The question of how the Dutch grew so tall has been hotly discussed in recent years. From changes in health and nutrition to natural selection tendencies in favour of taller partners, many explanations are currently in circulation.

Now a new analysis published in the online journal eLife, and overseen by researchers at Imperial College London, provides one of the most thorough overviews of human height in the last 100 years, offering clarification as well as some interesting revelations.

A comprehensive new study on height

Entitled "A century of trends in adult human height", and carried out by the NCD Risk Factor Collaboration (NCD-RisC), a worldwide network of health scientists, the project compiles and reanalyses data from 1.472 population-based studies.

As height corresponds with increased longevity, better education and higher earnings, the researchers set about investigating height trends over the last century as an insight into quality of life.

To do this they reviewed height measurement data of more than 18,6 million participants born between 1896 and 1996 across 200 countries. Here are some of their findings.

Dutch men confirmed tallest in the world

The study confirms that Dutch men are indeed the tallest males in the world, growing from an average starting height of 169,4cm in 1914 to 182,5cm in 2014. Originally ranked the 38th tallest nationality (male) in 1914, Dutch men are now ranked number 1.

Latvian women surprisingly lofty

Dutch women, despite undergoing an average height surge from 154,8cm in 1914 to 168,7cm in 2014, did not experience as much of an increase as women in Latvia, who the study recognises as the tallest women in the world with an average height of 169,8cm in 2014.

Similar to Dutch men, in 1914 Dutch women were ranked 38th tallest nationality in the world. In 2014 they now stand in second place after Latvian women.

Countries with biggest height gain

Iran and South Korea proved themselves to be the surprise performers of the study, with interesting tendencies in height increase depending on gender.

Iranian men experienced the greatest average male height surge of 16,5cm, while South Korean women's average height rose an impressive 20,2cm in the last 100 years.

Limited changes in other world regions

Another trend revealed by the study was the plateauing of the average height of the American population in the 1960s and 1970s.

Countries in regions such as South Asia (like Pakistan, India and Bangladesh), experienced smaller height increases of 1 to 6cm. While other countries, such as Sierra Leone and Uganda, actually experienced a decrease in average height since the 1970s.

Differences between countries

The smallest populations for 2014 can be found in East Timor, where men stand at an average height of 159,8cm, and in Guatemala, where women’s average height is 149,4cm.

The study found that the height differential between the tallest and shortest countries has remained the same today as it was 100 years ago, at around 19-20cm. The ranking of the countries, however, has changed constantly, and considerably, across that period.

Countries with tallest men in 2014*

1.	Netherlands (12)
2.	Belgium (33)
3.	Estonia (4)
4.	Latvia (13)
5.	Denmark (9)
6.	Bosnia and Herzegovina (19)
7.	Croatia (22)
8.	Serbia (30)
9.	Iceland (6)
10.	Czech Republic (24)

*1914 rank in brackets

Countries with tallest women in 2014*

1.	Latvia (28)
2.	Netherlands (38)
3.	Estonia (16)
4.	Czech Republic (69)
5.	Serbia (93)
6.	Slovakia (26)
7.	Denmark (11)
8.	Lithuania (41)
9.	Belarus (42)
10.	Ukraine (43)

*1914 rank in brackets