A large analysis of ancient human genomes suggests that many genetic variants linked to modern traits and disease risk have been shaped by ongoing natural selection over the past 10,000 years.
Researchers analyzed DNA from 15,836 individuals from West Eurasia, including more than 10,000 newly sequenced ancient samples. The dataset spans multiple regions and time periods, allowing the team to track how genetic variants changed in frequency over time.
To support this, the investigators developed a statistical method designed to detect “directional selection,” defined as consistent increases or decreases in the frequency of specific genetic variants. This approach helps distinguish true selection from other factors such as population movement or genetic drift.
The analysis identified evidence that hundreds of genetic variants were influenced by selection during this period. Rather than a small number of large genetic changes, the findings suggest that adaptation has occurred across many genes simultaneously, particularly those linked to complex traits.
The researchers estimated selection effects for approximately 9.7 million genetic variants, enabling detailed analysis of how groups of variants associated with specific traits have changed over time.
Changes were observed in genetic predictors linked to several traits. The data suggested decreases over time in variants associated with higher body fat and schizophrenia risk, and increases in variants linked to cognitive-related measures. These estimates are based on modern genome-wide association studies and may not directly reflect historical phenotypes.
The study also found that selection signals were more common in genomic regions associated with immune function, inflammation, and cardiometabolic traits. As shown in extended analyses, these categories showed stronger evidence of selection, with variation in intensity across different historical periods, including transitions such as the Neolithic to Bronze Age.
Importantly, the strength of selection was not constant. Analyses over time showed that selection pressures on specific variants changed, likely reflecting shifts in environment, diet, population structure, and disease exposure.
The findings provide context for interpreting genetic variation linked to disease. Many variants currently associated with clinical traits may reflect long-term evolutionary pressures rather than recent or isolated changes. This may influence how genetic risk is distributed across populations.
The authors note that interpretation is limited by reliance on modern genetic association data and that further work is needed to link these findings to clinical outcomes and disease mechanisms.
Newsletters
Receive the latest pathologist news, personalities, education, and career development – weekly to your inbox.
