Scientists have identified the 'Methuselah' genes whose carriers have a much-improved chance of living to 100 despite indulging in an unhealthy lifestyle.
The so-called Methuselah genes- named after the biblical patriarch who lived to 969 - protect people against the effects of smoking and bad diet and can also delay the onset of age-related illnesses such as cancer and heart disease by up to three decades.
"Long-lived people do not have fewer disease genes or ageing genes. Instead they have other genes that stop those disease genes from being switched on. Longevity is strongly genetic and inherited," The Times quoted study's lead author Eline Slagboom of Leiden University, as saying.
The genes are thought to include ADIPOQ, which is found in about 10 percent of young people but in nearly 30 percent of people living past 100.
The CETP gene and the ApoC3 gene are found in 10 percent of young people, but in about 20 percent of centenarians.
The studies show that tiny mutations in the make-up of particular genes can sharply increase a person's lifespan. Nonetheless, environmental factors such as the decline in infectious diseases are an important factor in the steady rise in the number of centenarians.
Dr David Gems, a longevity researcher at University College London, believes that treatments to slow ageing will become widespread.
"If we know which genes control longevity then we can find out what proteins they make and then target them with drugs. That makes it possible to slow down ageing. We need to reclassify it as a disease rather than as a benign, natural process. Much of the pain and suffering in the world are caused by ageing. If we can find a way to reduce that, then we are morally obliged to take it," he said.