Tracing Ancient Human Migrations into Sahul Using Hepatitis B Virus Genomes

Area of Science:

• Genetics and Evolutionary Biology
• Paleovirology
• Human Population Genetics

Background:

• Ancient human migration routes into Sahul remain debated.
• Unique hepatitis B virus (HBV) strains, HBV/C4 and HBV/C3, are endemic in Australian Aboriginals and Indigenous Melanesians, respectively.
• Mother-to-child transmission is the primary route for HBV genotypes B and C infections in endemic populations.

Purpose of the Study:

• To investigate ancient human migration into Sahul using phylogenetic and phylogeographic analyses of HBV genomes.
• To infer the origin, timing, and routes of HBV/C4 and HBV/C3 strains.
• To correlate HBV genomic data with established human migration timelines.

Main Methods:

• Phylogenetic analysis of HBV genomes.
• Phylogeographic analysis to infer geographic origins and movements.
• Dating of viral lineages using Bayesian inference and molecular clock models.

Main Results:

• HBV/C4 originated on the Sunda Shelf over 59,000 years ago.
• The most recent common ancestor of HBV/C4 in Australia dates to over 51,000 years ago, suggesting a southern migration route via Timor.
• HBV/C3 also originated on the Sunda Shelf and was introduced to Melanesia via migration north of the New Guinea highlands.

Conclusions:

• HBV genomes serve as valuable molecular markers for reconstructing ancient human population movements.
• The study provides evidence supporting specific migration timings and entry points into Sahul.
• Distinct HBV strains correlate with the movements of different ancestral human groups in the region.