These guys sound pretty heroic, but I don't think they're evidence that the racist transatlantic slave trade was worse than the non-racist Roman world. I'm not an expert on either, though.

Part of what I'm trying to assert is that people are capable of treating other people terribly, even in the absence of theories of racial superiority.

I'm pretty sure that the Romans looked up to the Greeks at the same time as enslaving them. And fairly sure that the Greeks enslaved other Greeks.

But you'd need to know a lot more about the classical world than I do to work out what kinds of racial theories were current.

And maybe they did have foreign groups that they mistreated particularly badly. If we think that xenophobia is a built-in feature of the brain then it would be damned weird if the Romans weren't superiority-complex racists. After all, consider the amount of evidence they had that their system was superior and that the gods loved them.

I'd be surprised if it wasn't worse to be the slave of someone who despises you and your type than the slave of someone who accepts you as a brother.

I just don't think any of this is particularly modern.

And on ethical matters I tend to think that progress is upwards (or at least correlated with per-capita GDP). If we think that the recent past was particularly awful it's usually because we've got better records of it.

So here's a prediction for you: There were things going on in the Dark Ages that were worse than either Roman or early Victorian slavery.

The problem is, I can't think of anything worse. There's something particularly terrible about mass industrial slavery. Maybe some passing atrocitologist can help.