Slavery was worldwide but we had adopted this in our Declaration of Independence. "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."<quoted text>
"But what caused American"? Back to just America, huh? Slavery was worldwide. Why don't you seek your answer from those who practiced it long before America did! You're right, it was ended. Like 150 years or so ago. Don't ask America "why", ask those who started it. But then you wouldn't be able to take your shots at America, would you?
And yet despite those words we held some men---and clearly they must have been Men, humans, since they performed complex tasks and looked after white children---as slaves and passed laws that allowed us to rape their women.
Sure, it was common around the world at one time. But we did it for about 100 years after declaring that all men were created equal. That is rather unusual. In countries where they believe that all men are NOT created equal, and where all men do not have the right to liberty, it can be understood. But that is not us. We did it despite our principles, and we need to know how that happened.