Humans are not, on the whole, getting shorter. Over the past century and a half, average adult height has increased across most of the world, with gains in many European countries running between one and three centimeters per decade. But the global picture is more complicated than a simple upward trend, because some populations have stalled, a few may have dipped, and the forces that pushed heights up are not guaranteed to keep doing so. Whether you are asking about your country, your generation, or the deep sweep of human history, the answer changes.
The Long Climb Upward
Since the 1800s, people in most industrialized nations have been growing steadily taller. Documented secular trends show increases of roughly 10 to 30 millimeters per decade in most European countries, driven primarily by improvements in nutrition, sanitation, and disease control.1PubMed. Secular trends in growth The gains were dramatic enough that a man born in the Netherlands in the mid-twentieth century stood, on average, several centimeters taller than his grandfather. This kind of rapid, sustained increase in height within a single population is called a secular trend, and it has been one of the most visible markers of improved living conditions worldwide.
Americans were once the tallest people on the planet. For more than two centuries, from colonial times through World War II, average American stature exceeded that of any European population. Then something shifted. Height gains in the United States slowed around mid-century, and a period of stagnation set in for birth cohorts from roughly 1955 through 1974, even as northern and western Europeans kept getting taller.2Social Science Quarterly. Underperformance in Affluence: The Remarkable Relative Decline in U.S. Heights in the Second Half of the 20th Century By the end of the twentieth century, Americans had fallen behind many European populations, lagging the Dutch by as much as five to six centimeters.3PubMed. The mysterious trend in American heights in the 20th century This relative decline happened despite America’s enormous wealth, which is part of what makes it so puzzling to researchers.
Where Height Gains Have Stalled or Reversed
Even in countries that grew dramatically taller, the trend does not run forever. In Scandinavia and the Netherlands, the height increase reached a plateau during the 1980s, while middle and southern European countries continued to gain.4PubMed. Height of conscripts in Europe: is postneonatal mortality a predictor? A study tracking Dutch children from 1955 to 2009 found that the world’s tallest population had stopped getting taller, though researchers could not say whether the Dutch had simply reached their genetic ceiling or whether environmental conditions had stabilized in a way that prevented further gains.5Pediatric Research. The world’s tallest nation has stopped growing taller: the height of Dutch children from 1955 to 2009
Sub-Saharan Africa tells a different story entirely. Despite declining infant mortality rates in recent decades, adult heights in the region have not increased.6PubMed Central. Health trends in Sub-Saharan Africa: conflicting evidence from infant mortality rates and adult heights This disconnect suggests that surviving infancy is necessary but not sufficient for reaching full height potential. Chronic undernutrition, recurrent infections during childhood, and economic instability can all blunt growth even when outright mortality falls. It is a reminder that global averages can mask strikingly uneven realities.
What Drives How Tall a Population Gets
Height is shaped by both genetics and environment, and teasing apart their relative contributions has kept researchers busy for decades. A recent study combining polygenic scores with environmental indicators like human development index and caloric intake found that models incorporating both genetic and environmental factors had the best explanatory power, with one combined model accounting for about 85 percent of the variation in population-level height.7Twin Research and Human Genetics. Polygenic Selection and Environmental Influence on Adult Body Height: Genetic and Living Standard Contributions Across Diverse Populations In practical terms, your genes set a range of possible heights, and your childhood environment determines where in that range you land.
Nutrition during childhood is the single most powerful environmental lever. Diets rich in animal protein and fat are consistently linked to greater adult stature. One longitudinal study found that boys who ate more fat and animal protein in childhood were taller both at age 13 and as adults.8PubMed Central. Childhood Diet And Growth In Boys In Relation To Timing Of Puberty And Adult Height For girls, total and animal protein intake from age three onward were independently associated with greater adult height.9The Journal of Clinical Endocrinology & Metabolism. Adult Stature and Protein Intake During Childhood and Adolescence From 3 Years Onward These findings help explain why the historical shift from grain-based diets to diets with more dairy and meat coincided with dramatic gains in height across Europe.
Conditions in the womb matter too. Mothers who are lighter, shorter, or thinner tend to have babies who are smaller and shorter at birth, with smaller heads and lighter placentas.10European Journal of Clinical Nutrition. Relationship between maternal nutritional status and infant’s weight and body proportions at birth Intrauterine programming in response to fetal malnutrition can induce permanent changes in the body’s structure and function, leading to shorter height in later life.11PubMed Central. Associations between birth size and later height from infancy through adulthood This creates a generational feedback loop: a malnourished girl grows into a shorter woman who is more likely to have a smaller baby, who may in turn grow up shorter. Breaking that cycle requires sustained nutritional improvement across multiple generations.
