The paper is called "Smoking and skin aging in identical twins.", and what makes it so interesting is that although I've always known that smoking ages you, I've never really gotten to see a compare-and-contrast case study that can serve as a way to visualize the difference. But now we do, thanks to twins!
In this study, the researchers took a look at a set of identical twins (so same genetics) with very similar lives to each other (lived in same town for 30 years, similar lifestyles with minor differences etc.), and the main difference was that one twin smoked, and the other twin didn't. Essentially this allowed for the researchers to conclude that any significant difference in appearance was quite possibly due to one smoking and the other not. In their words: "In this pair of twins with an identical genetic background, minor medical histories, and similar significant sun exposure histories, the clear difference between twin 1 and 2 was the extensive history of tobacco use in twin 1 that was absent in twin 2. This variable likely served as the major contributor to advanced skin aging in twin 1."
You can see the results below:
Now the first thing I'll say is that both ladies look great. They look energetic and full of life, and their eyes sparkle with personality (their eyes that are a lovely shade of blue, too!). And really, if you think about it, at the end of the day, your personality is what matters most, instead of trying to compare the number of wrinkles a person has. But since this post is meant to be a cautionary tale about the effect of smoking on skin from a beauty blog perspective, I will do the horrible and delve into the superficial. (Aww, just cut me some slack here. How many beauty blogs do you know that even write about smoking and health?)
You can indeed see a difference in wrinkles caused by smoking, although perhaps, not as severe as one might expect. But bear in mind - even the smoking twin didn't smoke all that much. The study reports that she smoked in the "approximately 52.5–pack-year" range, which is actually a pack a week. Given that a cigarette pack holds anywhere from 20 - 25 sticks, Twin 1's smoking habit was definitely very light, probably a 2-3 sticks a day. And yet, even at this very light rate, the difference is visible. If the researchers had used a set of twins where one smoked a lot more (say, a pack a day, still within the "light" range), then you can imagine the difference will be much starker.
So yes, it does seem that if you're smoking, you're more likely to get wrinkles, and this applies even if you're smoking just "a couple of sticks a day". The study demonstrated that those couple of sticks do add up over time - just like UV exposure, the damage seems to be cumulative. And this is particularly relevant for young adults, because even while heavy smoking has decreased in general, the number of young adult light smokers has been increasing over time. Perhaps such people feel that because their smoking is light/intermittent/infrequent, they aren't damaging their health by doing it, but that's not true. In fact, "low levels of tobacco exposure as seen in light smoking (4–7 cig/day) has about 70% of the effect of heavy smoking (≥ 23 cig/day)" (original source), because the dose-effect relationship is "highly non-linear". Wrinkles are just one part of what happens when you damage your body by smoking, even light smoking.
So there you go - I'm sure you knew it all already, but yes, smoking harms your health, even if it's the light kind of smoking that is deemed socially acceptable. Really, when it comes to smoking, any dose is bad for your health. But for those who don't care about their health, then perhaps, as the study's authors muse, "wrinkles, rather than the deadly consequences of smoking, may prove to be the most powerful motivator for smokers to stop smoking."