Nutritional "Boost" Making Westerners Taller, Healthier, Expert Says
for National Geographic News
|October 2, 2006|
It's no secret that in the past few centuries people in Western nations have been getting taller and living longer.
But now experts say that today's Westerners are the product of an accelerated spate of growth that is unique in human history.
People in the developed world are taller and more robust than their great, great, great grandparents probably ever imagined.
Robert Fogel, director of the Center for Population Economics at the University of Chicago, notes that Westerners are about 50 percent larger and live more than twice as long as those who lived 250 years ago.
He and other researchers have come to believe this startling boost cannot be attributed solely to advances in medicine or industrialization.
Western societies have certainly benefited from such advances as antibiotics, Fogel says. But the best indication of whether a person lives long and enjoys good health is a person's size.
The taller you are, the longer you'll live, Fogel believes. And the reasons for this, he and others suggest, go back to the womb.
Studies of Norwegian men in the 1960s found that taller men were more likely to survive longer. A 68-inch-tall (172-centimeter-tall) man, for example, was 50 percent more likely to die earlier than a 73-inch-tall (185-centimeter-tall) man was.
Intrigued by these studies, Fogel joined forces with economist Dora Costa, of the Massachusetts Institute of Technology in Cambridge, more than a decade ago.
Together they began comparing the records of U.S. Army veterans whose mean birth year was 1837 with those of veterans who were born in the early 1920s.
In both populations they found shorter men were more susceptible to chronic diseases.
Fogel thinks the explanation for this lies in fetal development. Babies with low birth weights tend to be smaller and more prone to illness as adults, he says.
David Barker, a professor of epidemiology at England's University of Southampton, has collaborated on several studies of populations throughout the world.
His research has linked low birth weight to coronary heart disease, chronic renal failure, diabetes, hypertension, and stroke.
"The embryo is very sensitive to the nutrients it's bathed in," Barker said.
He explains that the number of cells your body makes for vital organs is already determined by the time you are born. Stunted growth can have health repercussions throughout a baby's life, he says.
"We've spent the past 20 years of medical research looking at the way the heart is damaged by behaviors of people in their middle livesby what they eat, and how much exercise they take, and if they smoke," Barker said.
"It turns out that isn't the key thing. The key thing is how your heart was made in the first place."
Centuries ago it may have been difficult for pregnant women and their children to get proper nourishment, probably leading to smallerand therefore shorter-livedadults, Fogel says.
Fogel has raised eyebrows by demonstrating how malnourished and sick the ancestors of modern Westerners were in the Old World.
He has pointed out that the quantity and quality of food available to ordinary French and English families from 1700 to 1850 was meager.
In France the daily caloric supply was less than half what it is today. And about 20 percent of England's population in 1790 was so malnourished that they would not have had the energy to do more than walk slowly, Fogel says.
Even in North America, which was comparatively "awash in calories," according to Fogel, people were chronically malnourished, thanks in part to the high rate of infectious diseases.
"Every disease causes a loss of nutrients; it diverts energy from growth," he said.
The woes of earlier Westerners could have implications for how we attempt to thwart chronic disease today, Fogel and his colleagues say.
Barker agrees, arguing that the best thing we can do to prevent chronic disease is look after the health of mothers and their babies in the first two years of life.
"I think that's a bit of a stretch," said Lawrence Appel, a professor of medicine and epidemiology at Johns Hopkins University in Baltimore, Maryland.
Appel says it would be a mistake to ignore the importance of lifestyle influences like diet and exercise throughout a person's life span.
He describes populations in largely primitive societies that aren't exposed to the high levels of salt and fat found in Western diets.
"These populations have a low incidence of hypertension, low incidence of heart disease," he said.
"We don't know much about their [embryonic and fetal] environment. But I would suspect it's not as beneficial [as that of modern Westerners].
"Those are settings where nutrition problems are likely to be prevalent. And despite that, they have a low incidence of disease."
But, Fogel says, it makes sense to think that poorly developed organs may break down earlier than well-developed ones.
Today he is continuing his studies of humans' changing lives and wonders about "human potential."
The Western life expectancy has increased 2.5 years per decade since 1845, and Fogel expects it will continue to do so this century.
As for what heights Westerners might literally reach, "We don't know how tall people can get," he said.
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