|
2 minutes reading

Most human don’t have the capability to digest milk

Most human don’t have the capability to digest milk Most human don’t have the capability to digest milk
Source: Audree Lapierre via Flickr
A Brief History of Everyone Who Ever Lived
From a book
A Brief History of Everyone Who Ever Lived
Font size
A
12 24 17
A

It is a strange thing that we drink milk. Mammals are, of course, defined by lactation, by mammary glands and the suckling of our infants. It is specifically for neonates, and when mammals grow up, they put away this childish thing and stop drinking milk.

Except us. Though not all cultures do it, here in the West we drink milk in various forms into adulthood. It is a very European thing to do, and some African and Middle Eastern pastoralists do it too. But it was not always thus. Most adult humans today, and almost every human in history, do not even have the capability to digest milk. We all have an enzyme called lactase, encoded by a gene called LCT, and its sole job is to digest milk. The sweetness in milk comes from a sugar called lactose, and lactase seeps out of your stomach lining and slices lactose in half to produce the sugars glucose and galactose. Elegant names are not always a preoccupation of biologists.

For most of human history lactase has been active only in babies. After weaning, the gene's activity is radically reduced, and as a result, for most adults, for most of human history, milk has been off the menu. Most people, for most of human history, will have experienced a full deck of problems that come with drinking milk past weaning. Symptoms include bloating and cramps, vomiting, diarrhoea, flatulence and borborygmus, which is a technical word for a rumbly tummy. The absence of lactase, or its reduced activity, means that the lactose doesn't get digested in the small intestine, so it passes into the colon, where it encounters bacteria that can break it down and it ferments, causing gas build-up. That's the direct cause of the bloating and fartiness, but also the increased pressure triggers diarrhoea, and so on. This is called lactose intolerance, and admittedly though not particularly pleasant, it's not the worst condition someone can have, and is pretty normal for most people if they drink milk into adulthood. Which is why most people don't.

Except if you're of European descent. Your lactase continues to work throughout your life. This unusual phenomenon is called lactase persistence, and although a splash of milk in tea is the English way, or even a mug of hot chocolate might seem very normal to us, we are the weird ones. There are a handful of African populations, some in South East Asia and a few Middle Eastern peoples whose lactase persists, but for the majority of modern humans, milk equals tummy troubles.

Comments are small addendum used to provided quick feedback. They are intentionally limited in size and formatting.


Please enter a value.

Your example


Please enter a value.
Similar articles
Category:
Biology
2 minutes reading

Journalist : Do you think that people may be starting to think that ageing is the real enemy? Aubrey de Grey ...

| Approved
Category:
Biology
1 minute reading

It doesn't matter whether we are talking about criminality, or psychological characteristics, or psychiatric disorders, or perfectly normal human behaviours ...

| Approved
Categories:
Biology
7 minutes reading

Drugs are the product of a complex evolutionary game. As fungi and plants evolved, some developed chemicals in their leaves ...

| Approved
Categories:
Biology
2 minutes reading

Oxytocin is the most people's favorite chemical. It's the feeling of friendship, love or deep trust. It is the feeling ...

| Approved
Category:
Biology
7 minutes reading

The excerpt below describes the symptoms of the deadly Ebola virus as they appeared in one of its first known ...

| Approved
Row:Column:
×
Row:Column:
×