Stanford Center of Longevity's Laura Carstensen explains why people are living longer and how it affects future planning. : In the past 120 years, U.S. life expectancy has grown dramatically. Morningstar’s Christine Benz, director of personal investment, and Jeffrey Ptak, chief ratings officer, explored this topic in a recent interview with Laura Carstensen, psychologist and director of the Stanford Center on Longevity, on the podcast “The Long View.” Indeed, since 1900, there has been a 68% increase in average life expectancy, from 47 years at birth to 78.9 years at birth in 2014.