For being a fellow of above average height (<6'2" now - age will do that) traveling to Holland can be a strange experience. It seems like everyone is around my height. The men are tall, the women are tall. 

Netherlands has the tallest people in the world. Yet they used to be the shortest.  While everyone got taller during that time, Dutch average height went up 8 inches in two centuries.

Everyone has an explanation for this dramatic change in a relatively short amount of time - better food, for example. The rationale for that is research among Japanese people which found that children of immigrants in Hawaii grew taller than their parents, and better nutrition was listed as the cause, but all of Europe has more food.  

Maybe it is just that tall people marry tall people and have tall kids? 

Credit: Corbis. Link: Daily Mail 

I moved to California from Pittsburgh and, like Holland, there were a lot of big people. Not fat. Big. Even the women had good shoulders. It wasn't just because of nutrition, it was because people from Eastern Europe knew they could get jobs in steel mills and the region became populated by big "mill hunks" who married women from back home. Even if they married someone shorter so much of height is genetic that there was a good chance they would have above average height kids.

We used to be the tallest because of all those physically imposing immigrants, but no more. Holland is out in front, with no steel mills or Croatians. It could be a fortunate confluence of social and biological evolution. Studies show that taller people tend to be healthier, for example, a paper here on Science 2.0 directly linked shorter height to heart disease. If taller people have more health fitness leading to old age, they may have more health fitness at young age. Kids with taller parents may have had lower infant mortality.

A team of researchers set out to try and find out how much of each was involved. Writing in Proceedings of the Royal Society B, their analysis of  94,516 people in north Holland during the years 1935–1967 found that some of it is clearly a biological factor that may not be the same in other countries. Taller men in Holland were more fertile in the post-World War II era.

But was that instead social selection?  Women of average height had the most child survival while taller had more kids. If tall women just have more kids, that isn't really natural selection, even if it is evolution.

In the U.S. I always think it is strange for a tall man to date a really short woman - short women are impacting social selection for short men and tall women, which seems a little selfish. But short people may still have the last laugh; taller people have been shown to age faster.

Citation: Gert Stulp , Louise Barrett , Felix C. Tropf , Melinda Mills, 'Does natural selection favour taller stature among the tallest people on earth?', Proceedings of the Royal Society B 8 April 2015 DOI: 10.1098/rspb.2015.0211