In the modern world today, most adult mammals are lactose intolerant (lactase non-persistence), nevertheless in selective populations, some have the dominant trait of being lactose tolerance (lactase persistence). In this essay, I will consider the evolutionary concept for this.
Milk is a dairy product which contains saturated fat, protein, calcium, vitamin C and other nutrients. Before the cultivation of agriculture, most humans were not able to surpass the ability to digest mik sugars know as lactose after infancy. This is due to a decline in production of an enzyme called lactase-phlorizin hydrolase (LPH) in the adult mammals. This enzyme converts lactose into glucose and galactose into simple sugars to be absorbed into the bloodstream. Nevertheless, those early descendants that practised cattle domestication would somehow have the ability to digest milk into their adulthood giving them the traits of being lactose tolerant. This can be seen mostly in Europe, East Africa and the Middle East.
The variation of lactase persistence and non-persistence describes the different alleles of the lactase gene. Lactose persistence also know as lactose tolerance is a dominant trait, resulting lactose intolerance being a recessive trait which is homozygous as the latter is poorly expressed after the weaning period. In the human lactase gene, there are several polymorphisms and the persistence genes are widely seen in the human populations. Data from several studies in the European populations, found that there is a difference between persistence and non-persistence that varies in a single nucleotide located 13,910 bases upstream from a transcriptional start site of the lactase gene (the genetic basics for this mutation on the regulatory region was first described in 2002). The gene is known as T-13910-C the T represents lactase persistence and C represents the non-lactase persistence allele.
In some human population, people who...