Answer: The Native Americans died in record numbers (especially in the Caribbean) within decades of the Spanish arrival, primarily from foreign diseases, but also from overwork. The Spaniards and Portuguese needed a labor force to fill the lower rungs of the social ladder in order for the colonial expedition to be profitable. Since the enslavement of Africans was quite accepted in Spain and Portugal due to the former Islamic rulers having African slaves and participating in the African Slave Trade, it was only natural for the Spaniards and Portuguese to expand this trade and begin to use Africans to replace the dying Natives.
The Africans also had much better resistance to both European and tropical diseases since many of these diseases had become prevalent in Africa and, like Europeans, the populations that could not handle these plagues had already been wiped out. The Native Americans had no prior exposure and the immediate genetic winnowing easily removed over fifty percent of the endemic population.
It is important to note that in places like the Andes, where the Native American population did not die off rapidly, African American slaves were not brought in. This is why Peru and Bolivia have a very small percentage of African descendants today.
Step-by-step explanation: