Final answer:
African slave labor replaced Native American labor on sugar plantations after 1600 due to Africans' availability, resistance to diseases, and the establishment of a system of racially based slavery that was inheritable and lifelong.
Step-by-step explanation:
The labor on sugar plantations after 1600 was primarily replaced by African slave labor due to its availability and resistance to diseases. While European indentured servants were initially used, they could not survive the harsh conditions and diseases like malaria and yellow fever. Additionally, the labor of indentured servants was unreliable and temporary, as they worked only for a fixed term and there were legal limitations on how they could be treated.
Africans, on the other hand, were considered physically better suited to the strenuous work, were available in large numbers due to the slave trade, and could be enslaved for life. This ensured a consistent labor force for plantation owners. The enactment of racially based slavery systems in Brazil, the Caribbean, and North America facilitated the dominance of African slave labor on plantations.
In the New World, unlike in Africa, the conditions of slavery became permanent and inheritable, solidifying the plantation labor structure around African slavery. The tragic decline in the native populations due to diseases like smallpox and influenza also contributed to the shift towards African slaves, as there were too few native individuals left to meet the labor demands of the burgeoning plantation economy.