The reason is mainly that Asians lack an enzyme, namely the Lactase.Lactase is needed to split the milk sugar lactose into its digestible substances. Infants produce this enzyme in order to utilize the mother's milk. If it is missing, the milk sugar begins to ferment in the large intestine. This leads to symptoms such as flatulence, colic, diarrhea. The Asians are not the only ones who "suffer" from this deficiency, because most adult mammals - including humans - usually do not tolerate milk.
Northern and Central Europeans as an exception
But why is it that most Northern and Central Europeans are an exception? The reasoning is as simple as developmentally understandable: as long as humanity did not know the dairy industry, adults did not benefit from milk. Consequence: They lost the ability to make lactase after infancy.
However, this did not take effect until about 12, 000 years ago, people in the Middle East began taming animals and drinking their milk. They noticed that they did not tolerate the fresh animal milk. They were not dependent on milk as a source of calcium either. This for three reasons:
- They had enough green leafy vegetables for consumption
- They consumed enough sea fish and thus enough vitamin D.
- They took in enough sunlight to make the body produce vitamin D.
Unlike in northern Europe: there, the dairy industry gradually spread. But there was not enough green leafy vegetables available, nor was the sunlight enough to produce vitamin D. Milk was therefore used as calcium supplier.
The Northern Europeans, who were able to drink and digest the milk of their animals, were genetically successful and successfully propagated.