Burton K Wheeler
Moderator
What would be simpler than my other idea would be what they do to the lower class in Brave New World. The babies that will be born into the lower class are given alcohol while in gestation. This could help lower the IQ of the slaves.
Brave New World was my inspiration when I thought about this years ago. In order to have a slave population that functions as such, they should be a couple standard deviations shorter. Of course, as stated earlier, if you go back very far, people want the largest strongest slaves possible. So this would have to be a post-industrial society.
Intelligence is way more complicated and like physical stature, you don't really want to stunt it too much if you want a useful slave.