Your Body Is Running Ancient Software in a Modern World
The single idea that makes chronic disease make sense — and makes prevention non-negotiable.
Here’s a thought experiment.
Imagine two men, both forty years old, separated by 50,000 years.
The first man slept seven hours last night, waking naturally to a slight chill as the sky lightened just before dawn on the African savanna. There was no alarm, no snooze button, no blue light from a screen disrupting his melatonin production in the hours before sleep. His circadian rhythm is locked to the sun, as it has been every day of his life.
His body is lean and sinewy — perhaps 150 pounds distributed over a 5’8” frame, with roughly 10 percent body fat. His muscles are not the sculpted products of a gym routine but the functional result of a lifetime of movement: climbing, carrying, walking, running, throwing. His resting heart rate hovers in the low 50s. His fasting glucose is around 70 mg/dL. His blood pressure, if we could measure it, would be approximately 110/70 — and unlike modern humans, it will barely increase as he ages.
He rises and surveys his world. Around him, the 40 or so members of his band are stirring. He knows every one of them intimately — their temperaments, their skills, their family histories, their stories. He has never experienced true loneliness, though he has known grief. His children sleep nearby. His wife is already starting a fire. His aging mother, still active and valued for her knowledge of plants and seasons, is tending to a younger child. He is embedded in a web of relationships that provides meaning, identity, and a profound sense of belonging.
Today he will walk somewhere between 6 and 12 miles, depending on what the day demands. He will carry things: water, tools, meat if the hunt is successful. He will squat, climb, lift, throw. By modern standards, he performs the equivalent of a challenging CrossFit workout simply by existing.
His stress is real but episodic. A predator sighting triggers an intense fight-or-flight response; thirty minutes later, the threat has passed, and his cortisol returns to baseline. He worries about weather, about finding food, about the health of his children. But these concerns are concrete and immediate — not abstract anxieties about retirement savings or career trajectories. And they are shared within his community. When the sun sets, the worry largely stops. There is nothing to do in the darkness but rest, tell stories, laugh, and then sleep.
At forty, he is an elder. Many of his contemporaries have died — from infection, injury, childbirth, or violence. But having survived to this age, he is likely to remain healthy and functional for another two or three decades. He shows no signs of heart disease. He is not diabetic. He is not depressed. He is not frail. He will likely die from an acute event — an infection, an accident, a conflict — rather than the slow deterioration of chronic disease.
Now consider the second man.
He wakes at 6:47 AM to an alarm on his smartphone, the third one he’s set. The first two he silenced without fully waking, his thumb finding the snooze button through practiced muscle memory. His lower back has stiffened overnight into a familiar ache that will take twenty minutes of moving around to unlock. He lies there for a moment, phone already in hand, scrolling through notifications he doesn’t remember checking at 2 AM — though his screen time report will later confirm he spent twenty-three minutes reading about a plane crash in Indonesia.
He is 5’10” and 210 pounds — a body that happened to him gradually, five extra pounds a year for a decade, each year’s gain too small to alarm him, the cumulative effect too large to reverse without an effort he cannot summon. His waist is 38 inches. Beneath his skin, visceral fat wraps around his liver and kidneys, quietly secreting inflammatory cytokines into his bloodstream. His fasting glucose at his last physical was 105 mg/dL. “Prediabetic,” his doctor called it — a word that sounds like a waiting room, not a disease already underway.
He showers quickly, avoiding the mirror. He dresses in the dark so as not to wake his wife, though she is already awake, facing the wall, pretending to sleep to avoid a conversation neither of them has energy for. They will exchange twelve words today, most of them logistical.
He sits in traffic for 47 minutes. He will sit for another eight hours at a desk, then another 47 minutes for the commute home. His watch will register 3,400 steps. He has a gym membership he’s used twice in the last three months.
He eats breakfast at a drive-through: an egg sandwich engineered by food scientists to hit the exact combination of salt, fat, and carbs that lights up his reward pathways without triggering satiety. He eats it in four bites, barely tasting it, and is hungry again by 10:30.
