The secret to long life? It could be in the genes after all, say scientists | Genetics
Some people who live to old age attribute this to drinking some whiskey in the evenings, others to staying out of trouble. Now scientists think they may have uncovered the key secret to long life: genetics.
writing in diary ScienceThe researchers described how previous studies that attempted to uncover the genetic component of human lifespan did not take into account that some lives were shortened by accidents, homicides, infectious diseases or other factors originating outside the body. Such “extrinsic mortality rates” increase with age, as people generally become weaker.
Prof Uri Alon of the Weizmann Institute of Science in Israel and colleagues say the true genetic contribution to variation in human lifespan is being masked.
The team looked at “heritability”, which is the rate of variation in a trait in a population that is attributable to genetics rather than environmental factors such as height, body weight or lifespan. Previous studies of human lifespan have revealed a wide range of heritability values, from 6% to 33% of variation.
But Alon, one of the authors of the study, and his colleagues said these figures were underestimates. “I hope this will inspire researchers to delve deeper into the genes that influence lifespan,” Alon said. “These genes will tell us about the mechanisms that govern our internal clocks.
“These could one day be turned into therapies to slow the rate of aging and thus slow all age-related diseases simultaneously.”
The team created a mathematical model that took into account extrinsic mortality rates and the impact of biological aging, and calibrated it using lifespan correlations from historical datasets of thousands of pairs of twins in Denmark and Sweden.
They eliminated the effect of extrinsic mortality to reveal the signal of biological aging caused by genetics. The results show that approximately 50% of the variation in human lifespan is due to genetics; This figure, the researchers say, is on par with that seen in wild mice in the laboratory.
The other 50% of the variation in human lifespan is probably explained by factors such as random biological influences and environmental influences, they said.
“We would expect to find all the usual suspects here, such as lifestyle, diet, exercise, social relationships, environment and more,” said Ben Shenhar, a co-author of the study, adding that lifestyle and environment will likely become more important as we age.
The team tested their results using data from a study of siblings of centenarians in the United States and found that the heritability of lifespan was about 50%.
Further testing using another Swedish data set revealed that as extrinsic mortality rates decreased from the beginning of the 20th century (possibly due to factors such as improvements in public health), the estimated genetic contribution to lifespan increased; This supports the idea that exogenous mortality is an important factor when looking at heritability. The team also found that the heritability of lifespan varied with age and causes of death, such as cancer or dementia.
Shenhar added that daily experience shows that genetics play an important role in longevity. “About 20 percent of centenarians, for example, reach age 100 without any serious debilitating diseases,” he said, adding that this could indicate their genes have a protective effect. “Work has been done to identify these protective genes and many have been found, but there are certainly many more still waiting to be discovered,” he said.
Although the new study did not take into account the influence of genes on the immune system, Prof Richard Faragher, from the University of Brighton, said the research suggested humans were no exception when it came to the heritability of lifespan.
“And that’s useful because it means that humans are quite similar to the species in which we study aging. [and] “It gives you a certain confidence that interventions that work in mice will also translate to humans,” he said.
