After Filtering Out Accident and Infection Deaths, Heritability of Human Lifespan Exceeds 50%

An analysis overturning the common belief that human lifespan depends more on environment and luck than on genes appeared in Science. The team of Uri Alon at the Weizmann Institute of Science in Israel, together with researchers at the Karolinska Institute in Sweden and Leiden University Medical Center in the Netherlands, reported that the heritability of lifespan from ageing exceeds 50%.

Why earlier estimates were low

Until now, twin studies have estimated the heritability of lifespan at 20 to 25%, and large pedigree studies as low as about 6%. The researchers argued that these figures were diluted by extrinsic mortality, deaths from factors outside the body such as accidents and infections. Because extrinsic deaths occur almost independently of genes, mixing them in makes the genetic effect look smaller than it really is.

The researchers adjusted for this factor using mathematical modelling together with data from cohorts of twins reared together and twins reared apart. They found that, looking only at intrinsic mortality from ageing, heritability exceeded 50%. This is similar to the heritability of other complex traits and to lifespan heritability measured in other animal species.

If heritability is high, it means studies of longevity genes are more useful for uncovering the mechanisms of ageing. However, this figure is a population-level estimate based on model assumptions, and it does not mean an individual's lifespan is determined by genes.