As far as I'm aware there has never been a human population in history which were exclusively herbivorous. This is because humans have evolved eating a diet of plants and animals in much the same way that a dog or goat (or rather their wild relations) evolved to eat plants and animals.

The idea that humans should not kill animals for food is the same as saying that lions should no longer be allowed to hunt and eat game.

Would the veggies amongst us be in favour of implementing a world-wide ban like that?