How do you explain people who seem to love animals more than people?

Ok, I know that human relationships are challenging and sometimes downright infuriating. It seems so much simpler to relate to animals who just ask for our affection and tending to their needs. They are so much simpler to keep happy. That said, it sounds as if I have answered my own question. But bear with me. I ask this based on a story I heard last weekend. A friend of the family had a nephew who wanted to be a veterinarian. The problem was that he could not bear to see animals in pain. So instead, he decided to join the medical profession for humans. He is now working in the emergency room and has no issues with seeing human beings in pain. Somehow that is easier for him to cope with.

My sister, an avowed cat lady, says that maybe it’s because animals are innocent and helpless. I don’t buy it. Still, she says, “I cannot bear it either”. She can’t explain why, she just feels that way and always has.

Can you offer any explanations of this? Reasons it may be so? I find it so hard to understand.

Of course I understand that some people have had very negative experiences with the human race. Let’s just exclude these people from our discussion as their feelings are infinitely understandable.