On characterizing adaptive events unique to modern humans.

Area of Science:

• Human evolution
• Genomics
• Population genetics

Background:

• The completion of the human genome sparked interest in identifying human-specific genetic changes.
• Extinct hominin genomes (Neanderthal, Denisovan) offer higher resolution for human-specific genetic differences than chimpanzee genomes.
• Previous studies identified regions under positive selection around the human-Neanderthal split.

Purpose of the Study:

• To characterize the evolutionary history of candidate regions identified from the Neanderthal genome.
• To examine evidence for selective sweeps in modern human populations.
• To investigate accelerated adaptive evolution across ape species.

Main Methods:

• Analysis of Neanderthal and Denisovan genome sequences.
• Statistical tests for evidence of selection in modern human populations (P < 5 × 10⁻⁵).
• Assessment of accelerated amino acid substitutions in genes across multiple ape species (P < 0.01).

Main Results:

• Three of the top 20 candidate regions showed evidence of selection in at least one modern human population.
• Four genes within the top 20 regions exhibited accelerated amino acid substitutions across multiple apes.
• These findings suggest evolutionary importance across both recent and ancient timescales.

Conclusions:

• Evaluating evolutionary processes across different timescales is crucial.
• Candidate genes important around the human-Neanderthal split have been identified.
• These genes may have contributed to unique human morphological and cognitive traits.