Wednesday April 08, 2015

Why are the Dutch so tall? Scientists find new clue to the mystery

Listen 6:19

The Dutch are tall people. How tall? The average man stands 6 feet. The average woman is 5 feet 6 inches. And they've been growing taller at a much quicker rate than in other developed countries.

In the last 150 years, the average height of Dutch men has increased by 8 inches. The average American man has only grown 2.7 inches.

For years, scientists have been trying to figure out why. Now researchers have found evidence that natural selection may be a factor. In other words, in the Netherlands, taller people had more children.

Gert Stulp

Dutch researcher Gert Stulp, who lead the study on height and fertility, is 6 foot 7 inches tall himself. (Photo: London School of Hygiene and Tropical Medicine)

"We found that . . . men that who were taller than average had a higher fertility than those that were shorter," researcher Gert Stulp tells As It Happens host Carol Off. "And we also found that, in women, those of average height had slightly higher fertility."

Stulp and his team at the London School of Hygiene and Tropical Medicine discovered this by mining data from a large database of information about people living in the northern Netherlands from 1935 to 1967.

In the United States, the pattern was strikingly different. It was shorter women and average height men who had the highest fertility.

Stulp himself is Dutch and 6 feet 7 inches tall. But his parents are not especially tall.

"It must be all the milk [I drank]," he says.

Good diet is, in fact, a major factor in the stature of his countrymen.

NETHERLANDS TALLEST PEOPLE

Pieter Gijselaar, 7 feet (210 centimeters) tall, poses for a portrait next to his car in Amsterdam Thursday Sept. 14, 2006. Gijselaar had the seat of his Volkswagen Golf custom fitted, spends much of his life ducking doorways and can only sit in an airliner's emergency exit row. (AP Photo/Peter Dejong) (AP)

"We have also the welfare state and an excellent health care system and we also have low levels of social inequality, which also has been shown to increase a nation's height," he says, "But our study also suggests that, on top of those things, natural selection may also have a role."

There is no concrete explanation for why taller Dutch people have more children. But Stulp has a few guesses.

"One reason might be that, for some reason, Dutch value height a little bit more in their partner," he says. "Height may [also] be associated to variables like health and income a little bit more strongly in the Netherlands or the United States."

He adds the data was controlled for ethnicity.

Asked if Dutch men, like himself, are simply more attractive mates, he demurred.

"Well, I have my own experiences, but it might have something to do with attractiveness indeed."