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鈥淚t would make life much easier if you didn鈥檛 have to exercise every day, eat well and聽quit smoking鈥� (Image: Courtesy of Morgan E. Levine)

What drew you to old-age smokers when investigating the genetic basis of longevity?
There鈥檚 been quite a bit of animal research suggesting that those who survive the longest are simply better equipped to deal with biological stress. So I started thinking about common stressors humans deal with that might be similar. Smoking is a biologically stressful activity. And its effects on health have been well studied. So if an individual smoked from a young age, and still lived a long, healthy life, their genes seemed like a good place to look for something that made them more resilient.

How old did you have to be to qualify as a long-lived smoker for this study?
We looked at people who were 80 and older. In retrospect, 80 as the cut-off was a bit too young. We would have liked to study people who were even older. But it鈥檚 hard to find people who live past 80 who smoke. So we looked at people of 80 and older who had started smoking as teenagers or in young adulthood.

How many smokers actually make it that far?
I can鈥檛 give you an exact figure, but it鈥檚 a very small proportion. As everybody knows, smoking is related to a whole range of health problems; it is not something that promotes long life in the average person.

But your smokers seem to be immune?
They are much healthier than you would expect; they have pretty good clinical biomarkers and they look a lot like healthy people of the same age who have never smoked. So we think they are a biologically distinct group that have some genetic, and perhaps also epigenetic, factors that allow them to survive, and sometimes even thrive, despite their smoking.

What have they got that the rest of us lack?
It basically comes down to differences in some genes that are involved in a biochemical pathway called the insulin/IGF1 pathway, which has been linked to longevity in a variety of studies. There is good evidence that some variants of these genes help increase cellular maintenance and repair. People who have them, like our smokers, are better able to deal with stress at the cellular level. And that slows the ageing process.

Why do you think we are so compelled by stories about superagers, especially those who engage in bad habits like smoking?
Everyone secretly hopes that they are one of these people. It would make life much easier if you didn鈥檛 have to exercise every day, eat well and quit smoking. We鈥檇 rather not do the work!

But even though everyone knows of someone who lived to 95 while drinking, smoking, and eating fatty foods, they really are the exceptions. The truth is, if you want to have a long and healthy life, you have to have the right lifestyle. Even if you are lucky enough to be one of these individuals, living healthfully will still benefit you. You鈥檒l have an even longer, higher quality life. It鈥檚 not worth playing the genetic lottery.

This article appeared in print under the headline 鈥淪mokers die young, right?鈥