His stress has no edges. It is not a sabertooth tiger that appears and disappears — it is the general gloom of a Chicago winter, always present, varying only in degrees of severity. Some part of his brain is running calculations on whether his department will survive the next round of layoffs, whether his daughter is vaping, whether his mother’s forgetfulness is normal aging or something worse, whether his 401(k) will recover before he needs it. His cortisol never fully returns to baseline. He cannot remember the last time he felt genuinely relaxed — even on vacation, he checks his email.
He has 1,047 Facebook friends and could not name 10 people who would set aside a Saturday afternoon to help him move furniture. Last Tuesday, he ate dinner standing at the kitchen counter, scrolling through his phone, while his son did homework at the table ten feet away. Neither spoke.
At forty, he takes a statin and a proton pump inhibitor. His doctor has mentioned that blood pressure medication is probably next. His father died of a heart attack at 62, and he has accepted this as his probable trajectory — a genetic inheritance as fixed as his eye color.
He doesn’t think of himself as sick. He thinks of himself as normal.
And that’s precisely the problem.
Same Species. Same Genes. Different World.
These two men share virtually identical DNA. The human genome has not changed significantly in 50,000 years. Our genes today are essentially the same genes that built the body of a Paleolithic hunter-gatherer on the African savanna.
But their environments could not be more different. And the diseases that will define their lives — or end them — are almost entirely a function of that difference.
This is evolutionary mismatch. And once you see it, you can’t unsee it.
Your body was not designed for the world you live in. The genes you carry were shaped over millions of years to thrive in an environment of constant movement, whole foods, natural light cycles, deep social bonds, episodic stress with recovery, and lives of tangible purpose. The world you actually inhabit — sedentary, hyper-palatable, artificially lit, socially fragmented, chronically stressed, and often purposeless — bears almost no resemblance to the world your biology expects.
This isn’t a metaphor. It’s measurable. It’s testable. And it explains, with remarkable precision, why the chronic diseases now devastating modern populations are occurring at the rates they are.
The 24-Hour Day
Here’s another way to calibrate how unusual our current situation really is.
Compress all of human evolutionary history into a single 24-hour day. Start the clock at midnight with the emergence of the genus Homo — our evolutionary branch — roughly two million years ago.
For most of that very long day, we live as hunter-gatherers in small bands. We move constantly. We forage. We hunt. We sleep when it gets dark and wake when it gets light. We depend utterly on our social group for survival.
The agricultural revolution — the moment we began settling down, growing crops, domesticating animals — doesn’t happen until approximately 11:57 PM. Three minutes before midnight.
The Industrial Revolution hits at roughly 11:59:45. Fifteen seconds to go.
The smartphone arrives in the final fraction of a second before midnight strikes again.
This isn’t just a cute analogy. It has profound implications. For more than 99.5% of our existence as a species, we lived under conditions radically different from today. Our bodies, brains, and metabolic systems evolved to solve the problems of that environment — not this one. We are, in a very real sense, ancient hardware trying to run modern software.
The incompatibility shows up in our disease statistics.
Five Mismatches That Are Killing Us
The mismatch isn’t one thing. It’s at least five interlocking disconnects between what our biology expects and what modern life delivers. Each one, on its own, is damaging. Together, they’re devastating.
1. The Body That Moved — Trapped in a Chair
Our ancestors walked 5 to 12 miles per day as a baseline. They carried heavy loads. They climbed, squatted, dug, lifted, and threw — not as exercise, but as existence. Every calorie consumed had to be earned through physical effort. There was no distinction between “working out” and living.
When researchers study modern hunter-gatherer societies like the Hadza of Tanzania or the Tsimane of Bolivia, they find what our ancestors likely had: coronary artery disease rates approximately five times lower than in American populations, average BMI right in the healthy range at age 45, and functional strength maintained well into old age.
Your body evolved expecting this level of activity. Every system — cardiovascular, musculoskeletal, metabolic, neurological, psychological — is optimized for consistent physical movement. We are not designed for sustained stillness.
The average American sits for more than 10 hours a day. We have taken bodies built for constant movement and bolted them into chairs, cars, and couches. Then we wonder why our metabolisms are broken, our joints ache, our mood craters, and our cardiovascular systems deteriorate.
This isn’t laziness. It’s mismatch.
