Got milk? The 1990s ad campaign highlighted the importance of milk for health and wellbeing, but when did we start drinking the milk of other animals? And how did the practice spread? A new study led by scientists from Germany and Kenya highlights the critical role of Africa in the story of dairying, showing that communities there were drinking milk by at least 6,000 years ago.

Now archaeological scientists are increasingly using proteomics to study ancient dairying. By extracting tiny bits of preserved proteins from ancient materials, researchers can detect proteins specific to milk, and even specific to the milk of particular species.

Where are these proteins preserved? One critical reservoir is dental calculus — dental plaque that has mineralized and hardened over time. Without toothbrushes, many ancient people couldn’t remove plaque from their teeth, and so developed a lot of calculus. This may have led to tooth decay and pain for our ancestors but it also produced a goldmine of information about ancient diets, with plaque often trapping food proteins and preserving them for thousands of years.

Now, an international team led by researchers at the Max Planck Institute for the Science of Human History in Jena, Germany and the National Museums of Kenya (NMK) in Nairobi, Kenya have analyzed some of the most challenging ancient dental calculus to date. Their new study, published in Nature Communications, examines calculus from human remains in Africa, where high temperatures and humidity were thought to interfere with protein preservation.

The team analyzed dental calculus from 41 adult individuals from 13 ancient pastoralist sites excavated in Sudan and Kenya and, remarkably, retrieved milk proteins from 8 of the individuals.

The positive results were greeted with enthusiasm by the team. As lead author Madeleine Bleasdale observes, «some of the proteins were so well preserved, it was possible to determine what species of animal the milk had come from. And some of the dairy proteins were many thousands of years old, pointing to a long history of milk drinking in the continent.»

The earliest milk proteins reported in the study were identified at Kadruka 21, a cemetery site in Sudan dating to roughly 6,000 years ago. In the calculus of another individual from the adjacent cemetery of Kadruka 1, dated to roughly 4,000 years ago, researchers were able to identify species-specific proteins and found that the source of the dairy had been goat’s milk.

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Materials provided by Max Planck Institute for the Science of Human History. Note: Content may be edited for style and length.