During the past century, life expectancy in the United States has increased rapidly with advances in public health and living standards, improved diet, and rising levels of education. In 1900, life expectancy in the United States was 47 years. By 2014, U.S. life expectancy had increased to 79 years, and those who reached age 65 could expect to live another 19 years.

The increase in U.S. life expectancy is a public health success story. However, people surviving into their 80s, 90s, and beyond also experience a higher risk of age-related health problems and disability. Scientists hope to slow the process of aging to extend people’s lives and increase the number of years that they spend in good health and disability free, a period of life called “health span.”

Most people know about the importance of eating a healthy diet, exercising, maintaining a healthy weight, and avoiding smoking to prevent disease and increase longevity. But researchers have identified many other factors—including genetics, social connections, early-life experiences, and even certain personality traits—that may affect life expectancy..<