I was looking back up the thread, and saw Davie K's post about slavery, pointing out that slavery of one sort or another has existed in all kinds of societies and places.

Which is true - but it's worth remembering that the form of chattel slavery developed especially in North America and the West Indies was probably the most grotesque and repulsive form of slavery that this planet has ever known, in which the very humanity of the people enslaved was often denied.

Typically it's the "advanced" society that came up with the worst version. (As has happened in other contexts - cf Nazi Germany.)

As for Chicken Charlie's last post - the fact that someone's been saying something since 1910 doesn't mean it is not true.