2. Scarcity Software in a World of Engineered Abundance
Our ancestors’ brains evolved powerful reward responses to sugar, fat, and salt — because these were rare and metabolically valuable. Sweetness meant ripe fruit, available seasonally. Fat meant successful game. Salt was hard to come by. The people who craved these substances intensely were the ones who survived. We are their descendants.
That craving served us well for two million years. Evolution had no idea that Ben & Jerry would one day team up to make pints of cookie dough ice cream, available 24/7, no foraging required.
Hunter-gatherer diets were composed entirely of whole, unprocessed foods. Fiber intake was 50 to 100 grams daily (the average American gets 15). Nothing was refined. Nothing was engineered for “more-ishness.” Our ancestors never experienced the sensation of eating beyond fullness for pleasure, because no food in their environment was designed to override their satiety signals.
Now we live in an environment where food scientists at companies like Frito-Lay employ neuroscientists to engineer products that hijack the exact dopamine pathways our ancestors never needed to defend against. They have a term for it: “vanishing caloric density” — food designed to dissolve so fast your brain doesn’t register the calories. So you keep eating.
Your willpower isn’t weak. It’s outgunned by a billion-dollar industry that understands your evolutionary reward circuitry better than your doctor does.
3. The Sun-Locked Clock — Under Artificial Siege
For 99.9% of human history, human sleep was governed by the sun. When it got dark, you found a safe place, gathered with your group, and slept. Melatonin rose with darkness. Cortisol fell. The brain cleaned itself.
Studies of modern hunter-gatherer societies reveal sleep that is remarkably consistent: bed 2 to 3 hours after sunset, waking with the dawn, almost no insomnia. Their circadian rhythms are perfectly synchronized to natural light, and every physiological process — hormone release, immune function, metabolism, mood — runs on that clock.
Now we flood our retinas with screens at 11 PM, suppressing melatonin by up to 50%, and wonder why we can’t sleep. Then we label it “insomnia” and reach for Ambien.
It’s not insomnia. It’s mismatch.
If you wear a continuous glucose monitor, you can see this for yourself. After a night of poor sleep, blood sugar runs higher all day — sometimes dramatically so. Circadian disruption is linked to obesity, diabetes, depression, cardiovascular disease, and cancer risk. Night shift workers have shorter lifespans. This isn’t an abstraction. It’s metabolically measurable.
For most of human history, night meant rest. Your body still expects that — and rebels when it doesn’t get it.
4. Chronic Stress in a Body Built for Sprints
Our ancestors faced real stress — predators, injuries, conflicts, hunger. But there’s a crucial difference: theirs was overwhelmingly acute; ours is overwhelmingly chronic.
Acute stress has a beginning, a peak, and an end. The predator appears. Adrenaline floods your bloodstream. Your heart rate spikes. Thirty minutes later, the threat has passed and your cortisol returns to baseline. The parasympathetic nervous system takes over. Rest and recovery begin.
Chronic stress never resolves. It’s the job you can’t quit, the debt you can’t pay, the relationship you can’t fix, the future you can’t predict. There’s no predator to escape, no finish line to cross. The threat is ambient and unending — and so is the stress response.
Chronically elevated cortisol damages nearly every system in the body. It promotes abdominal fat storage. It impairs insulin sensitivity. It suppresses immune function. It disrupts sleep. It atrophies the hippocampus, impairing memory and emotional regulation.
But here’s what makes it worse: our ancestors rarely faced stress alone. When the drought came, the whole band was hungry. When a predator threatened, the whole group mobilized. When someone died, the community grieved together. Research consistently shows that social support buffers the physiological impact of stress. The same traumatic event produces different outcomes depending on whether you face it with allies beside you or bear it in silence.
Modern life has inverted this. We have replaced acute physical threats with chronic psychological stressors — and we bear them alone, behind closed doors, in nuclear households or solitary apartments. The stress response, calibrated for shared danger, is now running on a solitary loop.
Evolutionary mismatch isn’t a theory. It’s your Tuesday.
5. A Thousand Facebook Friends and No One to Call
Humans are hypersocial creatures. Our brains are roughly six times larger than expected for a mammal of our weight, and the leading explanation is the social brain hypothesis: we evolved big brains primarily to navigate complex social relationships.
