With regard to height:
For centuries, Americans were the NBA players of the world. We were two inches taller than the Red Coats we squared off against in the American Revolution. In 1850, Americans had about two and a half inches on people from every European country. But our stature plateaued after World War II, and since then, other countries shot past us. White Americans have grown a bit taller since the early 1980s, but African Americans haven’t.
And the tallest in the world?
[T]he Dutch are the tallest, at an average of six feet for men and five-foot-seven for women. They’ve come a long way: In 1848, a quarter of Dutch men were rejected from military service because they didn’t meet the five-foot-two height limit. “Today, fewer than one in 1,000 is that short,” the Associated Press noted in 2006. (The tallest people on record, though, are apparently the people of the Dinaric Alps, in the former Yugoslavia, where adolescent males are, on average, six-foot-one monoliths.)
The Danes, Norwegians, and Germans stack up right under the Dutch. American men and women, meanwhile, measure just 5’9″ and 5’4″, respectively, barely edging out the Southern Europeans.