Tom Hundley, Chicago Tribune, December 25, 2008
Call her The Incredible Shrinking African-American Woman.
In an age when the adult populations of most industrialized nations have grown significantly taller, the average height of black women in the U.S. has been receding, beginning with those born in the late 1960s.
The difference in stature between white women and black women has now stretched to three-quarters of an inch and appears to be increasing, according to newly released data from the National Health and Nutrition Examination Survey (NHANES) conducted by the federal Centers for Disease Control and Prevention.
The average height of a black woman born in the 1980s is just under 5 feet 4 inches; her mother, born in the 1960s, is more than half an inch taller. Even her grandmother, born in the 1940s, is a bit taller. The average white woman born in the 1980s is about half an inch taller than her mother.
The gap is “truly phenomenal,” according to John Komlos, an economist and historian who has made a specialty of studying human heights. “Such a steep decline is practically unprecedented in modern U.S. history.”
Komlos’ latest findings, based on the NHANES data, suggest that after nearly 25 years of stagnation, the average height of adult Americans born from 1975 to 1986 has edged up again—with the exception of black women, whose height is moving in the opposite direction.
The reason this matters, according to Komlos, is because “height is a very good overall indicator of how well the human organism thrives in its socioeconomic environment.”
His argument is bolstered by another discovery: While the heights of low- and middle-income black women are plummeting, upper-income black women are growing taller and rapidly closing the gap with their white counterparts.
An individual’s height is fixed mainly by genes, but the average height of different categories of people is determined to a large extent by external factors.
Also baffling, Adler [Nancy Adler, director of the MacArthur Foundation’s Research Network on Socioeconomic Status and Health] said, is the disparity between black men and black women, “since they are subject to the same pre-birth conditions” and then grow up in the same environment.
“The only reasonable explanation we can come up with is diet and the obesity epidemic among [middle- and low-income] black women,” said Komlos.
Over the last three decades, the prevalence of obesity among white Americans has tripled, while among blacks it has increased fivefold.
Black females were hardest hit: Almost 80 percent of black females are overweight or obese, compared with 62 percent of the total female population, according to the CDC.
Another oddity, according to Komlos, is that black children, both male and female, grow faster and taller than their white counterparts in early childhood, but whites catch up and pass them during the teen years.
Pediatric growth experts offer one possible explanation. High caloric intake from an unhealthy diet fuels an early growth spurt among black children, plus it speeds the onset of puberty, especially for black girls, who now begin menstruating 81/2 months ahead of white girls. This early onset of puberty reduces the duration of the critical pre-adolescent growth spurt, resulting in a lower adult height.