As kids, we couldn’t wait to grow up, tacking on “and a half” to our ages just to feel older. But somewhere along the way, the script flipped. Suddenly, we’re reluctant to share our age, or we catch our reflection and wonder why it doesn’t match how we feel on the inside. The good news? The age on your driver’s license isn’t the whole story, and something known as biological age is a better reflection of how you’re aging on a molecular and cellular level.
Biological age versus chronological age
If you’ve seen the viral videos marveling at how certain generations (cough, millennials) “aren’t aging,” there’s actual science to back up the idea that we all age in different ways.
This explains why some 70-year-olds are crushing workouts and climbing mountains while others, unfortunately, struggle with stairs or everyday tasks. That’s because an individual’s biological age (a conceptual reflection of how they’re aging internally, externally, and functionally) might be substantially different from their chronological age (the number of birthdays they’ve celebrated or how many times they’ve been around the sun.)
There are several different indicators of biological age, including grip strength, VO2 max, blood markers that are reflective of cardiovascular health and blood sugar control, and computational models called next-generation epigenetic aging clocks.
Next-generation epigenetic aging clocks are more contemporary aging biomarkers that use machine learning or artificial intelligence to predict something known as epigenetic age. Epigenetic age itself is based on epigenetics—changes that modify gene expression without altering genetic code. While your DNA contains all your genes and serves as the blueprint for your body, epigenetic processes such as DNA methylation dictate which genes are active or inactive in different cells and at different times.
Not only do epigenetic patterns dictate cellular behavior, but they affect everything from cellular repair to inflammation. Epigenetic patterns also change dramatically with age, and these epigenetic alterations are considered to be a fundamental hallmark of aging. DNA methylation and other epigenetic processes are also highly sensitive to lifestyle behaviors, meaning your daily habits don’t just affect how you feel as you age; they also shape how you age at the molecular level.