Studies over the past 20 to 30 years have investigated the influence of genetics on longevity and found that the influence is between 15 and 33%.
However, a new study was published in the journal science These estimates are likely skewed by the historical period in which the data were collected, suggesting that the influence of genes on lifespan may be even greater.
Previous studies of twins and families have relied heavily on data from people born in the late 19th and early 20th centuries, when deaths from causes unrelated to biological aging (such as infectious diseases, accidents, violence, and natural disasters) were 10 times more common than today, said Ben Shenhar, lead author of the new study and a doctoral candidate and researcher at the Weizmann Institute of Science in Rehovot, Israel.
These historical circumstances have created misleading signals, he says. “Sometimes you see twins where one died at 30 and the other lived to be 95. Nowadays that’s very rare, but back then it wasn’t.”
To obtain a more accurate assessment, Shenhar and his colleagues developed a mathematical modeling approach designed to distinguish between deaths caused by external events and those caused by biological aging.
Once they applied that model, things changed a lot. Researchers estimate that genetic factors account for about 50 to 55 percent of expected lifespan. This is about double the previous estimate.
“This study convincingly showed that initial estimates of the genetic contribution to longevity were too low,” says Charles Brenner, Ph.D., chair of the Alfred E. Mann Family Foundation Division of Diabetes and Cancer Metabolism at the Beckman Institute at City of Hope in Duarte, Calif., who was not involved in the study.
The findings also support previous research on the strong role that genetics plays in dementia: “We found that the heritability of death from dementia is about 70 percent,” Dr. Brenner said.
However, up to 45 per cent of dementia may be preventable through healthy lifestyle choices such as diet and exercise. Genes do not accurately determine a person’s lifespan But genetic risk may shape the overall range of lifespan associated with aging more than scientists once believed.
“Our findings don’t suggest that lifestyle isn’t important for longevity. That’s not the case at all. Even if 50 percent of longevity is inherited, there’s still another 50 percent left,” Shenhar says.
