Lactose tolerance evolved – it is a genetic change. At http://phys.org/print309711543.html … we have a story about milk digestion and lactose tolerance. A research undergraduate has analysed DNA from the teeth of a human living in central Europe around one thousand years ago. Not exactly historical, as such, but the results showed that people at that time had a similar genetic predisposition for milk digestion as in present day people in the region. In other words, lactose tolerance was more widespread than previously believed.
Five populations, in Europe, Arabia, and Africa have developed a genetic modulation which allows them to produce lactose throughout their lives – and not just as a baby. Up to 90 per cent of the European population is lactose persistent (another way of saying the same thing). Earlier studies, also using DNA, seemed to show that 5000 years ago the percentage was much lower, and it was fairly rare amongst Scandinavian hunter gatherers.
The same story is at www.geneticarchaeology.com/research/Central_Europeans_already_digested_m… while at www.geneticarchaeology.com/research/Calcium_absorption_not_the_cause_of_… … where the DNA of early Iberian farmers is said to show adoption of luctase persistence there had nothing to do with calcium absorption requirements. Milk is full of minerals, vitamins, proteins, fats, lactose sugar, as well as bountiful quantities of calcium. Vegetarians that omit dairy products from their diet are supposed to take calcium in some other form – but this study is interesting, as it seems to turn consensus views upside down. Archaeologists and anthropologists have worked on the basis that pastoral societies develop lactase persistence – and it is easy to see why they should think so. Why Europeans developed the trait has been laid at the door of calcium defiency – and milk has lots of it. Also, in cool and cloudy environments there is a distinct lack of sunshine in the winter months – which should incur lack of vitamin D. Milk has fair quantities of this vitamin and milk in some ways combats our gloomy climate. However, there was never a lack of sunshine in Spain and Portugal – so why did they become lactase persistent (or lactose tolerant). This means a rethink is on the cards, as to why Europeans developed a taste for drinking milk. Lactose tolerance has nothing to do with the consumption of cheeses or yoghourts, it is thought, just drinking milk wwhen an adult – although modern people that claim to be lactose intolerant also claim they can't eat other dairy products as it makes them feel queasy.