"Drink plenty of milk; it will make you grow healthy and strong, and it will also strengthen your bones." How many times have we heard this phrase as children, repeated by parents or grandparents like a veritable daily mantra. Well, that was advice, often overlooked, that today finds considerable scientific support. All this because behind that glass of milk lies an evolutionary story that has literally changed the human body. An international team of researchers has published a study in PNAS, in which they argue that drinking raw milk contributed to the growth and size of our ancestors in northern and central Europe.
The Link Between Milk, DNA and Height
Scholars analyzed over 3,500 skeletons from 366 archaeological sites belonging to people who lived over a period of 25,000 years. The goal was to understand how humans have changed over time in height and body mass in different regions of the world. The discovery was crucial: in Central and Northern Europe, the increase in height coincides with the spread of a particular genetic mutation, the one that allows us to digest lactose as adults.
In this part of the world, essentially, the persistence of lactase (the enzyme that allows us to digest milk into adulthood) led researchers to believe there was a connection with people's height. Essentially, height and body mass began to rise in sync with the expansion of genetic variants that allow lactase persistence. Thus, the genetic ability to digest milk acted as a biological "accelerator," promoting a new push towards body growth.
Researchers believe this mechanism may also be present elsewhere, such as among the Maasai of East Africa, known for their tall stature and traditional milk consumption. However, there is not yet enough data to confirm this global extension of the effect.
A "Liquid" Legacy" Left to Us By Our Ancestors
In short, if we have to draw conclusions regarding the interpretation of this study, we can say that there is a narrative beauty in this discovery. Populations that colonized the coldest or most difficult territories made milk one of their staple foods. "Abusing it," so to speak, led to a completely improvised and unexpected evolutionary strategy. Those with genetic variants for digesting lactose had a clear advantage: more energy, faster growth, and a greater chance of survival and reproduction.
Today, this legacy is evident in ourselves, too, and we see it in the average height differences between regions and countries. The human body is not a simple machine: genetics, diet, environment, pathologies, migration, and culture are intertwined. But seeing how a food like milk has impacted human physical evolution makes the dialogue between biology and popular culture tangible.
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