The Childhood Obesity Paradox
You might assume that overfed children would grow up to be tall adults, since excess calories seem like they should fuel growth. The reality is less intuitive. A study tracking children from age two to eight found that higher body mass index gain during childhood was associated with taller stature during childhood itself, but it also triggered earlier puberty, roughly six to seven months earlier per unit of BMI gained. That earlier puberty shortened the adolescent growth phase enough to cancel out the childhood height advantage, leaving no net benefit for final adult height.12Pediatric Research. BMI in Childhood and Its Association with Height Gain, Timing of Puberty, and Final Height
This matters for understanding modern height trends because childhood obesity rates have climbed dramatically over the past few decades in many countries. If more children are hitting puberty earlier because of excess weight, the population-level effect could dampen height gains even when caloric intake is abundant. Overnutrition, in other words, is not the same thing as optimal nutrition for growth.
Chronic Gut Inflammation and Stunting
In low-income settings, malnutrition is only part of the story. Environmental enteric dysfunction, a chronic condition in which the lining of the small intestine becomes damaged and inflamed from repeated exposure to pathogens, affects millions of children growing up without clean water and sanitation. A systematic review found strong evidence linking intestinal inflammation to both systemic inflammation and stunting, though the precise biological pathway is still debated.13PLOS Neglected Tropical Diseases. Environmental enteric dysfunction pathways and child stunting: A systematic review The gut does not just process food; it serves as a gatekeeper that, when damaged, can redirect the body’s resources away from growth and toward immune defense. This condition helps explain why giving food aid alone sometimes fails to prevent stunting in children exposed to unsanitary environments.
Inequality Within Countries
How tall you grow depends not just on which country you live in, but on where you sit within that country’s social hierarchy. A comparison of children across five high-income countries found that kids in more economically equal nations, specifically Sweden and the Netherlands, were taller at every level of household income and parental education than children in less equal countries like the United States, United Kingdom, and Australia. The gap was widest among children with the least-educated and lowest-income parents.14BMJ Paediatrics Open. Income inequality and social gradients in children’s height: a comparison of cohort studies from five high-income countries
Within the United States, the relationship between socioeconomic status and height varies by race and ethnicity. A positive gradient linking maternal education to height was observed in the overall population and in White and Mixed-race males and females, but no such gradient existed in Hispanic, Asian, or Black males or females.15PubMed Central. The association of adolescent socioeconomic position and adult height: variation across racial/ethnic groups This pattern suggests that factors beyond simple household resources, such as neighborhood quality, healthcare access, and structural inequality, contribute to height outcomes in ways that income alone does not capture. It also partly explains why American heights stagnated even as GDP climbed: national wealth does not automatically translate into the kind of broadly shared, nutrition-rich early childhood that maximizes growth.
Why Older People Are Shorter Than Younger People
If you have ever noticed that elderly relatives seem shorter than they used to be, you are not imagining it, but this is a different phenomenon from generational height changes. As people age, their spines compress. Age-related changes to the vertebrae include loss of bone mineral density, thinning of the structural supports within the bone, and dehydration and stiffening of the discs between vertebrae, all of which alter how the spine bears weight and lead to measurable height loss.16PubMed Central. Biomechanics of the aging spine A person can lose one to three centimeters of height between their peak in early adulthood and old age, and more if osteoporosis or vertebral fractures are involved.
This individual shrinking is easy to confuse with a generational trend. If you line up a group of 80-year-olds and a group of 30-year-olds in the same room, the older group will almost certainly be shorter on average. Part of that difference is spinal compression, but part of it is also a genuine generational gap: the 80-year-olds grew up in a time with different nutritional conditions and disease burdens. Separating these two effects requires careful study designs that measure the same people over time, rather than comparing different age groups at a single snapshot.
The Neolithic Lesson
The question of whether humans are getting shorter has a deep historical parallel. When early humans shifted from hunting and gathering to farming during the Neolithic transition, average stature dropped in many parts of the world. A broad review of bioarchaeological evidence found that height declined as reliance on agriculture increased, and that this pattern appeared across every continent where farming was adopted, regardless of the time period.17PubMed. Stature and robusticity during the agricultural transition: evidence from the bioarchaeological record The conventional explanation has been that farming diets were narrower and less nutritious than foraging diets, and that crowded agricultural settlements fueled infectious disease.
