'Whey'-ing the Benefits of Milk Using Ancient Teeth
Scientists have long wondered why human genes mutated to accommodate milk into our diets, and now a new study is trying to "whey" the benefits of this lactate-rich drink using ancient dental plaque.
During infancy, mutations enable the intestinal enzyme lactase to digest lactose milk sugar. Normally, scientists would expect lactase production to eventually stop, however that is not the case - something only seen in a handful of populations around the world such as in Northern Europe.
It's actually pretty easy during processing of yogurt and cheese to remove milk sugars that cause symptoms of lactose intolerance, such as diarrhea. That, combined with the fact that the mutation is only required for drinking raw milk or whey protein, left scientists puzzled and made them wonder why it is the strongest selection of any human genome.
Now an international team of researchers is relying on calcified dental plaque on ancient human teeth to shed light on our milk-drinking past.
"It is only within the last several thousand years that genetic mutations arose in Europe, East Africa, and the Arabian Peninsula that allowed lactase to persist into adulthood, a genetic trait that enables lifelong milk consumption," co-author Dallas Swallow at the University College London (UCL) said in a statement.
"The study has far-reaching implications for understanding the relationship between human diet and evolution," added lead author Dr. Christina Warinner, from the University of Oklahoma.
Using a mass spectroscopy technique, the team was able to identify the milk protein beta-lactoglobulin in the ancient remains, which is a dominant whey protein, proving that this human once drank milk long ago.
"We kept finding sequences of beta-lactoglobulin and at first we thought it could be modern contamination," explained lead author Jessica Hendy, from the University of York. "But we repeated the analysis several times, at three different laboratories in three different countries, each time finding the same results."
The results suggest that cattle, sheep, and goat whey were popular items on the menu for human populations over the last 5,000 years.
The findings were published in the journal Scientific Reports.
For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).