I. The Gap
Nine point six years.
That's the global average now—the space humanity has built between the end of flourishing and the end of breathing. The gap between healthspan and lifespan. The years we now spend at the end of life managing chronic diseases we have names for but cannot cure. Not the usual wear of aging. Metabolic syndrome. Autoimmune disorders. A decade of pills and accommodations and the quiet exhaustion of diminishment.
I find this almost too painful to contemplate, so naturally I've been contemplating it for months.
A December 2024 study published in Communications Medicine analyzed all 183 World Health Organization member states.1 The gap has been widening—from 8.5 years in 2000 to 9.6 years in 2019, a 13% increase in two decades.
We are living longer. We are spending more of those extra years sick. The gap between the two is where we've chosen to make our home.
But some of us have gone further than others. The United States has the largest healthspan-lifespan gap of any nation the WHO tracks: 12.4 years as of 2019. Not close to the largest. The largest. Twenty-nine percent higher than the global average. And widening faster—from 10.9 years in 2000 to 12.4 in 2019.
The U.S. isn't an exception to the pattern. It's the pattern taken to its logical conclusion.
This is what happens when you measure one thing and forget to measure another. We counted years alive. We got them. We forgot to ask: Years alive doing what?
Here's the other thing we forgot to measure: According to research from the University of New Mexico published in Nature Medicine, researchers analyzed brain tissue samples from people who died in 2016 and compared them with samples from 2024.2 Eight years. The concentration of plastic in brain tissue increased by roughly fifty percent.
Your brain is accumulating plastic. And the percentage is climbing.
Dementia patients have up to ten times more plastic in their brains than people without dementia. We don't know if the plastic causes the dementia or accumulates because of it. We just know it's there, where it shouldn't be, crossing a barrier we thought protected us.
These are not predictions or possibilities. These are measurements of where we already are.
Rather like discovering your house has been slowly filling with water while you were focused on adding a second story. Clever us.
II. The Substitution
There is a pattern here. An old one. Ancient, actually. It has a shape we should recognize by now.
We want something real—health, happiness, flourishing—but it's difficult to measure directly. So we find something easier to count. Years alive instead of years healthy. GDP instead of wellbeing. Consumption instead of satisfaction.
And then we make the substitution. We measure the proxy and call it the thing itself.
This is not an accident. This is not confusion. This is what we do when we want to believe we're succeeding without doing the harder work of defining what success actually means.
The Romans called this quid pro quo—"this for that." An exchange. But the exchange we make is stranger: We trade the thing we cannot easily measure for the thing we can, and then we forget we made the trade.
The Substitution doesn't feel like a compromise when you make it. It feels like progress. Like cleverness. Like finally having a metric to optimize.
The years we add to human life become proof that medicine is advancing. The GDP we accumulate becomes proof that economies are healthy. The products we manufacture become proof that we're providing for people's needs.
But the thing we said we wanted—health, happiness, human flourishing—slips quietly out of frame. We don't lose it in a single moment. We lose it one substituted metric at a time.
Nineteen forty-five. The war ended. American soldiers came home. And we made The Substitution twice in the same moment—two trades that looked separate but were the same trade.
First: We turned military chemical production toward civilian use. DDT, which controlled disease-carrying insects during the war, became available for every backyard. Wartime production capacity—bombs, fuel, industrial compounds—converted to domestic applications. Plastics. Pesticides. Synthetic substances for every corner of life.
By 1982, sixty-two thousand chemicals were in commerce. As of 2024: over eighty-six thousand substances listed on EPA's TSCA Chemical Substance Inventory, roughly half designated as active in U.S. commerce. Global chemical production capacity nearly doubled between 2000 and 2017. And it's still accelerating—the American Chemistry Council projected growth of 3.4% in 2024 and 3.5% in 2025.
Second: We made abundance into ideology. Consumption became patriotic. The Cold War was fought in department stores, measured in washing machines per capita. American capitalism versus Soviet communism, demonstrated through material acquisition. Political leaders said it explicitly: consumption defines freedom. More goods equals more liberty. Buy your way to the good life.
