On Longevity, 'You Don't Have as Much Control as You Think'

How long you live may be more baked in than you think, according to a new analysis of longevity that leans heavily toward genes over lifestyle. In a paper published Thursday in Science, researchers led by Uri Alon of Israel's Weizmann Institute of Science report that inherited factors appear to explain more than half of the variations in how long people live—far above earlier estimates of 25% or less. Using mortality data from Swedish twins born between 1900 and 1935, as well as Danish twins born earlier and US siblings of centenarians, the team tried to strip out deaths largely unrelated to aging, such as accidents and infections, to isolate aging itself.

Once the researchers did that, genetics emerged as the dominant factor. Lifestyle still matters, the authors say, but mostly around the margins: Alon estimates that healthy or unhealthy habits can shift life expectancy by roughly five years in either direction. If your genetic "ceiling" is about 80, for example, you might push that to around 85 with ideal habits—or cut it to 75 with none, per the New York Times. As epidemiologist S. Jay Olshansky, who wasn't involved in the research, puts it: "You don't have as much control as you think," adding that extreme old age generally requires winning "the genetic lottery for longevity at birth."

Outside experts are split on how firm that conclusion is. Some, like University of Copenhagen researcher Daniela Bakula, say the findings match what's known in other species, where lifespan is strongly genetic. Others, however, including University of Hawaii geriatrician Bradley Willcox, argue it's impossible to cleanly separate "intrinsic" biological causes of death from environmental ones, especially when genes can influence how severely a person responds to infection or other stressors.

Lifestyle can still play an important part. Thomas Perls, who runs the New England Centenarian Study at Boston University, points to Harvard data suggesting that a 50-year-old woman with healthy habits could expect to live to about 93, versus 79 with poor habits; for men, the spread is roughly 88 vs. 76. Still, when it comes to reaching 95 or 100, Perls and others agree that family history looms large. Even for the genetically fortunate, Olshansky notes, "it's easy to shorten your life but very difficult to lengthen it." Previous research, meanwhile, has come to the opposite conclusion.