Anthropologist Robin Dunbar estimated that the human brain can maintain stable relationships with approximately 150 people. But for most of human history, our daily social group was much smaller — 30 to 50 people living in intimate contact. You woke with them, ate with them, worked alongside them, slept near them. Your survival depended on them. Theirs on you.
Loneliness wasn’t a feeling to be managed. It was a danger signal as urgent as pain or hunger, indicating that something had gone catastrophically wrong. A lone human on the African savanna was not a predator. A lone human was prey.
Modern neuroscience confirms this: social isolation activates the same brain regions as physical pain. A meta-analysis of 148 studies found that social integration is as powerful a predictor of mortality as smoking, obesity, and physical inactivity.
We can literally die of loneliness. And scrolling through Instagram activates none of the neurochemistry that in-person connection does. You can have 200,000 followers and still be profoundly, biologically alone.
Why This Matters: The Template We Carry
I want to be clear about something. I am not romanticizing the past. Our ancestors’ lives were hard in ways we can barely imagine. Infant mortality was high. Life expectancy was low. Violence, injury, and infectious disease claimed most before middle age.
But that’s not the point. The point is that our bodies and brains carry the template of that existence whether we like it or not. We are adapted for movement, whole foods, tight social bonds, natural sleep patterns, episodic stress with recovery, and lives of tangible purpose. That’s not a lifestyle choice. It’s our biological inheritance.
The chronic diseases devastating modern populations — heart disease, cancer, diabetes, neurodegeneration, depression, frailty — are not random afflictions or genetic destiny. They are, in large part, the predictable consequences of taking organisms adapted for one environment and dropping them into another.
The American healthcare system spends $14,885 per person per year — more than any nation on Earth — and our healthspan ranks barely above the global average. Sixty percent of American adults live with at least one chronic condition. Forty-two percent are obese. We spend roughly 3% of our healthcare budget on prevention and 27% treating the diseases we failed to prevent.
We haven’t failed because we lack resources, technology, or knowledge. We’ve failed because we’ve fundamentally misunderstood the problem. We’ve built an elaborate system for treating disease while ignoring the conditions that create it.
The conditions that create it are mismatch.
The Hopeful Part
Here’s what I want you to take from this piece — and it’s the reason I started this Substack, the reason I left the ER, and the reason I wrote a book about it.
If the problem is not genetic fate but environmental mismatch, then the problem is solvable.
We cannot change the genes we inherited. But we can change the signals we send them. We can change our epigenetics. Every one of the mismatches I described above has a corresponding corrective — and when you apply those correctives together, the effects compound.
Move your body the way it was designed to move. Eat food that your biology recognizes as food. Sleep in alignment with the light-dark cycle your circadian system expects. Build real, in-person social bonds that activate the neurochemistry of connection. Find or create purpose — the sense that your actions matter to people you care about. And manage stress through community, not isolation.
These aren’t wellness platitudes. They’re evolutionary corrections. They are the Six Pillars — Move, Lift, Sleep, Eat, Connect, Purpose — and I’ll be writing about each of them in the weeks ahead, with the evidence and the clinical specifics.
But I wanted to start here, with the framework that makes everything else make sense. Because when you understand why your body is struggling, the what to do about it stops feeling like a checklist and starts feeling like a homecoming.
Your body knows what it needs. It’s been trying to tell you. It’s been telling you through the fatigue that sleep doesn’t fix, the weight that willpower doesn’t move, the anxiety that meditation barely touches, and the loneliness that social media makes worse.
It’s not broken. It’s mismatched.
And that’s something you can fix.
Live Well, Die Well.
— Dr. Vikas Patel
This is the third in a series of articles from the MD Longevity Lab Substack. If the evolutionary mismatch framework resonated with you, subscribe for upcoming deep dives into the Six Horsemen of modern disease, the Six Pillars that address them, and the industries that profit from keeping you confused.
Dr. Vikas Patel is a board-certified emergency medicine physician, former U.S. Navy Flight Surgeon, and founder of MD Longevity Lab, a precision longevity medicine practice in Chicago. He is the author of the forthcoming book Playing the Long Game.