In: Biology
Which of the three models for modern human origin and dispersal you think is best supported (by the evidence about fossils and genetics) and which is least supported?
Complete Replacement Model
Regional Continuity Model
Partial Replacement Model
The complete replacement model for the origin of humans is also known as Out of Africa model. This model asserts that the anatomically modern humans arose in Africa between 150000 to 200000 years ago as a new species Homo sapiens and migrated to the other parts of the world replacing all the other preexisting archaic human species like Neanderthal, Homo erectus, etc. This theory is the most supported theory for the origin of humans. The most satisfying fossil data that supports the complete replacement model is the finding of evidence of early modern humans (Homo sapiens idaltus) in Africa at 160000 years ago and the evidence of modern humans from the Omo site in Ethiopia tracing back to 195000 years ago. The genetic evidence that supports the replacement theory was obtained by studying the mitochondrial DNA. The analysis of mtDNA gave evidence that the most recent common ancestor of modern humans lived in Africa at around 200000 years ago.
The regional continuity model for the origin of humans suggests that anatomically modern human arise from the different populations of archaic human species that evolved from regional Homo erectus. This theory asserts that modern human developed different regions and not just confined to a single region. This model regional continuity for the origin of humans is the least accepted model.
The partial replacement model asserts that the anatomically modern human originated in Africa and migrated to the other parts of the globe and interbred with that primitive human species already existed there. This model is supported by the analysis and finding of the different archaic human gene pools in the modern humans. Today humans in the European and Asian population contains 1.5 to 2.1 percent of Neanderthal gene which is not found in African population.