Metchnikoff's Legacy: Progress in Longevity
The ancient cure for physical and mental decline
“Why not live longer, better?” This is the type of question Élie Metchnikoff would have asked you at the turn of the 1900s, with one eyebrow arched, glass of kefir in hand. Metchnikoff was not your typical scientist, for he questioned everything to do with life, starting with our very mortality. A maverick thinker, a Nobel laureate, and a fervent believer that microbes could solve humanity's biggest existential crisis, aging. Metchnikoff dared to think of death as a curable affliction, rather than an inevitability.
To understand Metchnikoff is to understand a man who looked at life's oldest problems, and dared to reimagine these challenges through the lens of evolution and microbiology. Inspired by Darwin's landmark work, 'Origin of Species,' he asked, ‘What exactly is it that makes us grow old and die?’ Could it be, he wondered, that the microscopic villains within our very guts were at fault?
For Metchnikoff, it wasn't just about longevity, it was about thriving. A zoologist and bacteriologist by training, his fascination with the intricate inner lives of microbes became a lifelong quest to understand how human beings might not just extend their lives, but also enhance their vitality. But this was not mere speculation, Metchnikoff was, first and foremost, an empiricist. He meticulously dissected the relationship between our gut bacteria and the process of aging, arguing that some of our microscopic inhabitants were, to put it bluntly, traitors to our biological ambitions.
The villains? Putrefactive bacteria. He envisioned them working their nefarious machinations inside our intestines, poisoning us slowly as we advanced in age. His solution? A revolutionary idea, turn our attention not merely to killing off the bad bacteria but to cultivating the good ones. Lactic acid bacteria, the same little critters that transform milk into tangy yogurt or kefir, became his heroes in this battle against internal decay.
There is something endearingly eccentric about Metchnikoff’s faith in kefir, the great elixir that would, according to him, not just cleanse the gut but ultimately extend life. His belief in the power of kefir wasn't simply an isolated obsession, it was an early insight into the broader concept of probiotics. Metchnikoff saw the potential of introducing beneficial bacteria to balance the gut microbiome and enhance overall health, and in doing so, he laid the foundation for what we now understand as the impact of probiotics on longevity and wellness. "Old age is a disease," he asserted, one that required treatment. And in this fight, bacteria, once synonymous with disease, could be our allies.
But where did this peculiar optimism come from? Perhaps it stemmed from his faith in what he called "orthobiosis", the optimal psychological and physiological functioning. He believed, with the conviction of someone seeing beyond his era, that health could be optimized, that each of us had a responsibility to take our own internal ecosystems into account. Imagine that, a scientist more than a hundred years ago already promoting the idea of balance, of probiotics, of a healthier gut microbiome. He was a pioneer of a holistic approach, one whose implications would reverberate throughout 21st-century nutrition and medicine.
Metchnikoff’s vision also extended beyond just science, he embodied a profound philosophical perspective. For him, progress wasn't just technological, it was personal. He questioned the meaning of life, pondering whether it was possible to feel fulfilled to the very end. He was no stranger to despair, having lost his first wife to tuberculosis and his mother shortly thereafter, but rather than accept misery as the natural state of existence, he dedicated his later years to exploring the science of well-being.
His critics dismissed him as too romantic, too speculative. Some would mock his kefir obsession or shrug off his longevity dreams as impossible, the product of a man whose mind had wandered too far into the territory of hope. But Metchnikoff, in his often-quirky way, refused to let go of the conviction that we are capable of something more, not merely in how long we live, but in how well we experience each day.
What can we take from Metchnikoff’s life’s work today?
First, the courage to ask questions that seem foolishly ambitious. To see aging as a problem with potential solutions, rather than a destiny set in stone. Metchnikoff’s line of inquiry, that we can create positive change through rethinking our relationship with our own biology, laid the groundwork for entire fields of study that explore aging as a malleable process, one influenced by diet, the microbiome, exercise and systemic balance.
Longevity science has matured since Metchnikoff’s day. Yet, it has been remarkable how often Metchnikoff anticipated recent discoveries in the field. One area where his early speculations resonate now is in the study of dementia and the microbiome. Recent research has shown that the gut-brain axis plays a crucial role in neurodegenerative diseases such as Alzheimer's and Parkinson's. For instance, studies have found that changes in gut microbiota composition can influence inflammation in the brain, potentially exacerbating conditions like dementia. Microglia, the brain's resident immune cells, are influenced by the gut microbiota, which impacts their role in clearing amyloid plaques and maintaining neural health. This connection between gut health and brain function reflects Metchnikoff's early observations, suggesting that the cultivation of a healthy microbiome could be key in mitigating the risks of cognitive decline. Furthermore, the influence the gut microbiota on microglia may suggest that Metchnikoff’s early observations about the connection between microbes and 'senility' and mental health might extend even into the realm of cognitive decline. We know for example that, combined with their presence at the gestation and birth stage microbiome influence early brain development, the role of these immune cells and their relationship with gut bacteria is an avenue of current deeper exploration, an idea that seems directly inspired by Metchnikoff's visionary work.
Probiotics
How might we treat our future selves. Metchnikoff suggested that we take seriously the notion of internal stewardship, being aware of what we consume, of consciously cultivating a body that is as resilient and as resistant to decay as possible?
Metchnikoff’s kefir-fueled optimism may sound quaint today, but his determination to tackle aging, by identifying fundamental causes and addressing them in innovative ways, remains a striking testament to intellectual courage. His legacy is not in the specific prescriptions, but in the mindset, one that views progress as deeply intertwined with individual agency, curiosity, and the stubborn belief that even life’s most daunting problems might have elegant, bacterial solutions.
So next time you pop open a bottle of kombucha or add a spoonful of Greek yogurt to your breakfast, raise a mental toast to Élie Metchnikoff, the quirkily brilliant scientist who dared to see the microbes within as both our antagonists and our allies, and who, in doing so, helped reframe what it means to live well and live long.
Stay curios
Colin
Image source The Lancet
This is part of a series of classic scientists, and books about, or by them, that I think should be widely read to help us have a better understanding of the world we live in, and of each other. Others in the series are:
Many more to follow.