spacerzimmer topbars
spacercz bottombooksarticlestalksblogcontactsearchspacer

Article Archives

[ 2017 ] [ 2016 ] [ 2015 ] [ 2014 ]
[ 2013 ] [ 2012 ] [ 2011 ] [ 2010 ]
[ 2009 ] [ 2008 ] [ 2007 ] [ 2006 ]
[ 2005 ] [ 2004 ] [ 2003 ] [ 2002 ]
[ 2001 ] [ 2000 ] [ 1999 ] [ 1998 ]



Natural Selection May Help Account for Dutch Height Advantage
New York Times, April 9, 2015

Gert Stulp stands 6 feet, 7 inches tall. His height makes him especially self-conscious at scientific conferences when he rises to describe his research as a demographer at the London School of Tropical Medicine. “It’s always quite embarrassing,” he said.

Dr. Stulp, who is Dutch, studies why his fellow citizens are so tall.

Today, the Dutch are on average the tallest people on the planet. Just 150 years ago, they were relatively short. In 1860, the average Dutch soldier in the Netherlands was just 5 feet 5 inches. American men were 2.7 inches taller.

Since 1860, average heights have increased in many parts of the world, but no people have shot up like the Dutch. The average Dutchman now stands over six feet tall. And while the growth spurt in the United States has stopped in recent years, the Dutch continue to get taller.

For years, scientists have sought to understand why average height has increased, and why the Dutch in particular have grown so quickly. Among other factors, the Dutch have a better diet than in the past, and they also have better medical care. But now Dr. Stulp and his colleagues have found evidence suggesting that evolution itself is also helping to make them taller.

The new study, published on Tuesday in Proceedings of the Royal Society B: Biological Sciences, was made possible thanks to a major medical database recently established in the Netherlands called LifeLines. The database contains a vast amount of information, including genetic profiles and medical records, about tens of thousands of Dutch families.

Dr. Stulp and his colleagues analyzed data on 42,612 men and women over age 45, looking at the height of their subjects and how many children they had. Dutch men who were taller than average had more children than those of average or lower than average height, the researchers found.

Among those born in the early 1950s, for example, men who were 5 feet 6 inches had on average 2.15 children. Men who were 6 feet 1 inch had 2.39 children. The scientists found that the trend toward taller men having more children persisted for more than 35 years.

Among women, the pattern was more complex. Over all, Dutch women of average height had the most children. But that was because taller women tended to take longer to become mothers. Once they entered their childbearing years, taller mothers had children at a faster rate than shorter women.

“I was not expecting to find these patterns,” said Dr. Stulp. “The Dutch really seem to be different.”

It is possible that an environmental factor caused some Dutch people both to grow tall and to have more children, Dr. Stulp said. Wealthier Dutch people could end up taller and with more children, for example.

But when Dr. Stulp and his colleagues controlled for how rich their subjects were, the link between height and children persisted. It also remained when they tried factoring out other variables, like education.

Dr. Stulp therefore suspects that genes are involved. Under identical conditions, some people will grow taller than others because they carry certain genetic variations.

How tall people are can influence their health. Earlier this week, for example, an international group of scientists linked genes controlling height to increased protection from cardiovascular disease: Shorter people, the researchers concluded, are more susceptible to heart attacks than taller people.

But Dr. Stulp doesn’t think that this can explain why Dutch people are rising to greater heights. Dr. Stulp and his colleagues are now gathering more data, analyzing the heights of parents and their children in the Netherlands. He hopes to determine how much of increase in height is a result of natural selection.

In recent years, other researchers have documented the evolution of height in a few human populations. Intriguingly, their results run contrary to the Dutch results. For example, Diddahally Govindaraju, an evolutionary geneticist at Albert Einstein College of Medicine and his colleagues have found that women in Massachusetts are getting shorter, not taller.

Dr. Govindaraju said it was too early to speculate on why some populations are evolving in different ways. What matters for now is that scientists are able to find these differences at all.

“Evolution happens differently in different environments,” said Dr. Govindaraju. “It’s wonderful to see them demonstrate that on humans.”

Copyright 2015 The New York Times Company. Reproduced with permission.
Content Management Powered by CuteNews