Lactose intolerance affects around 70% of the human population. This inability to digest milk as an adult can produce a range of unpleasant symptoms in sufferers and requires them to avoid dairy products entirely. However, only 5% of the UK’s population is lactose intolerant hinting at an ancient tradition of milk drinking in northern Europe. Although this fact has been long established, exactly when our ancestors started drinking milk and why has long been unclear, but now research from the University of York is shedding new light on this mystery.
Previous attempts to narrow down a timeframe for the evolution of European lactose tolerance have focused on identifying milk residue left on ceramic pots, or looking at the proportion of female animals in herds, but these methods are indirect and potentially misleading. For example cheese and yogurts, both made from milk, have far lower lactose levels due to processing and could probably have been ingested without the need for special adaptations.
New research, carried out by the University of York, has focused on teeth instead. They examined dental calculus which is a mineralised form of plaque and used mass spectrometry to identify different proteins inside the teeth. One of the proteins they found was called beta-lactoglobulin which is also found in the teeth of modern day milk drinkers and is linked to the ingestion of lactose. With this technique it is now possible to identify specific individuals who were drinking milk, giving a much finer picture of the diet of our ancestors. Using subtle differences in the shape of the proteins it is even possible to determine what animal the milk came from.
Already this new technique is revealing insights into the habits of our Bronze Age ancestors. The study has found that while most of Europe was getting its milk from cattle and sheep but in northern Italy goat was the animal of choice. There is hope that more studies will now be able to focus on who within the population was drinking milk and why.
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