During the 1950s and 60s, upward mobility—measured in things owned—became the main purpose of life.
These weren't two shifts. They were The Substitution operating at civilizational scale. We substituted chemical convenience for genuine safety. We substituted material accumulation for actual wellbeing. We substituted consumption for flourishing.
And then we exported it. The model went global. Chemical production didn't stay American. It went to Europe, to Asia, to everywhere the growth imperative reached. By 2023, China was rapidly expanding petrochemical production capacity and output. The Substitution that started in American suburbs became a global project.
In January 2025, more than twenty leading scientists—including current and former EPA officials—published a paper in the New England Journal of Medicine calling for urgent action on chemical regulation.6 The Endocrine Society, in their February 2024 report, documented that endocrine-disrupting chemicals "pose health threats globally."8 Researchers have described the situation as a massive uncontrolled experiment—and the description fits.
But it's not just America's children. It's all of us.
Uncontrolled. That word matters. A proper experiment has protocols. Control groups. Safety testing. Informed consent. We had none of that.
Here's what we did instead: Introduced eighty-six thousand synthetic substances into commerce. Most were never comprehensively tested for human health effects. Most were never tested for effects on children specifically. TSCA does not require companies to generate new safety data before introducing chemicals; manufacturers are not routinely required to examine potential health hazards. Waited decades to develop detection technology sensitive enough to measure what those chemicals were doing in human bodies.
We made The Substitution and called it an experiment. But we never wrote down what we were testing. We never asked what success would look like if it wasn't just "more."
We just measured what was easy to count and assumed it was the same as what mattered.
III. What Lives in It
The technology to look came late. We can now detect chemicals at parts per trillion—concentrations that would have been invisible when we introduced them. So we looked.
And found them everywhere. Surprise.
PFAS—"forever chemicals"—are in virtually every American tested. Microplastics have been detected in human blood, lung tissue, and placenta. BPA was detected in 92.6% of urine samples in NHANES 2003-2004. Brominated flame retardants (PBDEs) are ubiquitous; BDE-47 was detected in 100% of NHANES samples from 2005-2014.
Chemicals that didn't exist commercially before 1970 are now detectable in bodies of people born in 2020. We are all carrying what we made.
And the bodies themselves tell us what it's doing.
According to CDC data from 2021-2023, 15.8% of U.S. adults have diabetes.3 Another 38% have prediabetes (2017-2020 estimate).4 Together, these figures suggest a large share of the adult population lives with impaired glucose metabolism. Not genetic bad luck. People have not changed genetically in thirty years. An April 2025 study from the National Institute of Environmental Health Sciences found that environmental exposures predicted chronic disease more strongly than genetics.7
Environmental. That's the word we use when we mean chemicals we invited in.
The autoimmune crisis is global. Autoimmune disease prevalence has been rising for decades. A 2024 study in the Journal of Clinical Investigation, using electronic health records through June 2022, estimated that 15 million Americans (4.6% of the population) have been diagnosed with at least one autoimmune disease.5 According to Dinse et al., antinuclear antibodies, a marker of immune system dysfunction, increased from 11% of the population in 1988 to 16% in 2012.23 The most dramatic increase was in adolescents—prevalence rose from 5.0% in 1988-1991 to 12.8% in 2011-2012, an increase of 156%.
The January 2025 NEJM paper documented a 35% increase in childhood cancer incidence over the past half-century. Autism now affects one in thirty-one children—up from the prior CDC estimate of one in thirty-six (based on 2020 surveillance data). A 2025 study found approximately thirty-four chemicals in over ninety percent of samples from children aged two to four—nine of which have never been included in U.S. national biomonitoring. Children aged two to four had higher levels of certain chemicals than their mothers had during pregnancy.
We are poisoning our children more efficiently than we poisoned ourselves. You have to admire the optimization, if nothing else.
This is what lives in the gap now. This is what The Substitution gets you when you run it at scale for eighty years.
