My Polar-Opposite Grandmothers Both Lived to 104. What Were Their Secrets to a Long Life?

But who is, especially over the course of an extended life? The oldest person Perls ever met was Sarah Knauss, one of his study participants. Born in 1880 in Pennsylvania coal country, Knauss lived independently until her failing eyesight and frailty led her to a nursing home — at age 111. She remained cognitively sharp and disease-free, even while enjoying a life that defied all expectations.

“She loved sweets, like chocolate cake, and hated green vegetables,” Perls recalls, but none of that mattered. Knauss lived to 119, making her the third-oldest verified person in history.

Living as long as Knauss — or even my grandmothers — did not happen with shortcuts or simple solutions. But emerging science reveals practical, evidence-backed steps we can all take to add healthy, productive years to our lives. “The amazing thing is, a significant portion of Americans now have the opportunity to get into their late 90s and 100s,” Perls says. “With healthier habits and new ways to delay age-related disease and disability, it’s much more the situation of ‘the older you get, the healthier you’ve been.’ ”

The new secrets of aging

When my grandmothers were younger women in the 1950s, living to 100 was rare — only about 2,300 Americans reached that milestone each year. Grandma Charlotte and Grandma Ruth lived to see that change dramatically. Last year, more than 101,000 Americans celebrated their 100th birthday, and by 2054, that number is expected to soar to around 422,000. This shift is part of a broader wave: Right now, 62 million Americans — 18 percent of us — are 65 and older. By 2054, that group will grow to 84 million, almost a quarter of the population.

But here’s what’s fascinating: While more of us are living longer than ever, the reasons aren’t quite what you might expect. Scientists studying long-lived people have discovered surprising factors that go beyond the usual advice. These three hidden keys tell us something deeper about how humans thrive in their later years.

(From left) Husband-and-wife Abe and Grandma Charlotte. Hochman mostly remembers the two bickering. But according to a Harvard study, as long as couples felt they could depend on each other in life's hard moments, daily arguing didn't harm their mental health.

Courtesy David Hochman

Resilience. New research shows that mentally tough people tend to live longer, especially women. Looking at more than 10,000 older Americans, scientists last year found that those with high resilience — who stay calm under pressure, keep going when things get hard and feel their life has purpose — were half as likely to die over a 10-year period as less resilient people. Think about that. While there might be other factors at play, the findings suggest that building mental toughness may be as important for a long life as physical health.

Longevity researcher Barzilai’s uncle, who died at 102, lived through challenges most of us can hardly fathom. A Holocaust survivor, he endured five concentration camps, subsisting on the barest of rations and sheer willpower. “There wasn’t enough food, but at least the Germans paid for everything,” he would joke for decades afterward.

Barzilai believes these trials weren’t merely hardships his uncle survived. They might have actually helped him live longer. In biology, the concept is called hormesis, or, as you might know it, “What doesn’t kill you makes you stronger,” a bit of wisdom that may have started with 19th-century German philosopher Friedrich Nietzsche.

“You have to go through stress in order to increase your capacity to deal with greater stressors later on,” says Barzilai.

The principle is similar to the way intense exercise creates temporary inflammation that ultimately strengthens muscles and builds endurance. In aging, hormesis suggests that surviving difficult situations — like war or great loss — can prepare the body for other challenges.

“The body adapts to stress by strengthening its defenses,” Barzilai says, describing it as a kind of biological “toughening up,” often called the select survivor effect.

This effect might help explain why some groups known for enduring systemic adversity, like Holocaust survivors, WWII veterans and older Black Americans, often exhibit remarkable resilience and longevity. Despite hardships that should by all accounts have worn them down, they developed an extraordinary ability to push forward.

My grandma Charlotte was the embodiment of the select survivor. She lost seven siblings in the Holocaust, an unimaginable trauma she never talked about. It must have given her deep scars and steel-like strength. Getting through life’s darkest moments had forged in her a resilience that no ordinary hardship could break.

Love. If Grandma Charlotte’s survivor’s spirit carried her through life’s challenges, it was love that fueled Grandma Ruth’s remarkable journey. After more than 60 years in a devoted marriage with my grandfather, she found new joy and companionship after his passing. At 87, she met Herman, a retired chemist, and together they shared five blissful years — holding hands, walking on the beach, and even arriving late to my wedding because they were reading poetry to each other in their hotel room.

No geriatrician can write a prescription for a passionate affair, but love remains an often-overlooked cornerstone of healthy aging. Strong social connections are linked to a 50 percent greater chance of living longer. The bond between you and the people around you might be the ultimate key to aging well. The renowned Harvard Study of Adult Development, now in its 86th year, has tracked the lives of hundreds of individuals over decades. Its most striking conclusion? The single strongest predictor of healthy aging isn’t wealth, social status or even lifestyle. It’s the quality of your relationships. Or, as former study director George Vaillant put it: “Happiness is love. Full stop.”

Marital satisfaction, in particular, seems to act like a longevity booster shot. Among people in their 80s, those in happy marriages reported that their moods stayed steady — even on days when they were in more physical pain. The study also showed that people in warm, supportive relationships tended to live longer and happier lives than loners. In fact, loneliness as we age can be as damaging to health as smoking or alcoholism.

Meanwhile, people with strong social support experienced less mental decline as they aged and were less likely to overindulge in smoking or drinking. And the benefits of healthy relationships aren’t just emotional — they’re cognitive too. A recent finding of the study showed that women who felt securely attached to their partners were less likely to be depressed and reported greater happiness in their relationships. They even performed better on memory tests two-and-a-half years later than those with weaker ties to loved ones.

