why did us humans become way taller from 1900 to 1990? Is there a scientific reason to it? Why are we not becoming any taller in recent years?
In: Biology
Improved nutrition. This can be readily seen when comparing ethnic groups whose children were born and raised in wealthy countries with their relatives who are poor and still live in poorer countries where food scarcity is still the norm. The result is a noticeable height difference between very closely related people (first cousins, etc).
The reason we haven’t seen the trend continue is that nutritional availability allows someone to more fully meet their maximum height determined by their genetics, but doesn’t allow you to exceed it. So, especially in countries where food scarcity is uncommon, more people approach their maximum potential height today than they did in 1900.
Nutrition. Nutrition went up, now it’s going down again – although unlikely to go as low as it was as long as we stay in the modern age.
Better access to food and healthcare. Malnourishment results in stunted development. You can still see this in developed countries. Poor people may struggle to fully actualize their “genetic” potential.
As others have stated the answer is nutrition. The availability of fresh and nutritious food in a plentiful amounts has had a positive effect in ensuring more people fulfil their genetic potential in regards to height. That and exercise.
We are beginning to see the current generation begin to shrink in regards to height and this is because of the sheer amount of artificial ingredients in our food. These inhibit young people from reaching their potential height encoded in their genome. While much of the food we currently eat looks and tastes healthy, in actuality it really isn’t.
More specifically than just ‘nutrition’, there were incredible revolutions in fertilizer development in the decades around the [start of the 20th century](https://en.wikipedia.org/wiki/History_of_fertilizer), some of which were invented by Nobel Prize winners. The graph on the wiki page really shows that for much of history, fertilizer use was negligible compared to today and only really started to increase in the 1900’s, especially the 1950’s. The increased amount and quality of fertilizer allowed more humans to have better nutrition during their key growth periods (aka childhood and puberty).
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