The analysis of about 16,000 ancient and modern West Eurasian genomes found natural selection altered nearly 500 gene variants over the last 10,000 years. Selected traits include lighter skin, more red hair, greater resistance to HIV and leprosy, and reduced genetic risk for male-pattern baldness and rheumatoid arthritis. Some susceptibility alleles (for tuberculosis and multiple sclerosis) rose and later declined, reflecting changing environments or pathogens. The researchers published their AGES method and plan to apply it to other regions.
Large DNA Study Shows Recent Natural Selection Increased Red Hair and Reduced Baldness in West Eurasians
Researchers found that natural selection has acted on genes for red hair and male-pattern baldness. | Credit: Getty Images
Over the past 10,000 years, natural selection has measurably reshaped aspects of West Eurasian biology, according to a new analysis of roughly 16,000 ancient and modern genomes. The study identifies nearly 500 gene variants that changed in frequency across millennia — affecting traits from skin and hair color to disease susceptibility.
What the Study Found
Researchers developed a statistical pipeline called AGES (Ancient Genome Selection) to track allele-frequency changes across an approximately 18,000-year timespan in genomes from West Eurasia (Europe and parts of western Asia). Using this approach, they detected evidence of selection at 479 genetic variants; about 60% of these variants map to traits observed in people today.
Variants showing strong positive selection include those linked to lighter skin pigmentation, increased frequency of red hair, resistance to certain infections (including HIV and leprosy), and the B blood type. The analysis also found reductions in genetic risk for male-pattern baldness and rheumatoid arthritis.
Timing and Dynamics
The study emphasizes that selection was not constant: some alleles rose in frequency for millennia and later declined. For example, variants associated with tuberculosis susceptibility increased for several thousand years before decreasing around 3,500 years ago. Similarly, alleles tied to multiple sclerosis rose until about 2,000 years ago and then fell. The authors attribute these shifts to changing environments, new pathogens, cultural shifts, or other evolving selective pressures.
Interpretation and Limits
While the genetic patterns indicate that selection affected these variants, DNA alone rarely reveals the exact selective advantage. For instance, the increase in lighter skin pigmentation is plausibly linked to improved vitamin D synthesis in low-sunlight environments. The rise in red hair is harder to explain; it may reflect selection on another trait genetically linked to red-hair alleles rather than on hair color itself.
Open Data and Future Work
The team has made AGES and their data publicly available so other researchers can reproduce and extend the work. The authors are applying the method to other regions: a preprint examining East Eurasian populations (people with East Asian ancestry) reports broadly similar patterns, suggesting that selection has been widespread but shaped differently by local environments, diets, pathogens and cultures.
Lead author Ali Akbari (Harvard): "Human evolution didn't slow down; we were just missing the signal."
Bottom line: With larger ancient-DNA datasets and methods that separate selection from other evolutionary forces, scientists can now detect small but consistent shifts in allele frequencies — evidence that recent human evolution was more active than many earlier studies suggested.
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