These findings tracked with Grandma Ruth and her decades of loving partnerships. But what about Grandma Charlotte, whom I mostly remember bickering with my grandfather all day? It turns out good relationships don’t have to be perfect — or look perfect to outsiders. Some of the couples in the Harvard study — well into their 80s — argued daily. But as long as they felt they could rely on each other when it truly mattered, those everyday spats didn’t seem to harm their mental health or memory.

Faith. Tom Cole has spent decades studying what keeps people going into their later years. The rabbi and coauthor of The Oxford Book of Aging sees longevity through a different lens than most researchers do. Beyond genetics and lifestyle, he argues, there’s something more fundamental: the power of belief itself.

“I don’t think you can live to an old age without a belief system,” Cole says, “whether that’s religious faith or simply a deep conviction that tomorrow holds promise.” This framework of belief, he explains, creates a kind of spiritual resilience — an inner force that helps people push forward through life’s darkest moments.

Cole has found this particularly true among Holocaust survivors and others who’ve faced severe hardship. Many describe moments of profound connection that sustained them: a guiding voice, an unseen presence, a warm light that appeared when all seemed lost.

The science backs this up. Research from Ohio State University found that religious affiliation alone can add as much as nine years to a person’s life. A separate study showed women who regularly attended religious services had a 33 percent lower mortality rate. But the power of belief extends beyond religion — what matters is having something meaningful to believe in, whether it’s family, community or a personal mission.

Grandma Charlotte attends a wedding with Abe, her husband. Charlotte, who lost seven siblings in the Holocaust, was incredibly resilient, writes Hochman. And resilience is tied to a longer life, according to research.

Courtesy David Hochman

Whether faith or optimism, it’s common among people who live a long time. Boston University School of Medicine psychologist Lewina Lee’s research reveals that people who maintained a positive outlook had 50 to 70 percent greater odds of reaching age 85 than the least optimistic groups in her study.

Likewise, those who embrace the positive aspects of aging — such as accumulated wisdom and emotional maturity — live an average of 7.6 years longer than those who don’t. Yale public health psychologist Becca Levy found that these optimistic individuals gain their advantage through multiple pathways: They exercise more, make healthier food choices and show lower levels of stress-related inflammation in their bodies. These benefits mirror those seen in highly conscientious people, suggesting that our mental outlook shapes our physical reality.

Deborah Kado, codirector of the Stanford Center on Longevity, sees this play out in her oldest patients. She routinely asks them what they look forward to, and their answers reveal how the prospect keeps them going: a grandchild’s visit, lunch with a neighbor, a weekly game of Rummikub with friends. “These anticipations become anchors,” Kado explains. “They give life its forward momentum."

Perls, who runs the New England Centenarian Study, has a life expectancy calculator on his website, Living to 100. It asks 40 quick questions about health and family history, then estimates how long you might live—along with tips to add more years. Millions have taken the quiz. When I tried it, the result said I should expect to live to 104. My first reaction? “Amazing! Just like my grandmothers.” My second? “I better start saving.”

The truth is, even with all the tools and data at our disposal, we still don’t fully comprehend what stands between us and the numbers on those tables. Some experts believe we’ve hit a natural limit on age span.

In October, S. Jay Olshansky, a leading researcher at the University of Illinois, Chicago, concluded, in the absence of forthcoming aging interventions, “as long as we live now is about as long as we’re going to live.” His study predicts that maximum human life expectancy will plateau around 87 years — 84 for men, 90 for women. Many countries are already closing in on those averages.

This conversation is reframing how we think about aging. The focus is shifting from simply extending life to improving the quality of the years we have. For instance, health organizations typically recommend scaling back cancer screenings at certain ages — prostate cancer at 70, breast cancer at 75, colonoscopies at 85 — on the assumption that these tests might not significantly improve outcomes. Perls disagrees. “At any age, why die of something if we have the tools to identify and treat it?” he asks.

David Hochman, his son and Grandma Ruth. A positive outlook on life can add years to your life, according to researchers.

Courtesy David Hochman

Barzilai is looking beyond prevention to what he calls gerotherapeutics — medicines designed to target the aging process by reducing inflammation and repairing cellular damage. Some of these treatments are already in use. GLP-1 medications like Ozempic and Wegovy, originally developed for diabetes and obesity, show promise in reducing the risks of heart disease, Parkinson’s and Alzheimer’s. Combined with exercise, nutrition, sleep and meaningful social connections, these advances could help us enjoy the longest possible “health span,” as Barzilai calls it.

Both my grandmothers, different as they were, managed to do just that. Grandma Ruth, the extrovert and explorer, lived fully until the end. On a trip to Paris in her late 90s, she brushed away offers at the airport to sit in a wheelchair. “Don’t treat me like an old lady!” she said. Grandma Charlotte, the cautious and inwardly focused survivor, endured with equal strength. Up until the end, she was scrubbing her dishes clean and saying her prayers at the breakfast table. In their own ways, they represent what’s possible over a very long life — but not in ways that fit neatly into any prescription or blueprint.

After all my research, I’m convinced that neither of them was “right” and neither was “wrong.” My family and society created a narrative of contrast that seemed to make sense — but doesn’t. Ruth was the “shining example” and Charlotte the “anomaly.” But the reality is more nuanced. Longevity doesn’t obey the simple scripts we impose on it. Both grandmothers found their own ways to persist, and both ways delivered. Ultimately, lasting vitality isn’t about conforming to expectations or explanations. It’s about finding a way to hold on — to meaning, purpose and life itself — in whatever way works for you.