People have wanted to stay young for about as long as people have existed.
The ancient Greeks told stories about ambrosia, a food that supposedly kept the gods forever youthful. Old Chinese traditions passed down recipes for potions meant to stretch out a person's years. During the Middle Ages, some searched for a mythical liquid known as the water of life, convinced it could undo the effects of growing old.
None of that had much to do with science, at least not as we understand it today. People were hoping, not testing. That began to change in the late 1800s, when a handful of scientists started wondering whether aging might actually be something the body does, something that could be studied and explained rather than simply accepted.
A new review published in the journal Molecules walks through that whole story, from ancient myths to modern labs, and lays out what scientists currently understand about why we age and whether anything can be done to slow it down.
The scientists who changed how we think about aging
One of the earliest researchers to take aging seriously as a biological question was Elie Metchnikoff, a Nobel Prize winning scientist.
He had a theory that certain bacteria living in the gut released substances that sped up the aging process, and he thought eating fermented milk might counteract this.
He turned out to be wrong about the details, but he still deserves credit. He was one of the first people to try explaining aging through biology instead of folklore.
The real turning points came later in the twentieth century. In 1961, a scientist named Leonard Hayflick noticed something strange while growing human cells in his lab. The cells could only divide a certain number of times before they simply stopped dividing altogether. This came to be known as the Hayflick limit, and it changed how scientists thought about aging at the cellular level.
Around the same time, researchers discovered telomeres, small protective caps sitting at the ends of our chromosomes, the structures inside our cells that hold our genetic information.
Telomeres work a bit like the plastic tips on shoelaces, keeping the more important parts from fraying apart. Every time a cell divides, its telomeres shrink a little, and that slow wearing down is now considered one of the clearest fingerprints of aging inside the body.
What scientists focus on today
These days, researchers use the word geroscience to describe a field that links the biology of aging to the diseases that tend to show up later in life, things like heart disease, diabetes, and various cancers.
Instead of tackling each disease on its own, geroscience asks a more ambitious question. What if slowing down aging itself could lower the risk of several of these conditions at once?
Three biological systems come up again and again in this research, largely because they act like internal sensors, always tracking how much fuel and energy the body has on hand.
The first is called mTOR, a protein that helps cells decide when it is time to grow, based on how much nutrition is available. The second, AMPK, does something like the opposite job. It switches on when energy runs low, such as during fasting or a hard workout, and nudges the body to clean out old, damaged material inside its cells.
The third group, sirtuins, help repair broken DNA and control which genes get switched on or off, but they rely on a molecule called NAD+ to do their job, and NAD+ levels naturally fall as we get older.
Putting these ideas to the test
According to the review, scientists have tried a number of ways to influence these systems, mostly in animals so far, though a handful of small human trials are already underway.
Eating fewer calories while still getting proper nutrition, something researchers call caloric restriction, has repeatedly helped lab animals like mice and worms live longer. A couple of existing drugs have also caught researchers' attention.
Rapamycin, normally used to help prevent organ transplant rejection, and metformin, a widely used diabetes medication, have both shown encouraging signs in animal research and in a few small early trials with people.
Newer strategies are emerging too. Some researchers are testing supplements meant to restore NAD+ levels that decline with age, while others are studying a class of drugs called senolytics.
These are designed to clear out senescent cells, which are old cells that have stopped dividing but somehow refuse to die off the way they normally would. Instead, they linger in our tissues, releasing substances that trigger inflammation and can damage the healthy cells nearby.
Early trials of these approaches in people have shown some real promise, including improvements in inflammation and physical strength, though the scientists behind this review are quick to note that this research is still quite young.
A reason for careful optimism, not hype
It is worth pausing on what this kind of research can and cannot tell us right now.
This particular paper is a review, meaning it pulls together and summarizes existing studies rather than reporting brand new experiments, and it is honest about the gaps that remain.
Many of the human trials it references involved small groups of volunteers, ran for only a few weeks or months, and measured shifts in biological markers rather than whether people actually ended up living longer or staying disease free.
None of the approaches discussed so far have been shown to reverse aging or prevent disease in humans. The scientists are upfront that turning promising animal results into safe, effective treatments for people remains one of the toughest hurdles the field has to clear.
They also bring up a point that feels easy to overlook amid the excitement, which is that if effective treatments do eventually arrive, making sure they are available to everyone, not just those who can afford them, will matter just as much as the science behind them.
What started thousands of years ago as a search for magical elixirs has slowly turned into a genuine, evidence based effort to understand why our bodies grow old.
The researchers behind this review are not promising anyone immortality. What they are pointing toward is something more modest and, in some ways, more meaningful: a real possibility of helping people stay healthier for more of their lives, as long as the science keeps being tested with patience and care.
The study is published in the journal Molecules.
