How did the absence of humanitarian concerns influence the treatment of slaves during the slave trade between 1450 and 1750 ad

From 1450-1750, the slave trade was an extremely profitable part of the triangular trade between Europe, Africa, and the New World.  In the Caribbean, and eventually North America, there was a need for a large labor force for the enormous plantations that grew cash crops such as sugarcane, rice, indigo, tobacco, and eventually cotton.  Slaves were an important commodity to be sold, and were considered the owner's property once purchased.  Slaves had no rights because they were owned. 

As a result, the treatment of slaves during this time period was terrible.  The journey from Africa to the New World, known as the Middle Passage, was extremely inhumane.  As many slaves as possible were packed into ships headed across the Atlantic, leading to unsanitary conditions and the spread of disease. (See diagram: from Wikipedia)  Once in the New World, slave treatment varied on location, but was universally cruel and abusive.  Whipping was the most common form of punishment when a slave was disobedient; however, other forms of mistreatment included verbal and physical abuse, horrific working conditions, and even disfigurement or death.

In the 1700s, Enlightenment philosophers began to advocate for individual rights and humane treatment of prisoners.  This eventually was extended to discuss the moral and ethical issue of slavery.  In 1807, the international slave trade was banned, effectively ending slave commerce.  However, in America, slavery continued until 1865. 

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