Sunday, July 6, 2014

The ability to drink milk: the Wolverine in you!

Today I want to talk you about milk!

If you are an adult and you can still drink milk, well you and Wolverine have something in common, you are both mutants! In other ways, lactose intolerance is a normal thing.

But let's go in order...

Lactose intolerance is an impaired ability to digest lactose, a sugar found in milk and other dairy products. Lactose is normally broken down by an enzyme called lactase, which is produced by cells in the lining of the small intestine. Lactose intolerance in adulthood is caused by reduced production of lactase after infancy (lactase nonpersistence). If individuals with lactose intolerance consume lactose-containing dairy products, they may experience abdominal pain, bloating, flatulence, nausea, and diarrhea beginning 30 minutes to 2 hours later.... [Genetic Home Reference]

Did you know that it is estimated that about 70% of adults worldwide show some decrease in lactase activity during adulthood? 70%!!!

But also, did you know that the frequency of lactose intolerance ranges from 5% in Northern European countries (England, Scotland, Ireland, Scandinavia, and Iceland) to 71% in Italy (Sicily) to more than 90% in most African and Asian countries?

How can be that possible?

Most mammals normally cease to produce lactase, becoming lactose intolerant, after weaning but some human populations have developed lactase persistence, in which lactase production continues into adulthood. This lactase persistence in adulthood is due to a genetic mutation called Lactase Persistence Trait that scientists think first appeared 7500 in central Europe.

Natural selection favored this mutation to spread across in places and cultures in which dairy products are available as a food source. As already said, only about 5 percent of people of Northern European descent are lactose intolerant. This makes sense since milk and dairy-products are easy to store in cold environments and milk contains vitamin-D that is difficult to produce in places with limited sunlight exposure.

So if you can still enjoy milk, you are a mutant!

The subject of this post comes from the video below:

The sci-show videos are totally worth to watch!

No comments: