Studies on twins can help to elucidate how much a person’s genes contribute to specific traits such as life span.Credit: Pierre Andrieu/AFP via Getty
Genetics has a much larger role in how long a person lives than previously thought, finds a new analysis that challenges decades of scientific consensus.
About 55% of the human lifespan is heritable, meaning that more than half of observed variation in longevity across a population is attributable to genetics. That is a far greater proportion than the 10%–25% previously estimated, according to the research, which was published today in Science1.
The findings should aid in the quest to find specific genes involved in ageing and to develop treatments, says study co-author Ben Shenhar, a biophysicist at the Weizmann Institute of Science in Rehovot, Israel.
“There is much to be learnt from the genetics of ageing if we can understand what genes are responsible for healthy ageing,” he says.
Twin efforts
Shenhar and his colleagues say that previous estimates were far too low because they did not effectively separate deaths caused by extrinsic factors, such as infectious diseases or accidents, from intrinsic ones inside the body, such as the gradual decline of organ function stemming from DNA damage over time.
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To tease out these factors, the researchers re-examined data, going back to the 1800s, from twin studies in Denmark and Sweden, as well as studies on siblings of centenarians in the United States. Such studies can help to identify genetic components of traits, Shenhar says, because identical twins share 100% of their DNA, whereas fraternal twins and other sibling pairs share about half on average.
