- Genetics may account for over 50 percent of human lifespan according to new research
- Earlier estimates of lifespan heritability ranged between 15 and 33 percent
- Correcting for extrinsic mortality raises heritability estimate to about 55 percent
Genetics may explain about half of a person's lifespan, a study has suggested, pointing to a far more significant role of genetics than earlier research indicated.
The findings, published in the journal Science, show that once mortality due to external factors such as accidents or infections are accounted for, "heritability of human life span due to intrinsic mortality is above 50 per cent".
The researchers from Israel's Weizmann Institute of Science and Karolinska Institutet in Sweden said understanding the heritability of human life span is central to ageing research, yet measuring genes' influence on longevity remains challenging.
Earlier studies have estimated that life span may be 15-33 per cent heritable across varied populations, with a typical range of 20-25 per cent, they said.
The researchers show that the estimates "are confounded by extrinsic mortality -- deaths caused by extrinsic factors such as accidents or infections".
While genes linked to lifespan have been identified, external environment such as disease or living conditions can exert a powerful influence on how long one lives and often obscure or confound potential genetic effects, they said.
"Extrinsic mortality systematically masked the genetic contribution to life span in traditional analyses," the authors wrote.
The team added that historical data from twin studies -- often explored for understanding how genes interact with environment and contribute to noticeable traits -- lack sufficient cause of death information to correct for extrinsic mortality.
"We use mathematical modelling and analyses of twin cohorts raised together and apart to correct for this factor, revealing that heritability of human life span due to intrinsic mortality is above 50 per cent," they said.
"Correcting for extrinsic mortality raises the estimate for the heritability of human life span in twin and sibling studies to (nearly) 55 per cent, more than twice previous estimates and in line with heritability of most human traits," the team added.
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