Chemical body burden. Immune system dysfunction. Metabolic disorders. The years we spend sick at the end of longer lives. And plastic accumulating in our brains.
The U.S. has the worst numbers because we went furthest, fastest. But the pattern is everywhere The Substitution reaches. And The Substitution is reaching everywhere.
But here's what makes it unbearable: The abundance we traded this for didn't deliver what it promised either.
IV. The Exchange We Made
There is a body of research on whether material wealth makes people happier. The findings are so consistent psychologists call them "almost an axiom."
Once basic needs are met, additional wealth has diminishing returns on wellbeing. Wealthier nations are happier than poor nations. But within wealthy nations, decades of substantial economic growth barely moved subjective wellbeing. We got richer. We didn't get proportionally happier.
According to Dittmar et al.'s meta-analysis in the Journal of Personality and Social Psychology, using seven hundred fifty-three effect sizes from two hundred fifty-nine independent samples, materialism is negatively associated with wellbeing.15 The more you orient your life around wanting and acquiring, the less happy you are. More materialistic individuals experience fewer positive emotions, lower self-esteem, more anxiety, more depression.
This is not one study. This is hundreds of studies, across thousands of people, finding the same thing.
Materialism doesn't just fail to make us happy. It makes us measurably less happy.
And this is what we made the purpose of life in the 1950s and 60s. Upward mobility measured in consumption. The American Dream redefined as home ownership filled with convenience items.
We achieved that dream. We filled the homes. We made wanting itself the engine of the economy. And we exported that engine worldwide—the same growth imperative driving chemical production higher each year.
We made The Substitution: GDP for wellbeing. Consumption for happiness. Material accumulation for human flourishing.
And empirically, scientifically, it made us less well. At the same time, it poisoned us.
We live in the gap now. Breathing but not flourishing. Carrying chemical burdens our bodies weren't designed to metabolize. Wanting more and feeling worse. Accumulating plastic in our brains at an accelerating rate. Spending years at the end of the longest lives in human history sick with what we didn't measure.
It's rather like trading your health for wealth and then discovering the wealth doesn't buy health and also the wealth makes you sadder. The exchange rate turned out to be worse than advertised.
V. Why We Didn't See It
Before we had the tools to measure what was happening, we told ourselves a story. Look at the progress. Look at the achievement.
And the achievement was real. We need to hold this.
According to Our World in Data, we decimated extreme poverty. In 1820, about three-quarters of the global population lived in extreme poverty. By 2018, less than ten percent.26 We taught most of the world to read—literacy went from about one in ten in 1820 to nearly nine in ten today.27 According to the WHO, vaccines alone saved one hundred fifty-four million lives over fifty years.22
Infant mortality, maternal mortality, deaths from infectious disease—we transformed them. In the United States over the twentieth century, infant mortality fell by over 90% and maternal mortality fell by nearly 99%, according to the CDC. Childbirth stopped being a dice roll. Tuberculosis stopped being a death sentence. Smallpox, which killed an estimated 300 million people in the twentieth century according to widely cited WHO estimates, no longer exists outside of laboratories.
These are among the greatest accomplishments of human civilization. Millions of people are alive who would have died at birth, in childhood, from diseases we can now prevent.
I am not here to diminish that.
But while we were measuring mortality, something else was happening. And we weren't measuring it.
Life expectancy doubled from 1800 to now. Real progress. But healthspan didn't keep pace. The gap widened globally. And we didn't notice because we didn't think to measure the gap.
GDP grew decade after decade. Real wealth. But subjective wellbeing plateaued. And we didn't notice because we were measuring economic output, not human flourishing.
Deaths from infectious disease plummeted. Real victory. But deaths from chronic environmental exposure climbed. And we didn't notice because chronic disease develops slowly, shows up decades after exposure, and we hadn't invented the tools to detect parts per trillion.
A 2023 paper about Rachel Carson's Silent Spring noted that she wrote "when the field of environmental chemistry was in its infancy, and analytical data that proved ubiquitous exposure were lacking." She warned us in 1962, seventeen years into the experiment, before we had the tools to measure.
