Pre-civil war Americans often euphemistically referred slavery as "The Peculiar Institution".
Slavery is as old as civilization itself, although it's not as old as humanity because of our hunting and gathering ancestors.
From 1500 to 1880CE, somewhere between 10 and 12 million African slaves were forcibly moved from Africa to the Americas, and about 15% of those people died during the journey.
48% of slaves went to the Caribbean, and 41% to Brazil, and only about 5% of the total went to the US.
By the time Europeans started importing Africans in to the Americas, Europe had a long history of trading slaves.
The first real European slave trade began after the 4th crusade in 1204. Italian merchants imported thousands of Armenians, Circassian, and Georgian slaves to Italy. Most of them were women who worked as household servants, but many of them worked processing sugar. And sugar is a crop that African slaves later cultivated in the Caribbean.
None of the primary crops grown by slaves: sugar, tobacco, coffee; is necessary to sustain human life. So in a way slavery is a very early by-product of a consumer culture that revolves around the purchase of goods that bring us pleasure but not sustenance.
Africans were living in all kinds of conglomerations from small villages to city-states, to empires, and they were much too powerful for the Europeans to just conquer. And in fact, Europeans obtained African slaves by trading for them.
Because trade is a two-way proposition this meant that Africans were captured by other Africans and then traded to Europeans in exchange for goods, usually, like, metal tools, or fine textiles, or guns. And for those Africans slaves were a form of property and a very valuable one. In many places slaves were one of the only sources of private wealth because land was usually owned by the state.
Mark Twain famously described America’s societal norms which defended slavery as "a deformed conscience".
The horrendous conditions aboard slave ships at their largest could hold 400 people, But each slave had an average of 4 square feet of space.
As one eyewitness testified before Parliament in 1791: "...they had no so much room as a man in his coffin..."
Once in the Americas the surviving slaves were sold at a market very similar to the way cattle would be sold. After purchase, slave owners would often brand their new possession on the cheeks, again, just as they would do with cattle.
Slaves did all types of work, from housework to skilled craftwork, and some even worked as sailors, but the majority of them worked as agricultural laborers. In the Caribbean, in Brazil, most of them planted, harvested, and processed sugar, working ten months out of the year, dawn until dusk.
The worst part of this job, which is saying something because there were many bad parts, was fertilizing the sugar cane. This required slaves to carry 80 pound baskets of manure on their heads up and down hilly terrain.
When it came time to harvest and process the cane, speed was incredibly important because sugar sap can go sour within a day. This meant that slaves would often work 48 hours straight during harvest time. Working without sleep in the sweltering sugar press houses where the cane would be crushed in hand rollers and then boiled. Slaves often caught their hands in the rollers and their overseers kept a hatchet on hand for amputations.
The average life expectancy for a Brazilian slave on a sugar plantation in the late 18th century was 23 years. Things were slightly better in British sugar colonies like Barbados, and in the US living and working conditions were better still. So relatively good that in fact slave populations began increasing naturally, meaning that more slaves were born than died.
This explains why even the percentage of slaves imported from Africa to the United States was relatively small because slaves and other people of African descent came to make up a significant proportion of the US population.
The brutality of working conditions in Brazil, on the other hand, meant that slaves were never able to increase their population naturally, hence the continued need to import slaves into Brazil until slavery ended in the 1880s.
But Atlantic slavery was different and more horrifying because it was chattel slavery - a term historians used to indicate that the slaves were movable property.
Sociologist Orlando Patterson defined slavery as: "the permanent, violent, and personal domination of natally alienated and generally dishonored persons."
According to this definition a slave is removed from the culture, land, and society of his or her birth, and suffers what Patterson called Social Death. Ultimately then, what makes slavery slavery, is that slaves are dehumanized. The Latin word that gave us chattel also gave us cattle.
The Greeks were among the first to consider otherness a characteristic of slaves. Most Greek slaves were barbarians and their inability to speak Greek kept them from talking back to their masters, and also indicated their slave status.
Aristotle believed that some people were just naturally slaves, saying: "It is clear that there are certain people who are free and certain people who are slaves by nature, and it is both to their advantage, and just, for them to be slaves."
Slaves probably made up 30% of the total Roman population, similar to the percentage of slaves in America at slavery's height. The Romans also invented the plantation using mass numbers of slaves to work the land on giant farms called "latifundia."
The Judeo-Christian world contributed as well, the bible was widely used to justify slavery, and in particular the enslavement of Africans because of the moment in Genesis when Noah curses Ham, saying: "Cursed be Canaan, the lowest of slaves shall he be to his brothers."
This encapsulates two ideas vital to Atlantic slavery:
1. That slavery can be a hereditary status passed down through generations. And-
2. That slavery is the result of human sin.
Both ideas serve as powerful justifications for holding an entire race in bondage.
For instance, Muslim Arabs were the first to import large numbers of Bantu speaking Africans in to their territory as slaves. The Muslims called these Africans "Zanj" and they were a distinct and despised group, distinguished from other North Africans by the color of their skin.
The Zanj in territory held by the Abbasids staged one of the first big slave revolts in 869CE, and it may be that this revolt was so devastating that it convinced the Abbasids that large-scale plantation-style agriculture on the Roman model just wasn't worth it. But by then they'd connected the Aristotilean idea that some people are just naturally slaves with the appearance of sub-Saharan Africans.
The Spanish and the Portuguese were the Europeans with the closest ties to the Muslim world because there were Muslims living on the Iberian Peninsula until 1492. So it makes sense that the Iberians would be the first to absorb these racist attitudes towards blacks. And as the first colonizers of the Americas and the dominant importers of slaves, the Portuguese and the Spanish helped define the attitudes that characterized Atlantic slavery. Beliefs they'd inherited from a complicated nexus of all the slave holders who came before them.