According to a recent Pew Research Center survey of 8,750 U.S. adults, Americans say they would ideally live to an average age of 91, and 29% would like to reach age 100, even though U.S. life expectancy at birth remains around 78 years. At the same time, surveys reveal a strong preference for healthy years over simply more years. But what is behind the seemingly new desire for extreme longevity? Here’s what researchers have uncovered.