Most humans loses the ability to digest lactose, which causes them to become lactose intolerant.
In some population however, people are still able to produce lactase, the enzyme that allows people to digest lactose, in adulthood. The difference between being lactose intolerant and lactose tolerant adults is not only because they have different genes, but how their genes are controlled differently. This is mainly because of the mutation in a person’s DNA. Mutations are changes in the genetic code. While DNA is the genetic material used to code for certain physical characteristics. Mutations help allow the DNA to create proteins that functions differently than it would otherwise. About 12,000 years ago not many people in Europe or Africa had the ability to digest lactose. Some people, including a large fraction of individuals of European descent, the ability to break down lactose persists because of a mutation in the lactase gene.
This indicates that the allele became common in Europe because of the increased nutrition from the cow’s milk, which became available after the domestication of cattle. Without the mutation it brought hardship to their community, especially during the winter since not many people were able to eat anything lactose related without causing them death. For example, in a population, it is common for everyone’s body to reject lactose related foods, however if there was a mutation among two people it will allow the next generation to become more tolerable to lactose. Moreover, if the population dies due to the starvation of the harsh winter, it is up to the two individuals to make the an offspring that will carry on the mutation.
In result, nowadays it is normal for most individuals to produce lactase and if people are lactose intolerance, it isn’t as server as it would be 12,000 years ago.The adults ability to consume milk is known as lactose persistence, it is a recent evolutionary development. In other words, it is a product of natural selection that gives a population survival advantages as well as spreading among the community rapidly.