The lactase-persistence mutation would become common if it provided a survival and reproductive advantage in a particular environment. For example, in a population with domesticated cows, where milk is available, the ability to drink milk might have been advantageous in periods of drought or when food was limited.
How is lactase related to mutation?
The LCT gene mutations change single protein building blocks (amino acids) in the lactase enzyme or result in an enzyme that is abnormally short. The mutations are believed to interfere with the function of the lactase enzyme, leading to undigested lactose in the small intestine and causing severe diarrhea.
How did dairying drive the spread of the lactase persistence mutations?
How did dairying drive the spread of the lactase persistence mutations? Mutations, of course, occur at random. So before humans kept dairy animals, if a mutation arose that maintained lactase production, it could have vanished from the population. Without milk around, there's no known advantage to the mutation.
How did the lactase persistence start in humans and why did it continue?
But around 8,000 years ago in what's now Turkey — just when humans were starting to milk newly domesticated cows, goats and sheep — mutations near the gene that produces the lactase enzyme started becoming more frequent. And around the same time, adult lactose tolerance developed.
Is lactase persistence a substitution mutation?
Among persons of European descent, this trait is strongly associated with a C to T substitution at a polymorphic site 13,910 bp upstream of the lactase gene. This mutation results in the persistent expression of lactase into adulthood enabling individuals carrying a T(-13,910) allele to digest lactose as adults.
What type of mutation is lactase persistence?
Within European and populations of European ancestry, they are almost entirely correlated with the presence of the −13,910 C/T mutation in the enhancer region of the lactase gene (LCT).
Is lactase persistence dominant or recessive?
Lactase persistence is an autosomal-dominant trait that is common in European-derived populations.
What happens if a person with lactose intolerance eats dairy products?
If people with lactose intolerance eat dairy products, the lactose from these foods pass into their intestines, which can lead to gas, cramps, a bloated feeling, and diarrhea. Some people can have small amounts of dairy without problems. Others have a lot of stomach trouble and need to avoid all dairy products.
How is lactase persistence An example of biocultural evolution?
The Biocultural Coevolution theory proposes that pastoralism and lactase persistence coevolved. This means that they arose around the same time, and both changes were reinforced by the advantages of the other.
What type of mutation is lactose tolerance?
A single point mutation in the DNA near to the lactase gene changes the cytosine (C) nucleotide to a thymine (T). Individuals who have the thymine (T) nucleotide are lactose tolerant and can digest milk products in adulthood.