In an attempt to better understand why people of African descent are not the closest relationship with Neanderthals, has done an analysis that allowed us to estimate when Neanderthals exchanged genes for the last time with anatomically modern humans.
The analysis, conducted by scientists at Harvard University in Cambridge, Massachusetts, United States, and the Max Planck Society in Berlin, Germany, provides a historical context for genetic exchange. This analysis suggests that the exchange occurred when modern humans with Upper Paleolithic technologies, they encountered Neanderthals in their expansion out of Africa.
When in 2010 the Neanderthal genome was sequenced, it revealed that people of African descent are not shared with Neanderthals some genetic variants that people of African descent. A possible explanation for this is that anatomically modern humans interbred with Neanderthals when they left Africa. An alternative explanation, but more complex, is that African populations of the ancestors of Neanderthals and modern humans remained divided for some hundreds of thousands of years, and the most kinship with Neanderthals were subsequently left Africa.
The team of Sriram Sankararaman, Harvard University, measured the length of certain DNA fragments in the genomes of Europeans that are similar to those of Neanderthals. As recombination between chromosomes are produced when eggs and sperm in each generation reduces the size of the fragments, the longer you have been in the genomes of people present fragments related to Neanderthals, the smaller such fragments.
The research team believes that Neanderthals and anatomically modern humans exchanged genes by last between 37,000 and 86,000 years, long after modern humans left Africa, but potentially before they began to spread throughout Eurasia. This suggests that Neanderthals (or people with much Neanderthal ancestry) had children with the direct ancestors of the present people of African descent not.