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Type 2 diabetes and Alzheimer’s disease. According to researchers, major migrations of ancient human populations to Europe over the last 45,000 years have shaped the risk of these diseases in modern individuals. Two articles detailing the findings of this research were published in the journal Nature. The publications include an analysis of DNA from the bones and teeth of hundreds of ancient people. The oldest data dates back to the Mesolithic period (or Middle Stone Age). Scientists compared the DNA of these individuals with the genomes of modern Europeans.
What Scientists Discovered
The project shed light on the genetic legacy of three ancient migrations to different regions of Europe. This includes the arrival of hunter-gatherers from Asia around 45,000 years ago, Neolithic farmers from the Middle East 11,000 years ago, and herders from the Pontic-Caspian steppe (a region encompassing Eastern Europe and Central Asia) about 5,000 years ago. Overall, researchers compared the genomes of 1,750 ancient individuals with the genomes of approximately 410,000 white British individuals. Their data was stored in the UK Biobank. The study’s authors calculated how much ancient DNA was passed down to them, as reported by Live Science.
Scientists identified gene variants associated with multiple sclerosis (MS), which were carried by farmers from the Pontic steppe. They primarily migrated to Northern Europe, explaining why the disease is so prevalent among people of Northern European descent. The researchers concluded that these risk variants were “positively selected,” meaning they provided some benefit to migrants and were thus under evolutionary pressure to emerge.
It is known that certain gene variants related to immune function increase people’s susceptibility to multiple sclerosis. These include variants of the HLA gene, which help the body detect pathogens. However, like a double-edged sword, some HLA variants are also closely linked to autoimmune diseases, where the body attacks its own cells.
The study’s authors suggest that in the past, these variants potentially helped ancient farmers combat infectious animal diseases. However, as people’s lifestyles changed in terms of hygiene, diet, and medicine, these variants took on new significance. Scientists believe that understanding the evolutionary forces that drove the selection of these genes could aid in treating multiple sclerosis. “What we need to move towards is an attempt to recalibrate the immune response, rather than completely eliminate it,” noted lead author Lars Fugger, a professor of neuroimmunology at the University of Oxford (UK).
Additionally, the authors found that individuals carrying more DNA from the hunter-gatherer group may have a heightened genetic risk of developing Type 2 diabetes and Alzheimer’s disease. Modern populations with such DNA predominantly reside in Eastern Europe. Risk variants for Alzheimer’s disease may have been positively selected as well. For instance, one risk variant known as ApoE4 increases the risk of developing Alzheimer’s but may also enhance fertility in women.