But the picture is more nuanced than the textbook version. A large-scale analysis tracking body size across the Levant, Europe, South Asia, China, and the Nile Valley found that decreases in stature sometimes preceded the adoption of agriculture, meaning other factors like climate change or shifting populations may have played a role. Regions where domestication happened locally and gradually, such as the Levant and China, showed stable stature and body mass over time rather than a sharp decline. And in central and northern Europe, height and body mass actually increased in tandem with the spread of lactase persistence, the genetic ability to digest milk into adulthood.18PubMed Central. Long-term trends in human body size track regional variation in subsistence transitions and growth acceleration linked to dairying A recent analysis confirmed that the Neolithic height reduction was modest and driven partly by changes in genetic ancestry through migration, with lactose tolerance acting as a mitigating factor.19PubMed. Human evolution: Stature variation in the Neolithic
The Neolithic experience demonstrates that height is not a one-way ratchet. Populations can get shorter under the right combination of dietary narrowing, disease pressure, and population mixing, even when other markers of civilization are advancing. It is a useful corrective to the assumption that height only goes up.
Climate, Body Size, and the Very Long View
Zoom out far enough and climate itself shapes how big humans get. Across 247 Homo specimens spanning hundreds of thousands of years, body mass was significantly smaller during periods of climatic warming compared to cooler cycles, and body proportions shifted to become more slender in warmer periods and more stocky in cooler ones.20Evolutionary Biology. Climate Change Predictive of Body Size and Proportionality in Humans This tracks with patterns seen in other mammals: in cold environments, a larger, rounder body conserves heat more efficiently, while in hot environments, a leaner frame sheds heat better.
These climate-body relationships still hold today. In modern populations, body mass varies inversely with mean annual temperature, meaning people in colder regions tend to be heavier, and the ratio of surface area to body mass is higher in people from warmer climates.21American Journal of Physical Anthropology. Climatic influences on human body size and proportions: Ecological adaptations and secular trends However, the strength of these correlations has weakened over recent decades as nutritional improvements, especially in tropical developing nations, have pushed body mass up regardless of temperature. Population history, ecology, and diet all layer on top of climate as predictors of body size.22Scientific Reports. Population history and ecology, in addition to climate, influence human stature and body proportions Whether ongoing climate warming will exert any measurable downward pressure on future human stature remains speculative, but the deep evolutionary record suggests the relationship between heat and smaller bodies is real.
Could Environmental Pollutants Shrink Us
One emerging concern is whether modern chemical exposures might interfere with growth. Endocrine-disrupting chemicals, synthetic compounds that mimic or block hormones, are now ubiquitous in food packaging, plastics, pesticides, and personal care products. Epidemiological evidence suggests these compounds can affect prenatal growth, thyroid function, the timing of puberty, and other processes relevant to stature.23PubMed Central. New insights on the effects of endocrine-disrupting chemicals on children
Bisphenol A, commonly known as BPA, is among the best-studied of these compounds. A study following school-aged children found that boys in the highest BPA exposure category had height Z-scores roughly half a point lower than boys in the lowest exposure category, and this association persisted over the follow-up period. No similar effect was seen in girls.24Journal of Exposure Science & Environmental Epidemiology. Bisphenol A and pubertal height growth in school-aged children The researchers noted these findings need confirmation in further studies, and it would be premature to blame chemicals for any population-wide height changes. But the plausibility is there: if compounds in the environment disrupt the hormones that regulate growth, and if exposure is widespread enough, the cumulative effect on a population is at least theoretically possible.
