Neal Barnard has written an excellent essay...

about our thinking about other animals. You can read it online over at the PCRM website, the title is The Psychology of Abuse and is well worth your time. For instance he writes:

There is reason for some long-range optimism about human psychology. As we develop in infancy, our capacity to act on impulses matures before our capacity to inhibit or modulate those actions. So, we go through a stage in which we babble, wet ourselves, and throw and break objects. Only later do we learn to speak, to control body functions, and to explore the nature of objects without breaking them.

Civilizations mature in the same way. We developed the capacity for the most grotesque aggressions before we learned, gradually, to inhibit those actions. We gave up cannibalism. Human slaves were freed. Most of us have realized that wife-beating is unacceptable.

With animals, we're just emerging from the babbling, wetting, destroying stage. One day we will look back in embarrassment and shame at the suffering we caused them for so long.

One day, there will be no humans, except those identified as criminals, who have any memory of  deliberately doing something that resulted in the exploitation of or harm to a living sentient being. To think of such a time is both amazing and wonderful.

While none of us (at least I don't know anyone) occupy that position of blamelessness, we can each begin to grow up and initiate our journey in that direction by living as an ethical vegan.