In the 19th Century, "scientists" declared that animals were so inferior that they could not feel physical pain; therefore, it was all right to slit their throats, boil them alive, cut them up in experiments, etc. This kind of denial made it "okay" for people to treat animals with barbaric cruelty.

Now, we know that animals feel terrible pain when we cut them, beat them, kick them, boil them alive, push them with electric prods, and pour chemicals into their eyes. But we still do it. The human race has become so arrogant, we no longer need to be in denial about the suffering of other creatures--we just permit it because it is cost-efficient, and because we do not care.

Interestingly, the same people who express shock when they learn that somone has hurt a puppy or abandoned a horse will sit down and eat a dinner of cows or chickens that have endured unspeakable horror. Or put on mascara or shaving cream that has been tested by torturing rabbits and cats.