Paper short abstract:

Human migrations into island Southeast Asia can be traced back to at least 40 millennia ago. Using genetic markers in current day populations, we attempt to infer relationships and past migration events.

Paper long abstract:

The Southeast Asian region has seen many episodes of human migration events, dating back to at least 40,000 years ago (YBP). Current human populations in island Southeast Asia (iSEA) are predominantly Austronesian language speakers and were thought to have originated from the Out-of-Taiwan expansion. There are also phenotypically distinct indigenous groups called Negritos who are believed to have been descentants of the first migrants to the region. Using genome-wide autosomal SNP and mitochondrial DNA markers (mtDNA) from these present-day Austronesian and Negrito groups, we traced past migration events and inferred relationships between these iSEA groups. We found a dichotomy between Austronesian groups, and mtDNA haplotypes originating from South China that ranged from 30,000 to 10,000 YBP, suggesting an alternative to the Out-of-Taiwan expansion. The Negrito groups showed evidence of recent admixture with their neighboring Austronesian populations, and also contrasting patterns of admixture with archaic humans (Denisovans). Phylogenetic network analysis also suggests that the Negritos from Malaysia, Philippines and Andaman islands may share a common genetic link. Results from these genetic analyses highlights the human genetic diversity in the iSEA region and sheds light to past migration events.