Long life may be linked to genes, researchers say

A new study published in Science reports that about 50% of the variation in human lifespan could be attributed to genetics after accounting for deaths from external causes. The researchers used a model calibrated with historical twin records and data on siblings of centenarians to separate extrinsic mortality from biological ageing.

A new study in the journal Science reports that genetics may explain roughly half of the variation in human lifespan. The researchers say earlier estimates were lower because they did not separate deaths caused by external factors from those tied to biological ageing. The team built a mathematical model and calibrated it with historical twin records from Denmark and Sweden and with data on siblings of centenarians in the United States. They removed the impact of extrinsic mortality to try to reveal the genetic signal linked to internal ageing processes. What the researchers report: - After accounting for extrinsic mortality, the analysis suggests about 50% of lifespan variation is due to genetic factors. - The model was calibrated using correlations of lifespan from thousands of twin pairs in Denmark and Sweden and tested with a US study of siblings of centenarians. - The estimated genetic contribution to lifespan rose as extrinsic mortality fell over the 20th century, consistent with improved public health reducing external causes of death. - The heritability of lifespan varied by cause of death (for example cancer or dementia) and by age, according to the authors. - The researchers say the remaining variation is likely due to random biological effects and environmental influences such as lifestyle and social conditions. Summary: The study suggests a larger genetic role in lifespan variation than some earlier studies indicated, particularly when deaths from external causes are accounted for. The authors recommend further research to identify genes that affect biological ageing and to investigate the mechanisms behind protective effects; the timing and practical implications of such work are undetermined at this time.