I admit that I was actually unaware of the ‘Back to Africa’ theory until recently. The current belief is that primates evolved in Africa and migrated out of Africa. The “Out of Africa” migration occurred twice in case of Humans. First, Homo erectus left Africa. Recently, a hundred thousand years ago which is hundreds of thousands of years after Homo erectus, Homo sapiens began migrating Africa and reached distant parts of the world. This latter migration is called “Out of Africa 2”.
Apparantly there is a problem with this. “However, there’s a gap in Africa’s great ape fossil record between 14 and 7 million years ago. The Eurasian fossil record is rich at that time” according to Rutger University’s Anthropologist Rob Scott. He proposes when Europe cooled, some primates moved south in search of food and warmer climate. They encountered both in Africa. “Among the candidates for an ancestor of humans and other modern great apes are Rudapithecus hungaricus, Anoiapithecus brevirostris and Ouranopithecus macedoniensis. These apes have human like features and Ouranopithecus lived in Greece, was well-suited to eating nuts and tubers, and possibly was the first bipedal.