I think the logical basis was most likely to isolate groups from other tribes. We don’t live that group over there. That group over there is trading pigs. It is a new rule, no the law, that you can’t eat pig. No more trade. A generation or two pass and the logical basis is lost to time.
If you really want to get into traditionally, meat used to also refer to vegetables, a.k.a. green meat. The word meat comes from the Old English word mete, which referred to food in general. More recently, green meat might have referred to animals fed exclusively on vegetables or plant based feed. And today, with the existence of veg-burgers or Beyond and Impossible meats, those are also sometimes called green meat.
So take me back a few centuries, and everything you eat would be mete, including that fish.
I used to view these comics on thin sheets of folded paper.
Gary used a “sophisticated” humor. Sometimes you could get it immediately, like when comparing what dogs and humans understand when both species are talking to each other. Sometimes it was more of a puzzle, where the clues were in the panel and it would bring a smile to your face when you solved it and understood the humor. I think the majority of them were this later form. To me, I always liked them.
It took more to appreciate the humor but compared with the other strips that were in the paper, you were rewarded by “getting it.” Sometimes the humor was built upon characters introduced in other panels which rewarded loyalty. There was usually humor on its own, but being familiar with The Far Side Universe brought another level.
The cow is sacred in India, so they don’t eat beef. Most of the Western world won’t eat dog or cat, but that isn’t a universal thing and while probably not as common today, it doesn’t mean that it’s an unheard of practice. Until recent times, people would eat what was available which didn’t have alternative value.