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You’re only as old as you feel, so they say. Now biological clocks attempt to put a number on it.
These tools analyze proteins in your blood, chemical markers on your DNA, or even the makeup of your gut bacteria to essentially predict how close you are to death. It’s an appealing idea. So when a company offered me the chance to find out my own biological age, I took it.
The company, Elysium, was cofounded by Leonard Guarente, a scientist at MIT who has been studying the biology of aging since the 1980s. Today, Elysium is one of many companies selling tests for biological age, as well as several supplements that aim to target aging.
The test that I took is based on some of the first biological clocks developed by academics. Back in 2011, Steve Horvath, then at the University of California, Los Angeles, was analyzing saliva samples for epigenetic markers—chemical groups that attach to our DNA to control how genes make proteins. Some attachments might turn genes on or off, for example.
Horvath noticed that the patterns of epigenetic markers seemed to align with age. In fact, they aligned so well that he was able to train an algorithm to predict a person’s age. In 2018, Morgan Levine, then at Yale University, and her colleagues took a similar approach with blood samples, but they incorporated health data as well as age. Levine’s resulting PhenoAge clock is thought to give a good idea of a person’s remaining health span—the years someone can expect to spend in good health.
Guarente and his colleagues at Elysium based their own clock on the work of Horvath and Levine, although they say they have modified theirs, and use spit samples rather than blood. The idea is that the clock should tell you how physiologically old you are, giving a sense of how much healthy life is left in you.
Given all that, I was hoping the test would put my biological age below my chronological age—that is, the number of birthdays I’ve had. Guarente, who is 70 years old, tells me his biological age is six years below his chronological age. So I spat into a tiny tube, sent my sample off to the company’s lab in the US, and crossed my fingers.
I’ve always thought—or at least hoped—that I look young for my age. That should bode well—studies suggest that your biological age is linked to how old you look. A team that developed an aging “speedometer” found that people who are aging faster look older, even when they are in their 30s.
But the last few years have taken a physical toll, as they have for many others. I’m not the only one to have found the pandemic extremely stressful, and research by Horvath and his colleagues suggests that stress can increase your biological age, at least temporarily.
I’ve also had two children in the last five years. A few studies suggest that there’s something about pregnancy, birth, or breastfeeding that might influence the way we age. One study I covered back in 2018 found that giving birth was “equivalent to around 11 years of accelerated cellular aging,” according to the scientist behind the work.
And then there’s the sleep deprivation familiar to all parents and caregivers of very young children. While science is still getting to grips with what happens to our brains and bodies while we sleep, it’s obvious that it’s something vitally important. Anyone who has been kept awake for nights on end won’t be surprised to hear that a lack of sleep has been linked to a shortened life span.
It’s also harder to eat well and get enough exercise when you’re balancing a full-time job with parenting. As I was adoringly brushing my four-year-old’s hair the other day, she commented: “Mummy, you’ve got loads of lines on your face.” Thanks, sweetie.
My test result arrived a few weeks ago. Apparently, my biological age is 35—the same as my chronological age when I took the test. In theory, this means that I’m aging at a typical rate—no better or worse than the other 35-year-olds we have data for, on average. I couldn’t help feeling a bit annoyed. Yes, I have two small children and am chronically sleep deprived, but I also eat a largely plant-based diet and do yoga three times a week. Surely that should put me at least a little above average?
I’m clinging on to the fact that there’s only so much any of us can take away from a biological clock score, no matter how alluring it might be. Despite lots of promising studies, we still don’t really know how accurate these tools are, or how much they can tell us about our health and longevity. Plenty of scientists are trying to figure this out, and working to develop clocks that better reflect what’s going on inside our bodies.
“It [comes across as] a one true number for your health, and people really want that,” says Martin Borch Jensen, chief science officer at Gordian Biotechnology, a company that aims to discover new treatments for age-related diseases. “We need to keep doing the work to find out if we actually have that or if it’s just a mirage.”
I covered aging clocks in more detail in this piece, published in April. And Karen Weintraub has explored how insurance companies and hospitals might make use of them.
At the end of September, I attended a super-fancy longevity conference for the mega-rich in the Swiss Alps—and discovered a fascinating world of hope, hype, and self-experimentation.
Both Morgan Levine and Steve Horvath have now joined Altos Labs, a company exploring ways to rejuvenate cells that my colleague Antonio Regalado described as “Silicon Valley’s latest wild bet on living forever.”
Antonio covered the technology, known as cellular reprogramming, in more detail in this recent feature.
There are loads of fantastic stories about aging, life, and death in the latest issue of our magazine, which is all about mortality.
From around the web
Lab-grown meat has been given its first stamp of approval by the US Food and Drug Administration. Upside Foods should soon be able to start selling cultivated chicken in the US, once a couple more small regulatory hurdles are cleared. (Wired)
We don’t really know what’s in tampons—and how chemicals from them might affect our bodies. (Undark)
Video footage reveals just how stringent China’s zero-covid policy is, as evidence surfaces of children being locked into boarding schools and others being denied medical care. (New York Times)
Flu season started early this year in the US, and we don’t really know why. (Scientific American)
A new tick-borne disease is killing cattle in the US—and the tick responsible is predicted to spread across the country in the coming years. (MIT Technology Review)