Neolithic Europeans were drinking milk (no doubt with very sore stomachs) for thousands of years before evolving the gene that helps digest it.
According to a recent article published in the journal Nature, prehistoric individuals developed a taste for milk thousands of years before humans gained the genetic characteristic that allows us to digest it without hurting stomachs and gastrointestinal disturbances.
It was previously considered that humans developed lactose tolerance, also known as lactase persistence, when they began to consume milk more often as agriculture spread across Eurasia. However, the researchers were surprised to discover that this was not the case.
The researchers examined thousands of animal fat deposits identified on over 13,000 ceramic shards from 554 archaeological sites across Europe. Milk traces on ceramic shards imply that human intake of milk was high in Neolithic Europe from roughly 7,000 BCE onwards.
This was before the vast bulk of the populace could comprehend it. Lactose, the sugar found in milk, is converted into glucose and galactose by the enzyme lactase. Lactose is not broken down without the enzyme, or in inadequate levels, and instead drives bacterial fermentation in the gut, resulting in gas, diarrhea, and stomach discomfort.
Surprisingly, genetic evidence from prehistoric European and Asian populations revealed that the gene that codes for lactase synthesis was not widespread until approximately 1,000 BCE, over 4,000 years after it was initially discovered around 4,700 BCE. Within a few thousand years, it had spread like wildfire over the continent.
“This is quite alarming,” remarked Professor Mark Thomas, an Evolutionary Genetics and Ancient DNA expert at University College London, at an online news conference.
“The prevalence of the genetic variation that causes lactase persistence has grown at an alarming rate. Exceptionally fast. Inexplicably, and nearly instantly, “He continued.
“It’s very likely the most selected single gene feature to have emerged among Europeans, Africans, Middle Eastern, and South Asian populations over the previous 10,000 years,” Thomas added.
It was traditionally considered that increased milk intake was a major contributor to lactase tolerance, however this does not appear to be the case. So, how and why did the gene for lactose tolerance appear in such a large proportion of the population in Europe, southern Asia, the Middle East, and Africa?
Further investigation by the researchers revealed that while drinking milk with lactose intolerance may be uncomfortable, it is unlikely to harm you.
People with the lactase gene and those with lactose intolerance consume about the same quantity of milk, according to genetic and medical data collected from over 300,000 people in the United Kingdom. Furthermore, the vast majority of persons who were lactase intolerant genetically reported relatively minor unfavorable health impacts when they consumed milk.
This alters when a community is under stress due to starvation or disease, since a gastrointestinal disturbance might be the difference between life and death. The researchers used markers of historical famine and pathogen exposure in their statistical models, which clearly revealed that when there was hunger and more diseases, the lactase tolerance gene variation was under higher natural selection.
“If you’re lactase intolerant and drink a lot of milk, you can suffer diarrhoea.” You may fart often. You may experience cramping. “It may be painful and embarrassing, but you will not die as a result of it,” Profesor Thomas emphasized.
“However, if you have diarrhoea while exposed to other diseases, it can quickly escalate from a discomfort to a lethal illness.”
In other words, if you’re among the small percentage of humans who can comfortably digest milk, you can probably thank your forefathers for surviving decades of starvation and sickness.
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