AMSTERDAM—Insecure about your height? You may want to avoid this tiny country by the North Sea, whose population has gained an impressive 20 centimeters in the past 150 years and is now officially the tallest on the planet. Scientists chalk up most of that increase to rising wealth, a rich diet, and good health care, but a new study suggests something else is going on as well: The Dutch growth spurt may be an example of human evolution in action.
The study, published online today in the Proceedings of the Royal Society B, shows that tall Dutch men on average have more children than their shorter counterparts, and that more of their children survive. That suggests genes that help make people tall are becoming more frequent among the Dutch, says behavioral biologist and lead author Gert Stulp of the London School of Hygiene & Tropical Medicine.
"This study drives home the message that the human population is still subject to natural selection," says Stephen Stearns, an evolutionary biologist at Yale University who wasn't involved in the study. "It strikes at the core of our understanding of human nature, and how malleable it is." It also confirms what Stearns knows from personal experience about the population in the northern Netherlands, where the study took place: "Boy, they are tall."
For many years, the U.S. population was the tallest in the world. In the 18th century, American men were 5 to 8 centimeters taller than those in the Netherlands. Today, Americans are the fattest, but they lost the race for height to northern Europeans—including Danes, Norwegians, Swedes, and Estonians—sometime in the 20th century.
Just how these peoples became so tall isn't clear, however. Genetics has an important effect on body height: Scientists have found at least 180 genes that influence how tall you become. Each one has only a small effect, but together, they may explain up to 80% of the variation in height within a population. Yet environmental factors play a huge role as well. The children of Japanese immigrants to Hawaii, for instance, grew much taller than their parents. Scientists assume that a diet rich in milk and meat played a major role.
The Dutch have become so much taller in such a short period that scientists chalk most of it up to their changing environment. As the Netherlands developed, it became one of the world's largest producers and consumers of cheese and milk. An increasingly egalitarian distribution of wealth and universal access to health care may also have helped.
Still, scientists wonder whether natural selection has played a role as well. For men, being tall is associated with better health, attractiveness to the opposite sex, a better education, and higher income—all of which could lead to more reproductive success, Stulp says.
Yet studies in the United States don't show this. Stulp's own research among Wisconsinites born between 1937 and 1940, for instance, showed that average-sized men had more children than shorter and taller men, and shorter women had more children than those of average height. Taken together, Stulp says, this suggests natural selection in the United States pulls in the opposite direction of environmental factors like diet, making people shorter instead of taller. That may explain why the growth in average American height has leveled off.
Stulp—who says his towering 2-meter frame did not influence his research interest—wondered if the same was true in his native country. To find out, he and his colleagues turned to a database tracking key life data for almost 100,000 people in the country's three northern provinces. The researchers included only people over 45 who were born in the Netherlands to Dutch-born parents. This way, they had a relatively accurate number of total children per subject (most people stop having children after 45) and they also avoided the effects of immigration.
In the remaining sample of 42,616 people, taller men had more children on average, despite the fact that they had their first child at a higher age. The effect was small—an extra 0.24 children at most for taller men—but highly significant. (Taller men also had a smaller chance of remaining childless, and a higher chance of having a partner.) The same effect wasn't seen in women, who had the highest reproductive success when they were of average height. The study suggests this may be because taller women had a smaller chance of finding a mate, while shorter women were at higher risk of losing a child.
Because tall men are likely to pass on the genes that made them tall, the outcome suggests that—in contrast to Americans—the Dutch population is evolving to become taller, Stulp says. "This is not what we've seen in other studies—that's what makes it exciting," says evolutionary biologist Simon Verhulst of the University of Groningen in the Netherlands, who was Stulp's Ph.D. adviser but wasn't involved in the current study. Verhulst points out that the team can't be certain that genes involved in height are actually becoming more frequent, however, as the authors acknowledge.
The study suggests that sexual selection is at work in the Dutch population, Stearns says: Dutch women may prefer taller men because they expect them to have more resources to invest in their children. But there are also other possibilities. It could be that taller men are more resistant to disease, Stearns says, or that they are more likely to divorce and start a second family. "It will be a difficult question to answer.”
Another question is why tall men in Holland are at a reproductive advantage but those in the United States are not. Stulp says he can only speculate. One reason may be that humans often choose a partner who's not much shorter or taller than they are themselves. Because shorter women in the United States have more children, tall men may do worse than those of average height because they're less likely to partner with a short woman.
In the end, Stearns says, the advantage of tall Dutchmen may be only temporary. Often in evolution, natural selection will favor one trend for a number of generations, followed by a stabilization or even a return to the opposite trend. In the United States, selection for height appears to have occurred several centuries ago, leading to taller men, and then it stopped. "Perhaps the Dutch caught up and actually overshot the American men," he says.
Australia Prime Minister Advisor Says Global Warming is a United Nations Hoax to Create New World Order
Maurice Newman, the Australian PM's business adviser
rt.com
The Australian prime minister’s chief business adviser says that climate change is a ruse led by the United Nations to create a new world order under the agency’s control. The statement coincided with a visit from the UN’s top climate negotiator.
Maurice Newman, chairman of Prime Minister Tony Abbott’s business advisory council, said the UN is using false models which show sustained temperature increases because it wants to end democracy and impose authoritarian rule.“It’s a well-kept secret, but 95 percent of the climate models we are told prove the link between human CO2 emissions and catastrophic global warming have been found, after nearly two decades of temperature stasis, to be in error,” he wrote in an opinion piece published in The Australian newspaper on Friday, without providing evidence.
“The real agenda is concentrated political authority. Global warming is the hook,” he said, adding that the UN is against capitalism and freedom and wants to create a “new world order.”
The adviser’s inflammatory comments coincided with a visit from UN climate chief Christiana Figueres.
According to Newman, Figueres is “on record saying democracy is a poor political system for fighting global warming. Communist China, she says, is the best model.”
Figueres was in Australia to discuss practical climate change action, urging the country to move away from heavily polluting coal production. She also urged Australia to play a leading role at the climate summit in Paris in December.
But that call is unlikely to be heeded. During November’s G20 meeting in Brisbane, Abbott warned that the Paris summit would fail if world leaders decided prioritize the cutting of carbon emissions over economic growth.
Abbott, who called the science behind climate change “crap” in 2009, also repealed a tax on carbon pricing and abolished the independent Climate Commission advisory body in Australia.
The prime minister has been reluctant to take part in climate change politics, trying but failing to keep it off the agenda at last year’s G20 summit.
Both Abbott’s office and the United Nations have so far declined to comment on Newman’s statements.
A well-known climate change skeptic, Newman has made similar provocative comments in the past, calling the notion a “myth” and a “delusion.”
In February, he criticized renewable energy policies. Citing British charity Age UK, he stated that elderly citizens in Britain often die of “winter deaths” because they can’t afford power. He blamed renewable energy policies which drive up the price of energy.
However, when asked about his claim by The Guardian, the charity sent back a statement which referenced high energy costs, but failed to mention anything about renewable energy.
Just a few months earlier, in November 2014, Newman cited a Scottish government-commissioned study which allegedly said that for every job in the renewable sector, 3.7 jobs were lost elsewhere.
However, the report itself made no mention that it was commissioned by the government. In fact, the government called the study “misleading,” adding that the industry would actually have the opposite effect on jobs.
According to the UN’s Intergovernmental Panel on Climate Change, the global mean temperature could rise by up to 4.8° Celsius (40.6° Fahrenheit) this century alone. The prediction is seen as a recipe for droughts, floods and rising seas.