Legs got longer faster than torsos

Sunday, July 4th, 2021

Repeatedly, studies of families and twins find the heritability of height to be about 80 percent, David Epstein explains (in The Sports Gene):

For much of the twentieth century, denizens of industrialized societies were growing taller at a rate of about one centimeter per decade. In the seventeenth century, the average Frenchman was 5’4″, which is now the average for an American woman. The first generation of Japanese born to immigrant parents in America, known as the Nisei, famously towered over their parents.

In the 1960s, growth expert J. M. Tanner examined a set of identical twins that suggested the range of height variability caused by the environment. The identical boys were separated at birth, one brother raised in a nurturing household, and the other reared by a sadistic relative who kept him locked in a darkened room and made him plead for sips of water. In adulthood, the brother from the nurturing household was three inches taller than his identical twin, but many of their body proportions were similar. “The genetic control of shape is more rigorous than that of size,” Tanner wrote in Fetus into Man. The smaller brother was an abuse-shrunken version of the bigger brother.


Similarly, female gymnasts delay their growth spurt with furious training, but that does not diminish their ultimate adult height.


In World Wars I and II, European children were exposed to brief periods of famine during which their growth ground almost to a halt. When food again became plentiful, their bodies put the growth pedal to the metal such that adult height was not curtailed.


Consider that children grow more quickly in spring and summer than in fall and winter, and that this is apparently due to sunlight signals that enter through the eyeballs, since the growth of totally blind children consists of similar fluctuations but are not synchronized with the seasons.

The height that inhabitants of urban societies gained over the twentieth century came principally from increased leg length. Legs got longer faster than torsos. In developing countries that have gaping nutritional and infection-prevention disparities between the middle class and poor, the difference in height between the comfortable and the afflicted is all in the legs.

Japan displayed a startling growth trend during its “economic miracle” period following World War II. From 1957 to 1977, the average height of a Japanese man increased by 1.7 inches, and of a woman by an inch. By 1980, the height of Japanese people in Japan had caught up with the height of Japanese people in America. Amazingly, the entire height increase was accounted for by increased leg length. Modern Japanese people are still short compared with Europeans, but not as short as they once were. And they now have more similar proportions.


Every study that has examined race differences in body types has documented a disparity between black and white people that remains whether they reside in Africa, Europe, or the Americas. For any given sitting height — that is, the height of one’s head when one is sitting in a chair — Africans or African Americans have longer legs than Europeans. For a sitting height of two feet, an African American boy will tend to have legs that are 2.4 inches longer than a European boy’s. Legs make up a greater proportion of the body in an individual of recent African origin.


In their summary of the measurements of 1,265 Olympians from the 1968 Olympics in Mexico City, the scientists state that the successful body types within a sport are much more similar than body types between sports, regardless of ethnicity, but that “the most persistent of these differences” within sports are the narrow hip breadths and longer arms and legs of athletes with recent African ancestry.


In NBA predraft measurements for active players, the average white American NBA player was 6’7½” with a wingspan of 6’10″. The average African American NBA player was 6’5½” with a 6’11″ wingspan; shorter but longer.


“So maybe it’s not so much that white men can’t jump. White men just can’t reach high.”


In 1877, American zoologist Joel Asaph Allen published a seminal paper in which he noted that the extremities of animals get longer and thinner as one travels closer to the equator.


A 1998 analysis of hundreds of studies of native populations from around the world found that the higher the average annual temperature of a geographic region, the proportionally longer the legs of the people whose ancestors had historically resided there.


Africans with ancestry in southern regions of the continent, farther from the equator, do not necessarily have especially long limbs.


Nonetheless, the researchers reported that, compared with white adults of a given height, black adults have a center of mass — approximately the belly button — that is about 3 percent higher.

They used engineering models of bodies moving through fluids — air or water — to determine that the 3 percent difference translates into a 1.5 percent running speed advantage for athletes with the higher belly buttons (i.e., black athletes) and a 1.5 percent swimming speed advantage for athletes with a lower belly button (i.e., white athletes).


  1. Felix says:

    That equator / long limbs thing sounds suspicious. I’d want to see the details for people of India and Sri Lanka.

    And heat-gives-long-limbs? Is that true of Pacific Islanders compared to Eskimos?

  2. Altitude Zero says:

    Stereotypes confirmed as oversimplifications, but essentially true, example 1,254,193…

Leave a Reply