Oral microbiomes as forensic markers of origin and migration: Insights from an underrepresented population, Nigeria

The oral microbiome is shaped by environmental and host-associated factors, suggesting its utility for human profiling in forensics, particularly as an indicator of geographic origin and human migration. Using high-throughput sequencing and machine learning models, the predictive ability of the oral microbiome was assessed to determine the country of origin of the donors, using samples of individuals across 6 countries. The impact of migration on the predictive ability of the oral microbiome was also assessed through a longitudinal study of Nigerian migrants over a six-month period following migration. By analysing the oral microbiome at various time points during this timeframe, this study explores the influence of migration on the oral microbiome to provide insights into its applicability in forensic investigations. Our findings demonstrate that distinct microbial profiles correlate with the six geographic regions assessed in this study. Furthermore, the longitudinal sampling of Nigerian migrants revealed initial shifts in their microbiome profile, followed by a recovery to the original microbiome profile of Nigerian locals, observed after six months. These results highlight the forensic potential of the oral microbiome for geographic origin attribution, in migration tracking, and for providing intelligence information useful for forensic purposes.