As far as archaeology can go in Black Africa we find the proof, the hard evidence that objects were transported from one place, where they existed and still exist at times naturally, to other distant places where they had to be imported. In the same way, if Homo Sapiens became what he is today it’s because he was able to manage genetically well the “marriage exchange laws” necessary for the species to prosper. Homo Sapiens is by principle and from the very start a “commercial species” based on exchanges of goods and people.