At the end of last year, Jay Chan, a 30-year-old marine engineer, bought his mother a biological age test from Elysium, a New York-based biotech and health supplements start-up founded in 2014. The test was simple – it required only a saliva sample – and it helped that it was being offered for half off the usual $499 (£400) price.
For fans of the self-described “longevity movement” like Chan, the concept of biological age is liberating. Rather than simply measure the passage of time, biological age aims to quantify the age of our body’s functions and even predict mortality. Many scientists and longevity advocates believe this information can not only help us understand our own age process, but can give us the power to change it.
Chan felt his mother, Ivy, who is 59 years old, would benefit from knowing her biological age because she was anxious about getting older. “She always talked about entering her 60s and how it’s a big step, and this is the start of fading away,” Chan told me. But with her youthful looks, she still felt healthy. “She looks like a 40-year-old!” he said.
About two months later, they got the results back: Ivy’s biological age was 43.
“It was such a relief for her, because it gives her a newfound hope about life planning,” Chan said. “Knowing how fast she is really age, it gives her a renewed sense of self and how she should live in the upcoming decade.”
Dr Steve Horvath, a 54-year-old UCLA professor who pioneered the first “clock” to indicate human age by examining chemical changes to DNA, told me that “biological age is a better predictor of morbidity risk than chronological age. It is in some ways a tautology: if it wasn’t better, we wouldn’t call it biological age.”
The hope is that understanding biological age can lead to new life-lengthening interventions. But the first step is to try to measure it, and that’s not straightforward. “Researchers debate how to define it,” said Horvath.
One approach focuses on the length of telomeres, which are protective structures on the ends of our chromosomes, that shorten every time a chromosome replicates – making them an approximate yardstick for biological age.
Other approaches take blood samples and measure the presence of molecules that correlate with decreased bodily function. Some approaches even claim to determine mortality risk by scanning people’s eyes.
Horvath’s approach, called the “epigenetic clock”, is considered by many scientists to be the gold standard. Epigenetics is the study of how your environment changes the way your genes work. Horvath’s clock analyzes certain chemical changes to genetic material, a process called DNA methylation. In 2011, Horvath found patterns of DNA methylation could be used to accurately estimate human age.
Horvath compared methylation to sand moving through an hourglass. “As we age, certain parts of the DNA gain methylation and other parts lose methylation. It’s really millions of locations of DNA,” he said.
Horvath’s clock tracks several hundreds of these locations. The result was a formula able to estimate age across a human’s entire life course, from fetus to old age.
Since then, Horvath and other scientists have developed more accurate clocks, based on data collected from the blood samples of the same group of people over many decades. That data helps the clocks to identify unhealthy age with greater precision – and, Horvath suggests, “predict time to death”.
If that all sounds complex, it’s perhaps by the name Horvath gave his second-generation clock: Grim Age, as in the Grim Reaper.
In recent years, these methods have led to an explosion in startups that aim to measure biological age for consumers. These biological age tests are marketed as premium wellness products, often with sleek websites, minimalist packaging and influencer endorsements on social media.
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