The shores of West Africa were the point of embarkation for the bulk of the 10 million or so blacks who unwillingly left Africa to labor on the plantations and in the cities and mines of the New World. Among these unhappy voyagers were the progenitors of today's North American black population. Yet although the black diaspora ceased long ago the West African homeland continues to exert an enormous physical influence on the descendants of the original migrants, both in terms of outward appearance and biochemical anomalies that have dictated a different black disease experience from the North American white.

West African climate, disease, and relative isolation are the three factors chiefly responsible for this influence. These factors combined and recombined over millennia to mold and shape the inhabitants. They were sheltered by the Sahara desert against easy access from North Africa and its succession of empires and emperors, while turbulent seas and contrary wind patterns discouraged intrusion from the South Atlantic. This is not to say that no caravans crossed the desert to West Africa or that no ships visited West African shores prior to the Portuguese explorations of the fifteenth century.

But contact with the outside world was limited even though regular trade routes did criss-cross West Africa and penetrate into the heart of the continent.