Human adaptation over the past 40,000 years.

Area of Science:

• Human evolutionary genetics
• Population genomics
• Bioinformatics

Background:

• Methodological and data-driven advances have enhanced the detection of genomic signatures of selection in human populations.
• New analytical methods and large sample sizes of present-day genomes increase the power of selection detection.
• Ancient DNA analysis enables precise estimation of the timing and tempo of evolutionary events.

Observation:

• Despite improved detection methods, translating genomic signatures into specific traits under selection and their underlying causes is still limited.
• Detecting polygenic selection, which involves many genes influencing a trait, is particularly challenging, and its role in recent human evolution is unclear.
• Balancing selection and archaic introgression appear significant for maintaining immune diversity but may be less crucial for other adaptive traits.

Findings:

• Genomic signatures of selection can be robustly detected using advanced methods and large datasets, including ancient DNA.
• The functional interpretation of detected selection signatures, particularly for polygenic traits, remains a significant hurdle.
• Evidence for polygenic selection is weak, questioning its overall importance in recent human evolutionary history.

Implications:

• Combining data across populations and timescales can aid in interpreting selective sweeps and understanding evolutionary pressures.
• Further research is needed to elucidate the role of various selection modes, including polygenic selection, in shaping human traits.
• Understanding selection mechanisms is crucial for deciphering the genetic basis of human adaptation and diversity, especially in immune-related genes.