Theo Colborn identified the mechanism in the 1990s. Endocrine disruption—chemicals interfering with hormones at extremely low doses. She showed us how they harm. She wrote fifty years in, before biomonitoring was universal.
We're eighty years in now. We have the data. The warnings came early. The measurement came late. And in the gap between exposure and measurement, we optimized for what we could see.
This is what The Substitution does. It makes the proxy metric visible and the real thing invisible.
We measured years alive. We measured GDP. We measured consumption. And we got exactly what we measured.
What we didn't measure: Years healthy. Human flourishing. Chemical body burden. Plastic accumulating in brains.
By the time we developed tools sensitive enough to detect parts per trillion, by the time researchers thought to measure microplastics in human brains, eighty years had passed and exposure was universal.
We couldn't prove causation because we never designed a control group. There is no unexposed population to compare against. We are all subjects now.
This is what uncontrolled means. We didn't set up the conditions to know.
VI. Where We Are
CDC's National Exposure Report—the cumulative biomonitoring tables—extends through 2017-2018 as of early 2025. That data was collected six to eight years ago.
In eight years—2016 to 2024—microplastics in human brains increased by roughly fifty percent.
We don't know what's in our bodies right now. The data lags six to eight years behind reality. We're running an experiment without measuring the results in real time.
In May 2025, the EPA announced it would keep drinking water standards for PFOA and PFOS but proposed rescinding limits for PFNA, PFHxS, GenX, and the PFAS mixture hazard index. Compliance deadlines were extended from 2029 to 2031. The agency had tried to protect drinking water from multiple "forever chemicals." Water utilities and industry groups challenged the rule; EPA cited implementation concerns amid ongoing legal challenges.
That same month, states started stepping in where federal agencies retreated. Illinois enacted a ban on PFAS in consumer products in August 2025, effective January 2032—cosmetics, dental floss, juvenile products, menstrual products, intimate apparel. Minnesota, Colorado, and Maine enacted similar bans.
In Europe, the revision of REACH—the chemical safety regulation—has faced repeated delays and is now expected in early 2026, though timing remains uncertain.
Regulatory retreat is not just an American problem. It's happening wherever industry can push back. The EU chose a stricter approach in 2007—requiring companies to provide safety data and manage chemical risks under a "no data, no market" principle. But even there, the latest revision faces delays. The U.S. chose innovation-first regulation, assuming chemicals innocent until proven guilty and then didn't fund the trials. We're living with the consequences of that choice. But Europe is learning that choosing better policies doesn't mean those policies survive contact with industry.
Chemical production continues accelerating—projected at 3.4% growth in 2024 and 3.5% in 2025. China is rapidly expanding its share. The experiment is not only continuing—it's expanding and accelerating.
We are living longer than any generation in history. As of 2019, the global healthspan-lifespan gap averaged 9.6 years. In the United States, it had reached 12.4 years—twenty-nine percent worse than the global average.
We own more than any generation in history. And materialism correlates negatively with happiness.
We have chemicals in our blood that grant us convenience. And chronic diseases that didn't exist at these rates when those chemicals were invented. And plastic accumulating in our brains at a rate that increased by roughly fifty percent in eight years.
We optimized for what we could measure. We got it. And we built a gap between breathing and flourishing that is widening everywhere.
VII. What The Substitution Costs
This is not going backwards. You can't unlearn vaccines. Can't uninvent antibiotics. Infant mortality fell ninety percent and maternal mortality fell ninety-nine percent and those are among the best things we have ever done.
But you also can't uncirculate PFAS. Can't unmanufacture microplastics already embedded in brain tissue. Can't unmake the ideology that turned wanting into the purpose of life.
What you can do is look at what we built. See The Substitution clearly.
We made a choice in 1945. Turned wartime production toward peacetime consumption. Made abundance political. Made wanting patriotic. Introduced eighty-six thousand chemicals without testing them. Made The Substitution: measured mortality but not morbidity. Measured wealth but not wellbeing. Measured years lived but not years lived well.
And eighty years later, here we are.
