Hmm… Romans considered slavery a process of domesticating wild human animals. American colonialists considered their own a little more charitably, and considered africans far less charitably.
Roman slavery generally allowed you to progress upward and outward. Slavery began with agrarianism and ended with industrialism. So american slavery began with indentured servitude (contract slavery), and ended with chattel slavery (people as domesticated animal property).
In the ancient world, man was everywhere primitive and violence and starvation a constant threat. The romans ‘civilized’ people by the developmental sequence ‘wild(barbarian)’ -> Slavery-Child -> Soldier(Serf) -> Freeman(property) -> Citizen (political participation) -> “Peer” or Politician -> Nobility. Some people could make the transition and some could not. (Just like today under market conditions.)
In the American world, we were very little different from the Roman, but far more domesticated from centuries of manorialism.
It is too impolitic to answer this question honestly and directly. But in general, there is a very large difference between the late medieval and early modern european who was genetically middle class, and underutilized capital, in a europe where the church had made half of the territory into dead, rent-seeking, capital —-and the industrial world (after 1830) where we were importing people who were not (in the majority) from the genetic middle class, not pent up human capital in large numbers, into a world where capital (land) was freely available.
We are still struggling with this problem a century and a half later. Race is immaterial outside of politics and marriage, but CLASS IS NOT. And class is a consequence of current and past genetics.
And the problematic difference between racial groups is how successful or unsuccessful they have been at suppression of underclass reproduction over the past thousand years. Because with that suppression you get east asians, europeans, and ashkenazi jews. But without it you get the entire rest of the world: underclasses so large that it is not possible for their middle and upper classes to create a high trust high velocity socio-political economy.
You can measure all personality traits, IQ, testosterone levels, and age of onset of puberty. If you measure these traits in all groups you will rapidly see that the differences between the groups is largely demographic: class size.
https://www.quora.com/How-is-Roman-slavery-different-from-American-slavery