Being asked ‘how old are you?’ used to be a simple question to answer. If you weren't sure, you could always just count the candles on your birthday cake. The candles may no longer tell you the whole story, however. That’s according to a growing group of scientists who claim that you don’t just have a traditional chronological age, but also a potentially more fluid ‘biological age’. And that biological age could even be wound back… if you know how.
The excitement about this idea began around 2013, with the first DNA tests that could estimate your age to within a few years. The fact that a person’s DNA and chronological ages were usually slightly different raised a question: if the test deemed that you were older than your age in years, was that an error, or could it indicate something about how fast you’re ageing on a biological level?
A decade of intervening research has shown us that people with an older DNA age, known more correctly as an ‘epigenetic age’, do indeed seem to be older biologically, and so they tend to get ill and die sooner than others. It’s a scientific discovery that demonstrates what many of us have believed all along: people age at different rates. But what does this actually mean, both biologically and practically speaking?