Humans are growing taller around the world, but how tall could humans get in the future?
- So I'm 5'8", which is quite tall for the UK but is completely average in the Netherlands. And I always wondered if I'm tall just because I'm Dutch. I got a surprising answer from Dr. Eirini Marouli.
EIRINI MAROULI: Genetics in action. Humans are actually growing taller at the record speed if you like. So they have increased quite a lot in the last two centuries. And that's a matter of fact across the globe actually.
So for males between around 160 centimeters to 117, for females, from 150 to 160. In total, we can say that the average adult today is around 5% taller than their ancestors used to be 100 years ago.
- The incredibly steep rise in height is generally thought to be driven by better health and diet standards. But in Holland, where a 20 centimeter increase has been recorded in the last 200 years, something a little extra may be going on.
EIRINI MAROULI: That growth is a very good example of human evolution in action. An average height women had higher fertility compared to both shorter and taller women. And that taller men have higher fertility compared to the shorter men.
- Does that mean we'll keep getting taller forever?
EIRINI MAROULI: At the moment, Latvian women and Dutch men are supposed to be the tallest individuals on the planet, that they could be actually representing the limit that we could reach. The differences in average height are due to genes. And these are also different depending on the population that we are talking about, but also different also environments, lifestyle, and improvement in health and socioeconomic status. Actually, it's a combination of both. So height could have actually reached its limit. But only time can tell. And I would say it's a wait-and-see game.
- This all begs the question, why are scientists so interested in studying height in the first place?
EIRINI MAROULI: Height is a model trait for all the rest of the complex genetic traits because it's very easy to measure. So if we could master the genetics of a complex trait like height, that might give us actually the blueprint to start the other multifactorial disorders such as diabetes, heart disease, and so on. In the most recent published study from the [INAUDIBLE] consortium, we have identified a bit more than 3,000 genetic variations, genetic modifications, DNA changes that affect human height.
And if you had this genetic change, it could actually increase your height by up to two centimeters. Many of these DNA changes are also located in or close to genes that are involved in bone biology and skeletal growth. And some also [INAUDIBLE] biological processes that modulate actually height because it's quite interesting how we go from a small baby to an adult with an increased height. That's one of the very interesting and complex questions that we haven't completely answered up to now.
And identifying a gene that is located in the pathway, for example, of growth factors in the blood, that can lead quite a lot of new insights into therapeutic strategies to treat growth failure that effect, let's say, 3% to 5% of the population. And that could also inform treatment for other common diseases. So that's quite important.