What if I told you that for over 4,000 years, ancient Europeans were consuming cheese, milk, and other dairy products—yet their bodies couldn’t properly digest it?
This shocking revelation comes from groundbreaking new research that shows how ancient European farmers were eating dairy before they had the genetic tools to properly digest it.
It’s a fascinating insight into the complex relationship between culture, diet, and genetics.
For thousands of years, humans lived primarily as hunter-gatherers, without the ability to tolerate lactose, the sugar found in dairy.
But as farming took hold, dairy became a dietary staple in many cultures—despite the fact that their bodies had yet to adapt to digesting it.
And now, scientists have uncovered DNA evidence revealing that the ability to digest dairy didn’t appear as early as previously thought.
In fact, early European farmers may have been suffering from the digestive discomfort of dairy consumption long before they had the genetic mutation that allowed them to properly process lactose.
Dairy Eaters with Stomachs That Couldn’t Tolerate It
The new research sheds light on an intriguing piece of human history: the slow genetic shift that allowed certain populations to develop the ability to digest lactose.
While it’s well-known that many populations evolved the genetic mutation for lactose tolerance after they switched to farming, the timeline of this shift has always been uncertain.
Historically, scientists believed that lactose tolerance must have evolved around 7,000 years ago, when humans first began making cheese.
This assumption made sense because cheese-making, which involves fermenting milk to remove much of the lactose, would have allowed early Europeans to consume dairy without the uncomfortable side effects of bloating, diarrhea, and cramping.
But new DNA evidence, published in Nature Communications, has flipped that assumption on its head.
The study analyzed DNA from 13 human skulls ranging from 5,700 BC to 800 BC—covering a huge span of time in early European history.
The findings show that lactose tolerance didn’t appear until about 3,000 years ago, much later than previously thought.
In other words, for a solid 4,000 years, ancient Europeans were consuming dairy that was likely making them sick.
Yet, they continued to eat it—suggesting that the cultural importance of dairy may have outweighed the unpleasant physical effects for these early farmers.
Why Did It Take So Long to Adapt?
The results of this study challenge the conventional timeline that had linked the development of dairy farming with the rise of lactose tolerance.
According to Daniel Bradley, one of the co-authors of the study from Trinity College Dublin, the relationship between cultural and genetic evolution is more complex than we realized.
“The genomes do seem to shift as new technologies come about,” Bradley said in an interview with Rachel Feltman of the Washington Post.
“You can’t look at this and think that farming and metallurgy are technologies that come into the culture by osmosis.
They come with people. Genomes and technology migrate together.”
So, what exactly does this mean?
It suggests that while early Europeans began dairy farming and milk consumption early on, the genetic adaptation to digest lactose wasn’t a given.
Early farmers may have eaten dairy not because it was easily digestible, but because it was a cultural necessity—a vital food source that, despite its digestive challenges, helped support growing populations in a world that was rapidly shifting from hunting and gathering to agriculture.
Using Cutting-Edge DNA Technology
While the findings themselves are groundbreaking, the method by which the researchers obtained this information is just as impressive.
The study used cutting-edge DNA extraction techniques to analyze the remains of ancient humans from these early farming societies.
In a typical archaeological study, DNA recovery from ancient bones is often limited, with researchers able to extract only small fragments of genetic material.
However, this research team took a different approach, extracting genetic material from the densest bone in the human body: the inner ear bone.
This bone, known as the petrous bone, is much less likely to degrade over thousands of years, allowing scientists to recover far more DNA than they normally would.
In fact, the scientists were able to recover 40 to 87 percent of each individual’s genetic information, far exceeding the typical 1 percent of DNA that most bone samples provide.
As Rachel Feltman of the Washington Post explains, the inner ear bone “holds up better over time than other bones, meaning it offers a much higher percentage of usable DNA for researchers.”
This breakthrough enabled the team to trace the genetic changes that corresponded to the rise of dairy consumption—changes that, surprisingly, didn’t appear until long after dairy farming had already taken root.
Why Did Humans Continue Eating Dairy?
If ancient Europeans were consuming dairy that likely made them sick, why did they continue doing so for so long?
This is a question that many researchers are now exploring.
One theory is that the cultural importance of dairy may have far outweighed the immediate health consequences for early Europeans.
Dairy farming was a critical step in the shift from hunter-gatherer societies to agricultural ones.
It provided a reliable source of food that could sustain large populations in a way that hunting and gathering could not.
Cheese and milk were vital sources of protein and fat, and they could be stored and preserved more easily than other food sources.
For ancient Europeans, dairy was not just a food, it was a key part of their economic and social systems.
In societies where farming was becoming increasingly important, the idea of abandoning dairy would have been nearly impossible, despite the digestive discomfort it caused.
In a sense, these early farmers may have sacrificed their comfort for survival.
How Did the Mutation Spread?
The real surprise of this study lies in how long it took for lactase persistence (the ability to digest lactose) to develop across populations.
Lactase persistence is a genetic trait that allows individuals to digest lactose beyond childhood.
For most mammals, including early humans, the ability to digest lactose fades after infancy, but in some populations, the gene that allows adults to digest milk stayed active.
This genetic trait didn’t spread uniformly across Europe.
Instead, it was strongly influenced by the cultural practices of dairy farming. In regions where dairy was heavily integrated into daily life, natural selection likely favored individuals who could tolerate lactose, as they would have had a dietary advantage.
Over time, the frequency of the lactose-tolerant gene increased in these populations.
But it wasn’t until about 3,000 years ago that this mutation became common in the population—long after dairy had already been introduced into their diets.
This delay raises interesting questions about the role of cultural practices in shaping our genetic evolution.
Looking Forward
This new research sheds light not just on the ancient relationship between farming and genetics, but also on the dynamic evolution of our species.
The process of adapting to new diets—whether through changes in farming techniques, technological advances, or the development of genetic mutations—is far more complex than we ever imagined.
As researchers continue to uncover more DNA from ancient populations, we’ll likely learn even more about how early humans navigated the challenging transition from hunting and gathering to agriculture.
And as we learn more about how these ancient populations adapted to their environment, we gain greater insights into how modern humans are still evolving today.
One thing is clear: Our genetics are far more influenced by culture and environment than we may have ever realized.
Food, as it turns out, is not just fuel for our bodies—it is a fundamental force driving our genetic evolution.
A Fascinating Chapter in Human Evolution
The discovery that ancient Europeans were consuming dairy before they had the ability to digest it is both a fascinating and important piece of the puzzle in understanding our evolutionary journey.
It challenges the notion that cultural shifts in diet and lifestyle immediately result in genetic adaptations.
Instead, it shows how our ancestors’ resilience and innovative practices sometimes took years, even millennia, to reflect in their genetic makeup.
By piecing together these genetic clues, we are not only uncovering the dietary habits of early humans—we’re also unraveling the complex history of how human societies evolve, adapt, and thrive over time.
The next time you enjoy a glass of milk or a slice of cheese, remember: it took us thousands of years to get here, and our ancestors were willing to brave the discomfort of dairy for far longer than we might expect.
