@Doubt doubt,
A quick look at animals:
We all know what an animal rights activist is. Would we say that the ACLU is an example of that?
No. Humans aren't animals. So we note a definition of the word animal that is so much a part of our perspective that we take it for granted. In fact to suggest that humans are in fact animals can bring a harsh response. (I know, because this happened to me on this very forum.)
There's reason to believe this definition of animal (as non-human creatures) goes back a long way. There was a time when the distinction was related to class status. Prolonged, hard physical labor deadens the mind. The slave was the animal part of us.
This is not to say that a slave can't appreciate Bach, Shakespeare, or Michelangelo. But full appreciation of these hallmarks of humanity requires time to become educated and time to reflect. Slaves have neither.
And so we speak about the Athenians without much attention to the fact that we're really talking about a small fraction of the human population of Athens. Slaves made the expression of the potential of humanity possible.
As it turns out, not all our slaves were human. But the story of human slavery has been a long brutal one. In examining the meaning of the Slavery Abolition Act of 1833, when British announced that slavery is immoral, we might be simultaneously examining how our understanding of ourselves and animals has changed.
More later... gotta go!