The U.S. went furthest because we had the most industrial capacity to redirect, the most political will to make consumption patriotic, and the weakest regulatory barriers to slow us down. But the pattern exported. Where American-style capitalism went, The Substitution followed. The countries with the longest lifespans don't have the best healthspans. The countries with the most material abundance don't have the happiest populations. And nowhere on Earth is protected from the chemicals in our blood or the plastic in our brains.
We didn't fall in love with chemicals. We fell in love with not having to think. Not having to wait. Not having to choose between convenience and consequence.
And we're spending the end years of our lives sick with what we didn't think about. With brains that are accumulating plastic and getting worse.
But here is what I keep coming back to, the thing that makes this almost too painful to contemplate:
The gap is not a measurement failure.
The gap is the measurement.
It's what The Substitution looks like when you measure it honestly. When you put the proxy metric and the real thing side by side and calculate the distance.
We got exactly what we optimized for. We measured years alive, and we got more years alive. We measured GDP growth, and we got more GDP. We measured consumption, and we got more consumption. We measured chemical production, and it keeps growing.
What we didn't measure—years healthy, human flourishing, chemical body burden, wellbeing—those we didn't get. Not because we couldn't measure them. We can measure them now. We didn't get them because we didn't optimize for them.
The gap isn't the distance between what we wanted and what we got.
The gap is the cost of The Substitution. The distance between the proxy we measured and the reality we said we cared about.
We said we wanted health. We optimized for lifespan. We said we wanted happiness. We optimized for GDP. We said we wanted progress. We optimized for convenience. We said we wanted flourishing. We optimized for years.
And the gap—12.4 years in the United States, 9.6 years globally, and widening—is the space between those two stories. The distance between what we said mattered and what we actually measured. Between what we claimed to value and what we actually built.
The gap is where the truth lives.
We are excellent at solving problems. We solved mortality. We solved poverty. We solved infectious disease. These are genuine triumphs. We should celebrate them.
We are less good at noticing that the solution is tomorrow's problem. That the chemicals that gave us convenience are giving us chronic disease. That the materialism that drove growth is driving misery. That the years we added are being spent in a gap we built by measuring the wrong things.
And we are catastrophically, systematically terrible at admitting that we got what we optimized for.
The tragedy is not that we failed. The tragedy is that we succeeded. We built exactly what our measurements told us to build. We optimized perfectly for the metrics we chose.
We just chose the wrong metrics. We made The Substitution and forgot we made it.
The gap is not an accident. It's not an oversight. It's not something that happened to us.
The gap is what The Substitution costs when you run it at civilizational scale for eighty years.
It's the architecture of our priorities, made visible. The distance between the thing we said we wanted and the thing we actually measured. Between flourishing and breathing. Between health and years. Between wellbeing and wealth.
And now the gap is where we live. The space we built between what we claimed to value and what we actually counted. The 12.4 years—or 9.6 years, depending where you're standing—between the story we told ourselves about progress and the story the measurements tell.
We are still here. Still breathing. For years longer than we're flourishing.
That's the paradox. We call it progress. And by some measures, it is.
But the gap is honest in a way our words are not. It measures what we actually did, not what we said we were doing. It counts what we actually valued, not what we claimed to value.
And if we're willing to look at it clearly—really look, without flinching—the gap tells us something we might not want to hear but desperately need to know:
We are very good at getting what we measure. We are very good at making The Substitution and calling it progress. We just haven't been brave enough to measure what we actually want.
The gap is not the problem. The gap is the answer.
It's what happens when you finally measure both things—the proxy and the real thing—and see the distance you've built between them.
We can keep making The Substitution. Keep measuring years and calling it health. Keep measuring GDP and calling it flourishing. Keep measuring consumption and calling it happiness.
Or we can look at the gap. Really look. And ask what we'd have to measure differently if we wanted the gap to close instead of widen.
The choice has always been ours. We just keep substituting metrics for meaning and hoping no one will notice the distance.
The gap noticed. The gap is twelve point four years wide and getting wider.
And the gap is where the truth lives.