First there were hunter-gatherers about 45,000 years ago. The first modern humans arrived in a Europe where the Neanderthals still reigned. Then there were the farmers of the Middle East about 11,000 years ago and finally, about 5,000 years ago they were the nomadic pastoralists of the steppes of Central Asia.
That is, according to research published in the journal Naturethe common genetic heritage of Europeans. A heritage that explains why, in an incredible historical twist, multiple sclerosis affects us more.
A DNA mutating in the middle of the great steppe. While agriculture gained weight in the world, the great Eurasian steppe continued doing its thing. The culture yamnaa group of pastoral towns that arose in the enormous plains south of the Urals and east of the Black Sea, generations and generations passed living with livestock.
Variant. It was there that it emerged (and was selected) a small genetic variant that strengthened natural immunity against zoonoses; that is, against livestock infections that could easily jump to the human communities that raised them. 5,000 years later, this genetic variant is behind the fact that Europeans have a higher risk of suffering from Multiple Sclerosis.
The deep origins of current diseases. The study led by the Universities of Cambridge and Copenhagen (but with the participation of many more) analyze in detail from the DNA of almost 5,000 individuals spread throughout history. Some studied remains date back to about 34,000 years ago.
The reconstruction. Reconstructing humanity’s immense genetic tree, researchers found numerous keys to understanding why there are specific geographic areas or ethnic groups that suffer from some diseases more than others. They realized that southern Europeanswith a greater genetic legacy from the agricultural people of the Middle East, have a greater predisposition to develop bipolar disorders; that people from the East had a higher genetic risk of developing Alzheimer’s or diabetes; and those from the northwest had a heightened risk of sclerosis.
A medical enigma. For years, scientists have tried to understand why Europe has, with about 143 cases per 100,000 inhabitants, one of the highest incidence rates of sclerosis in the world. As I said in the previous paragraph, as you go south and east those differences fade, but (even so) the greater risk of developing this disease It is a European ‘differential fact’.
Understanding better. The most interesting thing about all this is that the idea that the answer lies in the genetic history of its inhabitants It is not only a historical curiosity. On the contrary, thinking about this from an evolutionary point of view allows us to understand the disease in a new way.
Image | Charlotte Venema
*An earlier version of this article was published in January 2024