If you don’t suffer from an upset stomach after drinking a glass of ice-cold milk, you’re one of the lucky ones. According to NPR, only 35% of the global population as of 2012 can digest lactose, the main sugar in milk. Even though that number seems low, 35% is a huge leap from 0% of the population who could drink milk over 20,000 years ago. Back then, no one past infancy was able to consume lactose without getting diarrhea, which in some cases led to death.
It wasn’t until about 7,500 years ago that the lactase enzyme, that being the enzyme that allows humans to digest milk, didn’t switch off after infancy.
A 2009 study led by researchers from University College London found that a genetic change occurred in early dairy farmers located between the Balkans and central Europe that allowed them to drink milk without getting sick.
“Most adults worldwide do not produce the enzyme lactase and so are unable to digest the milk sugar lactose,” said Professor Mark Thomas of the UCL Genetics, Evolution, and Environment department. “However, most Europeans continue to produce lactase throughout their life, a characteristic known as lactase persistence.”
He continued, “In Europe, a single genetic change (13,910*T) is strongly associated with lactase persistence and appears to have given people with it a big survival advantage. Since adult consumption of fresh milk was only possible after the domestication of animals, it is likely that lactase persistence co-evolved with the cultural practice of dairying, although it was not known when it first arose in Europe or what factors drove its rapid spread.”
Scientists originally thought that lactose tolerance evolved in Northern Europe where people needed to supplement their vitamin D intake due to lack of sunlight, but the 2009 study proved this theory unnecessary. Yet, Thomas still admitted to NPR that he’s not sure why lactose tolerance evolved the way it did, and so quickly.
He believes, however, that a combination of two things led to the rise of humans becoming lactose tolerant and spreading the mutation to those in Northern Europe.
Firstly, the people who first developed the lactase mutation near the Balkans experienced famine upon their migration into Northern Europe due to their inability to farm their crops in the shorter growing season. And secondly, Thomas believes that thanks to Northern Europe’s cooler climate, milk was naturally refrigerated. Therefore, people were drinking raw milk rather than fermented yogurt or butter, which doesn’t include as much lactose.
Milk drinking would most likely increase during times of famine, and therefore the malnourished people without the lactase enzyme were weeded out of the population. Diarrhea plus malnutrition in those days resulted in dehydration and certain death. Pepto Bismol wouldn’t be around for another 7,500 years or so.
Those who survived the famine passed on their enzyme mutation to their children, thus passing on the ability to consume milk.
Again, this is just a theory. We may never know why exactly the lactase mutation developed, and some scientists are still unsure of where exactly the mutation came from. A more recent study from 2015 provides evidence that Russian farmers from the Great Steppes region actually introduced the mutation to Europe more recently than previously thought.
Lactose tolerance, and intolerance for that matter, will remain a mystery for now. Until scientists can crack the ancient lactase code, we’re just going to have to deal with the fact that some of our ancestors evolved to drink animal’s milk and left some of us in the dust.
I had a lobster grilled cheese yesterday with a side of tomato cheddar soup to dip the sandwich into, and my lactose intolerant ass is still trying to process what happened to me.
— Kima Jones 🎀 (@kima_jones) February 13, 2019
And for that, we will forever be upset. As will our stomachs.
my lactose intolerant ass: *eats shredded cheese for breakfast*
— ☆ emma ☆ (@_little__bat_) February 11, 2019
my stomach: pic.twitter.com/QWrylAJMdB
Just think, if that population in the Balkans did not evolve with that genetic variant, our lives would be completely different. We probably wouldn’t have ice cream.
My lactose intolerant self: who gonna check me boo?
— Joshua Valdez (@Joshua_Valdez13) February 8, 2019
Ice cream:
💩💩💩💩💩💩💩
💩 👁 👁 💩
💩 👃🏻 💩
💩 👄 💩
💩💩💩💩💩💩💩
Or cheeses that aren’t aged. Or Alfredo sauce…
And perhaps we’d never have to live through that sudden realization that we’re lactose intolerant. Our lives would be… so different.
But that’s all in the past. What’s done is done.
History cannot be changed. Facts cannot be erased.
However, modern day science has removed lactose from milk so people without the lactase enzyme can actually drink it. And there are some great cow’s milk alternatives out there.
Although, let’s be honest. We like to take the hard way through life.
what’s it like to not be lactose intolerant
— sam clark (@14Samclark) February 10, 2019
So, to all you fellow lactose intolerant people out there, we raise a glass of poisonous yet delicious milk to you.
And to all 35% of you who can drink milk without needing to know where the closest bathroom is, we really envy your iron gut. Please, give us some of your enzymes.
Until the mystery of the missing lactase enzyme is solved, at least we’re in this lactose intolerance fight together.
