[coldtea]

>This doesn't address the fact that pigs are no less capable of experiencing pain and distress than dogs and cats.

No but it addresses the fact that there's no underlying grand principle beyond it all.

Some animals we grew to like more, because they were useful, and we kept them around. That's all.

It's no more strange than caring for some people because they are relatives, and not caring as much (or at all) for other people.