Human origins: why does the model include several groups?
A genetic model describes connected ancestral groups with gene flow between them. It is a testable proposal, not a story about one isolated population.
How the genetic model works
A weakly structured stem for human origins in Africa is a specific population-genetic study. Its proposals are model-based inferences from genomic evidence. Nature ↗
Ask how the model was tested
Compare the sampled populations, assumptions, competing models, and measures of fit. The model’s ancestral groups are analytical constructs, not named historical peoples. Nature ↗
Keep identities separate
Genetic ancestry, language, religion, archaeological culture, and political identity require different evidence. A demographic model cannot establish all of them through one inferred relationship. Nature ↗