Carl Zimmer has produced an absolutely fascinating look at
the various ways in which living things, including we humans, can inherit the characteristics
that define us. There are some very
surprising pathways available. He
presents his work in She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity. One of the topics he covers is the
inheritability of height. There clearly
is a correlation between parental height and that of a child, but the
correlation is not perfect. Figuring out
exactly how this transference is accomplished genetically is not a trivial
undertaking. In the process of explaining
the complexities of the necessary genetic analysis, he provides an interesting
discussion of environmental factors. Of
particular interest was the discussion of how height could be affected by
general health, nourishment and well-being.
In fact, researchers have spent a considerable amount of effort trying
to use average height within a population as an indicator of national
well-being.
The first effort in using average height as data is
attributed to Luis-René Villermé who tallied the
average height of the men who entered the French army during the Napoleonic Wars. He discovered that this value declined during
the war years but began to rise again once peace had been established. He attributed this effect to wartime food
shortages. It would be a long time
before the man’s hypothesis would be reexamined.
“Villermé’s insight went
neglected for the next 150 years, until a small group of economists led by
Nobel Prize winner Robert Fogel started charting height in different countries
over the course of decades. They made a
compelling case that height could serve as an economic barometer, recording the
well-being of societies.”
The historical data is quite compelling—and quite
interesting. Data from Europe goes back
about 30,000 years. There was a human
culture at the time referred to as the Gravettians. They seemed to be hunter-gatherers who had a
diet heavy in meat. This ample protein
supply elevated their average height to about six feet. When the beginnings of an agricultural
economy arrived in Europe, this development delivered a host of new diseases as
population density increased. The dietary
focus also shifted to lower protein sources such as grains. Average height indicated this “progress” was
very hard on humans.
“When agriculture arrived in
Europe some eight thousand years ago, people experienced a tremendous drop in
stature. Men lost eight inches in height….For
the next seven thousand years, European stature hardly changed, wavering just
an inch or two from century to century.
In the eighteenth century, the average European man stood five foot
five.”
Those moving to America in colonial times must have found
the environment considerably healthier than that which they left behind in
Europe.
“When English people emigrated
to the American colonies, men swiftly climbed to five foot eight, becoming the
tallest men in the world. By the end of
the eighteenth century, American apprentices at age sixteen stood almost five
inches taller than poor sixteen-year-olds in London.”
However, the current data on height suggests that the
United States is no longer considered a particularly healthy place in which to
watch your children grow.
“In both the United States and
Europe, the average height dipped in the first half of the nineteenth
century. But then, starting around 1870….people
in both Europe and the United States started getting taller. Over the next century, Americans grew by
about three extra inches on average, hitting a plateau in the 1990s. In Europe, the boom was even more
dramatic. With each succeeding decade,
Europeans added about half an inch of average height, and kept growing that way
into the twenty-first century. Northern
and central European countries were the first to begin this ascent, but the
southern regions started catching up by the mid-1900s. Today, Latvian women have become the tallest
women in the world, jumping from about five foot one to five foot seven. Dutch men rose from five foot seven in 1860
to just over six feet tall, making them the tallest men on Earth.”
Just a few years ago data such as these became available
for most of the countries of the world.
One can peruse data on people born from 1896 to 1996. National ranking for both genders can be
found here. Line plots providing more detailed
information over that period are available here
for average height in each country.
US women born in 1896 ranked fourth in average height
behind Sweden, Norway, and Iceland. US
women are now ranked forty-second in the world.
Latvian women headed in the opposite direction, going from twenty-eighth
to first. US men born in 1896 ranked
third behind Sweden and Norway. US men
are now ranked thirty-seventh. Men from
the Netherlands moved up from twelfth to first.
If one believes that height data is a measure of the “quality”
of the society which produces it, then there are significant political
implications. Jacob S. Hacker and Paul Pierson
addressed those political issues in American Amnesia: How the War on Government Led Us to Forget What Made America Prosper.
“Height has a lot to do with
genes, but height differences across nations seem to be caused mostly by social
conditions, such as income, nutrition, health coverage, and social
cohesion. Indeed, one reason for the
correlation between height and achievement is that kids whose mothers are
healthy during pregnancy and grow up with sufficient food, medical care, and
family support tend to be taller adults.”
“So it’s striking that Americans
are no longer the tallest people in the world.
Not even close: Once three inches taller than residents of the old
world, Americans are now three inches shorter.
The average Dutch height for men is six foot one, and for women, five
foot eight—versus five foot nine for American men and five foot five for
American women. The gap is not, as might
be supposed, a result of immigration: White, native born Americans who speak
English at home are significantly smaller, too, and immigration isn’t
substantial enough to explain the discrepancy in any case.”
These authors then add an even more troubling aspect to
the height data: it is mostly our current young who are losing ground to other
nations.
“….average heights have barely
budged in recent decades, so young Americans—again, even leaving out recent
immigrants—are barely taller than their parents. Older Americans are roughly on a par with
their counterparts abroad; younger Americans are substantially shorter. The United States is the richest populous
nation in the world. Nevertheless, its
young are roughly as tall as the young in Portugal, which has a per capita
gross domestic product (GDP) less than half ours.”
Our professional basketball teams—where height is
critical— have long been dominated by black athletes. The number of US whites making it into
professional ball dropped significantly as black athletes gained greater access
to improved training methods and high-level competition. A new trend has emerged recently that has
seen an influx of good white players.
Where are they coming from?
Mostly, they are coming from those taller, healthier European nations.
So much for a brief diversion into sports. As for the political implications, make of
the data what you wish, but at least the Europeans are finally catching up to
the Gravettians of thirty thousand years ago.
We are unlikely to ever get there.
The interested reader might find the following article
informative:
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