The origin of modern humans are still the object of intense investigation and debate. But some theories appear stronger than others ...
Recent theories postulate that modern humans evolved in Africa, and about 50.000 years ago populated Europe and Asia, replacing other human populations that became extinct.

Fossil records show that there were people in Africa 100,000 years ago or more, 100,000 to 130,000 years ago who were indistinguishable physically from us. In the same time, in Europe there were Neanderthals, very different from us. The replacement was probably complete, in Europe, 30.000 years ago.
In the Americas, humans entered from Siberia as small bands of migratory big-game hunters, possibly 15.000 years ago. Such a journey could have been made by means of a land bridge, known as Beringia, which emerged several times during the Ice Age.
The Asian derivation of the Native Americans is supported by the physical similarity of the native populations of East Asia and the Americas; both are classified within the Mongoloid race, and studies indicate that the DNA patterns of modern Native Americans are very similar to those of Asian populations.....

Other theories exist. The questions addressed by such studies, as well as other questions concerning the evolution of early humans, or the differentiation of populations within modern humans, touch our very identity and sense of self ... absolutely fascinating topics ...

The History and Geography of Human Genes by L. Luca Cavalli-Sforza, et al Time magazine Nothing less than the first genetic atlas of the world.... [This] landmark global study flattens The Bell Curve, proving that racial differences are only skin deep. Read more ..........