Ancient Human Skulls Reveal When Europeans Could Drink Milk

A Late Bronze Age burial from the site of Ludas-Varjú-dulo, Hungary dated to about 1200 B.C. This individual marks the onset of lactose tolerance in the region.

(Image credit: Janos Dani (Deri Museum, Debrecen, Hungary))

The DNA from ancient human bones is shedding new light on the prehistory of Europe, such as when changes in skin color and lactose tolerance occurred, researchers say.

This research unexpectedly revealed that ancient Europeans started dairying thousands of years before they evolved genes to make the most of milk in adulthood, investigators added.

Scientists examined ancient DNA extracted from 13 individuals in archaeological burial sites unearthed during highway construction in the Great Hungarian Plain in Central Europe. This crossroads for Eastern and Western cultures experienced significant transformations in culture and technology known to have shaped European prehistory. The bones at the site span about 5,000 years, from 5,700 B.C. to 800 B.C., ranging across the Stone, Copper, Bronze and Iron Ages. [Image Gallery: Our Closest Human Ancestor Revealed]

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After several years of experimentation with a variety of kinds of bones, the researchers discovered the best place to recover ancient DNA for analysis in humans is the petrous bone, a pyramidal bone at the base of the skull. The name petrous comes from the Latin word "petrosus," meaning "stonelike." The petrous bone is the hardest bone in the human body and very dense, forming a protective case for the inner ear.

"The high-percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold,"the study's joint senior author Ron Pinhasi, an archaeologist at University College Dublin in Ireland, said in a statement. "This gave us anywhere between 12 percent and almost 90 percent human DNA in our samples, compared to somewhere between 0 percent and 20 percent obtained from teeth, fingers and rib bones."

In the Neolithic or New Stone Age, ancient central Europeans did not look anything like modern central Europeans, "but were closer to Sardinians," or people from the Italian island of Sardinia, Pinhasi told Live Science. "With the Bronze Age, you get a total shift into populations that look more like Western Europeans, and in the Iron Age you get another shift, with people genetically coming from the East, such as the Caucasus or Asia. These shifts were probably associated with major migrations and population turnovers in Central Europe."

Surprisingly, Pinhasi and his colleagues found that ancient Central Europeans apparently remained intolerant to lactose, the natural sugar in the milk of mammals, until the Bronze Age, about 4,000 years after these people began dairying. Artifacts that archaeologists previously unearthed suggest ancient Europeans started dairying 7,500 years ago in the Neolithic period. Most of the world is lactose intolerant, unable to digest lactose as adults, and the evolution of the ability to break down this sugar in adulthood helped Europeans take advantage of animal milk, a highly nutritious food.

Charles Q. Choi is a contributing writer for Live Science and Space.com. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.