How long we live and how well we age may not be fully under our control, even if we eat healthy, exercise, and have good genes.
According to a new review from researchers at the USC Leonard Davis School of Gerontology, a surprising factor could play a big role in aging: pure chance.
Published in the journal GeroScience, the study suggests that “biological stochasticity”—a fancy term for random events that happen inside our cells and molecules—could explain why some people age faster or slower than others, even when everything else is the same.
The research was led by gerontology professor Ryo Sanabria and introduces the idea of the “stochastome,” a collection of unpredictable processes that influence how we age.
To study this, scientists looked at tiny worms called C. elegans. These worms are often used in aging research because they have short lives and are easy to control in a lab. They can reproduce by themselves, creating offspring that are genetic clones.
Researchers also made sure that all the worms had the same diet, environment, and temperature.
But even under these perfectly controlled conditions, the worms aged very differently. Some lived long and stayed healthy, while others aged quickly and died sooner.
The researchers believe this variation is due to random processes inside the body. For example, some proteins in the worms folded the right way and helped keep cells working well.
In other worms, the same proteins misfolded, which led to faster aging. These changes couldn’t be traced to genes or outside factors—they just seemed to happen by chance.
Other random events during development, like how brain or reproductive cells grow, also seemed to affect aging later in life. Even how cells respond to stress, like heat or infection, varied a lot from worm to worm. These patterns mirror what we see in humans, too. Identical twins, who share the same genes and often similar lifestyles, can still differ in lifespan by up to 20%.
This randomness is what the researchers call the stochastome. It’s a new way to think about aging—one that looks beyond genes and lifestyle to include unpredictable biological events. Sanabria says this chaotic side of biology could be one of the most overlooked parts of why we age differently.
The idea of the stochastome could also change how we treat age-related diseases. If scientists can one day measure someone’s unique biological randomness, doctors may be able to better predict health outcomes and personalize treatments. It’s a bold new direction for aging research—and, as Sanabria puts it, “insanely cool.”
