Based on the findings below, as well as findings in my previous posts ( http://on.fb.me/12FeQOa & http://on.fb.me/YIU6Dk ), my theory is that modern humans started out as one species and race, but as migration took place, these modern humans mixed with other similar species (adapted to their local climates) that lived in various parts of the world (Neanderthals, Denisovans, and another species in Africa) which caused the differences we see today and created the 3 primary races. This mixing actually strengthened our genetics by introducing diversity and adaptations. Then as these races migrated further and also mixed with one another, it created the variety of features we have in the world. This shows up in our genetics as many Europeans have approximately 2% Neanderthal genes, Asians have 2% Denisovan genes, while native Africans have 2% of another humanoid species. There may have been others as well.
“Our ancestors bred with other species in the Homo genus, according to a study published today in the Proceedings of the National Academy of Sciences. The authors say that up to 2% of the genomes of some modern African populations may originally come from a closely related species. Last year, an analysis comparing the Neanderthal genome sequence to that of modern H. sapiens showed that some interbreeding did take place between the two species in Europe some time between 80 and 30,000 years ago and that, to a certain extent, Neanderthals ‘live on’ in the genes of modern humans. Hammer and his colleagues argue that roughly 2% of the genetic material found in these modern African populations was inserted into the human genome some 35,000 years ago. They say these sequences must have come from a now-extinct member of the Homo genus that broke away from the modern human lineage around 700,000 years ago. Hammer says this disproves the conventional view that we are descended from a single population that arose in Africa and replaced all other Homo species without interbreeding. “We need to modify the standard model of human origins,” he says.”