Dutch people haven’t always been the tallest in the world. In fact in the mid-18th century Dutch military men were on average 165 cm tall; shorter than their European neighbours and men in the US. But over the last 150 years the height of Dutch men has shot up by 20 cm, overtaking that of Americans who have only grown by 6cm over the same time.
The impressive growth spurt in Dutch height has been attributed to nutrition and improvements in living standards. However, the researchers behind this study say that environmental factors don’t explain the whole story. They say their results show that natural selection might be favouring tall men in the Netherlands.
The team behind the study delved through records on a Dutch database and discovered a link between height and reproduction. The database holds records of more than 94,500 people who lived in the northern Netherlands from 1935 to 1967 and revealed that tall Dutch men and average height Dutch women had the most children, passing their tall genes on and driving Dutch people to taller heights.
The team found that taller men and women both tended to form partnerships later in life than their shorter counterparts, limiting the number of years they spent having children. For tall men, despite this later start in fathering children, they still on average had more children than shorter men. Tall women were more reproductively successful, having more children than short women. However, average height women came out on top, probably because they started having children sooner than tall women.
The team say although the data revealed that the size of the effect of height on fertility is small, it is stronger in men than in women. They add that the correlation in height and fertility could be caused by a combination of environmental and genetic factors but that together natural selection and good environmental conditions explain why the Dutch are so tall.