Researchers analyzed ancient DNA from bones and teeth of nearly 5,000 ancient humans from western Europe and Asia dated about 34,000 years ago, resulting to an extensive gene bank. Examining over 1,600 ancient genomes revealed traits in modern Europeans, indicating migration waves around 45,000 years ago introduced characteristics like a heightened multiple sclerosis risk.
The findings, including the origins of neurodegenerative diseases and the impact of major migration 5,000 years ago, were detailed in four related Nature papers.
Dispersal Ptterns Led Carrying Genetic Ancestry From All Three Waves of Migration
In the settlement history of Europe, three major waves of anatomically modern humans occurred: hunter-gatherers arrived from Asia around 45,000 years ago, farmers migrated from the Middle East 11,000 years ago, and animal herders or pastorials came from the steppes of western Asia and eastern Europe 5,000 years ago.
Contrary to assumptions of widespread mixing, geneticist Eske Willerslev and his team from the University of Cambridge discovered complexities. DNA from 317 ancient European skeletons, combined with existing data from 1,300 Eurasians, formed a family tree and migration map, revealing distinct changes in genetic characteristics across regions as populations moved.
The study unveiled instances where newcomers entirely replaced existing populations, with Denmark undergoing two such transitions. The comparison of ancient genomes with those of 410,000 modern individuals from the UK Biobank showed clear links between traits and specific migration waves.
Modern northern Europeans, with more ancestry from steppe pastoralists, are taller and lighter-skinned, while those with hunter-gatherer ancestry, common in northeastern Europe, exhibit variants associated with higher diabetes and Alzheimer's disease risks.
The dispersal patterns resulted in modern Europeans carrying genetic ancestry from all three waves, but the proportions vary by location. The study shed light on the evolution of traits such as lactose tolerance, suggesting that mutations near the lactase gene, which aids in milk digestion, could have helped early humans survive famines.
These mutations might have paved the way for the development of lactase persistence in adults. However, the advantage of other traits like height remains uncertain. Willerslev emphasized that while much history unfolded outside Europe, the settlement of migrants in isolated areas solidified specific genetic variants within populations.
READ ALSO : Early Human Migration: Jordan Rift Valley May Have Served As Route For Humans Out of Africa
DNA Analysis Helped Reveal Origins of Diseases
Evolutionary geneticist Tony Capra from the University of California, San Francisco said that the findings highlight the complex process of human evolution. But surprsingly, it showed that having predisposition to multiple sclerosis thousands of years ago played a strong evolutionary advantage.
In modern times, multiple sclerosis is deemed a devastating disease due to overactive immune system that attacks the nervous system. On the other hand, superpowered immune system in the past could have helped ancient people surviv plagues and pathogens.
Today, Northern Europe is known to have the highest prevalence of multiple sclerosis worldwide. This gene arrived in Europe along with the animal herders and became a common trait in northern Europe for the next thousands of years.
Researchers also found that genes for Alzheimer's disease and type 2 diabetes can be traced back to hunter gatherers who settled in Europe. They hope to probe deeper in the future to know more about the genetic markers of other neurological diseases.
The analysis of ancient DNA from humans who lived thousands of years ago helped researchers to trace the geographical spread of diseases and understand more about them.
RELATED ARTICLE: 36,500-Year-Old Human Genomes From Crimea Suggest Early Periods of Migration, Shed Light on First European Settlers
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