The hypothesis was tested by the analysis of the draft sequence of the Neandertal genome. The result showed that the amount of alleles which are shared between Neandertal genome and non-African people genome is greater than the sub-Saharan African people genome. The history of gene flow from Neandertals to modern human proved that the interbreeding between Neandertals and non-African modern human might occur during the time Neandertals expanded out of Africa to Europe and Middle East. Another possibility is that the population of the two groups of people was subdivided before modern humans expanded out of Africa. If this hypothesis is true, it can explain well why the genome of Neandertals has more similarities to non-African modern humans than to sub-Saharan Africa people.
Research results showed that there is a relation between the hypothesis of subdivision population structure of ancient modern human and Neandertals and the gene flow from Neandertals to modern humans. However, in order to answer the question why the genome of Neandertals is genetically closer to non-African