WeeklySA_AdminLONGEVITY: A Q&A with geneticist Anne Brunet explores what aging really is—and how science may reshape how we grow old…
By Olivia Maule
Aging is something every human being experiences, yet it remains one of biology’s most complex and least understood processes.
We recognise its outward signs—wrinkles, fatigue, declining strength—but what actually happens inside the body over time is far more intricate.
For Anne Brunet, a leading geneticist and professor at the School of Medicine, aging is not a single pathway but a layered biological transformation. Her research focuses on uncovering the molecular mechanisms that drive aging and identifying ways to delay or even partially reverse its effects.
Aging is not a single process—it’s a collection of
changes. If we can understand them,
we may be able to reshape how we grow old…
Her lab investigates how external factors influence longevity, how old stem cells might be rejuvenated, and how certain species—such as the remarkably short-lived African killifish—can help unlock answers to age-related diseases.
In a wide-ranging discussion, Brunet sheds light on how scientists understand aging today, how lifestyle choices influence longevity, and where the most exciting breakthroughs may lie.
What is aging, according to science?
At its core, aging is the gradual transformation of a young, resilient body into one that is more vulnerable to disease and, ultimately, death. But this transformation is not driven by a single mechanism.
Instead, scientists describe aging through a set of biological “hallmarks”—interconnected processes that change over time.
One of these is epigenomic change, where the way genes are switched on and off begins to shift, altering how cells function. Another is a decline in nutrient sensing, meaning the body becomes less efficient at interpreting and responding to energy and food signals.
Then there is chronic inflammation, often referred to as “inflammaging.” Over time, inflammatory molecules accumulate in the body, subtly disrupting normal cellular activity.
Each of these factors contributes to aging individually—but together, they compound, gradually eroding the body’s resilience.
Why does aging increase disease risk?
One of the central puzzles in aging research is why growing older increases the risk of so many different diseases—from heart disease to Alzheimer’s.
Brunet points to several overlapping explanations. The first is a general decline in resilience. As the body ages, it becomes less capable of maintaining stability, making it easier for diseases to take hold. The second involves shared biological pathways. Chronic inflammation, for example, plays a role in multiple conditions. While short bursts of inflammation help the body heal and fight infection, long-term activation can damage tissues and impair function.
In the brain, this can disrupt neurons—the cells responsible for transmitting information—contributing to neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Another factor is the accumulation of misfolded or aggregated proteins, particularly in the brain. As these proteins build up, they overwhelm the body’s quality-control systems, accelerating cellular dysfunction.
Because aging affects so many systems simultaneously, it increases vulnerability not just to one disease, but to many.
Can lifestyle choices influence aging?
While aging is inevitable, how we age is not entirely fixed.
One of the most consistent findings in longevity research is the impact of dietary restriction. Reducing calorie intake—without causing malnutrition—has been shown across multiple species to extend lifespan and delay age-related diseases.
The exact diet may vary, but the principle remains: periods of reduced caloric intake or fasting appear to benefit longevity.
Exercise is another powerful factor. While it may not extend the absolute maximum lifespan, it significantly improves average lifespan and overall health—reducing the risk of chronic disease and maintaining physical function for longer.
In short, lifestyle choices cannot stop aging, but they can meaningfully shape its trajectory.
Can aging be reversed?
The idea of “reversing aging” is often misunderstood. Time, of course, cannot be turned back.
Instead, scientists focus on whether certain interventions can make older tissues behave more like younger ones at a molecular level.
This concept—often referred to as rejuvenation—means restoring specific biological markers or functions rather than reversing age entirely.
In the brain, this is a particularly active area of research. Aging is closely linked to cognitive decline, even in otherwise healthy individuals.
Brunet’s work explores ways to counteract this. One approach involves reducing inflammation in the brain, which has shown promise in improving certain age-related changes.
Another involves partial cellular reprogramming, where gene activity is temporarily altered to encourage regeneration and the production of new cells.
Stem cells also play a crucial role. These regenerative cells help maintain tissues over time, and understanding how to preserve or reactivate them could be key to improving resilience in aging bodies.
What can a fish teach us about aging?
To study aging effectively, scientists need model organisms—species that can be observed and experimented on in controlled conditions.
Aging is not a single process—it’s a collection of changes. If we can understand them, we may be able to reshape how we grow old…
Brunet’s lab works with the African killifish, a unique species that lives for just six months yet shares key biological features with humans.
Its short lifespan allows researchers to observe an entire life cycle in a fraction of the time required for other animals like mice.
But the killifish has another extraordinary ability: embryonic diapause—a form of suspended animation in which embryos can pause development for months or even years.
In some cases, this dormant state lasts far longer than the fish’s natural adult lifespan. Proportionally, it would be equivalent to a human remaining viable for centuries.
This phenomenon offers a rare window into how biological processes can be paused, slowed, or preserved—raising profound questions about the nature of time and aging.
What is the biggest unanswered question?
Despite rapid advances, aging research is still in its early stages. The biggest challenge, Brunet says, is understanding the full network of mechanisms that drive aging—and how to safely translate laboratory findings into real-world treatments for humans. One promising direction is studying aging as a dynamic process, rather than a series of fixed snapshots.
Her lab is experimenting with continuously tracking organisms throughout their entire lifespan. By observing aging in real time, researchers hope to identify previously overlooked stages and critical intervention points.
The killifish, with its compressed life cycle, makes this kind of research possible.
It is an ambitious approach—but one that could reshape how we understand aging itself.
The future of longevity
For now, the idea of dramatically extending human lifespan remains a distant goal. But the science of aging is advancing rapidly.
Rather than chasing immortality, the field is increasingly focused on healthspan—ensuring that people live longer, healthier lives, free from prolonged disease and decline.
If researchers can delay the onset of age-related diseases, improve cellular resilience, and better understand the biology of aging, the impact could be transformative. Aging may be inevitable—but how we experience it is becoming a question science is finally beginning to answer. – Science X
