James Vaupel, founding director of the Max Planck Institute for Demographic Research in Germany, thinks the population of those living to 100 and older is doubling. “The number of centenarians in the U.S. and other countries has been doubling roughly every eight years. When the baby boomers hit, there’s going to be acceleration, and it might be doubling every five or six years.” Clearly, the number is increasing. Between 1980 and 2010, the numbers in America rose from 32,194 to 53,364, an increase of almost 66 percent. The latest population estimate, released in July 2015, reflects 76,974 centenarians. Is it genes or behavior?