For decades, scientists assumed that the first modern humans to arrive in Europe, around 45,000 years ago, quickly evolved pale skin to adapt to the region’s dim sunlight. The logic seemed straightforward: lighter skin allows more ultraviolet light to penetrate, helping the body produce vitamin D, a nutrient essential for human health.

However, a new study of ancient DNA challenges this long-held assumption. By analyzing the genomes of 348 individuals who lived between 45,000 and 1,700 years ago, researchers have uncovered a surprising truth: for most of Europe’s history, the majority of its inhabitants had dark skin. Only around 3,000 years ago did lighter skin tones become dominant.

Dark-Skinned Europe

Skin color is one of the most visible traits in humans, but its evolution has been shrouded in mystery. Early humans in Africa likely had dark skin, which protected them from the intense ultraviolet (UV) radiation of the equator. As humans migrated north into Europe and Asia through the Levant, where UV levels were lower, lighter skin became advantageous. This allowed for more efficient production of vitamin D, which is important for bone health.

But the new study reveals that this transition was anything but straightforward. Even well into the Copper and Iron Ages, around 5,000 to 3,000 years ago, half of the individuals analyzed still had dark or intermediate skin tones.

A 2023 study found that Ötzi, the famous ancient glacier mummy who lived 5,300 years ago before succumbing to a violent death in the Alps, was dark-skinned. His skin color was genetically determined to be darker than modern South Europeans but lighter than modern Sub-Saharan Africans.

“It’s the darkest skin tone that has been recorded in contemporary European individuals,” anthropologist Albert Zink, study co-author and head of the Eurac Research Institute for Mummy Studies in Bolzano explained at the time when the Ötzi DNA study was released.

Earlier, in 2018, when scientists sequenced the DNA extracted from Britain’s oldest complete skeleton, a 10,000-year-old male known as the Cheddar Man, they were stunned to find the man had dark-brown skin and blue eyes.

For much of the tens of thousands of years covered by the sampled DNA in the new study led by Guido Barbujani at the University of Ferrara in Italy, 63% of ancient Europeans had dark skin, while only 8% had pale skin. The remaining individuals fell somewhere in between. These findings are based on DNA extracted from bones and teeth, combined with advanced forensic techniques that predict skin, eye, and hair color from genetic markers.

The researchers used a sophisticated probabilistic method to estimate pigmentation traits from ancient DNA, which is often fragmented and degraded. They tested their approach on two high-coverage ancient genomes: Ust’-Ishim, a 45,000-year-old man from Siberia, and SF12, a 9,000-year-old individual from Sweden. By downsampling the data to simulate lower coverage, they found that their method could reliably predict pigmentation traits even with very limited genetic information.

A Slow March to Lighter Skin

The first signs of lighter pigmentation appeared in the Mesolithic, around 14,000 to 4,000 years ago, with a few individuals in Sweden and France showing light skin and blue eyes. By the Bronze Age (7,000 to 3,000 years ago), the proportion of dark-skinned individuals had dropped to about half. It wasn’t until the Iron Age (3,000 to 1,700 years ago) that lighter skin tones began to dominate.

But the real turning point came with the spread of Neolithic farmers from Anatolia around 10,000 years ago. These early agriculturalists carried genes for lighter skin, which likely gave them an evolutionary advantage in the less sunny climates of Europe. Over time, their genes spread, but the process was slow and uneven.

However, they also found that localized processes of migration and admixture played a significant role. In some regions, dark skin persisted for thousands of years longer than in others.

The study also uncovered intriguing patterns in eye and hair color. Light eyes peaked in frequency during the Mesolithic, long before lighter skin became common. While dark hair remained the norm for most of prehistory, the first instances of blonde and red hair appeared in the Neolithic and Bronze Age.

Why Did Skin Color Change?

The question remains: why did lighter skin become more common in Europe? The traditional explanation—that pale skin evolved to maximize vitamin D production in low-light environments—may not tell the whole story. Jablonski suggests that dietary changes played a crucial role. Instead, dietary changes may have played a key role.

As humans transitioned from small, nomadic groups to larger, agricultural communities, their diets shifted. They relied less on vitamin D-rich wild game and more on cultivated crops, which lacked the vitamin. This change, combined with the need to absorb more sunlight in northern latitudes, may have driven the evolution of lighter skin.

The Neolithic expansion and the massive waves of migration further east out of Anatolia may have contributed greatly to Europe’s transition to pale skin through the mixture of populations.

What about Neanderthals who occupied Europe for tens of thousands of years before modern humans came into the picture? Interestingly, the study confirms that modern Europeans did not inherit pale skin from Neanderthals. Previous research has shown that the two groups interbred, but the genetic evidence suggests that lighter skin evolved independently in modern humans.

The study also sheds light on specific genes that played a key role in the evolution of pigmentation. For example, the researchers identified two variants in the genes TYR and SLC24A5 that are strongly associated with lighter skin. These variants were absent in the Paleolithic Ust’-Ishim man but present in a Bronze Age individual from Hungary, who had light skin, blue eyes, and blonde hair.

While DNA provides the most direct evidence of ancient skin color, researchers have also looked to art for clues. Ancient Egyptian artworks, for example, often depict women with lighter skin than men. However, relying too heavily on artistic representations can be a trap.

In the end, the story of human skin color is not just about biology—it’s about the journeys our ancestors took, the environments they adapted to, and the genetic legacy they left behind. And thanks to ancient DNA, we can now begin to unravel that story, one genome at a time.

The findings appeared in the pre-print server bioRxiv.