As we know, when it needs food, our body indicates this to us with the feeling of hunger. But there are also other signals if specific nutrients are deficient. Meat is the best source of several nutrients. When our bodies are deficient in these, we become irritable and aggressive. This is a perfectly natural signal built into our genetic make-up over our evolution: our bodies are telling us to go out and kill something to eat. This is why strict vegetarians tend to be so vociferous. It is a trait that was recognised long ago; it was, after all, the vegetarian Cain who killed the carnivorous Abel, not the other way round. The vegan Kikuyu tribe in Kenya were the perpetrators of the murderous Mau Mau in the 1950s, not their wholly carnivorous, but peaceful, neighbours, the Maasai.
Mind-opening article. Dad always told me not to trust on anyone not eating meat.