Multiple sclerosis (MS), a disabling disease in which our bodies destroy their own brains and spinal cords, has puzzled scientists for years.
Why would our immune system overreact to normal body tissue and mistakenly start destroying some of our healthy and desperately needed cells and body parts?
It’s all due to our ancestor’s ‘migration’ thousands of years ago according to a study in the journal Nature gives a new explanation that makes a lot of sense.
Here is another question: why are Northern Europeans more susceptible to multiple sclerosis than their southern counterparts are?
The new study uses DNA from ancient Europeans to shed light on the origins of this mysterious condition, revealing a strong link to our ancestor’s past environments and lifestyles.
Led by researchers from the universities of Oxford and Cambridge, the team analyzed ancient DNA extracted from the bones and teeth of people who lived up to 34,000 years ago. This DNA was compared with modern genomes from the UK Biobank to trace changes over time.
They uncovered a genetic variant associated with a threefold higher risk of developing multiple sclerosis, known as HLA-DRB1*15:01, which is present in up to a fifth of northern Europeans today.
They traced this risky genetic variant back to the Yamnaya people, pastoralists from the Pontic Steppe region of Eastern Europe, around 5,000 years ago. Think Ukraine, south-western Russia, western Kazakhstan, and Moldova.
As these people migrated into Northern Europe, they brought with them genetic traits that, at the time, offered protection against infections from their domesticated animals.
So, how did helpful genes become harmful?
As societies evolved and sanitation improved, the advantages of these variants faded. In fact, in our modern environment, they contribute to an overactive immune system, a hallmark of autoimmune conditions like multiple sclerosis.
This explains the higher prevalence of this disease in Northern Europeans—think Sweden, Iceland, and Finland—who have more Yamnaya ancestry compared to Southern Europeans. It’s a fascinating example of how our genetic adaptations from the past can have unexpected consequences in the present.
Because these genes kept our ancestors healthy and protected them from pathogens and plagues in their densely populated, animal-rearing communities, they were positively selected to pass on to subsequent generations. But today, they’re just a huge and hazardous nuisance.