the journal Science, has been called a breakthrough in understanding the role genes play in determining human lifespan. But aging populations present new challenges to societies built around shorter life spans. Just ask House Minority Leader John Boehner, who got an earful in Washington last week for suggesting that the retirement age be raised to 70 to keep Social Security solvent. What role does a healthy lifestyle play in living past one hundred? What's the impact on society of an increasingly older population? How likely is a rise in the retirement age?