European males are on average 11 centimeters taller now than they were in the 1870s, which is quite a lot by all means. Everybody makes fun of Napoleon for being short, but as a matter of fact even he was actually standing above average height. But even by European standards,the Dutch are really tall! What have they been eating that makes them this tall? The average Dutchman now stands over six feet tall, and while the rest of the world seems to have stabilized their height,, they’re still riding a growing trendline. The answer may actually be evolutionary – the tall Dutchmen have more babies.
The average male height in the Netherlands has increased by 20 cm (eight inches) in the last 150 years, according to military records. By comparison, the height of the average American man has risen a mere six centimetres over the same period.
Dr. Gert Stulp, who unsurprisingly stands 6 feet and 7″ tall, studies why his fellow countrymen are the tallest on the planet. Not content with previous explanations like better food and access to medical care (it’s not quite exclusive to Holland), Stulp marched on an ambitious project in which he mined the LifeLines database. This is a sophisticated database with loads of records on Dutch families, including genetic and medical profiles. He focused on 42,612 men and women over age 45, and filtered the results by height and number of children given birth. This simple query reveals that taller men had more children.
Among those born in the early 1950s, for example, men who were 5 feet 6 inches had on average 2.15 children. Men who were 6 feet 1 inch had 2.39 children. And this trend has persisted for more than 35 years. This, of course, makes sense. Taller people make babies that grow to be tall and short people make short kids. It’s widely known that women favor taller partners, but this again is something that the whole world can relate to, not just the Netherlands. So, are Dutch women particularly biased? Are taller couples more sexually active, so they make more kids thus proliferating a skyhigh lineage? Clearly, this is far from settled. However, the evidence thus far does indeed seem to point towards a sexual selection explanation. Dr. Stulp and colleagues are now probing the records further analyzing the heights of parents and their children in the Netherlands.
“Height is very heritable – taller parents tend to have somewhat taller children than shorter parents,” Stulp said. “Because taller individuals would have more offspring in the next generation who would be taller, the average height in that generation would a bit taller on average than the preceding generation, if all else is equal.”
Stulp is also careful to highlight that by no means this is an absolute trend. For instance, he points out that shorter women and men of average height make the most productive pair as far as child bearing is concerned, hence height is definitely a cultural preference.
“There is much variation in what men and women want,” he said. “When it comes to choosing a mate, height tends to have (only) a small effect, which is not very surprising given the many other, more important, traits people value in their mate.”
Perhaps, the biggest takeaway we should all take from this is that evolution is a permanent work in progress. Even for us humans, it’s happening right now. With each generation, we adapt to an ever changing world. Our success depends on adapting at pace with the rate of change.