Height and Health Outcomes
Height is not just a reflection of past conditions; it also predicts future health in ways that are sometimes contradictory. A massive meta-analysis of over a million people found that for every 6.5 centimeters of additional height, overall death risk dropped by about three percent. Taller people had lower risk of dying from coronary heart disease, stroke, chronic lung disease, liver disease, and several other causes.25International Journal of Epidemiology. Adult height and the risk of cause-specific death and vascular morbidity in 1 million people: individual participant meta-analysis
But the relationship flipped for certain cancers. Taller people faced higher risk of death from melanoma, cancers of the pancreas, ovary, breast, prostate, and colorectum, as well as aortic aneurysm and pulmonary embolism. The hazard ratios for these conditions ranged from modest increases per 6.5 centimeters of extra height. These associations held even after adjusting for obesity, blood pressure, cholesterol, diabetes, and socioeconomic status, suggesting that height itself, or the biological processes linked to greater growth, plays an independent role.25International Journal of Epidemiology. Adult height and the risk of cause-specific death and vascular morbidity in 1 million people: individual participant meta-analysis The leading hypothesis is that taller bodies have more cells undergoing division, which means more opportunities for the kind of DNA errors that lead to cancer. From a population health standpoint, getting taller is not purely good news.
The Problem with Measuring Height at Scale
It is worth asking how much we should trust the numbers behind these trends, especially for modern surveys that rely on people reporting their own height. A systematic review comparing self-reported and measured height found generally good agreement overall, but with systematic biases: men tend to overreport their height, while women tend to underreport their weight.26PubMed Central. Validity of Measured vs. Self-Reported Weight and Height and Practical Considerations for Enhancing Reliability in Clinical and Epidemiological Studies Analysis of U.S. national surveys from 1999 through 2016 confirmed that both men and women consistently overreported their height relative to measured values.27PubMed Central. Comparisons of Self-Reported and Measured Height and Weight, BMI, and Obesity Prevalence from National Surveys: 1999–2016
This may seem like a minor technical issue, but it matters when large-scale surveys are the main tool for tracking population height over time. If overreporting tendencies shift across generations, perhaps because attitudes about height change or because older adults are comparing themselves to a peak height they no longer have, the data could create an illusion of either growth or shrinkage that does not reflect biological reality. Researchers studying the reliability of self-reported height have flagged that a lack of knowledge about one’s actual height may be a contributing factor in reporting errors, rather than deliberate exaggeration.28SSM – Population Health. How tall am I again? A longitudinal analysis of the reliability of self-reported height The most reliable secular trend data comes from military conscription records and clinical measurements rather than telephone surveys, which is one reason historical European data (drawn from army records) tends to be more trustworthy than modern self-report studies.
Why America Stalled While Europe Kept Growing
The American height stagnation is one of the more provocative puzzles in this field, because it happened in the richest country on Earth. Several explanations have been proposed, and most researchers think the answer involves multiple factors acting in concert. The U.S. has greater income inequality than northern European countries, and as the cross-country comparison of children’s height showed, inequality itself appears to drag down stature, especially among the least advantaged families.14BMJ Paediatrics Open. Income inequality and social gradients in children’s height: a comparison of cohort studies from five high-income countries The U.S. also lacked the universal healthcare access that many European countries built in the postwar era, meaning that childhood illnesses that could stunt growth were more likely to go untreated in lower-income American households.
Immigration patterns add another layer. The U.S. received large waves of immigrants from countries where average stature was shorter, which could have pulled down population averages through a compositional effect rather than any decline in the growth of people already living there. Diet quality is another suspect: even though calories were abundant in postwar America, the nutritional profile of the American diet shifted toward processed foods that may not optimize growth the way whole-food diets in Scandinavian countries did. None of these explanations alone is sufficient, but taken together they paint a plausible picture of how a wealthy nation can underperform on height even as it leads the world in GDP per capita.
What Happens When People Start Drinking Milk
Dairy consumption has played a surprisingly specific role in height history. The connection between lactase persistence and increased stature in central and northern Europe, described earlier in the Neolithic evidence, is not just an ancient phenomenon. The countries that top modern height rankings, the Netherlands, Scandinavia, and the Baltics, also happen to have among the highest per-capita dairy consumption in the world. Dairy provides a combination of high-quality protein, calcium, and insulin-like growth factor 1 that is difficult to replicate with plant-based foods alone.
This link between dairy and height continues to play out in developing nations. When countries industrialize and dairy becomes more available, childhood growth rates tend to accelerate. The genetic dimension is striking: populations with a higher prevalence of lactase persistence, the ability to digest lactose throughout life, tend to be taller even after controlling for other dietary and economic variables.18PubMed Central. Long-term trends in human body size track regional variation in subsistence transitions and growth acceleration linked to dairying In regions where lactase persistence never became common, such as much of East Asia and Sub-Saharan Africa, height gains from improved nutrition have relied on other protein sources and have sometimes been slower to materialize.