Reconstructing micro-evolutionary dynamics shaping local variation in southern African populations using genomics, metagenomics and personal metadata.

Geography is a well-known factor shaping genetic variation in human populations. However, the potential role played by cultural variables remains much understudied. This study investigates the impact of socio-cultural variables on genomic similarity and the saliva microbiome, using data from populations in Lesotho and Namibia. Geographic distance within Lesotho increases genetic differentiation, while shared clan affiliation surprisingly increases it. In Namibia, ethnicity is the predominant factor influencing genetic affinity. Saliva metagenomic data shows a negative correlation between age and alpha diversity, with notable differences in host-interacting taxa and viral load. These findings highlight the role of geography in shaping genetic affinity even at small scales and the complex influences of cultural factors. The saliva microbiome appears primarily affected by unrecorded individual behaviors rather than geographic or cultural variables. At population-level these oral microbiomes reveal insights into some dietary habits, oral health, and also the communal viral load, which appears to have greater incidence in Lesotho possibly related to the long-term effects of the HIV epidemic in the country.