Are Americans Decreasing in Height, or Are Others Growing Taller?
Written on
Chapter 1: Historical Context of American Heights
In 1914, American men were third tallest globally; today, they rank 37th. Is this shift due to genetic factors or environmental influences?
Pexels | Photo by Wallace Chuck
If George Washington were to create a dating profile today, he might understate his height. Unlike the common tendency for men to embellish their height, Washington would have claimed he was shorter. While he was often described as a towering 6-foot-3, he claimed to be merely “6 feet.” This humility, even in an era of boastfulness, is notable and reflects a deeper truth about human nature.
Most people are prone to the Dunning-Kruger effect, which leads individuals to overestimate their abilities. This inclination to exaggerate strengths complicates researchers' efforts to rely on self-reported data for measuring human traits, including height.
Because of this phenomenon, tracking height trends has become challenging. Starting in the 1960s, the Centers for Disease Control and Prevention (CDC) abandoned self-reported height data in favor of more reliable measurements. The CDC now utilizes The National Health and Nutrition Examination Survey (NHANES), employing trained professionals to accurately measure participants with advanced digital stadiometers, ensuring a minimal margin of error.
However, a recent article in the Washington Post by Andrew Van Dam titled “Why are Americans getting shorter?” raised some skepticism in the research community. The article's sensational tone and reliance on specific demographics, focusing solely on “native-born individuals aged 20 to 49” and predominantly white subjects, sparked debate.
Section 1.1: The Flaws in Data Interpretation
The decision to omit certain population segments from analysis raises concerns about the reliability of conclusions. It’s essential to recognize that people do not exclusively mate within narrow demographic boundaries, and failing to consider broader trends can lead to misleading interpretations.
This scenario exemplifies Simpson’s paradox, where trends may appear within distinct data groups but vanish when those groups are combined, resembling cherry-picking for attention-grabbing headlines.
Subsection 1.1.1: Analysis of CDC Data
The CDC has released two comprehensive height reports utilizing NHANES data. The first covers the years 1960–2002, while the second spans from 1999 to 2016.
From 1960 to 2002, the average height for American men aged 20–74 rose from just over 5-foot-8 to 5-foot-9½. Similarly, women’s average height increased from slightly above 5-foot-3 to 5-foot-4. However, from 2002 to 2018, both men and women experienced a slight decline in height.
Artwork: © Carlyn Beccia | www.CarlynBeccia.com | Data from The National Health and Nutrition Examination Survey (NHANES)
The Washington Post article suggested that the year 1980 marked a significant decline in height, attributing this to economic factors and healthcare changes. Yet, this analysis lacks nuance.
Section 1.2: Reexamining the 1980 Decline
Until 1988, the CDC's data on height calculations encompassed only those aged 20 to 74. Post-1988, the data included individuals 74 and older, a demographic known to experience height loss. Consequently, the inclusion of older individuals skews height averages downward.
The CDC data from 1999 to 2016 reveals that women lost an average of 0.4 centimeters (about 1/8 of an inch), while men lost 0.2 centimeters, too minor to support the Washington Post's alarming narrative.
Chapter 2: A Global Perspective on Height
Interestingly, while Americans are not necessarily getting shorter, their height is stagnating compared to growing averages in other countries. In 1914, American men ranked third in height; today, they stand at 37th.
A study published in The Lancet in 2020 analyzed data from 50 million individuals aged 5-19 and 15 million aged 20-30, revealing that young Americans' heights have remained relatively stable.
Source: The Lancet: VOLUME 396, ISSUE 10261, P1511–1524, NOVEMBER 07, 2020 | Creative Commons Attribution (CC BY 4.0)
Countries like China, Saudi Arabia, and India are witnessing increases in height, while regions experiencing drought and poverty, such as Mali, face declines.
Section 2.1: The Genetics Debate
Some media narratives suggest that increased immigration contributes to stagnant heights in America. The theory posits that mixing with shorter populations could lower average heights. However, this does not align with trends observed in the Netherlands, where even without significant immigration, Dutch heights have plateaued.
Dutch men born in 1980 were taller than those born in 1930, yet recent data shows a slight decrease in average height among young Dutchmen.
Section 2.2: Environmental Influences on Height
Height is often perceived as a fixed attribute primarily influenced by genetics. However, various factors, including nutrition, hormones, and physical activity, play crucial roles.
Nutritional access in early childhood is particularly significant; populations with lower nutrition levels tend to have shorter individuals. Nations such as the Central African Republic and Yemen struggle with food security, impacting their populations' heights.
Conversely, countries like India and Ethiopia have improved nutrition, resulting in taller individuals.
Chapter 3: The Broader Implications of Height
Height can be a sensitive issue tied to social status and desirability. Many Americans aspire to be taller and healthier compared to global averages. Unfortunately, the U.S. is facing rising obesity rates alongside poor nutritional choices.
With numerous factors influencing height stagnation and nutritional quality, it’s tempting to assign blame. However, scapegoating immigrants or younger generations misses the broader systemic issues.
What remains clear is that Americans were once taller compared to other nations, a status that has declined due to healthcare cuts, poor nutrition education, and the overwhelming demands on working families.
In reflecting on George Washington's humility, perhaps the U.S. could benefit from a renewed sense of accountability and awareness, ultimately leading to a healthier populace.
Update! For free content, subscribe to Conversations with Carlyn, or support my research by becoming a paid pledge. Only paid subscribers get exclusive content.