Global patterns of natural selection inferred using ancient DNA.

Area of Science:

• Human Evolution
• Population Genetics
• Ancient Genomics

Background:

• Ancient DNA studies on natural selection have primarily focused on European populations.
• Global adaptation principles and local selective pressures remain understudied across diverse human ancestries.

Purpose of the Study:

• To investigate genome-wide selection signals in 7244 individuals across 5 global regions using ancient DNA.
• To identify shared and region-specific adaptations and understand how selection varied over time.

Main Methods:

• Analysis of ancient DNA from 13 ancient and 19 present-day populations across Europe, East Asia, South Asia, Africa, and the Americas.
• Application of multiple statistical approaches accounting for complex demographic histories.
• Development of admixture-aware time series and polygenic selection tests.

Main Results:

• Identification of 31 genome-wide significant selection signals, including novel loci.
• Evidence for extensive parallel or shared adaptation across different regions.
• Demonstration of dynamic selection changes over time (e.g., LCT in Europe, ADH1B in East Asia) and directional selection on pigmentation/immune traits.

Conclusions:

• Human adaptation is a widespread phenomenon with significant parallel evolutionary events across continents.
• Selection pressures on traits like waist-hip ratio appear to be universal, suggesting fundamental morphological constraints.
• Ancient DNA analysis provides crucial insights into the tempo and mode of human adaptation globally.